submission - Independent Pilots Association

Airline 

Air Wisconsin 

Alaska 

Allegheny 

Aloha 

Aloha Island Air 

America West 

American 

American Eagle 

Atlantic Coast 

Atlantic Southeast 

Business Express 

Carnival 

CCAir 

Comair 

Continental 

Continental Express 

Delta 

DHL 

Emery Worldwide 

Express 

Federal Express 

Hawaiian 

r"ri ryit..D 

i. 

Aviation Rulemaking Advisory Committee 

Reserve Rest Working Group 

Proposal of 77 ,955 Airline Pilots 

January 8, 1999 

Pilots 

240 

l 153 

354 

r92 

64 

r532 

9508 

2055 

694 

763 

372 

2t9 

172 

1000 

4769 

1010 

9188 

395 

45t 

329 

3611 

285 

6000 

Airline 

Mesa 

Mesaba 

Midway 

Midwest Express 

Northwest 

Piedmont 

Polar Air Cargo 

PSA 

Reeve 

Reno 

Ross 

Ryan International 

Skyway 

Southwest 

Spirit 

Sun Country 

Tower Air 

Trans States 

TWA 

United 

UPS 

USAirways 

USAirways Shuttle 


1095 

804 

174 

262 

6103 

368 

186 

254 

33 

302 

t9 

257 

r32 

2735 

r54 

213 

206 

806 

25r6 

962r 

2100 

5092 

r67

Preamble 

TABLE OF CONTENTS 

Part I: Proposed Regulatory Lan_euage.. ...................5 

Part [[: Pilots' Proposal with Intent, Examples, and Rationale........... .........7 

Scientific Support..... .......... 16 

kinciples and Guidelines for Duty and Rest Scheduling in Commercial Aviation, 

NASA Technical Memorandum I10404 (May 1996)................ .Appendix A 

An Overview of the Scientific Literature Concerning Fatigue, Sleep, and the 

Circadian Cycle, Battelle Memorial lnstitute (January 1998)......... ..............Appendix B 

A Scientific Review of Proposed Regulations Regarding Flight Crewmember 

Duty Period Limitations, Docket #28081, The Flight Duty Regulation 

Scientific Study Group ..........Appendix C 

Remarks by Dr. William Dement to the ARAC Working Group Pilot Representatives, 

December l, 1998 ...............4ppendix D 

Fatigue, Alcohol and Performance lmpairment, Nature. 

Vol. 338, July-Augusr 1991 .. Appendix E 

Quantifying the Performance Impairrnent associated with 

Sustained Wakefulness, Nicole l-amond and Drew'öãffiilÌhe Centre for 

Sleep Research, The Queen Elizabeth Hospital, South Australia... Appendix F 

Crew fatigue factors in the Guantanamo Bay aviation accident, NASA abstract..........Appendix G

AVIATION RULEMAKING ADVISORY COI\ÍMITTEE 

RESERVE REST WORKING GROUP 

PROPOSAL OF 77,955 AIRLINE PILOTS 


PREAMBLE 

This document is submitted on behalf of approximately 78,000 commercial airline 

pilots. The proposal that follows contains our recommendations for Federal Aviation 

Regulations concerning rest requirements and duty limitations for reserve pilots. It is 

applicable to all Domestic and lntemational Part l2l operations under FAR Subparts e, 

R, and S. Part 135 re-øulations should be revised to provide a level of safety equivalent to 

this proposal. 

Our proposal is presented in two parts. Part I is the proposed regulatory language. 

Part II provides our intent, examples, and rationale. The scientihc support for our 

proposal is included in the endno!9s. 

We are pleased that both pilots and air carriers were able ro agree on the 

following elements of a proposed reserve rest rule: 

I ' A pilot should be scheduled by the operator to receive a protected time period 

as an oppomlnity to sleep for every day of reserve duty. The operator may not 

contact the pilot during this period. 

2. An operator should limit the movemenr of a pilot's prorected time period 

during consecutive days of reserve dut¡, to ensure circadian stability. 

3. A reserve pilot's availability for duty should be limired ro prevenr pilot fatigue 

as a result of len-ethy periods of time-since-awake.

4. Sufficient advance notice of a flight assignment can provide a reserve pilor 

u'ith a sleep opportuniry. 

We believe that it is incumbent upon the Federal Aviation Administrarion (F.\A) 

to include time-of-day as a factor in designin,e duty and rest limitations. A substantial 

body of resea¡ch and pilot reports shows that a decrease in performance frequently occurs 

during "back-side-of-the-clock" operations due to circadian factors. To address this 

issue, our proposal provides for a reduction in the reserve availability period when 

scheduled duty touches the 0200 - 

"window of circadian low." 

0ó00 time period, or what the scientists refer to as the 

Our submission refers to several documents that have provided us with a 

foundation of scientific support. Prominent among them is NASA Technical 

Memorandum I 10404 , Principles and Guidelines for Dun' and Rest Scheduling in 

Comntercial Aviation, (May 1996). This document, herein referred to as NASA Tlvf. 

offers NASål:-spec_rlc recommendations on duty and rest Iimitations based on more rhan 

20 years of extensive research into the cause and prevention of pilot fatigue. It is 

attached hereto as Appendix A. 

Another reference is An Overt'iew of the Scientific Literature Concernin7 

Farigue, Sleep, and the Circadian Ct'cle, Battelle Memorial Institute Study (January 

1998). This study, herein referred to as the Battelle Study, commissioned by the FAA's 

Office of the Chief Scientific and Technical Advisor for Human Factors, provides an in- 

depth revier"'of scientific research concernin-s sleep and fatigue. Drawing upon l6_5 

scientific references. the Battelle Report identifies major trends in the scientific literature. 

and has provided valuable information and conclusions. This study ìs attached as 

Appendix B.

-..-.-__-^ 

Another reference is A Scientific Review of Proposed Regulations Regarding 

Flight Cre*'member Dun, Period Limitations, Docket #28081, The Flight Duty 

Regulation scientific Study Group. This study \\'as sponsored by the Independenr pilots 

Association to provide a scientific review of NPRM 95- 18. It is refened to as the 

Scientific Srudy Group and is attached as Appendix C. 

The pilots met with sleep expert, Dr. William Dement, Director of Sleep Research 

and Clinical Programs at Stanford University. The transcript of that meeting appears in 

Appendix D. 

We have attached an article titled Fatigue, Alcohol, and Performance Impairment 

that summarizes a study conducted by The Centre for Sleep Research at the eueen 

Elizabeth Hospital in South Australia in Appendix E. This study quantifies the 

performance impairment associated with sustained wakefulness in terms of equivalent 

percent blood alcohol impairment. A subsequent study, titled, Quantifuing the 

-Performance Impairment associated *'ith Sustained Wakefulness, by l-amond and 

Dawson replicates this study and extends the initial findings. It is attached as Appendix 

F. 

The NTSB requested that the FAA conducr an expedited review of the FARs after 

pilot fatigue and continuous hours of wakefulness were found to be key findings in the 

crash of a DC-8 at Guantanamo Bay, Cuba in 1993. A NASAAITSB report titled Cr¿¡. 

futiguefaclors i,t the Guantanatno Bat'aviation accident is attached as Appendix G. 

Sereral airlines have switched to reserve pilot schemes very similar to the one we 

propose. These carriers include Continental Airlines, UPS. America Wesr. Alaska 

Airlines. and British Airways. The reserve pilots at these airlines have protected time 

periods of 8 ro l2 hours with reserve availabilitv periods of 1,4 to lg hours.

We owe a debt of gratitude to the many pilots who provided us with reports of their 

encounters with pilot fatigue. These reports reveal that pilot fatigue typically occurs during 

back-side-of-the-clock operations and after long periods of time-since-awake. 

The pilots would like to thank the FAA for providing this forum and the air 

carriers for contributing to the debate. We hope that this ARAC has demonstrated to all 

interested parties how unregulated scheduling can lead to dangerously high levels of pilot 

fatigue for reserve pilots. We urge the FAA to quickly remedy this very serious safety 

problem.

121 .xxx Reserve Rest 

(a) 

(b) 

(c) 

PART I: PROFOSED REGULATORY LANGUAGE 

Except as provided in paragraphs (b) and (d), no certificate holder may schedule 

any flight crewmember a¡d no flight crewmember may accept an assignment to 

reserve status unless a minimum prospective Protected Time Period (PTP) of l0 

hours during a 24-consecutive hour period is scheduled. The Protected Time 

Period must begin at the same time during any scheduled period of consecutive 

days of reserve status and the flight crewmember must be given no less than 24 

hours notice of the Protected Time Period. 

A certifìcate holder may reschedule a specific Protected Time Period during any 

scheduled period of consecutive days of reserve by the following: 

( I ) Rescheduling the beginning of a Protected rime Period a maximum of 

three hours later without prior notification. 

(2) 

(3) 

Rescheduling the beginning of a Protected rime Period a maximum of 

three hours earlier if the flight crewmember is provided 6 hours notice 

prior to the beginning of the originally scheduled Prorected rime period. 

Rescheduling the Protected Time Period by more than 3 hours once during 

any 7 consecutive days by providing the flight crewmember l0 hours 

not¡ce. 

A certificate holder may assign a flight crewmember and a flight crewmember 

may accept an assignment for flight time in scheduled air transportation or other 

commercial flying if such assignment is permitted by this subpart; 

( l) If the assignment is scheduled to be completed within 16 hours after the end 

of the preceding Prorected Time Period: however. 

(2) 

If the flight crewmember is given a flight assignment for any part of the 

period of 0200 to 0600 hours. any such fli_eht assignment must be scheduled 

to be completed within l4 hours after the end of the preceding protected 

Time Period. The operator u'ith the concurrence of the administrator and 

the pilot group mar designate any 4-hour period for all operations between 

0000-0600 hours in place of0200-0600 hours. 

These limitations may be extended up to 2 hours for operational delays.

(d) When there are no other reserve pilots who have sufficient reserve availability 

penods to complete an assignment, the certificate holder may schedule a flight 

creu'member for an assignment for flight time in scheduled air transportation or 

other flying permined by this subpart, provided that the crew member is given a 

minimum of l4 hours of advance notice and is released to protected time at the 

time of the notice. 

(e) Each certificate holder shall prospectively relieve each flight crewmember 

assigned to reserve for at leasl24 consecutive hours during any 7 consecutive 

days. 

(Ð For augmented Intemational operations, a certificate holder may assign a flight 

crewmember and a flight crewmember may accept an assignment for flight time 

in scheduled air transportation or other comrnercial flying as follows: 

(l) For single augmentation, the assignment must be scheduled to be completed 

within l8 hours after the end of the preceding Protected Time Period; or 

(2) For double augmentation, the assignment must be scheduled to be 

completed within 22 hours after the end of the preceding Protected Time 

Period. 

These limitations may be extended up to 2 hours for oper_4lio¡al delays. 

DEFTNITIO}JS 

--

12l.xxx Reseme Rest 

Part II: Pilots' Proposal with rntenÇ Examples, and Rationare 

(a) Except as provided in paragraphs (b) and (d), no certiftcate holder may 

schedule any flight crewmember and no flight crewmember mar- accept an 

assignment to reseme status unl¿ss a minimum prospective Protected Time 

Period efP) of l0 hours during a 24-consecutive hour period is scheduled. 

The Protected Time Period must begin at the same time during any scheduled 

period of consecutive days of reserte status and the tlight crewm¿mber must be 

given no lcss than 24 hours notice of the protected rime period 

Intent: To ensure that all reserve pilots are scheduled for and receive a prospective, and 

predictable, lO-hour oppornrnity every rqserve day to obtain 8 hours of sleep and to 

maintain circadian stabilitv. 

Example: 

Pilot - PTP 2000-0600 

Rationale: The human body requires an average of 8 hours of ¡¡ninterrupted, restorative 

sleep in a 24 hour period when sleeping during normal slée-þffiffi tvh.n auempring 

to sleep outside of normal sleeping hours, 8 hours of sleep is still required. However, 

scientific data indicates additional time is needed to obtain the required 8 hours of sleep. 

The l0 hour Protected Time Period (PTP) would, therefore, include an opportunity to 

prepare for and actually receive 8 hours of restorative sleep in all circumstances. 

Additionally, a lGhour PTP was selected '* ith the assumption that the minimum required 

rest for all pilots would be l0 hours (See N?RM 95-l8). A lO-hour PTP would maintain 

consistency of rest for all pilots. Starting consecutive PTPs at the same time is 

imperative to maintaining circadian stabiliry. The desired merhod of assigning pTp 

would be when the crewmember is assigned reserye. A minimum of 24 hours 

notification of a Protected Time Period u ill provide an opporrunity to prepare for 

impending reserve days. I

(b) A certifrcate hol.der may reschedule a Protected Time Period during any 

scheduled period of consecutive days of reserve by the following: 

Intent: To provide the reserve pilot with a predictable, prospective rest period and also 

give the oPerator scheduling flexibility to accommodate unforeseen circumstances. 

Rescheduling a PTP +/- 3 hours is only applicable to that PTP. Remaining reserve days in 

a block would begin at the original start time, Shifting of a PTp does not extend a 

Reserve Availability Period (RAP). 

Example: 

Ø Rescheduling the beginning of a protected rime period a 

marimum of three hours later wiÍhoul prior notificatian. 

(In this example, under no circumstances may a PTP start time be later than 2300) 

Day I 

PTP 2000 to 0600 (original PTP) 

Day 2 

PTP 2300 to 0900 

Day 3 

PTP 2000 to 0600 

2270 

,-Fæ. 

Rationale: Delaying a sleep opportunity, up to three hours. is not excessively disruptiye 

to circadian stability. In this case, no prior notificarion is required. 

0900

(2) Rescheduling the beginning of a Protected Time Period a maximum of 

3 hours earlicr if the flight crewmember ß provided 6 hours notice prior 

to the beginning of the originally scheduled Prolected Time Períod. 

Example: 

(In this example, under no circumstances may a PTP start time be earlier than 1700) 

Day I 


Day 2 

PTP 1700 to 0300 

Day 3 

PTP 2000 to 0600 

Rationale: Moving a sleep oppornrnity earlier, up to three hours. is disruptive to 

circadian stability. To accommodate and prepare for this rescheduled.sleep opportunity 

additional notice is required. 

9

(3) Rescheduling the Protected rime Period by more than 3 hours onci 

duríng any 7 consecutive days by providíng the flight crewmember I0 

houn notice. 

Rationale: Changing a sleep opportunity more than +/- 3 hours is very disruptive to 

circadian stability. For extreme circumstances beyond the control of the operator (i.e., 

inclement weather, closed airports, etc.) an operator has the ability to reschedule a PTP 

more than 3 hours from the original start time. A minimum of l0 hours prior notifrcation 

of the new PTP is required to allow the pilot a period of time to adjust for the rescheduled 

sleep opportunity. This provision is restricted to once in every 7 days because it is so 

detrimental to circadian stability. This restriction also would preclude the operator from 

arbitrarily utilizing this provision and¡et allows the certificate holder the flexibility to 

operate under extreme circumstances.' 

10

(c) A certiftcate holder may assign aflÍght crewmember and aftight 

cret+'member may accepl an øssígnmentforflighl time ín scheduled aír 

transportation or other commerciarflying if such assignment ís 

permined by thß subpart; 

(I) If the assignment is scheduled to be completed within 16 hours 

after the end of the preceding Protected Time períod; 

Intent: To establish a "Reserve Availability period" (RAp).3 

Example: 

ll

(2) If the flight crewmember is given a flíght assignment for any part of the 

períod of 0200 to 0600 hours, any such flight assignment must be 

scheduled to be completed within 14 hours after the end of the preceding 

Protected Time Períod. The operator with the concurrence of the 

administrator and the pílot group may designate any 4-hour period for 

all operøtions between 0000-0600 hours in place of 0200-0600 hours. 

2 Ìtl 

rlrnrion 

lf Duty Occurs Between 0200 - 0600 

16 hr RAP 

lf Duty Occurs Outside 0200 - 0600 

These limitations may be extended up to 2 hours for operational delays. 

Rationale: Time-since-awake contributes to fatigue. This section acknowledges timesince-aç'ake 

by limiting the RAP to l6 hours if the pilot is afforded the opporrunity to 

sleep during a normal sleep period. The science further indicates fatigue occurs sooner 

when given a sleep opportunity at a time other than normal sleeping hours. This section 

addresses that fact by reducing the RAP to 14 hours should duty occur during this normal 

sleep period.a 

l2

(d) When there are no other resene pilots who have sufftcient resene availability 

periods to complete an assìgnment, the certificate ioUt, may schedule a fligit 

crew member for an assignment for flight time in scheduled air transportation 

or other flying permitted by this subpart, provided that the ,rrn *r^ber is gíven 

a minimum of 14 hours of advance notice and is released to protected time al 

the time of the notice. 

Intent: All pilots are originally scheduled in a PTP system. Circadian stability is 

ensured by all pilots having a de 

pilots have been utilized, l4 hou 

à Rigt t. Once norihed of a fligh 

responsibility until he_reports for duty. While this method of assigning reserve is less 

than desirable, it enables the certificate holder to continue operations as necessary. 

Rationale: while advance notice can present a sleep opportunity, scientific research is 

very clear that circadian factors make it very difñcult anå sometimes impossible to take 

advantage of it. For example, consider a pilot who finishes his pTp at 0å00 an¿ is then 

contacted by the carrier for an assignment that report s at 2200. This would be an 

application of l4 hours advance notice. Circadian factors make it very difficult, if not 

impossible, for the pilot to sleep again until later, typically during the afternoon circadian 

low point ( 1500 - 1800) or earlier if possible. Howãver, úy receiving the notice early, he 

*rt pr.på.. himself for the afternoon 

illy, he would go to bed around 1500 _ 

rovide enough time to shower, dress, 

vance notice, this pilot could only 

expect to sleep 4 - 5 hours prior to reporting for a back-side-of-the-cloct assignment that 

could last until 1200 the following day. It should be apparent thar less than lã hours ._-_-{¡.-.*notice 

could result in less than 4- 5 hours of sleep ano ìàise the probability of serious 

pilot fatigue during the assignment. 

IJ 

he Denver ARAC meeting. At one 

rinion regarding what should be 

Dr. Hudson's response was l3 to l4 

to

(e) Each certifrcate holder shall prospectively relìeve each flight crewmember 

assigned to resene for øt least 24 consecutíve hours during any 7 consecutive 

days. 

Intent: All reserve pilos must receive a prospec tive 24 hour period free from duty 

during any 7 consecutive days. 

Rationale: Pilots assigned to reserve status must be conrinually prepared for any flight 

duty. These pilots should be relieved from this obligation for 24 hours during any 7 

consecutive days. The pilot must be notified prior to the beginning of that off duty 

period. 

l4 

- 

-fF 

-,-

A 

Example: 

Example: 

For augmented Internatíonal operations, a certificate holder may assign a 

ÍItght crewmember and a flight crewmember may accept an assignment for 

flight time in scheduled air transportation or other commercial flying as 

follows: 

(I) For single augmentatíon, the assignment must be scheduled to be 

compl-eted within I8 hours after the end of the preceding Protected Time 

Period; or 

(2) For double augmentation, the assignment must be scheduled to be 

completed wilhin 22 houn after the end of the preceding Protected Tíme 

Period- 


Intent: To establish a Reserve Availability Period (RAP) for long-haul international 

reserve pilots. 

Rationale: Long-haul international flights necessarily involve back-side-of-the-clock 

flying. Therefore, for a single pilot augmentation, we added 4 hours to the l4-hour backside-of-the-clock 

duty period and 8 hours for double augmentation. This is in accord 

with the NASA TM. ó 

l5

I 12I.xxx Reseme Rest 

Scientific Support 

(a) Except øs provided in paragraphs (b) and (d), no cenificøte holder may 

schedule any flight crewmember and no flight crewmember may accept an 

assignment to resertte status unlcss a minimum prospective Protected Time 

Period efP) of I0 houn during a 2&consecutive hour period is scheduled. 

The Protected Time Period must begin at the same time during any scheduled 

perid of consecutíve days of resene statas and the flight crcwmember must be 

given no less than 24 hours notice of the Protected Time Period. 

Scientific support: 

(a) l0 hour hotected Time Period to provide an opportunity to obtain 8 hours of sleep. 

Eacà individual has a basic sleep requirement that provides for optimal levels of 

performance and physiological alertness during wakefulness. On average, this is 

8 hours of sleep in a 24-hour period, with a range of sleep needs greater than and 

less than this amount. Losing as linle as 2 hours of sleep will result in acute sleep 

loss, which will induce fatigue and degrade subsequent waliing performance and 

alertness. 

NASA TM,II .1.1,p.2. 

Offduty period (acute sleep and awake-time-off requirernents) - Therefore, 

the off-duty periodqþ-uld be_a minimum of l0 hours unintemrpted within any 

24-hou r period,ïóäftlftIãäi 8 -h ou r sl eep opportunity[. ] 

NASA TM, t2.1.2,p.5 

Standard Sleep Requirements and Off-Duty Period - Research by Drs. Carskadon 

& Dement, 1982 and Wehr et al., 1993 support a minimum of 8 hours of sleep 

based upon a range of studies that use several approaches including: 

o Historical levels of sleep 

o Measures of da¡ime alenness 

. Sleep levels achieved when given the opportunity to sleep as long as 

desired 

Battelle Report, p. 15. 

. . . There appears to be substantial evidence that a minimum of eight hours of 

sleep is required for most people to achieve effective levels of alertness and 

performance. 

Battelle Reprorr. p. 21. 

t6

. . . It is important to realize that an individual *'orking nights is at risk for 

signif,rcant sleepiness for two distinct reasons: . . . an individual u,orking 

successive nights is forced to obtain sleep during rhe da¡'light hours at itime 

when the circadian pre-disposition to sleep is minimal. . . . As mentioned, sleep 

under these circumstances is typically fragmented. sleep state architecture is 

distorted, and the restorative nature of sleep . . . is reduced. 

A Scientific Review of Proposed Regulations Regarding Flighr Crewmember DuN period 

Limitations, The Flight Duty Regulation scientific Study Group, {2.6, p. 5-6. 

Minimum rest periods should be adjusted upward for sleep periods that include 

the time of peak circadian alerrness (4 - 6 PM.). 

xte 

efficiency of sleep during that time. (Emphasis added.) 

Scientific Study Group,Il5.l.2, 5.1.4, p. I l. 

Remarks of Dr. Dement: 

for dec 

Q: . . . One of the most basic tasks is for us to agree on a recommendation for a sleep 

opportunity . . . to afford every reserve pilot the opportunity of a protected time 

period so that he or she is absolutely insulated from contact from the operator. 

How many hours do you recommend for a minimum fixed sleep opportunity? 

A: I will start out by assuming that we would take 8 hours of sleep as the most 

requirement. Then you need to add iPmmo¡ to that in order to be able to get the 

froper amount of sleep. In your situation, I would think it would be a little larger 

than it might be for someone who really wasn'r doing anything. So, I'd add a 

couple of hours to get the proper ¿rmount of sleep. 

Appendix D, p. 4. 

Q: Dr. Dement, . . . we're really at the point now where we're going beyond the 

philosophy and we're trying to put our hnger on numeric values. Our position at 

least from the pilots' standpoint, is that we see the need for a l0-hou, sl..p 

opportunity knowing that the oppornrnity may nor alway's be at the best time of 

the day. We're facing an industry position that is looking for 8 hours as the 

minimum. Our position is predicated on the fact that 8 hours mav be adequate if it 

overlaps the WOCL. But since we don't know for sure when we're going to har.e 

that opportunity, we believe that, or we think that havin,s that extra 2 hours is 

going to give us a little more of a buffer, especially when it comes during the 

daytime. Would you consider that to be a consen'ative and a jusrified position? 

A: Absolutely. I don't think you could possibly assume someone is going to fall 

asleep instantly and then sleep continuously for 8 hours. nor even under the mosr 

ideal circumstances. Maybe it should be longer. 

Appendix D, pp. 5-6. 

t7

{¡+- 


(a) Scheduling the Protecred Time Period for the same rime each day 

Time'of-day / Circadian Physiology Affects Sleep and Waking Performance - 

. . . Time-of-day or circadian effects are important considerations in addressing 24 

hour operational requirements because circadian rhythms do not adjust rapidly to 

change. 

. . . Thus, circadian disruption can lead to acute sleep deficits, cumulative sleep 

loss, decreases in perforrnance and alertness, and various health problems . . . 

Therefore, circadian stability is another consideration in duty and rest scheduling, 

NASA recommends a sleep opportunity that is predictable (24 hours notice 

recommended), does not varv more than 3 hours on subsequent days to ensure circadian 

stability, and is protected from intem¡ption. (Emphasis added.) 

NASA TM, Il .3, p. 34; 12.6.2, p. 8. 

Conclusion - Reserve assignments should attempt to maintain a consistent 24 

hour cycle. 

Banelle Report, p.28. 

Remarks of Dr. Dement 

Q: Dr. Dement, thete's one a.rea that we really haven't touched upon at this point and 

I don't want to miss. These are questions regarding the maintenance of circadian 

stability. In your opinion, why is maintaining circadian stability so important? 

A: Well because usually... and by that you mean:your sleep opportunities and your 

wake opportunities are in that period of stability, then you have the best sleep and 

the best wake. If you get out of that cycle, then both sleep and wake will be 

impaired. 

Q: What happens to the body as you change a person's cycle? 

A: All sorts of things happen, but the major thing of course is that you are now trying 

to sleep when the body wants to be awake and you're trying to be awake when the 

body wants to be asleep because you left the circadian stability that you talked 

about. 


r8

(3) Rescheduling the Protected rime Period by more than 3 hours once 

during any 7 consecutive days by providing the flight crewmember l0 

hours notice. 


(b) Limiting the movement of the Protected Time Period to PIus or Minus 3 hours 

. . . the 8-hour sleep opportunity should not vary by more than 3 hours on 

subsequent days to ensure circadian stability. . . . 

NASA TM,12.6.2, p. 8. 


Q: . . . we're trying to insure that the protected time period, the rest period, stayed the 

same from day to day, assuming the reserve crewmember is not called. Or for 

that matter when he is called, he goes back into his cycle. We're anempting to try 

to snap him back to as close to that original cycle and maintain that same rtrythm 

from day to day. NASA has f,rndings on that. Their recommendation was to 

maintain that circadian stability plus or minus 3 hours. Do you agree or disagree? 

A: I absolutely agree that's better than no stability. Obviously the smaller that 

number, the better. I think practically it couldn't be zero, but I think we rend to 

feel there's kind of a daily flexibility within that range, like 0 ro 3 hours, O to 2 

hours. To go outside of that is, again, inviting a condition of sleep deprivation. 

So deliberately creating a bad siruation. 

Appendix D,pp. 16-17. 

l9

(c) A certificate holder may assign a flight crewmember and a flight 

crewmember ma! accept an assignment for flight time in scheduled air 

transportation or other commercial tlying if such assignment is 

permitted by this subpart; 

If the assignment ß scheduled to be completed within 16 hours 

afrer the end of the preceding Protected Time Period; 

Availability Period Limitation 

Continuous Hours of Wakefulness/'Duty Can Affect Alertness and 

Performance - Extended wakefulness and prolonged periods of continuous. 

performance or vigilance will engender sleepiness and fatigue. 

Extended flight duty period - An extended flight duty period should be limited 

to l2 hours within a 24-hour period to be accompanied by additional restrictions 

and compensatory off-duty periods. This limit is based on scientific findings 

from a variety of sources, including data from aviation, that demonstrate a 

significant increased vulnerability to performance-impairing fatigue after 12 

hours. It is readily acknowledged that in current practice, flight duty periods 

extend to l4 hours in regular operations. However, the available scientific data 

support a guideline different from current operational practice. The data indicate 

that performance-impairing fatigue does increase beyond the l2-hour limit and 

could reduce the safety margin. 

NASA TM, qq 1.4,2.3.4, pp.4,6. 

NASA does not provide a specific recommendation for the duration of a Reserve 

Availability Period. However, it follows that NASA's recommended maximum duty limit 

of l2 hours plus 2 hours for operational delays (total - 14 hours) obviously requires a 

pilot to be awake at least that much time. By adding report time to NASA's 

recommended maximum duty limit. it is apparent that NASA's duty limir is 

commensurate with our proposed I Ghour reserve availability period limit for unaugmented 

flying. 

The results of an NTSB analysis of domestic air carrier accidents occurring from 

1978 to 1990 suggest that time since awake (TSA) was rhe dominanr fatiguerelated 

factor in these accidents (NTSB, 1994). Performance decrements of hi-eh 

time-since-awake crews tended to result from ineffective decision-making rather 

than deterioration of aircraft handlin-s skills. . . . There did appear to be two peaks 

in accidents: in the morning when time since aw'ake is low and the crew has been 

on duty for about three to four hours, and rvhen time-since-awake s as high, above 

l3 hours. Similar accident peaks in other modes of transportation and industry 

have also been reported (Folkard.l99l). Akerstedt & Kecklund (1989) studied 

pnor time awake (four to l2 hours) and found a strong conelation of accidents 

20

with time since awake for all times of the day. Belenky et al. (1994) found thar 

flight time hours (workload) greatly increase and add ro rhe linear decline in 

performance associated with time since awake. 


Some symptoms of fatigue are similar to other physiological conditions. For 

example, with fatigue one's ability to attend to auxiliary tasks becomes more 

narrow, very much analogous to the effects of alcohol (Huntley et al., 1973; 

Moskowitz, 1973), hypoxia (McFarland 1953). and heat srress (Bursill, 1958). 


Australian researchers Drew Dawson and Kathryn Reid (1997) evaluated performance 

after 17 hours of wakefulness and found performance degraded to a level equal to that 

caused by a blood alcohol concentration (BAC) of 0.05 percent. At 24 hours, 

performance decrements were equivalent to that of a 0.10 BAC. After ten hours of 

sleeplessness, the decline in performance averaged .74 percent per hour. Their study 

titled Fatigue, Alcohol and Perforrnance Impairmenr appeared in Narure, Vol. 338, luly- 

August 1997. Gee Appendix E). These findings were replicated and extended by 

Nichole Lamond and Drew Dawson in 1998. (See Appendix Ð. 

If an individual has been awake for l6 to l8 hours, decremenrs in alertness and 

performance a¡e intensified. If time awake is extended to 20 to 24 hours, alertness 

can drop more than 40 percent flVRAIR, 1997: Morgan et al.. 1974; Wehr, 1996). 


The NTSB cited pilot fatigue as the probable cause of rhe crash of a DC-8 at Cuantan.¿mo 

Bay in 1993. The individual crewmembers were continuously awake for 19, 21, and23.5 

hours prior to the accident. 

Mark R. Rosekind, et al., crew fatigue factors in the Guantanamo Bav* aviation accident. 

& Appendix G). 


Q: Dr. Dement, after our reserve pilots receive their sleep opporn-rnity, they become 

available for duty. We call the availability period the "reserve availability period" 

and that's basically the time they are available for work. for flyin_e. After the 

sleep opportunity, what would you consider to be a safe limit of time since awake 

for a crewmember? 

For the lO-hour (sleep opportunity) period? 

Yes. 

A. Fourteen hours. And I wouldn't say that's 100f? safe but if rou have a number, 

that adds up to the 24-hour day. It ought to be reasonabl,"- safe. 

2l

a 

A 

a 

A 

a 

V/here do you get your number from? 

Well, it comes mainly in my head from circadian type 24-hour studies to see the 

pattern of the manifestation of the drive to sleep versus the awakening effect of 

the biological clock. If you're getting outside the 24-hour cycle, then you're 

going to have periods of greater risk. . . . 

That assumes that the individual wakes up ¿rs soon as his protected time period is 

over. So in other words, you see a complimentary factor: t hours of rest should 

dictate a l5-hour availability period? 

Yes. I think most people would agree that would be the ideal. 

Going beyond that, what is probably the most greatest points of contention right 

now - the debate between the pilots and the industry operators - is the fact that 

the operators would like to extend this reserve availability period in excess of 

what you say is 14 or l5 or l6 hours, whatever the case may be, to a larger 

increment, extending that reserve availability period based upon an advance 

notice of a nap opportunity. ln other words, a pilot comes on call at 8:00 a.m. He 

is then told at 9:00 a.m. that he is to report for duty 5 hours later. The industry's 

position is that the notice constitutes an opportunity for additional rest which then 

would be utilized to add more restorative energy or analogous to putting more 

charge into a battery, and then carry that pilot into more of an extended duty 

period with an additional amount of time.... up to in certain cases 24 hours of 

duty. What is your feeling on that type of scenario? 

A: To me, that's a recipe for disaster because iffi;*sponsible, professional 

pilot -- who has a reasonable schedule, - who is not honibly sleep deprived, and 

who has a fairly stable circadian rh¡hm, then the likelihood that he can get 

adequate slecp by trying to nap I think is relatively small. I would not depend on 

it at all. I would think also to have to do it sort of unexpectedly like this. ...Oh! 

Take a nap....Only people who are very sleep deprived.... 

a 

[.et's say I have a 10-hour sleep opportunity: l0 p.m. to 8 a.m. That means I'm 

available for l4 hours unless they fly me into the next l0 p.m. slot tonight. Could 

I not get a call say at noon and say instead of you being off tonight at l0 p.m., we 

want you to work until seven tomorrow morning but you aren't going to go to 

work until l0:00 that night. So they call me at noon. they give a lO-hour notice 

that I'm not going to have to go to work until l0 hours from noon, so at 2200 I 

report for work, and they want me to fly until 0800. So that would be a total of 24 

hours from the time I theoretically woke up and I'r'e had a lO-hour notice that I 

was going to be flying this fatiguing schedule. Would that be safe? 

A: Well, I wouldn't be on your plane. No. I think that's almost insanity in the 

sense of savins that is safe. First of all. naps can't be depended on - even under 

ideal circumstances - to get you through this period when the biological clock 

)1

alerting is gone, when you're alone with your sleep debt so to speak, during the 

WOCL. There's no way that isn't going to be dan_eerous. . . . 


:)

(2) If the Ílight crewmember is given a flight assígnment for any part of the 

period of 0200 to 0600 hours, any such flight assignment must be 

scheduled to be completed within 14 hours afier the end of the preceding 

Protected Time Period. The operator with the concurrence of the 

administrator and the pilot group may designate any 4-hour period for 

all operations between 0000-0600 hours in plnce of 0200-0600 hours. 


(c ) Reducing the Reserve Availability Period by two hours during Back-Side-Of-The- 

Clock Operations (0200 - 0600) 

Otr-duty period (following standard flight duty periods during window of 

circadian low) - Extensive scientific research, including aviation data, 

demonstrate that maintaining wakefulness during the window of circadian low is 

associated with higher levels of performance-impairing fatigue than during 

daytime wakefulness. . . . 

Definition: 'fuindow of circadian low" - The window of circadian low is best 

estimated by the hours between 0200 and 0600 for individuals adapted to a usual 

day-wake/night-sleep schedule. This estimate of the widow is calculated from 

scientific data on the circadian low of performance, alertness, subjective report 

(i.e. peak fatigue), and body temPerature. . . . 

NASA TM.1l1t 2.t.4,2.3.2, pp. 5-6. 

' The ingredient of day versus night long-haul flights raises a second concern, the 

time qfuþ¡þ,parture. Because sleepiness and fatigue are strongly related to 

circadiãiì rhythmicity, they should not be controlled by regulations, which ignore 

time-of-day in favor of elapsed time. . . . For the sake of efhciency and safety, it is 

incumbent upon regulatory authorities to include úme-of-day as a factor in 

designing flight crew duty and rest limitations. 

R. Curtis Graeber, et al., Aircrew Sleep and Fatigue in Long-Haul Flight Operatiorts, 

Tokyo, Japan (October 26-29, 1987), p. 13. 

Back of the Clock Operations, Circadian Rhythm and Performance 

There is a substantial body of resea¡ch that shows decreased performance during 

night shifts as compared with day shifts. The reasons for this decreased 

performance include: 

a Circadian pressure to sleep when the individual is attempting to work. 

a Circadian pressure to be awake when the individual is attempting to sleep. 

o Time since awake may be substantial if the individual is up all day before 

reporting for the night shift. 

o Cumulative sleep debt increase throughout the shift. 

Research conducted by Monk et al. (1989) indicates that subjective alertness is 

under the control of the endogenous circadian pacemaker and one's sleep-u'ake 

cycle (time since auake). When time since auake is long and coincides with the 

^l ,l 

:a

circadian lo*'¡here is a very sharp drop in alertness, a strong tendency to sleep 

and a significant drop in performance (Perelli, 1980). Alertness is relatively high 

when the circadian rh¡hm is near the acrophase and time since au'ake is small. 

Monk (1996) argues that this cycle is consistent with the NTSB (1994) finding of 

a peak accident rate occurring in the evening. . . . 

Battelle Report, p.23. 

Microsleeps have been shown to be a useful approach to assessing the effects of 

time of day on sleepiness levels. EEG brain wave changes confirm that pilots 

experience grea¡er sleepiness and decreased alertness between 2:00 to 4:00 a.m. 

(Gundel, 1995).. . . 


. . . In determining maximum limits for extended duty periods, consideration also 

needs to be given to other fatigue-related factors that could contribute to excessive 

fatigue levels during extended duty periods, including number of legs, whether 

the flieht impinges on the window of circadian low [WOCL). and time since 

awake. (Emphasis added.) 


Night operations are physiologically different than day operations due to circadian 

trough and sleep loss. This carries a higher physiological cost and imposes 

greater risks of accidents. One of the most established safety issues is working in 

the circadian trough between 0200 and 0600. During this period workers 

experience considerable sleepiness, slower response times. increased errors and 

accidents (Miùer, l99l: Pack. 1994). Manv recent accidents from various 

transportation modes have been associated with this circadian trough (Lauber & 

Ka¡en, 1988). Lyman and Orlady (1981), in their analysis of the Aviation Safety 

Reporting Sysem researcher state that 3l percent of incidents occurring between 

2400 to 0600 hours were fatigue relatec. 

In Japan, 82.4 percent of drowsiness-related near accidents in electric motor 

locomotive drivers (Kogi & Ohta" 1975) occur at night. Other landmark studies 

over the past s€\'eral decades have documented the increase in accidents and error 

making. Klein et al. (1970) argue thattheirresearch with simulators proves that 

night flights are a greater risk than day fìights. Their research found 7-5- to 100percent 

mean perforrnance efficiency decrements in simulator flights during the 

early morning hours, regardless of external factor such as darkness or increasing 

night traffic or possible weather conditions. 

. . . A study of naval watch keepers found that benween 0400 to 0600, response 

rates drop 33 p'ercent, false reports rates 3l percent, and response speed ei-eht 

percent, compared with rates between 2000 to 2200 hours (Smiley. 1996). 

Samel et al. (1996) determined that many pilots begin night flights already having 

been awake more than l5 hours. The study confirms the occunence of as many 

as five micro-sleeps per hour per pilot after five hours into a night fli_eht. . . . The 

authors concluded that "During day time, fatigue-dependent vigilance decreases 

?{

with task duration. and fatigue becomes critical after 12 hours of constant \\ ork. 

During night hours fatigue increases faster u'ith on_goin_e duty. This led to rl-.: 

conclusion that l0 hours of work should be the maximum for night flyin_e." 

[Note Samel's conclusion - Reduce the duty period from l2 to l0 hours.] 

Gander et al. (l99ll found in an air carrier setting that at least I I percent of pilots 

studied fell asleep for an average of 46 minutes. Similarl¡,. Luna et al. ( 199Ì r 

found that U.S. Air Force air trafhc controller [sic] fell asleep an average of 55 

minutes on night shift. A possible explanation for these sleep occurrences, in 

addition to circadian nadir, is the finding of Samel et al. that many pilots beg:n 

their night flights after being awake for as long as l5 hours. 

Battelle Report, pp. 24-25. 

reduced. (Emphasis added.) 


. . . flight dutv regulations that adequately account for circadian modulation in 

the capacity of sleep and in human performance have been used in the United 

Kingdom for 6 years . . . and by account appear to be working well. The SruJy 

Group is aware of no qualitative reason why adjustments such as those 

incorporated in the UK regulations could not be used in the US as well. 

Scientific Study Group. ta.2. p. 10. 

Flight duty periods during window of circadian low. 

. . . Therefore, it is recommended that in a Tday period, there be no extended 

flight duty period that encroaches on any portion of the window of circadian low. 

[Note: a standard fli-eht duty period should not exceed l0 hours within a 24-hour penod.] 

NASA TM, lq 23.5.8.. 2.3.3. 

26

(d) When there are no other reseme pílots who have sufficient reseme 

availability periods to complete an assignment, the certificate holder may 

schedule a flíght crew member for an assignment for flight time in scheduled 

air transportation or otherfiying permitted by this subpart, provi^ded that the 

crew member is given a minimum of 14 hours of advance notice and is released 

to protected time at the time of the notice. 


(d ) Minimum of l4 Hours Advance notice 

Considerable research into other arenas has taught us that individuals are better 

able to cope with unusual or extended duty schedules when they can plan for them 

in advance. This forewarning allows them to develop time-linked performance 

goals and to schedule their rest and activity optimally before reporting for duty. 

R. Curtis Graeber, et al., Aircrew Sleep and Fatigue in Long-Haul Flight Operations, 

Tokyo, Japan (October 26-29,1987), p. 12. 

... In other words. simply bein,g off duty was not a sufficient condition for crew 

members to be able to fall asleep. . . . 

Philippa N. Gander, eT al., Crew Factors in Flight Operations: VIIL Factors Influencing 

Sleep Timing and Subjective Sleep Qualim^ in Commercial Long-Haul Flight Crews 

(December l99l ), p. 29. 

. . . In the limited time remaining, he attempts to sleep irrespecti"'e of his 

physiological readiness to sleep (circadian phase) and the local time, both of 

which may compromise the quality and quantity of sleep he is able to obtain. 

Philippa N. Gander, et al., Crew Factors in Flight Operations: VIII. Factors Influencing 

Sleep Timing and Subjective Sleep Quality in Commercial l-ong-Haul Flight Crews 

(December l99l), p. 31. 

This reinforces the importance of ensuring that adequate time is available for sleep. 

Conclusions -. 

. . Flight and duty time regulations can be interpreted as a means 

of ensuring that reasonable minimum rest periods are respected. However, the 

perspective highlighted by this study is that the time available for sleep is less 

than the scheduled time off duty. . . . 

Philippa N. Gander, et al., Cre*' Factors in Flight Operations: VIII. Facrors Influencing 

Sleep Timing and Subjective Sleep Qualin' in Cotnmercial Long-Haul Flight Crev,s 

(December l99l), p. 33 

27


a 

A 

a 

A 

a 

A 

a 

How about that the flight is _eoing to happen, There is going to be every day in 

America, pilots that report to work at 2300 or whatever and fly until 0800 the next 

morning. Now, what's different about the man who knou's a week, a month in 

advance that this is going to be his schedule and the reserve pilot who finds out at 

noon after having woken up at 8 a.m.? What would be the difference? 

You know that the time you do all of the things you can to move toward a better 

situation . . . You can never get to perfection, but the more practice, the more 

warning, the better you'll be able to handle it. Some people learn that there is a 

time when it's quiet and if I do this, I can pretty much depend that I will fall 

asleep. It'snot l00Tobutyoukindof learnthatoryoupr¿ìcticeorwhatever. But 

if it's without warning, all bets are off. 

Dr. Dement, you've kind of led the discussion into another area of this 

rulemaking that has to do with an alternative method. Assuming that the pilots in 

this protected time period method were depleted, the carriers then want to give 

pilots advance notice to cover any mission or any assignment. They are looking 

at l0 hours as the criteria. We don't believe that to be adequate based upon . . . 

Are you talking lO-hour warning? 

Ten-hour warning, yes. To do an¡hing. 

That would be 1007o wrong. 

whv? 

Well, because the l0 hours could fall sort of toward the beginning of what we call 

"clock dependent learning." There's no way you could sleep. And then you go 

into your duty period at the worse possible time you could have in that situation. 

What sort of time would you think would be adequate to give a guy enough time 

to get an opportunity to rest so that he would be safer than l0 hours? 

A: Trventy-four hours. At least a day before. Wouldn't you think? I don't see how 

vou can get notified as the day is beginning and feel you could depend on being 

able to take a nap. If it happened every day or somehow ¡ ou know that you could 

certainly -set the probability up, but it's not something that 1'ou could ever really 

control. Again, there ought to be a better way. 

Appendrr D.pp. l0-l l. 

28 

"-F-'--

a 

A 

a 

A 

a 

A 

We're shooting around the subject. I hate to break any of this up, but this 

question has been plaguing this committee. The industry keeps harping on the 

fact that there should be no difference between the schedule holder who knows 

he's got to fly from midnight to 8:00 a.m. If he can do it safely. why can't a 

reserve that wakes up at the same time in the morning t8:00 a.m. or 6:00 a.m.). 

Why is it not safe for this reserve pilot who does it with notice? 

I don't think it's safe for either pilot. Maybe a linle less dangerous in the sense of 

performance, etc. But I think at least he has preparation. warning, etc. and knows 

his own strengths and weaknesses whereas the other pilot I think is always 

without warning and has really no chance to prepare. I don't think the two groups 

are the same. 

Are you implying that the preparation should acrually start the previous night? 

Yes. If I was going to drive all night, I wouldn't want someone to tell me that 

day. 

They're really killing us for making that same argument. I mean we make that 

argument across the table and we get smiles and nods of the head and shrugs of 

the shoulders from the other side. They say it's not a valid argument. That's 

always what they come up with. 

They say it's not a valid argument? It is a supremely valid argument. I mean 

that's just like sayin_e down is up. 


29

u (f) For augmented International operations, a certificate holder may assign 

a flight crewmember and a flight crewmember may accept an 

assignment for flight time in scheduled air transponation or other 

commercial flying as follows: 

(I) For single augmentation, the assignment must be scheduled to be 

completed within 18 hours after the end of the preceding 

Protected Time Period; or 

(2) For double augmentation, the assignment must be scheduled to 

be completed withín 22 houn after the end of the preceding 

Protected Time Period. 

These limitations may be extended up to 2 hours for operati.onal delays. 


(Ð ( I ) and (2) augmented crews 

Extended flight duty period: additional flight crevy - Additional flight crew 

afford the opportunity for each flight crew member to reduce the time at the 

controls and provide for sleep during a flight duty period. Consequently, with 

additional flight crew and an opportunity for sleep, it would be expected that 

fatigue would accumulate more slowly. In such circumstances, flight duty 

periods can be increased beyond the recommended limit of l2 hours within each 

24-hour period. For each additional flight c_rew member who rotates into the 

flight deck positions. the flight-õffid can be extended by 4 hours as long as 

the following requirements are met: I ) each flight crew member be provided one 

or more on-duty sleep opportunities; and 2) when the extended flight duty period 

is l4 hours or longer, adequate sleep facilities (supine position) are provided that 

are separated and screened from the flight deck and passengers. Controlled rest 

on the flight deck is not a substitute for the sleep opportunities or facilities 

required for additional flight crew members. 

NASA TM,I 2.3.6. p.7. 

30

V 

X 

I q 

N 

g 

d 

d 

V

NASA Technical Memorandum 1'lO4O4 

Principles and Guidelines for 

Duty and Rest Schedul¡ng in 

Commercial Aviation 

David F. Dinges, University of Pennsylvania Medical School, Philadelphia, Penrsylvania 

R. Curtis Graeber, Boeing CommercialAlrplane Group, Seattle, Washington 

Mark R. Rosekind, Ames Research Center, Moffett Field, Califomia 

Alexander Samel, and Hans M. Wegmann, DLR-lnstih¡te of Aerospace Medicine, 

Cologne, Germany 

May 1996 

National Aeronautics and 

Space Administ¡ation 

Ames Research Center 

Motfen Field, California 94035- 1 @0

Table of Contents 

l.O Crcnerat Principlcs 

2 

l.l Slecp, Awakè Tinæ Off, and Recovery a¡c Primary Considerations........... .................. 2 

l.l.l Slccp 

l.l2 Awaicc dme off .... 

1.1.3 Recovcry........... 

123 

133 

1.1 

4 

l5 bilities Exand o Fl 4 

1.6 of Individuals.......... 4 

1.7 hecludc an Absolute Solution........ 4 

20 Spcciñc Prirriples" Guidelincs, and Rccom¡ændations 

2.l'Off-Duty Pcriod 

Zl.l De6trition:'offdut¡f ......... 

Zl2 Ofiduty pcrid (aanæ slecP and awale-time-offrequireocnts) 5 

' 2-1.3 Otrduty pcrioe (recovcry requireænt)............. 

21.4 Otrduty period (following standsrd flight duty pcriods during wiodow of circadian tow).--. 5 

5 

L2Dlny Pcrioás' 

22.1 Dcfir¡ition: "duqf 

z22Drcñrition: "dury p€riod" ................-. 5 

6 

223 Duty pcrid 

ii*trÍ:lm:ti'r*i;,':::: ::::: ::::::: ::: ::: ::,: :::::::::::::::::::::::::::::::::::::::::-- : 

23.3 Sta¡dård füght duty pcriod 6 

L3.4F:vndcd flight duty pcriod 6 

235 Exænded flighr dury perioð rcstrictions and compensatory off{ury Perids 

6 

2.3 Flight fiu-ty pe¡o¿s ...;.............. 6 

23.6 Exændcd flighr duty pcriod: additional flight crew 7 

23.7 Flitt'tt duty pcrioa (cr¡mulative)............. 7 

2.a Exccptions DuCo Unfo¡escco Opcrational G¡cumsu¡rccs 7 

24.1 Reduc.cd offdury pcriod (exccption)................ ..............-.... t 

L42F;xte¡dcd flighr dury period (exception)................ I 

25 Træ DifTcrenccs 

2.6 Rescrve Starus 

26.l Dcfinition: "ai4løt standby rcscrye" I 

t 

262 Definition:'oo

PREFACE 

This documcnr is inændcd o provide scientific input ¡o rhc issuc of dury a¡rd rest scheduling of flight crcws 

in commcrcial aviadon. Ir is availabtc ro any in¡erlted party rhar is addrcssing ùesc complex issues' 

opcrational dcma¡rds. To add¡ess this 

rhlsc dema¡rds uæt to devclop prirriples 

rcial aviation. 

ed areas of scientiñc lnowlcdge 

daa ræ¡e avail¡ble a¡d also a¡eas 

ent scicotific knowlcdge, gcoeral princþles directly 

ablishcd. Wiù thc gcsalpirciples as r basis' 

scientific Basis for principles and Guidetincs. Tbe scientific worki¡g gTouP ì1'8s cofl¡Poïd of 

scientisa a"1ir6y i¡vorvcd i¡ cxamining tbcsc issr¡cs.in aviuion scnings. The grorp inands- o poducc rwo 

documcns bascd on tÌ¡cir r/crt This nåt ¿o.,t*or is intcnded to be concisc, o bc focuscd oa opcrational 

planncd thar an iniriål draft of rhis sccor¡d docutrEnr E'ill be Ña¡autswithin approximavly 12 months' 

ation of these principles urd guidelincs may 

rs include cconomic,lcgd, coRltcncfit, and othcr 

cing gouP rc addrcss ú¡esc issues, and thcy a¡c left 

'deliberatioo 

duals a¡ld not as fcprcscntadves of ury orgurizatioo or of a 

, rhc views and çinioru expresscd in this docuæ¡t a¡e thosc 

necessarrlly rcflcct thosc of any qgurization' 

In alphabcdcal order, thc scic¡¡tific working glouP 

Mark R Rosekind,ÉtD, Alcxandcr Saæi,R¡'n, 

this dæuænt to the scicntific working got¡p' pleasc 

ber'PhD' 

about 

Mark R Rosckind, Ph-D. 

NASA Amcs Ræca¡ch Ccottr 

Mail Stop 2624 

Moffen Ëicld, cA 94o3tl0æ 

(415) &3Y2t (Office) 

(415) M3729 (Fax) 

Hans M. Wegmann, ÌvtD. 

DLR-Insituæ of Aeroepacc Medicinc 

ü¡¡derHoehc 

Þ'51147 Kocl¡ 

Germany 

49 ?203 û1 I exr 36ó7 (Officc) 

49 2203 696372 (Fax)

INTRODUCTION 

PrinciPles and Guidelines for 

Duty and Rest Scheduling in Commercial Aviation 

David F. Dinges, R. Cunis Graeber, Mark R' Roækind, 

Alexañder Saæ[, a¡d Hans Ìrd' tilegmann 

(¡n aþhùetùnl ordcr) 

Twenty-four Hour RequÍrements of the Aviation Industry 

æct oPcrational dcma¡rds Grounù in global long' 

cstic o'pcrations will continue o increasc these 

: available to suPpqt 24-hour-aday operations to 

tcrnuional aviatioo can also reqt¡ire crossing multiple 

schedules, 

Thesc 

impairing 

knowtedge an{ cùsnsver possibla inco'rpøaæ 

circadian physiologr ino 24-bou cviatioo 

cpcrations. fJriliz-¡ie¡ of zuch scientific i¡rforoatiø can help promote crew perfoElanoe ard alermess 

drring flight operations and t¡c¡eby maintain and improve the safery margin. 

Chaltenges to Human PhYsiologY 

alertncss during operations. Over rhe past 4O 1æars, 

physiolory, sleepinesValermess' 

iñ.."d tigni¡c¿nrfv. Scientiñc 

cnvhonænts, including ñeld urd simuluor studies 

aviarcrs of performand-i-p"iting fatigue rcsulting from the slecp loss, circadian disnrption' and 

y¡orkload engendered by cr:rrent flight and duty practices' 

Hr¡mans a¡e ccntral ¡9 aviation operadons a¡d continue n perform cridcal fi¡¡lctions þ Ecct the 

?*hotnrcquiremen¡5 of the industry. Tlrrefoæ, human physiological capabilides, and [i6itr¡is¡¡5, 

rcmain *rà"t faaors in maintaining safety and produai"ity in aviaiæ- 

Principles Based on Scientific Knowledge 

Tbough ¡esca¡ch on fatigue, slecp and circadian physiology, and shift wort schedules has generatcd 

- "*i"*i"e body of sciãndfic knowledge, rhe application of this information to the requircmens of 

opcrational scnings is relativcly riew 

increasing, is transfer to operatiors 

counærDeåsr¡res) offen the greatest 

schcduling pnacticcs rarely acknowledge or incorE 

e 

al

dær¡ocnt is to ourlinc scientifically-bascd prirriples that can bc applied ¡o ¡l¡e dury and rest scttcduling 

rcqui¡eæns of thc aviation industry. 

Sharcd Responsibility 

Tbcæ is no one absolurc or pcrfect solution to thc demar¡ds of duty and rcst scheduling in aviation. It 

is crhl;al that safery be acknowledged as a sha¡cd rcsponsibiliry anong all the indutry particþutts 

Facb coryonent of the aviuion s)rytem should bc cxamined fq avenues to incorPoratc scientifrc 

infqm¡ion and to apply guidclincs and straægies that will oaximizc perfømancc and alcnncss during 

flight operarions. Regulatory considerations, scheduling practices, pcrsonal strategies, and tcchnologt 

desgn ue spccific compo¡¡cns of thc industry ùu could be subject to such an exami¡æion 

Each of thesc cornporients is complex and prescnts rurique challenges. This docr¡ment is focr¡scd on 

scientiûcally-bascd principlcs and $idclincs fødrry a¡rd rest scheduling. Howevcr, i¡ is acknowlcdged 

thet rcgula¡ry action involves Eeny corsidcrations, zuch as legal" economic, and curre¡t practica It is 

Éc intcnt of úris docuocnt ôu rclwant scieilific information be considcrcd in üe rc$laffiy dmain 

'6afC can be Difficult to Quantify 

Detcrmining a "safe" operation is a cooplex tlsk Aircr¿ft accidens arc such rare occumenccs that they 

Eay nor proyidÊ ùc bcs outcoæ variable to esimaæ safe opcrations. The aviation indt¡stry r¡d flfng 

publb dcmar¡d a high margin of safety and reó¡nda¡rcy. Amng Eodcs of transportatioq üre aviatio 

indusrry's reputation for safcry 's welldescrrred. As many scgmcnts of thc industry incrÊåss thcir 

activitics, as tcchnologl enables longer fligh¡f ar¡d as overall growtlt continues, the challengc will be o 

rnaint¡in, and whcre possible, improve tl¡e safcty margin Thc fatigræ factors addressed in tl¡esc prirciples 

can crea¡e a wlnerabiliry for decremens in perforurance a¡d alertncss that can reduce the safety Eargin. 

Guidclines designcd to ¡pccifically addrcss thesc factc¡n can help to minimize this vulncrabiliry. 

Objectives 

Thc øEary objective of this docr¡me¡rt is o provide cmpirically derived principles and guidefines for 

duty and rest scheduling in comærcial aviatiæ. In ¡he Fmt section, scientifically-bascd prirriples 

rclared to operational issues poscd by the aviation industry are outlined In the sccond scctioo, the 

prircþles are applied ro guidelincs for duty a¡¡d ¡est scheduling in commercial aviation, with specifics 

provided wherc appropriaæ and available. In thc thi¡d scction, a brief ovcrview of othcrpotential 

indusry strategies ¡o add¡ess thcsc issues is pnovided 

r.O GENERAL PRINCIPLES 

1.1 Sleep, Awake Time Off, and Recovery are Primary Consideratioru 

l.l.l Steep Sleep is a vital physiological necd- Sleep is neccssary ¡e ¡nai¡ffi alermess and 

performance, pos'itive mood, and overall heålth and well-being. Each individual has a basic slecp 

requircænt that provides for optimel levels of performance a¡d physiological alertness druing 

u¡akefulness. Or¡ average, this is 8 hours of sleep in a 24-horu perid, with a range of sleep needs 

grcårer than a¡d less than this amounr Losing as linle as 2 hou¡s of sleep will rcsult in aanæ slecp 

loss, which will induce fatigue and degrade subsequent waking performance and alertness. Over 

days, sleep loss-any amount less than is requirefwill accn¡e into a cumulative sleep dcbr The 

physiological need for sleep created by a dcficit can only be rcversed by sleep. An individual who

has obtaincd required sle+ will be bcncr prcpared æ perform after long hor.r¡s awatc or altcrcd 

work schedules than one who is operating with a slecp deñcir 

l.lJ Awake time off- Fatiguc-rclarcd pcrformance decrements a¡e traditionally defined by 

,cnt on a given t^sk. Breaks from continuoos 

ing, are impøtant to nainuin consistent ¡txl 

wake time ofris introó¡ccd here to describc timc 

time off and slecp a¡e needed to ensurc opimum 

lcvels of Performanca 

l.lj Recovery- Rccovery from a¡r acutc slccp deficit, cumulative slcep debt' Prolonged 

pcrfamance a¡rd alc¡tness 

12 Frequent Recovery Periods are Important 

promote perfømancc and aleruress. Thesc ¡rp 

cd periods of wakeñ¡lms G.e-, ù¡ty) and ci¡cadian 

corrcry is impøant oredrrce cumulatiw cffccs 

rformance and alermcss 

fatiguc morc effcctively than less frequent oG' 

rcr likelihood of rcliwing ecute fæigue üæ 

s tha¡ cnsurc m¡nimum days off pcr weck ae 

vcr longerPcriods of timc (e.g-, montb yØ). 

1.3 Time-of-ilay/Ciicadian Physiotog¡r Affects Sleep and TVaking Performano? 

Thcre is a clock in the human brain, as in other organisurs, that regulates 24-hor¡¡ Pattcrns of body 

functions This clæk cmrrols not only slecp ar¡d wakefulness altcrnuing in panrbl with thc 

e¡¡vi¡onmcntat lighr/dart cycle, but also thEoscillalory nature of most pbpiolog:cal,Psythologcal' 

and behavioral fu¡rctions 'iìc wide range o¡ body functions controUed by the 2¿l-hor¡r clock includes 

body tc'pcran¡rc, hømne sccretion, digestio+ physical a¡d mcntal pcrformancc, moo4 and many 

o.È*. On a 2,4-hor¡r b6sis', rhcsc furrctions flucn¡¡rrc in a rcgular pattcrn wi¡h a higb lerrcl u onc ti-æ 

of day a¡d a low lcvel u anothcr time- 

wakcfulr¡css and islecp is programmed 

circadian clockt e""L üis pãnern e¡ ¿ daily tnsis 

@ü) 

to 

O6m, arc identified as a time when the body is prognmmcd to sleep urd during which pcrformancc 

is degnded- 1-rmeofday or circad.ian effecs are important consideratiæs in addressing 2Á-bot¡r 

o,pç¡.ã',ion"f requi¡emens because circadian rhythms do not adjust rapidly to change. 

Fa exaryle, an indiviô¡al operating during the night is maintaining wakefulness in dhect oppositioo 

,logical, psychological, and behavioral ñ¡ætions a¡l 

by Þing awake and acrivt. 

position to physiological 

p,rograrnming to be açalc. Thc circadian system prc of functioning during day that 

cDunteracts the abiliry o sleep. Thus, circadian disrnption can lead to acute slecp deñcits, cumulativc 

3'

slecp loss, decre.ases in performancc and alertness, ar¡d va¡ious health problems (e.g., gastroi¡æsdnal 

Therefore, circad.ian srabiliry is another consideration in duty and rcst æhcduling. 

--pt.itto). 

1.4 Continuous Hours of Vgakefulness/Duty Can Affect Alertness and Performance 

Exrended wakefulncss and prolonged pcrids of continuors performancc ø vigilancc m a task will 

cn 

aP 

of 

cumulative effecs car¡ bc addresscd by weekly tirqi 

e¡pport guidclines for acutc timitations than todeteroine qpccific cr¡mulativc limitatiæs" Neverôcless' 

c.-,rl"Cr" tirnitatirns (weckly and bcyod) ¡emain an important considcmtio¡ f6 minirnizing 

ærcumul¡tioo of fuigue effccrs 

l5 lluman Physiological Capabilities Extend to Flight Crews 

fqmancc dcficis rcflect these physiological limis. 

rm that of other humans. Therefore, it mr¡s bc 

fccting perforrnance and alermess in expcrimenal 

f pcrsonnel, and othcn also affect flight crcws. It 

h¡siological capabilities and pcrfømancc dcEcis 

froo fæig¡e, slecp loss, and ci¡cadiur physiology cxænd to fligltt crc\trs. 

1.6 Flight Crews are Made Up of Individuals 

Thcre a¡e considerable individual differcr¡ces in the magniude of fatigue efrecs on pcrformance, 

phpiologi 

slecp¡ ¡et", 

Individual 

other fact6s. Individuals ca¡r also vary in their pan 

druing a subsequenr dury perid (e.g., commuting across long distances immediaæly Pnor to starting 

a dury pcriod). 

1.7 DifÏerences and Variability Preclude an Absolute Solution 

Ir mgst bc acknowledged rhar ¡hc aviation indusuy rspres€nB a diversc range of required work 

dcmands and operarional environmcns. Sections 1.5 and 1.6 highligh¡ the divcrsc si¡utions and 

individtuls that are encompasscd by gercratized guidclines. This funt¡er ilh¡stntes tlrat guidclines and 

regulations qìnnor compleæty cover all pcrsonnel ø opcrarional conditions a¡rd thu úcre is no singlc 

abcolute solution to thesc issues. 

2.0 SPECIFIC PRINCIPLES, GUIDELINES, AND RECOMMENDATIONS 

Tbc following are specific principles, guidelines, and rccommendations to add¡ess üe 24-hour duty 

and rest schjutingiequireæntsof rhc aviation industry. Thesc prirriples and guidelines, bascd on 

the General princifles inroduced in scction 1.0, arc intended to provide a consisænt margin of safery 

across aviæion operations. Thercføe, rlrey are intended for application to minimum flight crew 

complemens of -r*o or morc. Similarly, they are intended for consisænt application across Part l2l 

and ihn 135 operarions. There is no scientiñc basis to differentiate betwecn these opeÎations. Thesc

speciñc principles and guidetines also apply actpss all flþg dury of flight crcw trÌembcrs required o 

p"rfot Þ* 9t or milirary füght opcrations befqe or aficr scheduled commerciel operatioos. 

In ødcr ¡9 provide specific guidelines, it is nccessary o dcfine the terms uscd in ttresc guidclin¡s 

Altcring thèsc defrnitions may invatidaæ the prûriples tl¡at follow. 

2.1 Off-Duty Period 

2.1.1 lÞfinition: *off-duty"- A continuous pcriod of unintcrrupted tiæ during which a crcw 

æmbcr is froe of all duties 

Z.I.Z Off-duty period (¡cr¡te sleep a¡d awaketime.off requirements)- Thc offduty 

p"ti"¿ should ¿lo* for ùrcc coryon 

offduty palnis an 

'ghoo 

slecp opporn¡niry. Tbc gencml 

slecp dcûcit ?{ I 

cumulativc-steep AcUt.å" ¿"gn¿" pcrformancc 

bc ¡eæg¡izcdùrt an 

r faII asleep. Tt¡c scoond codlPoDent is awatetiæ 

I pcrfømance of requircd tasks The ùird 

rg an offduty pcrid Tbcsc otrcr rieccsstt 

lapttr accoomodations' boal check i¡/oq æâ¡s' 

sbowcr, and pcrsonal bygiene. Therefore, rbe offdrry Pcriod st¡ould bc a minimum of l0 hous 

unintemrprcd *itnio any-Z+norrr pcrio{ o includc ¡n &hor¡r slecp opporunity, awake tiæ off' 

and tiæ ior other necessary activiries. (In üe casc of cxænded fligbt duty pctio4 scc sccri¡ 

2.3.s.) 

2.lS Off-duty period (recovery requiræmentÞ The general principles outline the 

impøtancc of rccovery ro Einimizc the cumulative cfrects of slecp loss and fæiguc. Tuo 

nighs of r¡sual slc€p is a minimr¡m rÊquireænt to stabilizc sleep panerns a¡d rcûEri 

-*outir" 

uraking pcrf6suncc and ale¡tr¡css to usual þvels. Two consccutiræ nigÞs of recovcry slecp can 

providi-rccovery from slecp loss. The¡eforc, rhe sta¡dard offduty pcriod fcrreco¡ery shætd bc 

ã -ioi-u- of 36 continuous hor¡n, to include two consccutive niglrs of rccovcry slccp, wiúin a 

74zy perid 

2.L.4 Off-duty period (following standard flight duty periods during window of 

circadian low'I--Extensive scientific rrscarch, incÌuding aviation data demonstraþ thår 

mînraini¡g wakefulness druing the window of circadian low is associatcd witb bithcr lert+ d 

performancc-impairing fariguc-than during dayrimÊ wakcfulness. Thcrcfqe, flight dury paidsthat 

occur dgring t¡e *in¿ó* oi"io"¿i- low bave a higtrcr potential for fatigrrc and incrÊascd requiremenr 

for recovery. It is recorrr-cnded rha¡ if rwo or rnorc füght duty periods wiütin a74ay Pcdod 

encroach on all - -y portion of É¡e window of ci¡cadian low, then the su¡da¡d otrduty pøiod (36 

continuous hours within 7 days) be extendcd to 4t bours recovery. 

2.2 Duty Periods 

2.2.1DeÍtnition: .duty'- Any task a ctew membcr is required by the oPsrator O pcrfono' 

including füght time, administrative worh training, dcadheading, and airPqt sundby rcscÛ!. 

2.2.2 Definition: .,duty period"- A conti¡uous period of time during which tasks a¡c 

perforrned for thc op"*tor, determined from rcport time until frec from all required tasks. 

' For defrniúqr of 'wi¡dow of circ¿dian low.- see scctia¡ 23å 

5

223 Duty period- To reducc vulncrabiliry to performancc-impairing fatiguc from cxtended 

hours of conrinuous wakefulness and prolonged pcrids of continuous pcrformancc requirements, 

cr¡mularive dury pcr 24 horns should bc limitcd- It is rccommcrded that this limit not exceed 

14 hot¡n wi¡hin a 24-hotu perid. (In the case of additional flight crew, sec section 2.3.6.) 

2.3 Flight Duty Periods 

23.1 Definition: 'ftight duty period"- The period of time that begins when a ctew membcr 

is required ro rcport for a duty pcrioa dret includcs one or møe flighs and ends u thc block-i¡ 

tiæ of ûre ñnal flight scgnrcnt At a minim,,m, this perid includes required Pre-f,i$t activities 

and ftight timc. 

232 Definition: "rrindow of circadian low'- The window of circadia¡ low is bcst 

estinaæd by thc houn between 0200 and 0600 fq individr¡als adaptcd o a r¡sr¡al day-wakqhigùtslccp 

schcdule. This estimate of tbe window is calculatcd fr,m scie¡rtiñc data on thc circadian low of 

cc, alerrncss, srbjectivc repct G.e., peak fatiguc), a¡d body tcmpcratr¡re Fr flight duty 

psriods thet cross 3 q fewcr timc zo¡¡es' tl¡e wi¡rdow of circadi¡ri low is ç5tirnatcd to bc 02tr to 

0600 Uoæ-base/domicib time. For flight duty pcriods üat cross 4 or mqe tiæ zones, the window 

of circadian low is estimated to bc 02tr to 0600 home-basc/domicile time føùc frst 4t hors only. 

After a cr€w membcrrcmains mre tban 48 hor¡¡s away from bme-basc/domiciþ, thc window of 

ci¡cadian low is g5tim¡¡¡{ to be 0200 o 0600 rÊferred to local timc at the point of dcprure 

233 Standard flight duty period- To reducc vulnerability to pcrformance-imPairing fuigue 

from exænded hou¡s of continuous wakefulness and prolonged pcriods of continuous performance 

rcquirements, cumulative flight duty pcr 24 hor¡rs should be limitcd It is recommended ùu fø 

standa¡d opcrations, this cumulativc flight dury period not excccd l0 hor¡n ,¡/ithin a 24-bor¡r 

penod- Sta¡da¡d operations i¡rclude multiple flight segrrrnts a¡rd day or night flytng. 

23.4 Extended flight duty period- An extended cu-ulative flight dury príod should be 

limitcd to 12 hours u/ithin e 24-hour period to be accompanied by additional rcstrictions a¡rd 

compcnsarory off-dury periods. This limi¡ is based on scientific findings from a variety of sources, 

including dau from aviuion, that deoonstrate a significantly increascd wlnerabiliry fø 

performance-impairing fatigue afl¡cr 12 hor¡rs. It is readily acknowledged tlrat in current practicc, 

flight dury pcriods exter¡d to l4 hor¡rs in regular operations. Howevet, the available scicntific data 

s¡ppqr a guideline different from currc¡rt operarional practice. Thc data indicue that perfømanccimpairing 

fatigue does i¡¡creasc beyond t¡e l2-hor¡r limi¡ ¿¡¡i could reduce the safety magin 

2J-5 Extended flight duty period: restrictions and compensatory off-duty periodstf 

¡þs çnmulæive flight dury period is exændcd o 12 hor¡rs then the following rcstriaions a¡d 

compensatory off-dury p€riods should bc applied 

A. Cutnutatíve $ecs: tøxínm cumdaíve løu¡s of øension. Over time, ex¡ended flight dury 

periods can result in cumulative effecs of fatigue. To support opcrational flcxibility and still 

minimizc ttrc potential for cumulative effecs, it is rccommended ¡hat extended flight dury pertods 

can bc schedr¡led for a cumulative total of 4 hor¡n u/ithin a74ay perid For example, Ûterc could 

be wo 2-hou¡ extensions of the standa¡d lGhou¡ flight dury pcriod (2 x2 = 4 hr) or fou¡ l-hour 

extensions(4x1=4hr). 

B. Flíght dtuy periods duríng wíndow of círcodian low.As described in Section 2.1.4, the 

window of circadian low (as defined in Section 2.3.2) is associated with higher levels of

perfomrance-impairing fatigue. Thercforc, it is recomær¡ded that n a74ay pcriod, there be no 

cxrcndcd flight oury frioa-trat encroaches on any ponion of ttre window of cLcadian low' 

2 s.6 Ex ten ded n is¡t d utv peri od: a d di ti onar 

bllowing the flight 

rlcovery from ú¡e acurc fatigue 

cllw 

Promdc 

i¿itimal offduty tinc is rccomocnded' Tbc 

,t¡ld bc cxændcd by thc tinc duration of tl¡c f,ight 

t f,igbr dt¡ty pcriod of ll.5 bor¡n wor¡H bc 

bcing extcnded to 11.5 hours 

Jlíli,å'i#Hin"#;itriJÏg 

rf a¡¡ exte¡rded flight dury pcriod is inc¡eascd according o tl¡e above requireæntg the Eaximuo 

flight dury pcrioa-timiroó*"do the l4-horu duty psi4limil (s€ctio¡Z2)' 

2-weck limi¡ 5þ6¡¡ld atso bc scL Also, thesc cun 

4-hour cuoulative fligbt duty pcriod limit' a 

¡ecificd offduty rÊcovsry P€riod 

per 7 days focus 

¡sidcr¿tions To minimizc fuigrc üat is rct 

rce exccssive accr¡mula¡ion ætoss longcr pcriods 

s úe rÊcorrr¡rrnde¿ Thcre is not slfficicnt 

ús a¡ea- Howc:vcr, the gcncral prirriples apply'Fcr 

yea¡ly emunt$ tbc 30{aY 

Thc yealY sr¡muluivc Oigbt 

dury period limitatiqr should be dccreascd a Pcfcentage from úrc 3o{ay arþunl This wiu ñrÎ}tcf 

rcducc thc poæntial fø long-term aær¡mulæion of fæigue factors 

2.4 Exceptions Due tO unforeseen operational circumstances 

Excep 

of the 

These 

spond rc unforcsccn circurnstanccs bcyond thc conuol 

They rre not intended for use in rcgular practicc. 

7

2.4.1 Reduced off.duty period (exceptionÞ To suppon opcrational flexibiliry, it is 

engntzúthat duc to circumstances bcyond the control of tl¡e opcrator, it may be ncccssa¡y o 

reducc an offduty perid to t hours. This reduction would occur only in rcsPonsc to an 

unforcsccn opcrarional requirenrent. In this siruadon, the srbscquent offdury perid should bc 

extcr¡ded to ll hours. 

2.4.2 Extended flight duty period (exception)- To support opcrational flexibiliry, an 

cxtcnded flight ôrty pcriod can be increascd by up to a uraxinu"' of 2 hor¡n duc to unforesccn 

si¡çurnst¿¡¡ccs beyond the conuol of thc opcr¿¡or. The subscqrrcnt required ofrduty pcriod should 

bc inc¡eascd by üc timc by which tlr flight duty pcriod is incrcascd. 

25 Time Differences 

In geocral, the longcr a flight crcw æmbcr is away from thc hoæ-basc/domicile time zooe, üre møe 

rccovcry rimc is riecdcd for readjustment back to home-basddomicile time. Tbcrefqe, it is 

recomændcd rhat fcr flight duty pcriods tbat cross 4 q more tiæ zones, ar¡d tl¡u involvc 48 hor¡rs q 

Eue away from tbc bome-basc/domicile time zone, a minimr¡m of 48 bours ofrduty be allowcd upon 

rennn tobooc bascöomicile time. 

2.6 Reserve Status 

nigbt c¡ew mcmbcrs on Fessrye $au$ prorvids a critical eleænt o opcrational flexibility ar¡d tbc 

oppom¡nity to meet unanticipatcd necds It is impøant thu f,ight crew membcrs on rescrve status 

obtain required slecp p¡ior to a flight duty pcriod 

2.6.1 Definition: "airport standby reserye'- A rescrve flight crew membcr required to bc 

available (on standby) at an airpon fø assignmcnt to a flight dury Pcrid 

An airport standby rescrye ftight c¡ew mcmber should bc considered on duty and the prcvious dury 

perioa guidelines apply. 

2.6.2 Definition: *on-call reserye"- A rcserve flight crew member required to be available 

!o an opemtor (away from thc airpon) fø æsignrnent to a ftight duty perid 

On-call rescrve sratus should not be considerci dury. However, it is imporunt that the flight crew 

æmbcr bas an çpornrnity o obtain sleep priø o an assigned flight duty period Two spccific 

principlcs shor¡ld bc applied Tbc füght crew mcmbcr should be provided e 1) prediaablc ar¡d 2) 

prrotccrcd 8-hour slecp opportuniry.'?redict¡ble" indicates that thc füght crew Embcr should have 

prior informaúø,(24 hours notice is recommc¡¡ded) as o whcn tbc 8-horu slec,p oppomniry can b 

obtained wirhin rhc 24-houon-call ¡escrve time. The 8-horu slecp oppornniry should not vary by 

mrc tha¡¡ 3 hor¡¡s on subsequent da)6 to ensurc ci¡cadian stability. "A ¡rrotected 8-hour slecp 

oppornrnity" sbould bc protected from inæmrption by assignment to a flight duty period Any 

approach that æs the requirements of thesc two principles could be utilized

2.7 summary overview: Guidelines and Recommendations 

Fi*¡re I prwidcs a summary ovcrr¡icw of ¡hc guidelines and recomændations discusscd in 

this docuænt- 

t, o 

= 

Ìt o() 

CN 

Þ I:t 

Þ(D 

C) 

rn 

c 

D 

P.. 

2a{r 9.rbd 

Off-Duty Perlod Duty Period Ftight DutY Perlod 

P.r 

r¡f 

1) A¡ bar 

36 cofllirÞ 

!þu3 lþut!. 

ro hdudc 2 

consocrrtþc 

nþhts ol 

rccovcry 

deç, h r 7. 

dsy psbd. 

21.8 

continuous 

trcr¡¡s h e 7daü 

pcrbd 

(loloilùìg 

trlght dutY 

p€rird h 

circadian 

low). 

q¡t Þ.a 

¡+lú 

t-lrl 

¡¡8 contiÞ 

tpr¡s lpurs 

uporì r¡tum 

tsna 

lolbwi¡ 

flþH dtty 

period 

acfoss 

mutti¡lr 

t¡rn 

zones. 

tholly, 

llontHy, 

ln¡¡¡¡ly 

11h^l Therc b nol 

sufficient 

scientlic dalr 

to prwilc 

specilic 

guidance h this 

afe¿ 

Dr 

taaú 

¡.rlcd 

Pt 

r.d 

brúrl', 

^rYr.Iy 

'10 hrs The¡¡ b not 

¡uffþicnl 

¡cientif,c 

dd¡b 

prwid. 

¡pcc¡frc 

guUam h 

thb arcr; 

lþwcvct 

c¡¡muhtþc 

llþhl duty 

12 hrs llaximut 

(reqdres f 4 curr¡ 

fesriid at¡vc 

landngs. rcurs cl 

max¡Tl¡ll 

cumublþc 

hours, 

comp€nsåtorl 

otlduty time). 

For dt 

additi¡n¡l 

fþûú crer 

meirùer, ffighl 

duty lime can 

be ¡sees.d 

by t hrs 

(requiræ 

sle+ opportunity 

lor eac* 

crer mernbd. 

andbr FDPt 

> 1¡l lus, e 

bur* facilttY). 

E¡tcndcd 

FDPcan be 

increased by 

upb2hrs 

(srËequent 

ofl{uty 

perird 

inøeased by 

an equal 

amount). 

Figwe I. Srormary oveÌniûv of guidelíncs and recotun¿nd¿tiotts. 

9 

perkrd 

limitdiræ 

sho¡rld b. 

edjustcd 

do*rnvatd 

owf 

irueasing 

l¡me framca. 

cn 

I =CL 

Þ 

ct 

m 

x 

o =o. 

(D 

o. 

G t9m 

dx 

õc) õo 

-t, 

e9 

(' ltt 

=P go 

Êlæ 

to 

(D 

¡â

3.0 OTHER INDUSTRY STRATEGIES 

öcsc issucs in aviation Howcvcr, tbcrc is no singl 

dc'ands of t¡e aviation industry. To highlight this sha¡ed responsibililY, scveral other indutry 

srrategies fq add¡essing thesc issues wiu Uc described- Thesc a¡e intendcd to complement thc 

rccorrrr¡cndations listcd abotæ. 

3.1 Education and Training 

I inforocd about tl¡e exænsivc lnowledge now 

rsiology as it rclates to perfamancc urd aviation 

d ino d¡ily opcrations. Thc infømation can bc 

ersor¡al srategies to rlranage performance and 

g modules to meet this need re available a¡d 

stry. 

3.2 Scheduling Practices 

Thc scþnrific infcmatim ay¿ilable can be particululy uscful in gt¡tding rational and ph¡rsiologcaly' 

rx a¡¡d multi-determined proccss. HoY,wcr, it is 

ttunan physiology as a faaø for considcratiou 

st/beneñt considerations are critical Therc a¡e 

rrmation on fatigue into schedule constn¡ction. 

33 Controlled Rest on the Flight Deck 

Scientific data obtained during flight opcradons have clearly demonstra¡ed the effectivcness of a 

planncd cockpit rcst pcriod torprromotc pcrfomrancc a¡rd alertness in flight 

gPeradons. C-ontrolled rcst is a single operational stralegy and is not 

opcrations. It is abaolutely not inænded as a su 

ht ctew, 

dês, ø ¡ts support for ex¡ended dury. All possible strategics ¡hat maintain q 

argin should bc considered 

3.{ Operational Countermeasures 

A variery of other straægies fcr usc during flight opcrations should be examined and utilized wherc 

apprryriarc. This includcs the design and use of rechnology to prornote pcrformance and alertness 

dG"; op€rarions. varying work dema¡¡ds or other creative uses of flight deck auomation could be 

Oc"efãfr to maintain alcrures and perforrrance. Ser/eral activities in this areâ arc underway with 

sorne succcssñ¡l applications currcntly in usc. 

35 Future DeveloPments 

Ttprc a¡e a number of other possibilities that a¡e in diffe¡ent sBges of development hovæative 

laboratcry studies of sevcral *un¡srmeasures are often cited. However, validation of their effectiveness 

and safety in opcrational scrings is still needed prior to widespread impleræntation. Resea¡ch continues 

and mayþroviãe furthcr findings on counterrneasurcs rclevant to regulatory, scheduling, personal 

strategies, and technology approaches to manage alertness in aviadon operations 

10

REPORT DOCU]VI ËNì AI'ION PAUts, OLlB No.07UAræ 

P,ä. rreot'ùño Þrfõn tor ¡x oo¡laclrdl ol nlol'naüql a a 

o¡t¡rúe rrv me,ør,nng tìa 6¡'r¡ ñaa

fl 

x 

I 

o 

N 

fl 

d 

d 

v

Uterature Reyiex' 

An Overvlew of the Sclentiñc Llteraü¡rc 

Coocerning Fatigug $oP, ¡nd the Circ¡dhn Cycle 

Prepared for the Ofüce of the Chief Scieutif¡c 

¡nd Technic¡l Advisor for Euman Factors 

Federal Avl¡tlon Adrninis tra tion 

By 

Ba ttelle Memorial tnst¡ tute 

JIL Inforuration Syste ms 

January l99t 

Page I

Introduction 

An Oven'ierc o[ the Scientific Literature 

Concerning Fatigue. Sletp, and the Circadian C.r cle 

Thjs docurncnr provides a bricf rcview of rhc scicntifìc resea¡ch relating to issues of pilot fatiguc 

arising from crcw schcduling practiccs. A massive ¿rmount of rcsearch has bccn conducæd on 

s¡cb iisues as thc cnvi¡onrncntal conditions that cootribuæ ¡o thc occt¡rrc¡ce of fatiguc, acute and 

ch¡onic slccp debt and tlrci¡ effccts on pcrforrnancc. and thc inflrrcncc of tbc ci¡cadian cyclc on 

alert¡rcss. This papcr attcmpts to idcotify major trcnds in this üærarr¡rc tbat might be of value in 

addressing spþ6{ul i ng reguluory iss¡Ë. 

Tbc papcr is organizcd i¡to scvcn scctioos. Tbc frnt scctioo,'\ilhat is Fatiguc," attcmPls !o 

pro"idé a functional dcfinition of fatigr.rc that scrves to dehne thc scopc of issues thu necd to bc 

considered, including variablcs that contributc to the occr,urence of fatigttc and rncthodologies for 

asscssing the impact of fatigrrc on human functioning. 

Scction two, "Indications and Efrects of FUigr.rc," briefly rcvicws the hurna¡l performancc and 

pbysiologlcal i¡dicators of farigrrc. Tbc inænt is to idcnúfy possible dccrcmns in pcrformancc 

that could bave a safery impact. This scction dso briefly add¡esscs the complcxitics involved in 

rneasuring farigue levcls. As this scction cxplains. fuigue is a complex conc€Pt thar docs not 

aJu.ays produce expected me¿surable de¡rcrnents in pe rformancc. 

Scctionr¡rec, "Fariguc and thc Aviatioo Envi¡onment," add¡esscs tbc issue of fatiguc *ithjn the 

aviationenvi¡onrnent. Beforc changes a¡e madc to existing regularions, tlre question of *hether 

rhere is a problem that needs to be rcsolved should bc addresscd. Available research on the extent 

ci farigue *ithln the aviation envi¡onrrrcnt s rcr'ie*ed. In addition. factors that compLicate the 

assessrnent of the extent of the faUgue problem ln an oP€rational envltorìrDent a¡e also described 

A piJor's lerel of alertness at any tinrc dcpcnds upon a complcx interactlon bet*ecn a number of 

ya¡rables. Fou¡ va¡iables. in particular, nccd to þ considered: tin¡e on task. time si¡ce au'a-ke, any 

exisring sleep debt. and tbe pi.lot's own ci¡cadian cycle. Scction fou¡. "Sta¡rdard Dury Period," 

descnbe s the resc¿rch trends pcrtairung to orne e¡ 1asft and un¡c si¡cc a'*'alie while scction fìr'e. 

"Sra¡dard Slecp Requirenrnts," addrÊsscs Írcutc and ch¡oruc sleep debt, including 

recommendations for slecp debt recovery. Scction sü, "The Circadian Cycle and Fuigue," which 

looks ar rhe resca¡ch on ci¡cadian cycles and thei¡ implications for back'of-the

\l'hat Is Fatigue 

The oblectir.e of rhe regulations proposcd in the NPR.\Í is to idcntr$ sç'heduling constraints that 

wilt mirurruzc rhe impact of pilot fatigue that ariscs from dury unp and sleep debt duc to crcw 

schcdulcs. The terrn "fatigue," has ya to bc defined in a concretc fashion (Malrcr & McPbcc, 

l99a): Mendelson. Richa¡dson & Roth. 1996). Fatiguc, as addresscd in the buman pcrforrnance 

litcraru¡e. rcfers to "deteriora¡ion in human performance, arising as a consequencc of scveral 

poæntial factors, including slcepincss" (p. 2). Slccpincs, in cont¡ast has a morc prccisc 

äcfrnitioo: .slccpirrcss, æcording to an enErging cooscasus üDoot slccp resca¡chcrs and 

clinicians, is a basic physiological starc (like) hungcr or thi¡st. Dcarivatioo or rcstrictioo of sloep 

increascs slecpiæss a¡d as bungcr or thirst is rcvc¡siblc by eating or drinking, rcspcctively, slecp 

reverscs slccp-incss- (Roth ct al., 19t9, citcd by Mendclson, Ricba¡dson & Roth, 1986, P.2). 

In kecping with curren¡ thinking on tlrc concept of fatigræ. Mahcr and McPbec's approach is uscd 

bcrc: 

.Tatigue" must conti¡ue to have thc stahrs of a hypothetic¿l constn¡ct, an cntify 

*hose existence and dimensions a¡e infened from anteccdent and consequent 

evenLs or variablcs" (P. 3-4). 

This ræans that farig¡c is trc¿ted as a conccpt that occurs in rcsponsc to prcdefined conditions 

and has physiological and performancc conscquences. Tbe antecedent conditions of i¡ærest bcrc 

i¡clude: 

o Trrne on task, including fì-ight ti¡r¡c and dury pnod du¡a¡oo 

. Trme sincc awale wbcn bcginnrng the dury Pcnd 

r ,{cute and ch¡oruc sleep debt 

. Cúcadian disruptron. multiple time zones, and shrft uork 

The objectives of this docurne nt are to rcr'iew the scientific rese¿rch tn order to: 

o l,Jenrify the impacr of these anæcedent variable s on huma¡ pe rformance 

o Relare rlesc variabtes to appropriate pbysiological measu¡es that have bee n demonstrated 

ro bc accomPanicd by decrenrents i¡ huma¡ pcrformance 

Idenrify. ro rhe extenr possible, limjtarions and requirements concerning dury Period durations, 

minimum sleep rcquirernenLs, etc. that should be rcflecæd in the regulatioDs. 

Lite rolure Rev teu 

Page 3

lndicatioru and Effects of Fatigue 

The massire ltrerarure on fatigue has identifred a numbcr of symptons that indicate thc presence 

of fatigue. including: increased anxiety. decrcascd short ærm rnemory. slowed reaction tirnc. 

decreascd work cffrciency, rcduccd morivational drivc. dccre¿sed vigilancc, incrcased variabiliry 

in work pcrformance, incrcascd crrors of omission which increasc to commission whcn tinre 

prcssure is addcd ro rhc rask, and increascd lapsc with incrcasing fatigtæ i¡ both numbcr and 

äuration (Mohler, 1966: Dingcs, 1995). Many of thcsc syrnPtoms aPPcer ooly aftcr substantial 

lcvcls of slecp dcprivuion havc bccn imposcd. A rcview of thc litera¡¡¡e tb¿ involvcd fatigue 

lcvels likely to be cxpcrie¡ccd by pilots suggests that a conunon fatigtE slrnPtom is r change in 

tbc lcvel of æptablc risk a¡ individr¡al will tole¡aæ' 

Brown et al. (l97O) bad subjccs d¡ovc for for¡¡ 3-hor¡r sc^ssions. Tbc prformancc ræesurc uscd 

was a count of thc numbc¡ of æcasioos in which thc subþt cxecutcd wh¡ thc cxperirncnær 

considered a risþ passing r¡a¡ìcuver. \I/ben driving pcrformance bc¡pccn tbc lst aDd 4th scssions 

werc comparcd. a 50% increåsc in th€ occurrencc of risþ passing rnaDcuvcrs in laær sessions, 

when subjecrs $'ere Prcsullìåbly morc fatigucd, was obtaincd' 

This change in tlre levcl of acccpøblc risk was confi.rrrrcd by Bartb a d. (1976) and 

Shingledecker and Holding (1914) who found that fariguc caused subþs to cngage in greatcr 

risk taking activiry in an cfforr to avoid additional cffort. In the Shingledcckcr and Holding srudy' 

subjects pe rfornrcd 36 choicc-of-probabifiry (COPE) tasþ, which i¡volved locating a fault in one 

of th'er remo\able ban-ks of one-wan rcsistors, eacb r¡'ith "'arying degrecs of probabiUry- that tbe 

banli had farled. Twenry

cf inaction t1'pical of fatigue (Ncwman, 199ó)' 

r a full minute before thc crash, they rnadc no 

ristic of fari-eue . Tlis is due to a rcduccd lcvel of 

d abiliry to cognitively makc a connection 

bct*.ecn causc and cffccr. one may recognizc a problcm but not translatc is effcct duc to lack of 

full comprchension of thc siruation or simple failu¡e to initiate an actioo' 

Relucd cvidcncc exigs tha fatigued workc¡s a¡e satisficd with lowcr pcrformancc and rh¿ 

bc a factor whcn ai¡cnft cfews ane conoentranng 

dcvclop duc to ttcglccr 

In thc case of thc l9t5 ctrina Airlincs Fligbt 006 mishap, thc pilot þca¡æ focuscd oo thc loss of 

power in one eng 

injuncs occurrcd 

from 31,000 fect 

In rhc Guantanamo Naval Basc accident" tbe pilot was so focuscd on finding a suobc ligbt that he 

rts that thcy werc aPProåching a stall sPccd - - 

rvestiguion of Ai¡ Force C-5 misbaps or ricår- 

son¡c symptotns of faugue a¡e simila¡ 

farigue on.', abilìr¡* to:anend to auxili 

aled ¡o ancntiond focus problcms a¡td 24 Pcrcent 

ological conditions' For example, with 

mes r¡orc n¿urow' very much analogous to 

the effecrs of dconor (HuntJey er al., t i¿. 1973), hypoxia cMcFarla¡d t953)' and 

bc¿r strcss @ursill, lg5g). Dawson and Rcid (lg evaluared pcrformance aftcr l7 bor¡rs awake 

and found pcrformancc dcgraded to a lcvcl equal to that c¿uscd by a blood alcohol coDccntration 

(BAC) of 0.05 P€rcent. nt Z¿ bou¡s, pcrformancc decrcnrens werc equivalent to that of a 0'10 

BAC. After ten hou¡s of sleeplessness, the decline in pcrformancc averaged .74 pcrcent per hour' 

Finally. Harnson a¡rd Horne (19?9) found that slccp loss result 

ideal word or phrase for the idea or thought the pcrson wanted 

loss in intonation and an overall dull¡ess which suggestcd loss 

rhar ùus may very well result in penonal communication probl 

Literalure Reviev 

ä 

4 

ting the 

re was a 

ggest 

Page 5

EfTecs of Fatigue and Steep Loss on the Brrin 

nc¡ion. Hornc ( l99l) states that this restora(ion is 

tcx of thc bra¡n. This is consisænt with the 

timc sincc awake significantly incrcased the 

981) found that dominant EEG @uencics in 

þntiooâl focr¡s. Thcsc EEG changes are 

anc¿ dccærrcnts occur' Howin cr d' (lftt) 

found that under higb workload siruations the 

¡f thosc disPlaYed bY fresh Pilots' 

Anoúer physiorogical ¡ne¿Lsure of fatigue and srecp is bnin grucosc revels. All riszue of the body. 

*.he¡hcr it bc heart muscle, kidneys, lungs, or the brain'sorks electroclrcmically' and conforms to 

one principle: thc more work donc, rhe Ãore fucl uscd. Thus, by nrcasuring glucosc utilization' 

oxyten .onsunl¡ion.and blood flow in the brain, a¡eas whicb afe very activc druing various 

t¿sks ca¡¡ bc determined. 

Thomas er al. (1993), using posiUon emrssion ropography (PET) scan has provided strong 

ph¡srological evidence U"] ,top loss is accompanied by a decreasc in brai'o glucose nrc¡abolism' 

Tbc a¡eas mosr involvsi werc rhc prcfrontal cortcr' thc inferior paneu'l conex' and thala¡nus' 

Dunng 48 houn slee p depnvation, Ú¡e orerall brain glucosc ucilz¿rion dcc-uftcfT percent' whtJe 

rn t-be a¡eas of higher order thinking declines ranged from l0 to l? Percent (Thomas' 1997)' 

r over a 48 hour Pend. Gold ( 1995) reccnt'ly 

ha¡ges could signifìcantJy enha¡cc cogrutire 

ealthy yo{¡ng aduls, elderly, and se rerc sutes of 

Jronr Pabents. 

PET sca¡s of recovery sleep, taken sequentially ttÚough the nighr and sy'nchroniz¡À wiüt EEG 

changes. sho*, that släw ,*,áue slecp appears to have-is greåtest effecs on the sarnc brain a¡eas 

rhar Thomas et al ( 1993, l99z) showed were most afrcctcd by sleep loss (Braun et al., 1997)' This 

rndicates that a¡eas of the brain invorved in are rtness, anentionar focus, concentration. short term 

r¡crDor) . drir e a¡d initiative, problem solving, complex rcasoning' and decision making a¡e tbe 

gt r,.ri be neficiaries of deep sleep Q-amberg' 1996)' 

Sioce the front brain is rcsponsible for analysis of information' judgnrnt' planning' decision 

mahng.andthernitiationofactions.itisnotsurprisingtharNTSBfounddecisionmaking 

abiUues suffered *'ith high time since aw'ake' 

Litera:ure ßet tex 

Page 6

The orderty planning and sequencing of complex trharrors. the abiliry to attend to 

several components simulnneously. and thcn flexibl¡ altcr thc focus of 

concentrarion. rhe capacit¡ for grasping the context and gst of a complex 

siruation, rcsis¡ancc to distraction and intcrfcrence, the abrlqv to follow multi-step 

instructions, thc inhibirion of immediate but inappropriarc rcsPons€ tcndencies, 

and thc abiliry ro sustain behavioral outpr¡t... may each bccon¡c rnarkedly 

disrupæd (Resak, l98t). 

Many of tbc functions dcscribcd by Restak are thc sarne funcúoûs Hcssary to a pilot's ability to 

competentlY flY an aircrafr. 

Meesuring Fetigue 

Although the srudies just lisæd do show perforrnancc decrenrenls dræ to fatigue. other studies 

have strown no effect (c.g., Roscnthal, 1993), particularly *'hen slecp loss lcvels up to 24 hours, 

or small ch¡onic partial slcep loss levels of only one or two hor¡n Pcr day arc uscd. The lack of 

dcfinirive rcsuls in panid sleep deprivation srudies rnây þ duc to differcnces in æsting 

proccdures. Roscnthat tcsted on four scpa¡atc occasions, wþsreås othcrs ¡csæd only once Pcr day. 

in . ror. s€vere stecp deprivation srudy, Thornc (1983) made t-be rc$ilg i¡stn¡nrcnt the primar¡' 

task. *,hich lasted 30 mlnutcs of e¿ch hou¡. As slecp loss bcca¡r imrcasingly greåter, subjects 

became slower, Thereforc, the tirne to complete the sclf-paced t¿sk r¡creased about 70 perce nt, 

and at timcs doubled 

Evans er at ( l99l), in a rcvie'*' of fatiguc in combãt, clearly' stalùJ Lhat gudies using embedded 

testing. such as Thorne (1983). Angus and Heslegrave (1985), a¡d \lulla¡ey et al. (l9El), 

consisrenrl¡,sho* -srearer effecrs of farigue and slecp loss performance decrements tha¡l short 

durarion isolared inrusire tesLs Belenk) et al (1986) notes that Jt^rìtr.rìuouS embedded æsting 

rcr,eals Iarger performance decremenLs soonerthan does interrruaen¡ tesring. [n Angus and 

Heslegrare (1985). anal¡sis of results found a78% decremenl ur en''oJing/decoding performance 

and a 43% decremenr rn logical reasorung afrer 24 hours a*aj¡e H.r:lam (1982), using non' 

embedded testing, for¡nd no decrerncns and 29%, rcsP€ctivel) 

The greater sensitiviry of embe dded æsting is not surprising grcn that tlrey rrrasure performance 

for a more prolonged pcnd. Brief, intn¡sive psychomerric tesls. in conrasq a¡e novel a¡d act as a 

resr break, distraction, and temporary stimulus, thereby incre¿si¡s sbort ærm mobilization of 

effort thus boosting prformance. Tbe use of such an inswment *ould function similar to the 

effecr Chambe rs (1961) found in an i¡dustrial output study when outPul rcmains higher when a 

r*orker was switched to different jobs periodically than to stå)'al ooc job. 

.A.notherexplanation for tÌ¡e varying effects of performance due ro fatrgtrc is that performance is. 

Lileralure Reyier' 

Page 7

in parr, depcndent upon the cr¡cad.ian physiology of úe subject' subjccs cxpcriencing circadian 

dysrhy,thr* o, op.r",ing dunng the' ciicadian trough âf€ rTìcrFC ltkely ro yield substa¡dard 

pe rformance- 

Also, 

"Both 

bchav 

luionship bctwccn fatigue and performancc' 

have a largc impæt on rcsults' particularly t ù! 

cffecs are freqræntly most aPParcot ocar thc end 

of studies (whcrc pcrfornrancc improvcnrcnt is sonrti¡æs for.rnd) but also m¡ly account for rhe 

difñculry in showing ¿or"r*oo L¡y io pcriods of shcp læs" (Bonnct' 1994' p' 5o). 

h 

n 

" 

function. 

s coosidc¡ed to incre¿se scnsitiviry in tcsting for 

rch¡dc conti¡r¡or¡s perforrnancc, prolonged 

;is sbown to wort in dccrerænt ô.8 to noisc 

ravc bccn rcportcd to bc less atrectcd by slccp 

oo lÈ Naitoh. 19?4). Fæigrrc effccs ænd to be 

motivuing. a¡d fccdback is given' On the uhcr 

of newlY acquired skills' and 

s is bccausc wort'Paccd tasks 

*scrve caPacirY of brain 

nreasu¡es 

Roth et al. (1994) supPort loog 

of 

dcærioration 

sleep loss de cremeniand slecp 

bccn 

of skiils o'er rime a promisili 

anempted in a','iation ,o..t"ùUy Neville a al' ( lgg2) 

recordcrs for 

. L - ^L - r---. ^..^. 

rncasuring parafncrers of fligbt over timc. This proccdufe fDrly be the best avenue ya for mrly 

measunn! performance dccrcn¡cnts r¡ an opcratrond sening' 

l\f icræleePs 

performance ¡T€åsures have obvious value for asscssing the effects of fatigue and slccp-rclated 

rch. Mjcrostecps werc fust recognizrd by Bills 

intervening yeå-rs thcy bave also bccn called 

ps." Thc pbysiological drive to slccp can result in 

utcs. The laner ærminology is the result of EEG 

fo nnati on proc es s i n g, su bjects m onpntaril y sü P 

into a light sleep. This occufs with the cyes open an! u-sually *'ithout the knowledge of the 

individual, a¡ observation fi¡s¡ rcportcd-by Miles (1929). Bonnct and Moorc (1982) found that 

beforeYslya*areoffallingasl*p'.¡"yhadbeen 

asleepinconsciousnessimpairperformanccby 

leadin 

on ln se rial tasks that are work paced' 

I)te ra,ure Ret iew' 

Page E

mrcrosleeps can also lead to enor of commrssion a¡d. if frequent enough or long enough, ca¡ le¿d 

to loss of situational atr a¡eness. 

Microslecps have bccn shown to be a uscful approach to asse ssing the effects of tinrc of day on 

slccpiness levels. EEG braln wave changes confirm that pilos expenence greater slecpiness and 

decreascd alertness bctween 2:0O ¡o 4:00 a.m. (Gundel, 1995). Alpha rraves in EECn indicate 

micro cvents or micro slecps and have bccn found to bc threc times grearer during night than 

during day flights (Sarncl. 1995). Sarrrcl et d. (1997) found that during or¡tbound flights, pilos 

expcrienccd 273 microshcps or aD avcragc of l.3t microslccps per pilot pcr hour. On rcturn 

flighs thc fotlowing night, pilots expcricnccd 544 microslecps or 2.47 microslcc¡¡5 pcr hour pcr 

pita. Both fectings of fatigrre and duty tiræ 

progf€,sscd. Rosckind et al. (1994) rogressive increasc 

as flights progressc{ particularly in thc latær por ings confirm botb 

thc physiological occurreoce of microslccps in commercial aviation pilots, and the accu¡nulative 

na¡urc of fatigue in succcsive night opcrations. 

The beneFlcial effects of taking brcaks havc also bccn demonst¡ated by rncasuri-ng microslccps. 

\L'orkers pcrforming continuous tasks without br€åks (Bills, l93l;Broadbent, 1958) orsuffering 

from slecp loss bcgan ro demonst¡atc signs of micro slecps much sooner than those with rcst 

breals or getting adequatc resL resPectively (KjeUbcrg' 1977b). 

Tl¡e resea¡ch cited in this section suggests that fatigue may bc a faclor in ¡he aviation envi¡onrnen( 

due to drect performance decrerne nrs and, rndi¡ectJ), through nucrosleeps that disrupt pilot 

functioning. The next secuon looks at data relari-og ¡o the occurrence of faugue in tbe aviation 

env¡¡oruTle nL 

Fatigue and The Aviation Enrìronment 

The unique characreristlcs of the aviation envÛon¡ænl mav malte prlots particularly susceptible to 

farrgue. Environrnental factors such as mo\em€nt rcstriction. Poor alr flo*', lo* light levels. 

background noise, and vibration a¡e known caus€s of fatigue (\fohler. 196ó). In addi¡ion, tìe 

rnuoduction of advanced automation into tle cockpit has changed the na¡u¡e of the job for man¡' 

pilos. Hands-on flying has been replaccd by greaær demands on the crew lo pcrform vigilant 

mon|roring of thesc systems, a task which people ænd to frnd tinng if pcrforrncd for long pcrids 

of rime. For example, Colquhoun ( 197ó) found that monotonous vigilancc tåsks could decrcasc 

alenness by 80 pcrcent in one hor:¡, which is conelated with increascd EEG theta activity or 

sleep-like stare. Since physical actrvity and inærcst in the task ca¡ he lp to mirumizc the decline in 

prrformance due to continuous r+ork and slecp loss flVilkinson. 1965;Lille. 1979), automat¡on 

may conrribute to increased drowsiness in pilots suffering from fatigue or sleep loss. Also, æ witl 

bc shonn below, rhese cognitire-based activities rnay þ susceptible to t-he effects of fatigue. 

Itteralure Reviev' Page 9

AJrhough these envronment¿l cha¡actenstics a¡e suggestire, the acrual extent to n,hicb fatigue is 

a safet¡' issue ne¿ds to be asscsscd. A srudy of ASRS incident reports suggested thar I lVc oÍ 

incrdens*erefatigue-related Thisñgurewaschallengedb¡ Baker(199ó).whopoinredourrhar 

rhe databasc is a biased sysæm due to sclf rcporting, and the data werc fu¡tìer biased by thc 

rescarchcrs' interprctation of thc rcports. Kirsch (1996) argues that thc âcrual ASRS esrimâte is 

fou¡ to rven p€rc€nt. Graebcr (1985) clarifìes thc siruation as follows: 

tu initial analysis of NASA's Aviation Safery Rcponing Sysæm (ASRS) in 1980 

rcvcalcd that 3.t pcrccot (77) of thc 2006 air transport crew ræmbc¡ crror rçports 

rcccivcd sincc 1976 *r¡e directly associatcd with fatigue (Lyroan &, Orlady, 

l9t0). This may sccm likc a rathcr srnall proportion, but as tþ authors cmphasi2¿, 

fatiguc is freqæntly r pcrsonal cxpcricoce. Thus, while onc crrw trErDbcr rnay 

anributc atr error to fatigr.rc, anoôcr rnay anributc it to a rrþrr directly pcrccived 

causc such as inattcntion or a miscomm"nication. When all rtporu whicb 

npntioned factors directly or indirectly rclated to fatigue a¡e included, the 

pcrcentage incrcascs to 2l.l perccnt (426). Thcsc incidens tendcd to occru n¡orc 

often betwecn 0O:0O a¡d 06:0O flocal ti¡ncJ and during the desccnt, approach or 

landing phases of fligbt. Fu¡tberrnorc, a large rnajoriry of thc rcports could bc 

classifred as substantive, potentially unsafe errors and not just minor errors. 

ln a srudy of fligbtcrcw-involved major accidcnts of dorne stic ai¡ ca¡riers during the 1970 rhrougb 

1990 pcriod (NTSB, 1994), ooc conclusion pcrtained di.nectly to the issue of fatigue: "Half rhe 

capøins ior whom data were available had been awake for more tha¡ ll bou¡s prior to their 

accidens. Half the Frst officc¡s had bccn awake more tha¡ I I houn. Crcws comprising capr¡in5 

a¡rd hrst officers whosc ti¡r¡c sincc awakening was above tbc mcdia¡ for tbei¡ crcw position rnade 

rrrore enors overall, and sigmfìcantly more proccdurd and tacuc¿l dccision errors" (p. 75). This 

finding suggests that farigue rnay be an important factor in the ca¡rier accidents. Because the 

study rnrolredonJydomesticcameraccidens,itremainsunclea¡asto*hetherotàerfatiguerelated 

factors, such as long flght tirr¡es and cúcadian disruption due to multiple trme zones 

r¡ould aJso appear as causative factors. On the basis of this srud¡. the \TSB recom¡r¡ended rhar 

thc FA{ addrcss the issues of flight dury dnæs and rest penods 

AJt}ough the results of this srudy are suggestivc, the acrual impact of fuigue has yet ro bc 

dctcrmi¡ed. Sincc no real effon bas bccn made to identify theeffe¡sof fuigue in accidenr a¡¡d 

i¡cidencc iovestigation, it is difficult to asscss the magnirude of thc problem. In additjon, ir is 

possiblc that sclf-reponing systerns, such as ASRS, rnay bc affected by the inabiliry of pcoplc ro 

accuratcly ¿ìss€ss thei¡ own fatigue levels (Sasaki et al.. 198ó; Richa¡dsooet al., 1982; Dinges, 

1989). Subjective eva.luations of sleepiness have not þen found to bc rcliable excepr in exr¡ernc 

sleepiness. Rosekind and Schwartz (1988) notcd that the scientihc literarurc generally 

demonst¡ates a discrepancy between subjective reports and psy'chophysiological nreasu¡es, rhe 

result be ing underestimations of one's level of sleepiness (cf. Dement & Cankadon, l98l). 

Dement et al. (1978) and Rotlr et al. (1994) reported that some subjecs.¡udged thernselves alert 

Literature Ret'iev Page l0

\ hen in fact they *'ere in thc process of falling sleep' 

Graebe r et al. ( 198ó). summ¡nzing the collaborative efforts tret*een Europran. Japanese. and 

Amencan investigators to e\duate sleep in long haul atrcrer¡s. reported that subjective 

evaluations ile sometirnes cnoneous ÍLs to the true narure of the psychophysiological søæ of 

stecpiness. These rcsults uerc obnined in two scParate srudies by Denrcnt et al. (t986) and 

Sasaki et al. ( 1986). Mullancy ct al. ( 1985) also found that subjecs subþctively felt that thcy 

pcrformed bcrær under slccp loss conditions when paired *'ith anothcr subject, when in rcdiry it 

Lad no effcct on actual pcrfornrance dccrcnænts. Rosckind e{ al.(1994) found pilots unablc to 

subjcctively evaluare changcs in pcrforrnancc duc to a short inflight uep. Although pilots did 

show physiotogical improveu¡cnts in alcrtrrcss, they could not 

Bclcnþ er at. (1994) poios or¡t that duc to thc psychophysiol 

cognitivc judgmcnt a¡e¿s wirh fatigue and slccp loss, thesc ch s 

abiliry to cvaluarc his or hcr own performancc accurately. 

One possible rcason for tbcsc frndings is that the prcscncc of certai¡ fæton masks slccpirns and 

the abscnce of other factors unmasks slecpiness. Envi¡onrnental factors that have a maskilg affect 

includc noisc, physical ætiviry, caffei¡c, nicotine, thi¡st, hunger, cxciærnent, talking about 

somcthing intercsting, etc. fur example, Howia et al. (1978) fouod ttr¡¡ slecP deprived pilas in 

opcrational senings felt no ooticcable farigue oncc flight prcparations werc under way and flight 

conuncnc€d. This explanaion is supporæd by rcscarch that r¡scd the multiple sleep laæncy tcst 

(Dernent et al.. 1986, Sasaki et al., 1986; Rorkind et al., 1994; Roth et al', 1994)' [n conuast to 

rhe subjective ev'aluation. t-hc multiple slee p laæncy test asks subjecrs to quietJy lie do*'n. closc 

their ey'es and try to slecp. This in essence temoves many of the maskrng factors, whercas 

subjectir.e alcnness in relæion to EEG recording aPPears to bave bencr correlation beca¡¡sc both 

ca¡l be rccordcd in rhe sa¡r cnvi¡onmental sctung. Ogrlvie et aJ. 11989) rcponed that zubjecuv'e 

sleepiness responses to t-be Sanford Sleepiness Sca.le onJy reached signiÍrcance uhen subjects 

,*ere entering srage I sleep Thus it nÉy be that ''rhen EEG aJpha and uheu actiriry appcars there 

is truly a feeling of sleePuress. 

AJrhough masking reduces percei"'ed fee lings of sleeprness. it does Drrt courìtÈract the effecs of 

fatigue on performance. Kecklund and Alentedt (1993) conclude that aJthough sleep-depnved 

subjects may not fecl ¡Ì¡cr¡ sleepiness or fatigue due to environmental ranables, the slecp prcssure 

is still latently present. 

Standard Duty Period 

The first regulatory issuc tlat nee ds to be addre ssed concerns the durarion of the standard duty 

perid."standa¡d" i5 r¡s€d bere to refer to dury periods that do not involve n'indow of ci¡cadian 

low (WOCL) effects orriroc zone changes. The pnma.ry focus of the standard duty period issue 

addresses the buildup of fa,rigue as a function of perform.in-s the various lasks tnvolved in adut¡ 

I)teralure Ret ieY+' 

Page I I

pe nñ Six factors that may need to be considered are 

a 

a 

o 

a 

O 

a 

Time on task 

Time since arvake 

Task type 

Duty period extension 

Cumulative duty times 

E¡vi¡onnrcntal factors. 

Each of tlrcsc factors is discusscd bclow. 

Time-On-Tesk 

Therc appeå-rs to be some consensus that thc effects of tinre-on-¡ask on performanc€ ¿trc difficult 

to ¡rssess (e.g., Malrer & McPhec, 1994) a¡d a¡e affected by a number of variablcs, including time 

of day, the narurc of the task, the subject's motivational level, and if fatigue or slccp loss arc 

dready prcscDt (Dingcs & Kribbs, l99l; Maåcr & McPhee . 1994: Mendclson, Richa¡dsoa & 

Ro{h. 1996). [n spite of this, pcrformancc on nuny labontory tasks follows a simila¡ cr¡rvc 

(Vrics4ricver &. Meijman, 1987): relativcly low starting performancc, followed by optimal 

pcrformance, which then declines due, prcsumably, to fatigue. The poinu at which o¡io{ 

pcrformance begins and then starts to degnúc va¡ics witlr the task. For sorne cognitive tasks, 

optinøl performance is achieved afterabout five bou¡s. then dec[nes to its lowest levets afrer l2 

to ló houn s¡ r¡s|ç (Spencer. l9STlNicbolson. l9E?l Sorne tasks. such as monitoring rasks that 

requrre h.rgh ler els of vigilance, show perforrnatrce decrernenls after shoner durations. Colquho_un 

ll9?6) found that monotonous vigilance tasks could decrease alenness b1't0 p€rcent i¡ ooelour 

ba.ed on increased EEG thera activiry *'hrch conelates uith a sleep-like stare. Reducrioos in task 

pe rformance o\ er time a¡e also accompanied br a¡ incre ased need to sleep. as sho*,n b¡,Lisper et 

al rl936t. rrho found thal ca¡ drirers shoued a¡ tn,'rea-.ed lr]tellh.rod of fa.lling asleep afur9 

houn of dnr ing 

T¡.nron-task me¿sures for a single task may hare limited applicabiliry ro rhe aviation domaln as 

the pilot's job involves perform:ng a number of tasks during a given duq' period. Switching 

bet*een i¡dividual t.sks may override some o[the effects of fatigue due to tinre-on-task. Srudies 

which have investigated the effects of extended shift du¡ations on \\orker pcrfornance rnay þ 

re ler a¡t as the!' ass€ss fatigue and performalìce as a function of the set of tasks that are prformed 

during a shift rather than perforrnance decrenrnts that accrue on a single task. In a ma.oufacruring 

enrironn¡ent (Rosa & Bonnet. 1993), the numbcr of cnors made uas relativcly high ar rhc 

be ginning of the shift. then decreased becausc of rc-familiarizâtion u'ith the task. Optirnal levels 

'*'erc reached r*ithin a few hours. then declined over the eight-hour shift. In general. worliers on 

l2-hou¡ shifts becamc considerably more fatigued than in more traditional eight- ro lQ-bour shifts 

(Ros¿ & Colligan. 1987) Tlis fìnding has been \.'onfirrned in nurses (\f rlls et al., 1983). indusrnal 

Literoture Ret iev Page l2

shift *orkers (Colligan & Tepas. 1986). night shift *orkers (Rosa & Colligan. 1987). sea *'atch 

*orkers (Colquhoun. 1985). and truck drirers (Hanrelin, l9t7). The laner stud¡ also found an 

increase in the numbrr of accidents that o\-cur *'hen I 2'hour shifts are used. 

This increascd likelihood of accidcnt risk due to long duty pcriods has becn found in other 

srudies. The relative risk of an accident at l4 houn of dury riscs to 2.5 times thar of the lowest 

pornr in thc f-rst eight hours of dury. Askenedt (1995) rcports accidcnt risks to bc th¡ecfold at l6 

hours of duty, whilc Harris and Macki e (1972) fo¡nd a th¡ecfold risk in just over l0 houn of 

driving. These levefs of risk a¡e simila¡ to that associaæd with baving narcolepsy or slccp apnca 

(L-avþ er d., 1982), or a blood alcohol lcvcl of 0.10 pcrccnt. Wegmann et al. (19t5), in a srudy of 

ai¡ carrier pilots, argucd for a duty pcrid of l0 houn with t.5 hours or less of flight duty pcriod. 

Time Since Awake 

The rcsults of an NTSB analysis of dornestic ai¡ carricr accidens occurring from l97t to 1990 

suggest thu time sincc ar*'ake (TSA) was the dominant fatigue-relaæd factor in these accidents 

(ì{TSB. 1991). Pcrformancc decrerncns of high tinrc-sincc-awake crews ænded to rcsult from 

ineffecrivc dccision-making rather than dc¡erioration of ai¡craft þ¿¡¡dling skills. Thcsc dccrcn¡cnts 

were nor felt to be rclucd to tirrrc zone crossings sincc all accidens i¡volved sbort haul flighs 

*,ith a rna¡imum of ¡wo tirne zones crosscd. Therc did appcar to bc two pcåks in accidents: in the 

morning when ¡irne since awake is low and the crcw has be¿n on dury for about th¡ee to fou¡ 

hou¡s,anduhentime-since-awakewash.rgh.above l3houn.Similuaccidentpeatsinother 

modes of rransportauon a¡d industry hare also bcen rcportcd folkard. 1997). Akerstedt & 

Kecklund (1989) srudied pnor trroc a*'ale (fou¡ to l2 hou¡s) and for¡¡d a st¡ong correluion of 

accrdenrs uith tirr¡e since a*'ake for all omes of the da¡'. Belenþ et al. (1994) found that flight 

time hou¡s lr¡orkload) greatlv incre¿se a.îd add to the lineardecline in prrformance associated 

uith unr srnce a*'ake. 

Task T¡'pe 

The effecu of rask typ€. as they conrribuæ to the buildup of fatigue. need to be considered from 

t\Ä o p€rsPe ct¡\'es: 

o \\hether certain ac¡ivities can be excluded from duty period time 

o \\"f¡erher certain actjvities are inherently more fatiguing and may need to be restricted. 

The cunenr regulations regulate only flight time. No limits are provided for dury tirnc. The 

resulaiions proposed in the Noticc of hoposed Rulemaking 95- l8 (ì"PRM) allow for the conccpt 

of "assrsned time," which also is uffegulated as to maximum limits Tle extent to uhich 

acriuries caregorized as non-flight time or a-ssigned time contribute to fatigue has ¡,et to be 

Ulerature Reviev' Page I 3

emprncalr ascertarned. However. it is clea¡ that thcsc activitics would contribute to fatigue in the 

form of trmc since a*,ake. consequenrly, ir ma¡ tr appropnate to limit rìese acriviries in eirher of 

t\r o wa) s: 

o \À'i¡h rcspccr to when they occur rclative ro flight ti¡nc so as ¡o avoid pilos achieving high 

tirrt.since-awakelevelsduringflighttirrreperiods. 

o hor.ide maximum levels for these acúvities comparable to duty Pcrid tinrc levels. 

othcr duq pcrid activitics. Bec¿r¡sc hea¡t rate in r - r-r - 

suggests öar proposals to limit landings for flighs rhat have other bown fatigr¡c faaon (c'g., 

tinre sincc awake, window of ci¡cadian low, cxtcndcd flight dury periods) may bc appropriue' 

The rclarionship bctween task tyPc and fatiguc buildup in thc aviation domain rcmains to bc 

derermined. The demands placei on rong-haul pi.ros are crearly differcnr from thosc of the 

: lþrdri ve n airpl anc witb I'imitcd ar¡ to rnari oo. 

lc lcg of si¡ or rmre hours. Thc mai¡ task'rclaæd 

rritive fatiguc due to vigilancc. Thc rcgional pilot. 

luc to the high wortload involvcd in pcrforming 

six or morc takeoffs and tandings. For this rcåson. it may prove nectssafy to develop s€Paratc 

regulations that a¡e appropriue for each major tlPe of ope ra¡ion' 

DurY Period Extensions 

The rese.¡-.'h cited on dury'PeriÑ duration sug-sesLs that duty pe nods at or above l2 houn a¡e 

a:sociaæd *rth a higher nsi oierror Thrs factor. together *'ith the trmc-si¡cc-a'*aIe fa.-tor, 

suggesrs rlar extend-ed duty pe nods also inrolre a higher poæntial for crew efror' In determrning 

maximum hnuts for exrended duty penods. consrderation a.Ìso needs to be given to other fatiguerelated 

facrors rhar could contnbure ro excessire fatigue levels during e¡ænded dur¡' pcriods. 

includine number of legs. wherher the flight impinges on thc *indow of ci¡cadia¡ low (1\'OCL)' 

and tirne srnce arl'ale, 

Cumulative DutY Time 

No data,¡ere found that provide guidance for maximum dury tirnes over longertime penods, such 

as one month or one Ye¿u. 

Literalure ReYiev' 

s 

Page l4

Environmental Factors 

The ph¡sical environmenr of rhe co.'kpit is a source of other factors tà¡l can conrnbute to fatigue 

r\fohler. l9óó) Factors such as vibration. poor ventilation, ooise. and thc availability of limiæd 

auromarion can contribure to rhe buildup of fatigue or accelerate its oosct when coupled with time 

since a*'ake. numbcr of tegs, and whetlrcr the fìight involvcs thc I#OCL. This may hate 

impticauons for regional c¿rricr pilots who fìy propcller{'riven ai¡cr¿ft. 

Conclr¡slons 

Tlrc resca¡ch ciæd suggests an incrcasc i¡ the liketihood of crror as Ory Pcrids a¡e extcodcd 

bcyond l2 bor¡rs. This finding is cspccially critical for exænded duty pcriods whicb are likely to 

occqr under conditions (e.g., wcuher) tb¡t, in and of thernsclvcs, rDay incrcase thc probability of 

crew efTor. 

The interactions be twecn multiple fatigue-rclated factors must also be considered. Scparaæly, 

dury pe riod du¡ation, tirnc si¡ce arlake, number of lcgs, and envi¡onmtal factors cont¡ibuæ to 

fatigue buildup. Wtren ¿rny ooe of thesc factors reaches a high level, coosidera¡ion should bc 

given to rcducing thc maximum allowable levels on tbcsc other factqr Tiræ sincc awake also 

has obvious implications for rescne assignrnents and for pilos who mmutc. 

Standa rd Sleep Requirements 

Standard Sleep Requirements end Off'Duty Period 

There is a generally consisænt body of resea¡ch whjcb demonstrates t-h¡ most pcople requre an 

a\erase of t houn of sleep pr ni-eht to achreve normal levels of alerocss tfuoughout daytt¡ne 

hours *.irhour drowsiness a¡d to aroid tlre buildup of sleep debt (C¡ntadon & Demen¡, l98l: 

\\'ehr er al.. 1993). This figu¡e is bascd upon a range of srudies that r.¡scd several approaches. 

rnc ludins. 

o l-Ilstorical levels of sleep 

o }leasures of da¡iroc alertness 

. Sle€p tevels achievcd when given the oppornrniry to sleep as long as desi¡ed. 

Webb and Agne*,(1975) reported that habirual sleep around the rur¡ of the cenrury was about 

nine hours. A 1960 srudy of more than 800,000 Anrericans found tha¡ l3 Percent of men and l5 

p€rcenr of '*omen, ages 35ó5, slept less the seven hours with 48 PercÊnt of both obtaining less 

rhan eighr hours of sleep pr nighr l,L'ake Up America, 1993). B¡ 1977. one in eight Anæncans 

I)terature Review' 

Page I 5

eponed gening sú or feuer hours of slecp pe r nighr {Schoenborn & Danchik' 1980) Br 198-ì' 

jusr six yiars later. rhat number had jumpcd to one rn four (Schoenborn & Cohen. 198ó). 

The average distribution of habitual sleep ranges bet 

ht' and 

includes 95 pcrcenr of rhe adutt population with an a 88). Most 

researchers scem to agrcc with this fìgurc (['cvinc ct l99l' Dinges 

ct al.. 1996; Bonn., d et"nd. 1995)' However' \l'cb indit'idual 

differences in habirual sl€cp in a samplc of morc tlran 30,0oO individuals from I I industrial 

counrries. In rhis srudy ¡wo pcrcent werc rcporæ/ to slccp less than five houn pcr nigbt whilc 

five pcrccn¡ reporrcd stæping morc than l0 hor.¡rs. Thesc aycr€es bave bccn rcportcd in simila¡ 

findings across various populuion grot¡Ps' 

Most rcsca¡cbcrs advocac an avcrage slæp requirerncot for aduls of 7.5 to t.0 bours pcr day 

(l-cvine ct al.. lgtg: Ca¡skadon, & Roth, l99l: Dinges et al., 1996). Although early oo, Denpnt 

et al. (lgg6) indicated tha¡ g hours was ncccssary for optirnal alertncss throughout thc day, Hornc 

considered 6 hours ..corc slecp" sufficient. Although Horne's advocacy of 6 hours core slccp has 

detracæd soræwhat from what most slccp rcsca¡chcrs now fecl to bc optimal slccp, it hæ not 

dislodged thc weight of evidence. 

carskadon ( lggl ) rcpons tlar t? pcrceor of college srudents habitually slecping scven to 7.5 

thc aftcrnoon with 60 perccnt rcponing acnrally 

lvocaung only 6 hou¡s of "core slecp," thcr 

ljers specify a habirual amount of slecp above 

nt. The six-hou¡ core arnount does Dot s€€m to 

apply to many. bascd upon the sclf-pcrceived adequacy of slecp' 

Roeh¡s er al il9g9l sho*.ed rhat *'hen shoñ or long sleepcrs were re4uire.d to slay in bcd for ten 

hours. alJ :ub.¡ect_s sle pr abour a¡ hour longer ùa¡ usual. The result was that all subjecs unprored 

in theú alenness. rigilance, a¡d reacúon time necded for dnving or morutorl.ng modero conuol 

panels Dlr ¡ded anention pe rformance showed sigruficant rmproren¡ent, ud cent¡al øsk 

pe rformance sho*.ed some*,hat bcner improrerrlent rhan pcripheral task prformancc. Da¡rime 

sleepiness decreased for both troups. but ro a grËterextcnt for the individuals who prcriousl¡' 

reporred suffering from slecpiness. Subjecrs uho'*erc usually slecpy *'ere morc alert, a¡d those 

u.ho usua¡¡ functioned at a high tevel be¿ame eien sha¡Pe r (Ca¡skadon et al'. 1979) 

A_llou.ing just one hour extra sleep pe r night over four night rcsulted in a progressive rcduction in 

da¡,time si.e piness of ncarly 30 pe rce nt '*r¡¿¡ ¡eåsured by the Multiple Slecp latency Test 

tViSlf l. ,{Uo*'ing stecpers who r¡'pically slept ? -í hou¡ Per day to sleep ad libitum, otiet 

resea¡chers found that sieep tirne increased2S perc€nt from 7.5 to 9.6 houn' (Taub, l98l:webb 

& Agneu.. l9?5). Taub ( I 976) srudied the magnirude of differences berw*een regular (7 to 8 

hours) sleepers and long (9.5 to 10.5 hours) slecpen when their slecp tr'æ phase shifted t¡re€ 

hours for*a¡d or backwa¡d. They'also examined changes when both groups had sleeppnods 

I)teralure Rettew 

Page I6

exrended or reduced ,{,lthough resulLq shoued degrecs of impairmenl from the acuæ alterations in 

rr sleepen consistently showed grcater 

) found that extending the total tin¡c in bcd from 

lo*ed thcm to incrcase tl¡ei¡ total slecp tinrc on 

grufrcant improvenrcnt in daytinrc alerhcss 

tended slccp. suggesting a rcpaying of slccp debt. 

Thc rcsea¡chers fclt thar ¡his improvemcnr supporæd suggestions that eight hor¡n of bcd tirnc rnay 

rcprcs€nt a ch¡onic slecp dcprivation c 

søir-step rcsPonse with thc lcngth of s 

scones for alertncss were bancr for æn 

and two nighs witb ñve hou¡s werc betrcr than s 

than scorcs with no slccP. 

)3) found in a foru-cieck tcst thu yotrng adults 

excess of l0 bot¡¡s a day during tbc fust thrcc 

) bours. The rcmai¡dc¡ of thc 28 days lcvelcd off 

ral base-line slecp wasT .2 boun. Thc initially 

of ch¡onic slecp dcbt A similar slccp 

a Walær Recd rcsc¿¡cb æ¿m (1997) in an interim 

toncal data indicue that optimal slecp 

;lecp with an averate of about 8'5 hor¡¡s, 

The be nefirs of slecp are presenrly considered ro be logarithmic in narurc, *'ith the initial boun 

showrng significantiy treårcr 

be nefirs ùrat diminish as ooc approacbcs his o¡ her optimal sleep 

lerel. This accounts for bo*'nrany can slecp less a¡d appar to still function normally. Ho*ever 

the findings of Roh¡e (lggg) and Taub and Berger t1976) indicate that during the fi¡st si¡ hours 

of sleep. pe rformance is resrored ro a sarisiactor¡ lerel under normal conditions, although 

ajenness and rigor ma¡,srilJ be diminishec In r-he houn bey'ond sLr houn of slecp the restoration 

process further restores alenness and vigor a¡d ¡he bral¡'s capaciry to handle siruadons above 

that of normal and for longer priods' 

,â,neramplcof rhisisbcsrillusraædby Sarrrl eraJ.(1997) whercthesecondof rwonightflights 

showed a considerable reducúon in ¡otera¡,'e il)d a¡ rncreasc in fatigue aftcr only th¡e¿ houn of 

flighr whereas on rhe hnt night fatigue did nor sct r,n until after t hor¡n. Tbt¡s. thc additional 

hours served as a res€r\.e capacity againsr norkload (Howin et al.. 1978) orhou¡s of duty (Sarncl 

et al., 199?:Gundel et d ' 1997)' 

l)teralure Ret teu 

Poge I7

Other Variables 

tndividual Differences In Sleep Requirements. Many of the srudies describcd above showed 

that there appears 

iliry in individual sleep necds. Thus, the eight'hour 

slee p rcqui¡erncn¡ 

lecp nceds, but does not take into account of the 

n"".i, o¡hosc ind 

onal slecp and who represcnt a fair perccnt of thc 

population. 

Age-Reletcd Ctanges 

nightly slccp dr.rc to inc 

1980; Carskadon ct al., 

individuals. habiruat nigbniræ slccp is ¡ìccomP¿u 

dosing. and napping.Thit incre¿sc in 

quantrry and appcÁ to indicatc that s 

tif.tim. Miles & Dement' 1980; FIab 

næmbe rs may have particular diñìculties in achie 

schedule (cf. Ca¡skadon, Broum & Dcrncnt, 1982)' 

normal slecp 

person's adult 

older crcw 

a normal dury 

Logist¡cål Issues. A number of srudies have investrgated thc issue of the amount of slecp that is 

,.*^tty achrere,J as a function of rhc length of the off-dury p€nd Tbcs€ studies demonsLrate 

tbar ofidurl, penods rhat appcar to provide an acceprable slee p oppornrnitl may not' in rcaliry' bc 

sufficienr. In one srudy...àú.uont in slccp of t*'o to th¡eehou¡s pr24 bou¡s occurrcd when tbc 

r rme be r* ee n shrfts oi work was rcduccd to only' n ine hor¡¡s (Knauth, l9t3). In the NASA srud ies 

of shon.haul prJou (Gander et al . 199.1:Gander & Graebe r, 1994), pilos reported an average of 

ll 5 hou¡s off-durl rinr bet*een dutr penods, but onJ¡ obained 6.7 bou¡s rcst. 

Obsen auons of nurses on l2 hou¡ shifu *ork-rng ll.5 hours * irtr I I .5 hours off bctri'etn shrlts 

obtaine,J an a\.erage of 6 9 hours sleep (Ìvfills er d.. 1983). ,q.nother srudy of long-haul and short 

haul-rruck dnrers 1,1yRAJR, l997lsho*ed that short-haul drirers r¡irh sirrula¡ rest penods 

bet*'een shifu obtained ercn fe*er slecp durations 

Commercial rn¡ck drivers' (FI{\I'A, 199ó; Mirler et al., 1997) sleep/off duty schedules a¡e shor¡¡ 

i¡ Table l. \\'hen rruckers (cl-10) had 10.7 houn off dutl'bet*een l0 hourday shifts, sleep 

durarions of onJy 5.4 hours werc achieved. On a l3-hour day shift (C1'13) with 8'9 hours off 

berw.een duty periods. sleep durarions averagcd 5.1 hours. On l0-hou¡ routing shifts (C2'10) uith 

g.7 houn off dur¡ , the sleep rinre r+ as 4.8 hours and after a I 3-hour night shift (C3- l 3) witÌ¡ 8.6 

hours off. rhe re sulting sleep diminished to only 3.8 hours. In quick changeovers *'ith 8 hours off 

ber*.een shifu. Tonerde¡ tigg0lfound rhat *orkers only acquired 5.1-l hours sletp. Kurumata¡r 

r 199{) found a;crrelauon (r=.95)berween the hours betr*een shtft and sleep duration. The¡ 

Lileralure R¿t lf r. 

tual 

Page I 8

concluded (hat at least ló hou¡soff duty tirnc *ere needed.bctç'ecn shifu to ensure ?-S hour 

sleep. ¡ conclusion reiterated in a recent review (Kecklund & Akentedt' 1995)' 

Tablel.Truckdriversshiftr¡pea¡doffdutyhoursinrclationtotimesPentinþdand 

sleeP tirne' ( 1996) 

leep betwecn quick shi-fr changeovers may bc tbe 

orsvall and Akerstdt (1988) showed that ships' 

ecreased qualiry of slecp * hich thc¡ anributed 

sicians in smaller bospitals and appcan to be 

*'ing day (A*erstedt & Gillbcrg. 1990)'- - 

Other reasons for ùe lo*'leyels of actual rest achiered is due to the other actirities that must b€ 

ç,e rformed during the off-dut) FËnùc For pilots on la¡o\eFs' these actirities include Senlne to 

a¡d from the hoter. rne ars. and prsonar h¡giene. Thesc acti'vicies creuly take a*ar from the unr 

available to sleep (Samel et al ' 199? I 

Reduced Rest 

Condition 

Cl-10 daY 

C3-13 night 

C4- 13 daY 

Houn off'dutY 

Hours in Bed 

rsiological and task performance has failed to 

nay be reduced before a signifìcant impact on 

i ,*ere described previously in tle section entìtled 

981) reduced subjecs' sleep to onll frve hours 

:nl increase i.o sleep te ndcncy. Bascd on this 

nclude that as little as two hou¡s of sleep loss can 

:tions in alertness. V/ilki¡son (1968) r'aned sleep 

î^^^r J-^.oo.o¡ iquantit),b¡dIo*,ingsubjecs0.l.2'3.5,or7.)hoursin*.hichtosleep.significantdecre¿sesi¡ 

Lilero¡ure Ret iew

.igilance performance \r'ere found the follo*ing de-"" *hen sleep'*as reduced belo* th¡ee houn 

foi one night or [e*er than fir'e hours for tuo conrccutive nights. Cankadon. Haney and Dcment 

( lggl ) found ¡ncreased daltime sleepiness. as rrriured by the ¡vlSLT. after one night of slerp 

reduced ro four hours in a group of l2-year-olds. although pcrformancc decrements \¡'ere Dot 

found. 

Restriction of sleep in young adults to jusr 5 houn increases sleepiness on the MSLT the next dar 

by 25 pcrcenr and by 60 pcrccnt the scvcnth day rCankadon & Derncnt, l98l). rWhco slecp was 

rcduccd to five hours or less. perfoffnancc and dcrtncss sr¡ffered and slecpincss significantly 

increascd (Wilkinson et al., 196ó; Johnsoo, l9t2: Carskadon & Roth, l99l:Gillbcrg & Akerstcdt 

1994; Taub lt, Bergcr, 1973; Ca¡skadon ll Denrnr. lgtl). A reccnt snrdy of Ausralian tn¡ckcrs 

for¡nd that 20 perccnt of drivcrs slecp 6 hours or less a¡d æcor¡nt for 40 pcrcent of thc hazardou 

cyenrs rcportcd (Arnold et al., 1997\. Drring Opcration Descn Storm, tbc pilots of thc Military 

Airlifr Cómmand flighs obtaining only I I hor¡¡s slecp in 48 hours werc found to bc in dangcr of 

experiencing diffrculties i¡ concentrating and su¡ ing awake (Ncvillc et al., 1992). Furthcr pilot 

oblrvarions indicated that to prevent fuigue in tbesc pilos. at least l7 hours of slccp in 4t bours 

(?.5 hou¡J 24 hours) werc requi¡ed 

Dinges (1997)showed sigoificant cumulative effects of slecp debt on waking functions wbcn 

subþs werc rcsrricæd from thci¡ usual 7.41 hor.rn slecp to only 4.9t hou¡s (sd .57 hrs) of usual 

steep (67 percenr). Across rhe scven oreigbtda¡sof slecp rcstrioion subjccs showcd increasing 

levels of subjecrive sleepiness, fatigue, confusion. tension, nrcntal exhaustion indicators, sùess, 

and lapses in,-reasing ih frequency and duration These escalating cbanges prol'ide strong 

evidence that partial sleep rcstriction similar ro ¡-hat experienced by pi.los has cumularive effecs 

simlla¡ to thosc found rn total or morc excrÊfne pafttal rcstriccion. 

In conrra-st. Hocker's r1986)anal¡sis of pa,rid sleep depriration srudy findings revealed rrunimal 

performan.-e changes bur rhere *ere sigruiì:¡nt rtJuctions in rieila¡ce, efhciency. and increased 

subjective sleepiness *ith a¡d mood detenoratloo 

These resulrs suggesr that rcducing rest b¡ an hour should have linle impact on a pilot's 

pe rformance ri rhe pilor is *ell rested prior to the reduced rest. If the pilot is suffenng from sleep 

debt prior to the reduced rest. there may be an rnpact on the pilot's performancc. If so. a reduced 

dut¡, pe nod should follow rhe reduced rest pe riod Ln order to comP€nsate for the possibility tiat 

the pilot may' bc more susceptible to tirnc.since-au ake effects. 

Required RecoverY Time 

Complete recovery from a slecp debt may not oc.-ur after a single sleep period (Ca¡skadon & 

Dernenr. 1979: Rosenthal et al.. l99l). Typicall\. two nighs of recover-r are required (Carskadon 

& Demenr. l9?9: Kates er al.. 1970), atthough t-be required recovery P€nod may depend on the 

lengrh of pnor *'aliefulness (Ca¡skadon & Dernent. 1982). Forexample, Kales et al. (1970 found 

U te rat ure Ret ie¡ 

Page ?0

thar re:tncrrng sleep to 5 hor.¡¡s pcr night for ? da's' which morc closel¡ rcscmbles cre*'slecp 

p¡(rerns. requrred ;i; ; singleirtenãtJ nignr of sltep of l0 hours for full reco\er]' \f orris 

( r996) foun,J ratigul-reiultiig from rhe rosiof 1.5 hours of srecp in one ru-shr uas nor adequatel¡ 

rcsrored in spite of t hours oislecp on one recovery night' Srudies of C'l{l creus fì¡ing to 

sourheast Asia during the viemam conflict found uairtr¡ee nighrs werc required bcforc slccp 

rerurned ro normar åi,i. fou¡rh nigt,r irt.nma¡r. lgTl). These rcsuhs *erc obscned even rhough 

the crc,*'s averaged 7'5 hours sleep pcr nrght' 

rhc rcscarch arso susscsts ùat ! fiiî.HffiiTt:t#* 

effective if rhc slccP oPPornrniq 

supporr efrcctive uútiåion ort 

;lccp gaincd depends morË uPon 

ngrh of prior wakefulncss 

the circadian pbasc a¡ whicb slc 

(Strogatz. K¡ooauer & Czcisþr' 'l'' 1975)' 

Conclusions 

There appcars to be substa¡ciar e'idence thar a minimum of eigbt hours of srccp is required for 

most pcopt. ,o .rr..,¡u. lc"ets of alert¡¡ess and pcrfor*-".. This rcsr þver dso caables 

""ui.* 

rhe individu¿r to copc with reduced rest should the necd a¡isc. Achieving tbc required eight bours 

under la¡,over .onã¡,ion, depnds upo-n the length of the offdury P€rid' Tbc dalå suggesl that an 

off_dut¡ p€nd hours'may noi b. sufficient ro supporl an eight-bo.r sreep opporturury' 

"fi;; 

Reducingr}rercstpenodblanhourshouldbavelinleeffcctgn.P'iIo."Ii:ïandperforrnanceif 

the indiridual is *eU ""tå' Reduced sl€cP' r*'ben aceompanied b1'an'exrsting slecp dcbt 

.Jrminishes p.rio.n.,"n.e and rhe auiliry orthe individuar ro mainain arertness rhroughout the dury' 

p'enoJ e s:'e .-rallr rf a long ttme since ¡u ake is involved' 

Recoren fromsleepdebtoftcnrequwst\,\orughrsof 

rest T}usrcsultputsintoquestiontìe 

sffsç!¡r.eness of extending r-he off-dutr Pe nd fãllo*ing a¡ exænded duq peno*J Also' if no 

sreep debr is alro*ed ro a-ccumul.r.. ii i, not clea¡ rhar *eekj¡ breaks a¡e required Howerer. rhe 

data suggesr rhat sleep debt is likely to accumutare if l0-hou¡off-dutv pnods a¡e uscd' 

The Circ¿dian CYcle and Fatigue 

B iol ogical Circad ian Rh]'th ms 

Chronobiolog¡,is the srud¡ of time'dependent changes in'a¡ious levels of the phy'siologic 

o r g an r za u o n ¡, o.", r'' ll;;' ; * þ 

.1 " lî : J :- :T,:;)l "l: :'" : : ",ï1i.îå1 i î i' Ï:i 

:lt"Ëi:.äiÏir'r;;;;, rn a predictable rh¡rhnuc fashron a¡d a¡e refened to as osciuations 

Lit¿ r;ture Rer lex 

Page 2 I

The oscillarrons appear as \ a\es, and the time to complete one full '*'a\e !-ycle is called a 

"çrenod." The¡ are dirided rnto th¡ee -sroups by'lengrh of ¡le rh¡thm L'ltradian are rh¡rhms of 20 

hours or less. Crrcad¡an encompasses rh¡rhms bet'*een 20-lS hours. and Infradian a.re rh¡rhms 

grearer tha¡r l8 hours The laner include rhythms called circaseptan 17 days, t 3 days). 

circadiseptan (14 days t 3 days). circavigintan (21 days, t 3 days). circatrigintan (30 days. r 5 

days) and ci¡caa¡rnual (one )'ear. t 3 months). According to Haus & Touitou (1994) thcrc is 

cvidence of 7 dzy,30 day a¡d annual rhythms in humans, as well as the circadian and ultrdia¡r 

rhythms. 

Circadian rhythms have bcca recognizcd for dccadcs. Ye¡ thc biological clock that regulatcs thc 

24-hour physiological a¡d bcbavioral rh¡hms was not idcntificd until the 1970s. Tbcsc t*o 

bilaterally locaæd nrrclci cellcd thc suprachiasmic nuclei (SCN) a¡e locarcd above thc opth 

chiasm in thc antcrior hypothalamus. Tbcsc nrrclei arc coosidcred the circadian pæcrnalcs 

Destrucrion of thcsc nuclei producc an arrh¡hmia and scverc disruptioo bctwccn bchavior and 

physiological pararncæn including the timing of food i¡take and slecp. Thcy appcar not to 

rcgulate thc amount of cither of these behaviors (Turck & Recth, 1996). 

Signals produccd by the SCli a¡e botb hormonal and neuual. Graflcd nuclei withot¡t ncurd 

connections restorc ci¡cadia¡ rhythrns of eating and activiry. Mcluonin sccrctions, howeve¡, a¡t 

not restored, suggesti¡g neuÍon control. MelUonin reccPtors bave becu found in thc SC?.f and 

appear to bc part of a fecdback mechanism thar causcs shifu i¡ thc ci¡cadia¡ clock. Tbc SO.f has 

bee n found to possess its own built-in rh¡hm. Ev'idencc gathercd thus far indicares that SCÎ{ 

receive i¡for¡ation about the light-dark cycle via t*o neu¡al pathwal's fromthe optic nene. one 

from the retinohy'pothalamrc t¡act and the other tfuougb the genicu.lohypothalamic Fact. Tbc laner 

path*a' appcå¡s to pro\ide inforrnation or signals tlrat bclp witå recnrr¿i¡¡ænt a.ftcr a shiñ i¡ thc_ 

lighr-dark c¡cle. Bur reccit rese¿¡ch appea¡s to indicate tàat otler photo receptors may also Þ 

inrolred i¡ the entrilrunent process rCampbell & \lurphr. 1998' 

Peaii lerels oiph.\srolragrcal functronrng, occur dunng the [rght pha-se of the Ught/dark c¡cle This 

sy'nchronizalrr--¡n of ph¡sroloercaJ rh¡thrns enhances *ork pcrformance during the da¡irnc and 

supporrs slee p at rughr b¡ rurrung dox n the rne nbolrc thermosut The internal synchronizarion of 

rhe ranable metabolrc p¿rram€ters *ith the light/dark cyclc are runed for optimal functioni-og. 

Over 100 b'rologr;al rh¡rhrns are geneùcally generated withrn the human body, then enrai¡ed or 

synchroruzed to bener *ork in concen 1'Wehr. 199ó; Talahasi, 199ó). The greaær the 

synchromzation bet,*'een hormone production. nrclabo[c rale. enzyrnc a¡d neurotransmiue¡ 

s) nrhesis. r}e hLgher tle amplirude of the rh¡hm and the gre¿ter the communication ber*ecn the 

body's cells Thus, tìe maintenance of a suong circadian rh¡hm ca¡ries with it considerable 

ramifications for good heållh, *ell-being. and functioning Cw*eiu. 19961. 

The suprachiasnuc nuclei, togetlrer'*itb the pineal gland, function as rneøboüc a¡d behavioral 

concen conducton n cue *ith enrúonmental facton such as hghVdark. næal timing. social 

inreraction, and phrsrcal activity. This synchronization of internal and behavioral *'ith the 

Li leralure Ret rex Page 22

e\rernal en\rronrrcnt around the24 hour da¡' \circa--about: dies-4a¡')is callcd ci¡cadian rh¡-thm 

entralnfT¡€nt. 

AJrhough o¡her internal a¡rd cxternal factors do ptay a role, thc light-dark cycle is the major 

enrrainrncnt factor for most of the animal kingdom. For huma¡s. though, thc Light-dark cycle is 

fett to be a rclativcly weak svnchronizarion of 

","*:ffiîïïil#iffit;täneåsons' 

inæ nsiry requ ired for c i¡cadia¡¡ sync hronizari on 

rstimatæ re.ngc from 120G250O lt¡¡ (Reinbcrg &' 

re adcquacy of indoor tigbting. Sccon( man is 

ht cyclc. 

Sociat environnrcnt appcafs to play a fûoFe important rolc i¡ cntrainrænt sæial factors tbu can 

rhythrlts includc tcmPcrarurË. flight duty, stess, 

I & Wcgmann, 1987). Exercisc or activity dso 

ption. Ferrcr et al. (1995) ci¡e evidcnce ¡hat 

rts to shift work changes regardless of irs 

ically frt and cxcrcisc rcgularly havc highcr 

als, and those with high circadian rh¡hm 

er et d., 1995). This belps to cxplain u'hy age' 

to incre¿scd sleep diffrcultics' poor adjusÙn€n¡ to 

night uork a¡d transnæridian flighs in thosc over 50' 

Back oi the CtocX Operations, Circedian Rh¡'thm ¡nd Performance 

There rs a subsrantiaJ bod¡ of research th¡r sho*'s de.'rea:sed pe rformance during night shifts as 

compared uirh day shifts. The reasons for tlus decrcased prformance tn;lude: 

o CLrcadran Pressure 

to sleep when the rndir idual is anemPting to *ork 

o Cúcadian pressure ro be awake when the i¡dividual is anempting to sleep 

o Time s,nce a*ake r¡ay bc substa¡rrial if the individual is up alJ dav bcfore rePonin-E for the 

nigbt shift. 

.Cumularivcsleepdebtincreasethroughoutrheshift. 

Rese¿rch conducted by Monk et al. (1989) indicates that subjecute alenness is under ¡he control 

of the endogenous ciróadia¡ pacemaker and one's sleep-wakc cycle (tinrc since a*'alte). \åften 

tirne si¡ce au,ake is tong and coincides with rhe circadian lo*'there is a very sharP drop in 

alerness, a s¡ong tendÃc¡'ro slecp a¡rd a significant drop in performancc (Perelli, 1980)' 

Alenness is relatively higb when the ci¡cadian rh¡rhm is ne¿¡ the acrophæc and tinre since a\[alie 

is small. Nfonli (1996).r!u.t that this c¡cle is consistent with the NTSB (1994) frnding of a peak 

accident rare occurring irithe evening. The srrength of the ci¡cadian clcle is substa¡tial Alerstedt 

Literoture Retiev' 

Poge 23

,1989 )argr.res that. up to 24 hou¡s without slecp, crrcad¡an influenc¡s probabl¡ have greater 

cÌTects tha¡¡ time since awake. 

ln Japan. 8J..1 percent of d¡o*siness-related near accidens in elect¡ic motor locomotive dnr6¡5 

rKogi & Ohtå" 1975) occur at night. Othcr landma¡k srudies ovcr the past scveral decadcs 

bave docunæntcd the increasc in accidcns and crror making. Klein et al. (1970) argue that thei¡ 

resca¡ch uitlr simulators proyes that night flighs are a gr€åtcr risk ùan day fìights. Thei¡ rcscarch 

fot¡nd 75- to 100-pcrccnt rrìcan perforrnancc efticicncy dccrcments i¡ simulator flighs during the 

carly rnoruing bours, rcgardless of extcroal fætor s¡ch as darkncss or increasing night tra-ff¡c or 

possible *'e¿ther conditions. 

Task perforrnâncc in a varicry of nigbtiù6 has bcen comparcd with pcrformancc of tbcir dayrtnrc 

co.¡nrcrparts. and rcsults consisæntly show dc¡erior¿ion of pcrfonnance on the night shift. 

Browne ( 1949) srudied tclephonc opcraor:s' responsc tirnc in answering incoming callc in relation 

ro rhe bour of the day and found tbc lmges nesponsc ti¡rrcs occr¡rred bctwccn 0300 and 0400 

bours. Bjcrær et al. (1955) exami¡cd t¡ìs company hourly ledger computations of gas produccd 

and gas uscd over an l8-year perid and found that rccording error werc highest at 0300 hor¡rs 

rirh a smallcr sccondary pcak at l50O bot¡rs. Hildcbrandt et d. (1971). investigating automatic 

u:ain braking and acoustical warni¡g signal alarrns sct-ofrs, also for,¡¡d rwo peaks u 0300 and 

1500 hor¡rs in thesc safery-rclatcd eveots. Simila¡ ñnding have been rcported in ur¡ck accidcnts 

fHa¡ris, 197'l¡ and in Ai¡ Forcc aircrañ æcidcnts (Rjbak et al., l9t3). Othcr accident analyscs of 

unrc of day and hours of work show ¡hat borh ci¡cadian rhyttun and hor.¡¡s of dury play a 

srgnificant role in the occurrence of accidents (Folka¡d, 1997:l¡n¡c et al., 1997). tn addition. the 

incidence of accrdental injury nearly doubles dunng tàe night shrft compared to morning shjfr. 

rrhrle tlrc rveriry of injr.ry i¡creascs 23 pcrccnt (Sm¡th et al., 1994). Night nurses make nearly 

r*ice the pauent medication errors as da)'nurses and expcrience nearlv tlr¡e¿ tinrcs the auto 

ac,-idents corrmutine to and from *'ork (Gold et al.. 1993). 

\Ìerstedr rl988l revie*'ed the effecs of slecpiness from ni_eht shift *ork and found rhat the 

¡.'tentiaJl¡ hazardous siruatron resulting from i¡creascd sleepiness dunng night shrft is reaj and 

underesrrmared. Akerstedt (19t8) also rcports that fatigue rn shrft *orkers is highcr rhan in dav 

*orkers. h.rghesr in night workers, folloned by morning workers Over¿ll, sleepiness among rught 

norken s estrmaled to be around t0 to 90 percent. Rotì et al. (1991) i¡dicaæ that rates for 

'¡orkers ialling aslecp on tle job whrJe on night shift have bcen reported to be as high as 20 

Pcrce nt. 

\ight operations are physiolopcally different than day operaùons due to ci¡cadlan trough and 

sleep loss. This cames a higber pbysiologrcal cost and imposes greater nsks of accidents. One of 

ûre most established safety issues is working in the circadian trougb be rueen 0200 and 0600. 

During this period workers experience considerable sleepiness, slouer responsc times, i¡cre¿scd 

errors and accidens (Mitler, l99l:Pack, 1994). Nlany recent accidenr from various 

ransponåtion modes hare been ass,rciated *'ith tlus cúcadian trough (Lauber & Ka¡ten, 1988). 

Uterature Revieu Page 24

L¡,m- and orlad¡ ( 198 I ). in ther¡ anal¡ sis of the Aviation Safetl Repcnrng System resea¡cher 

srare uì31 3l percenr of incident, o..utTing bet\¡een 2'{00 to 0ó00 hurun uere fatigue related' 

hours after beginning the shift' 

rilots erhibited paniaJ adaptation to night *ork 

ly temperarure. uith subjective fatigue and 

;. pi.loa still expe rienced a rh¡ee-fold increase in 

:cent) and a 1.2 hour slecp dcbt per night 

bc dtæ to tinrc since tbc last slccp' Pokorny a d' 

'year period and for¡od tbat, dthough tltc ti¡nc of 

þnätt fætors in driver æcidcnts was how early 

vecn 0500-060O had about six timcs as many thc 

A Pcåk in accidens also occurrcd two to four 

rs. decrcments in alenness and performance are 

r hou¡s. alertness can drop morc than 40 pcrcent 

5). A study of naval uatch kccpers fouod that 

)rcanr. falsc rcpons ra¡es 3l percent. and rcsponsc 

spcrd eight p€rc€nt. compared with raæs between 20O0 to 2200 hours (Smiley' 1996)' 

Sanrl a al. (l996) dcrermi¡ed rhat many piJocs begi¡ rught fìights ar¡e¿dr ha'ing bccn au'ake 

more ûra¡¡ t S troun. nre srudy coofirms'thc occrrrrencr of as many as ftve micro-sleeps pe r hour 

, also found thar 62 pcrcent of aJl pilos srudied 

ìi'-y longer after tÌ¡eu rught flight This 

t fìights rhat shou ed sigruficant ph¡ sioloeicaJ 

ase after flying tuo rught flights (outbound a¡d 

Nthough flights raned from north-south and 

1.5 days. sleep debr aççea¡ed similar' East-*'est 

flrghs had signifìcantly longer layovers but werc disruptive to cir'-adien rhyrhms' Tle authors 

concruded t¡"t..puring ¿.yii*., fatigue-dependenr vigirance decreascs uirh task durarion. and 

fati-rue becomes criticãl aftcr l2 houn of consta¡rt work During night bours fatigue increases 

fasrer*ithongoingduty.Thisledtotheconcrusionthar r0hoursof uorkshourdbe tremarimum 

for night flYing." 

Gander er al. (1991) found in an ai¡ carrier sening that at least I I pcrccnt of pilots studied fell 

asreep for an "r.*g. of 46 minures. Simila¡ly, Luna er al. (r99i¡ found ¡-hat u.S. Ai¡ Force a-rr 

traffrc controller fell asleep an average of 55 minutes on night shift' A possible explanation for 

the- sleep occufrences, in addition to ci¡cadian nadir, is the Flndin-e of Samel et al that many 

pilcr_. beg; theu' nigbt flighrs after b'eing au'ake for a-s long as l5 hours 

Lite rat u re Ret teu' 

Page 25

The effecr of tinp srncc the last slccp is e\en greater rIa sleep debt aJreadl eriscs. An NTSB 

hcavy trucks accident analysis (NTSB. 199ó)clearly shous that "back of the clock" driv'ing wir} 

a slecp debr ca¡rics a very' high nsk Of 107 single-rehicle rruck a,.'cidents. l- dnvers exceeded 

rhc hou¡s of dury. l.íincry-two pcrccot t2ó) of ¡hese had farigue-related acc¡dents. Tle NTSB 

report also shows tha¡ 67 pcrccnt of tn¡ck drivers with irregular dury or slecp panerns had fatigue. 

rctacd accidcns compared to 38 pcrcent i¡ drivers with rcgular duty or sleep panerns. 

Lrrcgulariry resultcd in a decreasc oi I ó houn on average in slccp with a total of only ó.1 hor¡¡s 

compared ¡o7.7 hours in rcgular parcrn drivers. Thc f,iTSB report indicatcd that they could not 

daerminc wbcrbcr irrcgula¡ dury/slccp pa¡tcrns pcr sc led to fatiguc but sonp experinrcntal dara 

s¡pport this notioo. Tbc ñnrl¡ngs of fu NTSB not only for¡¡d shifted slccp pancrus but this shift 

was couplcd with slccp loss. Tar¡b ad Bcrgcr (1974), whilc rnai¡taining slæp leogth, shif¡cd 

slccp tirm and found thu pcrformacc oo vigilancc, calculatioo t"sks, and rnood werc 

significantly irnpaked. funbcrmc, Nicbolson et al. (1983) showcd thu irregular slec/work 

resultcd in increasing pcrforrnancc iryairmcots which nas fr¡¡thcr incre¿scd by tinre on task. 

cumulative slccp loss. and working through thc ci¡cadia¡ nadi¡. 

Performancc cån also bc afTecfcd b1'cumuluive fatigue buildup across multiple days. Gundel 

( 1995) found rhat pilots flying rwo coosccutive nighs wit! 24 hor¡¡s bctwecn fligba slept about 

rwo and a half bours less during tbcir daytirnc layovcn (8.6ó hours versus ó.15 hours), and 

cxpcrienccd a signiñcant dccline i¡ alcrmss on thc sccood night flight. Alerbcss during tbc fint 

si¡ hou¡s in both fligbts appcaren o bc thc sarrE. Tbe laucr part of the sccood flight showed 

i¡creascd dcsyochroniz¿tion of EEG dpha wave activir.v, i-odicating lo'*'er levels of alertness. 

Spontaneous dozrng indicared an i¡crea-d susceptibilrry sleep. Subjectrvely. pilos felt grearer 

farigue on the sccood night. Tbercfore. wrth ti¡rrc since auake berng the sarnc. slerp qualir.v and 

quantiry during tbc da¡ime layover rcsultcd in i¡cre¿scd fatrgue. 

Samel et al. (1997) monitored I I rugbt flight rotations from Frankfon to Ifa}e/Seychelles 

crossing th¡ec ti¡nc zones. Piloa slept on average eight hwrs on base l-lne nighu. On lavover. 

sleep *as reduccd to ó.3 bou¡s. Pil..ts amved at SEZ after ll hor.¡¡s of beLng ar*ake (except for 

approximaæ 1.5 hou¡ nap pnor todepamrre.t Fatigue scores increased orerboth outbound a¡d 

i¡bound flighs *'ith ll.-l mrcro-slecps pcr pilot outbouod and2a.7 on rerurn. Prior to the 

outbound FRA-SEZ flight 85 pcrccnt of piJos felt rcsted *hereas on rÊturn onJy 30 percent 

reported feeling so. Thesc srudlcs docurncnt t-hu night fìrgbs a¡e associated r*ith reduced sleep 

quantity and qualiry, and arÊ accompanied by cumuluire sleep debt. 

Borowsþ a¡ld WaIl (1983) found t-hat flight-related accidents in \ar'¡ aucraft xere significantly 

higher in flighs originating bct*'ec¡ 2400 and 0600 hou¡s. The hrgher nushap incidence was felt 

ro be the result of ci¡cadian desyncbronizaúon and disrupted sleep-u'ake *'cle. Sharppell and 

Nen ( 1993) divided the operational day of nary pilos in Desert Shield and Dese rt Storm 

operations in to fou¡ quartiles bep-oning al 060l-1200 uitì 0001 to 06O0 beine the fourtl¡ 

quartile. They found that therc tras a progr€ssive incre¿se in pilots' subjectrre need for rest 

tre rween flighs as flights originated later a¡d later in the da¡ from quartile I to quartile 4. In 

Uterature Reyiev' Page ?6

addit¡on murriplc missions and cumurarive days flling also in.'reased rhe pirors subjecurc need 

for addirional resr bet$een missions. The tanir effect is the cumulatire effect of fatigue' As slecp 

tirne increased Þfore a flighr the sub.¡cctire rest needed before the nert flight decreased' 

SleeP P¡tterns During Tbe DeY 

rypc of shift aod rotatioo. tbc¡e cao bc l¡ 

sboc/cd ürat slccp duration was dcPcDdcot oo thc ci¡cadian Pbasc' 

ripino"tly reduced compared to nigbt tiræ sleep' 

Thus da¡iræ slccp was 

Tbc propcnsiry to slecp is high durin-g_the night and low during the day' But tbcrc is a gradient 

effect in slecpincss. gir*".D six and r2 hor¡rs a*ake. sleepiness in conr¡ol subjecs increascd 

scyeD pefccnt; bctwecn six a¡d lt hor¡rs, 28-37 Percent (Mi¡or & \\'aterhour' 1987: Minor et al'ì 

l9g6). This is r-be rcsult of a myriad of otbcr rh¡lms-horrnond, sccrerory, rcmpe raure-rhat 

orcbcg¡arc an rorernal envi¡onnpnt for action ã*i"g the day a¡d for r"st ar night. Tbe effect of 

ci¡cadian rbyth' oo p"rro.."ncc is ilr¡strarcd i¡ tbc findings of a srccp deprivation srudy on 

mulri-task pcrrorm-c e. Cæüer er et. (lgg4) poiDts out rha¡ alertness and prformancc would 

normalry decli¡c as a function of ti¡nc since awake, exccpt s'hen co.rpred to the ci¡cadian risc in 

body æmperaru.re, tle two functions stay rclatively søbiJe through most of thc waking boun Tbe 

bcg.inning of a drop i¡ alert¡css stars th¡ec to fou¡ hours prior to normal bcdtinrc' At þdtirne 

thcre is a suddcn å¿ ¿r.r-aic-lt-20 perccnt-fall irupcrformance a¡d dertness, coiociding 

*ith tbe rapid drop in body tcmPerarurc' 

Nighr s,ork uhrch rcquires daytinr srecp bas becn shor¡n ro reduce rhe amount of sleep obu:ned 

w.herher on pcfroanent rugbt or roøting shifts (cotligan & Tepas, l9tó) [n quick changeovers 

,îrh t bou¡s off ber*ecn sbfu. Tonerdetl (1990) found *orkers onl¡ acquircd 5-14 hours sleep 

Kurumaram (1991)obscned that workers getting off at ló0o hfs and rcquued to began sgaln at 

24OO boun srepr 2._15 hrs. or a similar shift cba-oge bur gening off ll00 hß and rerurning ro dun 

u 2400 h¡s workers werc onry abre to get 3.0 hn sleep. The'. researcbers found a correraúon 

(r=.95) bctwecn the hou¡s bcr*een shft a¡ld sleep duration' They concluded that at le¿st ló houn 

off dury tirnc werc oeedcd bcrween shifu to insu¡e 7-8 hou¡ slecp, a conclusion reiterated in a 

recent review (Kecklund & Akerscdt' 1995)' 

T ra nsme ridia n OPerations 

Tra¡rsræridian oçerations create simila¡ problems in attempting to \\ork uhen the bod¡ \\ants to 

sleep and sleep nhen the body wants to be au'a\e The b'rggest chal)enge posed by multiple time- 

Literature Rer iex 

o 

Page ?î

zone flighrs is rhe rime required for tbc body to ad.¡ust to the ne'* time ¿one. The pcnod of 

adjusrment appcars to depcnd on thc drection of t¡avel. Adjusrment appars to be faster aficr 

\r.esr\rard fìights than eastward fligbs (Klein & tÀ-egmann. 19801. Adjustnrnt follou'ing 

wesrward flights appears to occur ¡u a rate of about 1.5 houn per day ,* hile e¿st*ard-flight 

adjustnrenr occrrs at about I hour Ft day. This ma¡' be due to the body's inherent tendency to 

lengrhen irs pcriod bcyond 24 hours. which coincides uith wests'ard flighu. These data also 

suggesr thar phasc shifu bclow si¡ bor,rs can have a significant impact (Ascboff et al., 1975). 

Asidc from tbc obvious irnplicatioos for tra¡rsnrcridian opcrations, tbcsc dau dso apply to rcscrve 

pilots whosc protcctcd slccp opporuniry rnay vary as to is occrrrÊnce ¿rc¡oss assignnrcnts. Evco 

if a proæctcd tfuæ pcrid is predicreblc, unlcss it includcs thc night boun, it may not provide an 

effcctive opportunity for slccp a¡d thr¡s rnay not lcsscn fatigttc. 

Conclusioos 

The follo'*ing conclusions can be dracm from the rcscarch cited abote: 

o An indiviô.¡al's tf/OCL sbor¡ld bc deñDed on the basis of ¡he ti¡r¡c zonc *herc he/she 

rcsides, which may Þ difrcre¡t from the honr domiciJe. 

o D'rry pcriods conducted during V/OCL alrcady carry a fatigue pcnalry due to the ci¡c¿dia¡ 

cycle. Conscquently, duty pcriods involvi-og WOCI- should bc rcduccd 

o The number of dury p€nds involvrng WOCL tha¡ must be pe rfonrrd *ithout trrne off 

sbould bc limitcd. 

o Becausc tbc ci¡cadian cyclc is longer tha¡ 24 hours. each dutl' pcnd should sta¡t later 

than the previous dury period. 

. Re-ne assignments should anemp( to maintarn a consisten( l-i-hou'*cle 

¡ Du ection of rotatron for borå back-oi-the -cloe-k f'ly rng a¡d drrectron of t¡ansmendian 

operauons should bc considercd Gire n the bodr's preference forertending the da¡'. 

backwa¡d roLation should bc used *heo possible 

. Tra¡srrrridian operations should be scheduled in accordance rr i¡.lr eitler of t*o 

approaches: 

o For short pcriods, it may rnale scnse ¡o anemp( to kee p the prJot on home-donucile 

tirne. 

o For longer pcriods, reducing the dury pcrid and providing more opp'ornrnities to slecp 

rnay Þ the best aPProacb. 

Literalure Re.''ieu Page 28

Augmented Cren's 

Linle rescarch has been performed to assess rhe effectr\eness of managrn-l irtrgue through the use 

of augrncntcd flight crews. However, two recent .\-ASA p ted to srudy long' 

haul ãugrncntcd flighr operarions (Roseklnd et al., 19981. 

survey to 

examinã facrors thai promoted or interfercd with slee p in on ai¡craft. 

Rcsults werc collected from rrone than 1,40O crew¡ncmbc 

ing U'S' ai¡lincs' 

It was concludcd that. even though sonr difficultics \rcrc noþd, flight crccæmbers werc ablc to 

obtain a reasonabte amotmt and qualiry of slccp whilc rering in on-board h¡nfs. Furthcr, thc 

slecp obtaincd was associatcd with improvcd alcrtncss and pcrforrnancc. This study also 

i¿cnrifrc¿ factors tbar cot¡ld bc uscd to dcvelop stratcgics to obtain optimal slccp. 

and qu"lity of slæp obtaincd in 

Thc sccond proi:cr w¿Ls a fìcld srudy thar examincd thc çartity 

on-boa¡d bunks during augmented, long haul flighs. DaÞ werc collectcd frorn two airlines 

involved in differcnt rypcs of international opcrations. a¡d a corPorate oP€ra¡or. hetiminary 

rcsulrs showed rhat crcwmembcrs obraincd a good qu¡nuw and quality of sleep. Additional 

analy'ses are prcsently being conducted' 

Cooch¡sion 

A rcview of tàe scienriFlc [iterarure pertaining to fatigue. slee p, and ci¡cadian physiology w:Ls 

the major iszues tbat necd kr be considered rn dcveloping a 

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International Journal of Neuroscience,52' 29-37 ' 

Literalure Retteu 

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Page I I

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!-landborrl,

O X-éZlrj¡ú'uÞ

A SCmrsrrrrC R¡ræw OF hOpOSpp RTCULATIONS REGARDNG 

Fltcrrr CnrwusIuBER Durv Pnnrop LnnrlrloNs 

Docxer #2E0tf 

The Flight Duty Regulation Scientif¡c Study Group' 

Preperrtion of this docum€nt w¡s supported by e grant from the 

Indepcndent Pilots Associ¡tion 

Running title: Review of proposed flight duty regulations 

Correspondence to : Cary S. Richardson. lvlD 

Endæn rr -H¡perænsion Division 

Brigham a¡d V/omcn's Hospiul 

221 l.ongwood Avenue 

Boston. MA 021 15 

'Ce'Charrs: Wallace 

Bngham & *'omen's 

Hospiul. 

A.Mendelson. MD. Clevela¡d Chnic Foundation: Gary S. Richa¡dson, MD, 

Hospital and Han'ard Medical School;Thomas Roth, PhD. Henry Ford

"Review of propccd flþht d-ury E4la]iors" 

î,. night öury ncgt¡btqr Scientific Snrdy Crroup 

Ttm FLIcrr DUry RT,CUTTIoN SCnrnnc STUDY GnOup 

orders. 

tory and 

y recogology 

of 

both hc 

t€ri{r¡¡ Sleee Dlsorden Assæiaúon' and partbi' 

olicy on thc-diagnosis urd uearne¡rt of sleep'dis- 

circedian ràrdrms in human sleep and aþnn 

Depafidt'of fr. porr.tion anä_indrstry ol_tlr effccts of shift work and sleep {p 

rivation on hqn¡¡¡¡ frä*, and performance. ft h¡s been ar¡ officer on tlre executiw 

boad of tlre Sleep Research Society' 

Thom¡s Roth, PhD, is Director of Resca¡ch for tþ Henry Ford Heal¡Ì¡ System in 

De¡roit- Hc is also Direcor of tþ sl 

ognized authority on slee^p' sleepine's 

Uõrn r}rc SlecP Rescarch SæierY qtd 

Chairman of -rÌrc Advisory Council ft 

ùre Naúonal lnsdrure's of Health' Dr' 

of Transporuúon. Naúonal Highway Traffrc Safery Associauon and NASA. 

Members: Ruth Ber¡ca. MD. PhD 

U ni versitY oI W isconsin/Madiso n 

Madrson. WI53792 

Cynthia DorseY. PhD 

Mc[¡an HosPita'l 

Belmont MA 0217t 

Barba¡a PhilliPs. MD. MSPH 

Good Sama¡ita¡r HosPiul 

læxington. KY 4O5Ot 

TrmorhY Ræhrs. PhD 

HenrY Ford HosPital 

Der¡oit MI48202 

Mary A.Carsk¡don, PhD 

Bndley Hospital 

East hovidence. RI 029 l5 

Ma¡t Mal¡owdd, MD 

Hennçin County Medical Cenær 

Minrrapolis. MN 55415 

James Walsh. PhD 

Sr Luke's Hospital 

CÌ¡esærf¡eld. MO 6301? 

Gary ãmmit" Pt¡D 

Sul-rùe's-Rooscvelt HosPital 

New York. l$l 10025

"Review of proposed flighr dury rcSulations" 

î," night Oury neguta¡ion Scicntific Sn'rdy Grroup 

1. Introduction 

s of fatigræ a¡ld sleep dcprivatioa uì fligh! crew, 

æ availablc sþntiEc information" both Ùr¿t exlf 

scie¡rtif¡c'litcr¡¡¡re rcgarding tÞ origitu of hu- 

by rcgularory efforts in other industries and by 

ing the n 

roþ rn is solution. However, tl¡e Srudy Group. feels 

-tÃngty isc of allæated rest dme should no( relreve regulato$ 

iu*roïiy 

tions. lt is our hope rhat mury of the important-ac 

oroduced by this efforl where¿s other issr¡cs cle: 

base . ttnsè will requirc additional resca¡ch arær 

making efforts. 

ùat adequae rrme is provided for restction 

that. despia is evident hmiuúons. the pronant 

and vah¡able progress. Th: Srudy Croup 

The goal of providing saferravel 24 hor¡rs a day req.uires optimum crew alen¡ess and performance 

at aüïmes. Sltrce hu-man alert¡ress is highly dependent on the complex regulatory system gov-ern- 

' riew by summarizing current underst¡nding of tìe 

lulness. a¡¡d tþ facon t]rat cont¡ibute to huma¡ 

to beue¡ address these issues wiù tlr god of op 

tl

'i!îiîri'Jüffi ,['å3åo,ilfi ff.""Jö'** 

2. Scientific Beckground 

2.1. A working dehnidon of fatigue 

-SlæPincss. æcording o 

pbysrotrgical satl (lilc) 

and as bunger a thir:¡ s 

(Figure 2'l). 

htio¡ of tbc PlYsiolo6ic frctor¡ 

contributio3 lo bumin frtiSuc la lust¡incd opcretions 

osed modific¿tiors to tÌ¡e FAA regulatiors v-aria' 

f.*¡U" ttre physioiogrcal condiuon arising .from 

árus when wákefulãess is forced during phafs 

rplicarion of rhis uså8e is -th¡t tlpsc erms :ut uli'* 

,¡", ¡lrey a¡e no[ and confusion of tþ two 

Uãis of peifo-.ttce errors and the appropriaa 

lef'rniúon: 

FrurRu.b'T..¿t¡¡l..Dayu.rrslcrpncssarrclalcru¡csg'i.mPrinciplcsolúProtttceofsleepMedicinc'M.HKfy. 

g.r, r Roù, and w.c. úr¡enu Fis lgtg, \,v.B.Saunders: Pbiladelphie. p la-13. 

12

"Review of propord flight dury rÊgulatio¡s" 

Ttre Flight Oury negulaton Sciêndf¡c Sody G'roup 

2.2. Homeost¡tic regulation of sleep 

carrees of fatigræ is ¡ dccline in human alermess 

e{lærtcc of sleep deprivation. ^Sleep. dcprivarion 

r-horocosta¡ic r¡eed for sleep(2), eitÌ¡e¡ over tþ 

r gredual sleep deprivation over thc longer term 

Tlæ homeosåric mecha¡rism is refþcred in common serls obscrvatioo ¡hat a¡r individual who does 

wi[ bc 

factors 

is t¡pibc 

suf- 

¡notlrcc 2) TIE cfiectirær¡css of sleep in mainne- 

and &clirps i¡ oldc¡ ete (3). This suggests 

ut inadoquaæ 

5). Two or th¡ 

following slee¡ 

2.3. Circadian modulation of sleep' sleepirrcss and performaræ. 

The second fæ,w¡ in determining the levels of sleepirrcss is ttæ phasc of-tl¡e ItuT* circadian clæk 

(Fieure 2-l). Circadian rhyrhmi-ciry is ¡he arm "s€d to descriþ diumal variations. in.physiologic 

ÈunZ,io* rhar derive from-ume-képing sysæms within tÌæ organism. Circadian rhythms a¡e at 

d anirnals. and this ubiquiry suggesls tl¡at in¡ernal 

rhythms * irì resPect to exæmd dme. In diurnal ('' 

caãiar¡ clæk is onented so ¡Ìrat alenness' n¡e¡abol 

by day ro faciliure rhe physicaj activity and behaviors exhibired at thqse trnes (t). By night,. alertnfus 

ít decre¿sed and méubobc æúvities are commensurably reduc€d o facilitate sleep and cons€rve 

meråbolic energy. I-aborarory studies of tlre rnfluence of tÌ¡e ci¡c¿dian clock rypically rely on 

conr¡nuous body æmperan¡rc r¡cåsuremenLs o rrack tþ clæk's inflwncc on metabolism. Core 

body ærnperaruir is rema¡kably_rhythmic in humans wl¡en it is me¿sured in conditiors carefully 

designed to ehminate ouside rnfìuences- 

have de¡nonstrated clear ci¡cadian rhythms in scve 

ariation in sleepincss (¡.¿. minimum in perform- 

,n 4 and 6 AM) coincident with minimum body 

, data a¡e corsisænt with tþ generally accepted 

rformance is a secondary corLsequence of the ci¡- 

Further. an exærsive bodY of labo 

light-dark va¡¡aúon to orient ci¡ca 

ùris effecr on ù¡e rnærsiry of the 

onenuúon of an indrvidual's circadian clock- Sruc 

13

"Review of proposcd flight d-uty rc.gulations" 

l* nignt puty negrrlat'on Scientific Surdy Group 

úon and li 

esdmares 

sut=, on 

ancc (l l). 

¡þ poin! wþ¡e it is rnw pcsible to malcc rc¿sonablc 

l. wirh tlrc conscque¡rr dtcntig* in tight-d¡ft gxpo 

tþ dependcnt rtryrfrms in derr¡less and pcrform' 

conclr¡sions rcþvant to extended-duty pandi ¡rns 

aioos, ¡trir intero¡l ci¡cadian systems raay Þ out 

nt (12). Thr¡s thøy may bc in tþir own in¡ernal 

rtiodesigning 

schcdules ¡lut dlow for tl¡esc cjrcådiarl 

I of i¡difür¡¡l v¡riarion in tþ abiliry o ed.ept o 

ro this individud variability the abiliry o rdapt o 

rcc older cnew memþn a¡e morc likely o experisleep 

and waking. Second, the abiliry o adjst to 

of transmeridian ravel. In general sbort-term 

¡avel arc morc diflicult o rdapt to ¡han egnivalent 

4uiv 

fiUs 

¡iæ zone. 

ases of tt¡e 

oved is comPlex 

nental factor-- tle amount utd timing of exposure 

?.4. ¡,r.,s 9¡ rask 

TIE ùird facor rhar ca¡r conrribuæ to farigr-c is rlr durarion of tinc spnt working.wiùout signifr- 

- idence suggests that a complex rclaÙor¡ship exiss 

obabitiry of error. and ume spent working on the 

obabiLiry of error begins at a ælatively high level at 

). rapidly decltnes to opdmal levels within a few 

r of rlr (rypic¿t) eight-hor.u shift ("t¡sk fatigue"). 

uggest t-he raæ at which performance deæriorates 

fris has been an imporunt factor in efforu to limit 

7). 

Time-on-r^sk effe¡s a¡e the lerst studied and le¿st understood of ¡.lre factors con¡¡ibuting to human 

fïrrgue. Forexample, rmlike shep deprivarion which can only þ.reverscd by.s-J.ep. prformance 

deråorarion .r*ði.r"¿ with pro[ongäd usk duraúon appears q Þ task peci[c. rcvtrsing with 

l;;;tfrom rhe rask. even if rÌ¡e ti¡r¡e-is spent y.ttt ql=t waking activities. But important data 

about ¡l,e-nar,rrc of rl¡is cffect, particularly as it might rela-tr to complex tasþ ¡u9h as.tÌ,ose.P9liñ;Jby 

flighr crews. Ls nor yèr availablé. It is not clea¡. for example, whetlrer inherentJy variable 

tof. .-'rúUae ûr nte at-which performance deteriorates. Further. tlpre a¡e Lm.ponant metho¿orogi.rl 

Lssues rhat iuve nor all been addressed in available studies of úme-on-t¡sk effecs. For 

io"g År durarions. i.¿. t or more hours. sleep deprivaùon -a¡d ci¡c¿dian phase effecs *ìll r¡ecesiã¡Ïv 

vary signifrcanrly over rhe cours€ of rÌ¡e ¡¡sk, confounding inrerpretaúon of prfsnnance 

14

'Review of propæcd flight dury rcgulatiotls" 

The Ftight p"ry n S,rladon Scþnrific Study Crroup 

clranges. Su¡dies sysæmarically varying oo (homeostatic) infhæ¡¡ces to 

isotaÉ rþ d¡æ-oo-¡ask eIïectsturæ not 

g collætion of such da¡a idc- 

alli jpectftc o fligfrr crew þb requircmenll av¡ data none¡heless _raisc signili' 

ãit jerrrat conoúns abouísus¡aii¡ed shiñ durations. partrcularly thosc greater than l0 t¡ot¡rs. 

¡nof ti¡nc s¡ r¡sk effecs is rask inærsii¡-. Fatigræ 

-dcs tl¡an in low intensiry tasks, suggcsting ùat 

r, in pracdce, 

n ¡¡scd o jr¡son 

üe widely 

siw aspect of ¡viuion. 

2.5. Incrætions 

¡nd ¡hc probabifiry of error, eæb of thc physiolothers 

to potenti"t¡ ¡dverse effecs. Thnq the errodr¡ccd 

by moderaæ sleep depriv¿ion is geaær e 

rich time-on-t¡sk cffects on perform¡¡nce accumu- 

o\¡er a numbcr of successive nighs results in ch¡onic sleep deprivation as a consoqrææ of i¡¡pairÊd 

¡t¡l¡¡y to slecp drring ¡lr day. Ths sbcp &privarion c¡n ¡hca potcntiaa Ûr prfmnancc 

impairrrrnt on l¡ær night shift-r 

Tt¡€se inærætions traræ madc it diffrcult to irclaæ tÞ physiologic contributors o faúgræ in ttp 

deprieffecible. 

2.6. Shift-work 

The focus of rhis effon on the rheduling of fligfrt crews occurs in the conext of gerrnl cor¡cern 

abour exrended d uty. night work. and conseque nt sleep deprivaúon in a large numbe r of æcupaúonswi¡h 

public safery implications (lt). A growing number of US. workers a¡e calþd uPon to 

routinely work other tlran rcguJar daylight hours. It is esúmated ¡hat some rwelve million pople in 

rhe Uru¡¿d Sra¡es now fit this broad dehniúon of shifrworker (19). A number of stratcgies have 

evolved o provide for extended duty and nighnime coyerage of tÌrc growing variety of scrvice and 

ma¡ufærr.¡ring scrtings ¡lut require continrrcu staffing. The mæt common of tlæ is tlÉ 

"rourrng" shift scl¡edule in which crews of workcn work successive shi[s for one or mqt weeks 

ar a úme. Tþ shifs rypically are days (8 AÀ,1 o 4 PM). evenrngs (4 PM to midnight) and nigùts 

(midnighr o t Al'{). While routing shifs of this kind. varying slightly -with regard to suarting time 

and di¡ecuon of rotaúon, probably the most oommon irnplementation for continuous coye¡ìIge. a 

number of ot.h¡er approaches have been used as well. As 

impæt of a given shift schedulc. or even specifrc shift 

ness, or o¡.tre¡ huma¡r factors af€ not aJways ava.¡iable. It 

úon from resc¿¡ch resuls rcgarding a specific rtrcdule to dl shift work is rarely jusúfìed- 

¡¡ ¡ ¡çcoprized that night-wort can be delete¡iors to workers' safe¡y and.produc_tivity in Pú þ: 

cause of -¡he increasel ñsk of performance errors during the early morning hours (betnæen 4 a¡d 6 

AI,f). V/hiþ various shift work rhedules may be capable of modulatint this risk to e treâter or 

lesser degrec. recent work on rhe importance of sunlight to human circ¿dian funcúon (see above) 

has esrebislrcd rhar rhis nighuime vulr¡erabiliry o error persists even in shiftworken with years of 

re.aiizÊ that a¡ individual working nighs is at risk for signs: 

Frrst work during the early morning hours (beruæen 4 

usly-derribed circadian ir¡cre¿se in sleepiness urd sleepiness 

mediared performa¡rce errors. In addiúon, an individual working successive nighs is forced 

lS

"Review of proposcd flight dury rcgulariorrs- 

The Ftight Duty ncgulaúon Scþntific Snrdy Crroup 

o obain slcç during thc daylight hours u ¡ ù 

miniro¡t (20). As mentioncd. sleep under thesc 

archi¡ccu,¡¡e is disorted and ùe rcstoradve n¡ru¡¡l 

2.7. Farigrr and safety in flight operatioos 

rivatim- 

as a rnaærial contributing fæ,tor in morc than one 

æ ùnr fatigrr is a signilìcant safety issue in the 

;rcgarding timiurions on flight-dury schedules are 

tlrc idenrifica¡ion of ou¡corne meåsunes to be used 

Whiþ ¡vaihbls meåsutËs t¡aw adequaæly docuappe¿r 

to be inadeqr¡ac for tlre t¡sk of _assessing 

rely following irnplementation of new flight-dury 

:ns studred by the I'{TSB makes this me.asure too 

ly be expecred o æcur in respotts€ to small Proacin 

maxrmum duty timc for example At thc same 

ume. ùle pocnu 

Group fecls suo 

and validaúon o 

of rhis and fu¡r¡re rev¡sions wi¡hout rclying on ca 

ent meåsure. 

3. Summary of proposed guidelines 

for Dury ard Rest 

tion of ù¡e I.¡PRM 

tiors and úÉ ftnd 

ess dury perid, flight. Ùrnc, and rest requiremens. 

Secondarily.rley discuss reserve periods as well as cumulaÙve duty priods for a week and a 

month. 

rroposed guidelines. TÞ fi¡st it tt 

16 

predication of 

lighr üme. Specilrc regulaúons of duty du¡ations 

wirlrout an intervening penod of rest) and for otrl 

second imporranr ger¡enl change is tl¡e corsolidarrauors 

covered by Pan l2l (covering domestic. 

rinaúon of differencqs þrween relevant pans of the 

ons (covering commuer and on-demand flighs). 

ed corsLstency in fìight reguJat-iors.

"Rcrriew of proposcd flighr dûry rc.qula-úors" 

The night Oury neguhton Scicntiñc Sudy G'roup 

Tr¡t s 3-l: SunnA¡Y oF Pronoseo Rscuurnoxs 

t. FllSbt dutY drretloo 

Crcr ¡l¡c 

2. Ml¡lmum nd dur¡tlo¡ Crcr ¡l¡e 

3. Fligbt timc li¡nits Timc frrmc 

tV'th facilities lor sleeptn2 n lltght 

I 

2 

3 

3t 

4r 

PEr e'tct 

Pe¡ ooth 

Fcr 

3. l. Rerised Flight'Dury Duratiors 

Under tlæ proposed regulations. ùe base duraÚ 

hours. This wõuld include l0 hours of flight um 

iry of on-fìight sleeping quaners. urd operationa 

time and 20 hours of flight tinlc- [ncre¿smg cn 

availabiliry of sleep oppornrnity o I t hours. ar 

hmirs can'be increä\e¿by 2 hours for unplanned ope¡ationd delay. 

3.2. Rest Period 

The basic unit of resr, associared with the basic I 

hou rs. 

I 

2 

3 

3' 

1l 

DcrcnFoa 

M¡¡.d¡r¡tlon 

(d uty/ftlglt) 

l,üt 

l¡l/t0 

t6t72 

IMó 

Ml¡" drr¡3lo¡ 

(lo¡rr) 

t0 

l0 

¡1 

It 

,1 

M¡¡. fligbl 

tlmc (Lour¡) 

tt 

læ 

lÐ 

.lt't:- ''' 

n

"Rerriew of pmposcd flight duty ægulalions" 

The Flight Dury Regulation Scþntific Snrdy Crcup 

3.3. Stand-ByAssignmens 

Reserve time in this proposal is ¡ period of ti¡æ wlre¡ ¡ flight c¡Ew membcr is not on dury but 

nonetleless must be ablc to repon upo,n noticc (i.c. gezs ò¡n a¡c hor¡¡), for a dury period. TÞ 

guidel.irrcs explicitly rcjcct relating arnor¡nt of time of micc to ti¡ne of day. Ratlcr, it rclaæs arnount 

of timc of advance notification to ùe maxiru¡¡¡o duratioo of the subsequent duty period. With less 

than 4 hours of noúce. only a 6 hor¡rs dury period is ¡Ilouæd- As Dotific¿¡ion period goes !o ten or 

morc hours, ¡ full duty period, up !o 26 hor¡rs depending oa cim¡msl¡ures, is allowable. fu¡ al¡ernaúve 

to this slandby scheduþ i5 ¡¡¡ai ¡tîning a corist¡nt 6 bour protccted time (by requesÐ for eæh 

24 hor¡rs of rcserve tirDc. During this ürnc, ¡tÉ ccrtific¡æ bolder E¡ry Dot conurct tþ crew nrembcr 

to pLæ tþm on duty. This 6 þ* por{ must.þ ¡ssigrÊd before t}r c¡ew.Ten}ber begirrs.rhc 

reserye time assignmenL TÞ duty perid must bc comp¡e¡ed iD lt hours wiùin tlp reserræ riræ 

and mr¡st bc in æcordance with üre gencral guidelhes 

3.4. Cumuluiræ Limis 

Tþ cumulatiræ limis fc flight hor¡rs are set u 32 hours for any 7 üy period, and 100 hours for 

any calendar month. The ¡æarly period is set by multiplying tÞ monthly requiremenr by 12 (i.e. 

l20O hours). 

4. Ev¡luation of proposed regulations 

It is important to rciterate and emphasize ¡Ìrc, Study Grurp's position ùat ¡þ proposed reguladons 

as def-rned in tÌ¡e current NPRM on tÌ¡e whole r€present an imponant advance over exisúng fligùrrdury 

rcgulations. The principat improvement lies in tlrc æw dependence of ¡lp rcgulatiors on ror¡¡l 

duty time, ratÌ¡er than just flight time, in seaing limis on roÐdÍoum work duration. As rcvienrd 

above. thls is a mrch more physiologically rcund appmæh rcflecting tlr imponance rhar aII work 

dme has in the generation of fatigrrc. 

oposed regularions rlur 

inæntion "...to incorpo 

physiology inro regulashould 

address each of 

¡Ìr rssr¡es identifred below. 

In comparing tlrc proposed regulaúons to the s¡ated goals outJined in the inr¡odr¡ction ro rl¡e }.IpRM 

and to availabb data rn tþ scientilìc li¡crarurc. tlre Study Group identified two imponurr gerrral 

rssues. 

4. l. Excessive dury duration 

While regulaúon of tÌrc maximum duration of total duty time (ratlrer than jrst flight time) represena 

an imponant rmprovement from the perspective of tÌ¡e limits of human physiology, rhe acrrul dr¡aúon 

of the proposed work pcriøs subs¡antially excecds what can reasonably bc jusúfred by scientific 

data on human performancc and fau 

duraúons in exccss of 12 hou¡s ¡¡re assæ 

man crrú independent of circadian phasÊ 

scientific justification forbaseline work duntions of l4 hours, þ aloræ tlre greater durarions permiucd 

under opcrational dcley conditions. Ttrc specific duty ard tirne limitaúors a¡e tlre same ¡¡s 

those specifred in tlrc NASA recornmendatiors (22), although tlrere arc potcnti¡lly imponanr difÏerences 

between ùe NASA rrcommendations and 

tìe NASA document rcçsgnizes thc importancc c 

4), it provides no evidence in suppon of the staæ 

ficient limitation (Section 2.2-3), nor was the Sn 

these shift dunúors might be æceptable in the u 

tånt to note û¡a¡ these dury perids are signifrcant 

work senings where regulatory arænùon has be 

forma¡ce de¡remens. including most other uansponåuon s€ctors. 

/t

"Revicw of proposcd flight dury regulatioos" 

The Flight Dury Rcgulation Scicntific Sudy Crroup 

Absent research data to thc conrary. tÞ only rclermt findings sugScst that performa¡rcc deterio 

rares signifrcantly for shift dr¡rarions greatcr than 12 hours, and tþ rccqnmended Limis for dury 

tirnc in the NPRM arc not consisænt wiù tlÉ impticaoons of ùosc findings. As ot¡¡lined above, it 

is not clear wlrtl¡e¡ tlrc variabiliry of task inherent in ôe flight{ury assigrunent, i.c. shorær durations 

of flighr ùDc wirhin tle conæxt of ¡Ìrc longer ôry rhedule, might mitigaæ tlp deteriontion 

in performa¡rcc assæiated wiû strifs of cq_uivdent dr¡rarion in othe¡ work settings, however sciendfrc 

endorsement of tlæ safe¡y of ttrcsc shift duratioas urust await ernpirical confirmarion of sr¡ch an 

effect- 

Similarly, tþ ex¡rærdinary duty duraúors r¡ndc¡ circumstarccs wtere crcw nu¡nþr is augrnented 

and/or arrangemcris for sÞcp during flight rre provided are in@nately jr¡stifrcd by available scienrific 

dat^ It is ccriainly r¡ot clca¡. bascd on ¡ rcvLw of tlp st¡¡dies publisÌrcd by NASA or any 

u¡tr i¡ a magial irrcrease in olera¡rcc for sleep 

û¡ntion of tþ specificd magniurdc. Othe¡ con- 

:arraten¡ens for slccp for argmenred crews in 

very coocerned about thc adequacy of sleeping arrangemenLs 

tl¡at will bc providcd in tlEse situations so thet crcw members can obtain some sleep 

while relieved by tt¡e extra c¡ew. To or¡¡ rtúew, provision of such fæiliúcs addresscs only one of 

several imporunt concerns about tlr impæt of exæ¡ded dury arrangemenb. It remains to be deærmired 

wtætlær adeqrnte sleep can ar¡d will þ obhined under operational conditions. While 

available dat¡ on cockpit napping haræ demonsrraæd that brief naps have a clearly ber¡eficial effqct 

over rhe shon ærm on cnew dermess (24), publis!¡ed srudiqs have not yet shown that ùis improræment 

is suff¡cient in magnirudc and dr¡rarion o allow a signifrcurtly slec¡deprived crcw 

me¡nber !o return to duty. The sccond half of this cqrem is thil serænl studies in ottpr conrexls 

haræ demonsmad thar simply providing tþ oppor¡¡¡rity for sleep in tþ extended-dury sening 

dæs not guarantee that such sleep will æl¡¿lly Þ ohained. t#ithout express stipularion abour tþ 

¿unount and scheduling of rest/slecp to be obtaincd by cæw members. it is our coricern that tÌrc ævised 

regulaûons sa¡rction exraordir¡a¡ily long exter¡ded duty arrangements without providing any 

rcasonable likclihood that adcquate slccp wiü þ obt¿ired. 

Finally. tlc provsions for rcst do not appcår artegr¡¿æ to compensaæ for tÌrc clearly treroic demands 

of dury- durations of up to 26 hourv- Rest dlc*arìc€s are adjrsæd for ¡he rest periods following 

exænded duty, not for ûrc rest period preccdrng it- Thus for cre*rruembers moving ¡ìmong 

assignmens of varying duration, it is possible to be called upon to work very long shift dunúoni 

of 21- 26 hor¡rs afær limiæd (as few ¡s t hor¡¡s: "rEdLEed resd'), with no stipulation rÌ¡ar rhis ti¡ne 

be provided at a circadian phasc conducive to sbep. 

ln summary of this f-rrst conccrn. thc Sudy Group dæs not feel therc is edegua scientif¡c j,xtilica¡ion 

for dury dr¡r¡tions glc¡tcr ùan 12 bor¡rs. Nor is the Study Group conlìdent thar compensatory 

¡urangerrìenls of exra cnew. sleeping quariers in flight. and ex¡ended rest provide ade4uaæ 

proccúon frun the exrerne fatigr assæiaæd with wry long work schedules permitted under tl¡e 

proposed rcgulaúons. 

4.2. No adjrstment for "bæk side of thc clæk" 

Ou'second maþr concern is that thc proposed regulaùors maþ no effort to adjust prescribed limis 

on work duraúon or nest dr¡raúon bascd on tlre tinr of day u which those acúvities a¡e schedulcd. 

This is tlr most disappointing omission. a¡¡d particularly difficult o urderst¡¡¡d in light of rtrc 

express predicarion of the reviscd regulaúms on tlp NASA-Ames database, a body of resea¡ch that 

has done mæh o ct¡aracterize tÞ dependcnce of sleep and performance in tte aviation sening on 

human circadi¡n ptrasc. Bascd botì orr tÌtc NASA srudies and the larger body of scientif¡c evidence 

developed in ¡his area, tlse can bc no doubt about tþ imponance a¡d relevance of ci¡cadian 

physiology o tlre modulation of human performance a¡d the ændency o human error, a¡d ro the 

abiliry to obtain sleep and thereby reversc performurce decrements arising as a cons€quence of 

sleep deprivaLion. 

t9

"Rcview of proposcd flight d-ury req¡¡l¡jioos" 

î* night Oury n"g,rl"too Scþntifrc Sudy Crroup 

4.3. Inærætiors 

bly producc. 

caiors of thc 

as rcvþuæd 

and no comwell 

ouside 

hout adjrsunens of rest period duration for cir' 

le to have a routiræ 14 hou¡ night shifc followd 

) PM. r.c. preclscly coirridcnt with tþ circadi¡n 

orbidden zone"), followed by a 26 hour shifi 

n of in-flight tirne for slecp can not þ assr¡med ro 

riens ¡hat ma¡athon dury of this kind will i¡evit* 

ion stems from the abser¡ce of any adjrstment of 

s cor¡ld demorsrrae th¡ a succcssion of 14 hour 

rablc performance limis. it is very unlikely tlrat a 

ly validaæd. Unless maximum shifi duraúons a¡t 

kepr well within humrnaerforrnance hmirs. d.¿. less tl¡an-llhor¡rs'. som€ adjustment for tlæ compounding 

effccs of time-of'day necds to þ includednarios 

¿ue not likely to bc rcprescntative of tpicd 

on of tìe Study Group th¡t no reliable Protec¡,ioo 

:heduling cur be had withor¡t express adjusmens 

circadian clock. urd signifrcant reductions in thc 

4.4. Reserve Trme 

The Srudy Group has sepante but rclared co 

gttg+p n:' 

seße Timc. As reviewed above. two dlstir¡ct e within ¡t¡e 

th of a dury 

perid.TÌ¡e window is the s¿me during each successive day on rcs€rve. 

The Study Group is conccrræd that ûrc v¡riabte r¡otice aÍangelncnt is bascd on-tþ unproved sup 

pÑú* tiJ.turp deprivaúon resrlung from a short-noticc call c¿¡r be adcqnately compensrted for 

. Twclvc bo|xs is fclt o bc tbc ma¡i.stusr safe shift du¡arioo in many shifiwork s€tun8s. e.g. nursing. However, 

rb€rÊ -'e rrar¡ d¿¡¡6¡1çs1¡ng an irrrr:sc r¡ perforr¡a¡rcc crrrs bctwecn t a¡¡d 12 bc¡¡¡s of shift d,u¡ariq¡, suggcsting to 

sorre rh-r tbc appoprarc merimun shifr d¡,¡r¿rioo in safcry-scnsiúve shifrwrk rttrngs sbou¡d be t boun (17). 

/r0

'lcview of proposcd flight d-uty rcguLr-tiols" 

nr nignt fiury ncgr¡leton Scientific Snrdy Crroup 

5. Recommend¡tions 

5. L Recommended ævisions to thc proposed regulatiors: 

5. l. l. 

dcprintio d this kiDd- 

ts. 

in ttæ curreot NPRM reserve ¡Íangemens is ütc 

rns abo¡¡ 

adequatc 

occumnS 

me¿ 

Light-duty rcgulations represcnt ur important.ad- 

¡d l¡mis rt¡at-minimÞe faúgræ and optimÞe flight 

of thc specific regularions rcúewed above arl nd 

¡$ quo. irs¡c¡d. rhe Srudy Group urges exPedienl 

tþ following modifications: 

slcepincss(4-6AM)- 

5.1.2. Minimr¡m rest periods st¡ot¡ld be ¡djgs_ç{ upward for sleep perids t}¡t ir¡clude Û¡e 

tirrrc of pc¡k cñ¡dian ¡lcrurcss (4 - 6 PM)' 

5. 1.3. Thc provision allowing cxtcnsion of duty maximums. up .to 24. houn (26 yith oper.donal 

&Otl in augnreãrcd crews and in "signn¡cns that include facilities for in-flight 

sfeep sftóuiá nor Ë i-pt .e¡ted until scieñúfrc evidence is available demonstnting 

r¡ar'in flighr ¡urangerrlcns prescr.æ alertness at æccprable levels, i.c. at levels equiEbnt 

to thãr on ¡he routi¡æ shifi durarions' 

5.1.4. Reserræ tirrc arrurgerurs strould be adju¡cd so ttrar protected windows dultng ül: 

time of-peak circ¡di-an ¡lcrr¡rss are excrúcd þ cqrip€¡lså¡c for dccreased cffrcierry of 

sleeP during that tinrc- 

5.2. Recommendatiors for futr¡¡e rcvisions: 

Scræral of rlrese issr¡es illusrraæ thc Ed for addiúornl daq and even with adjrstmens rccoroi 

minimum rtst duration will represent quantiurivt 

;urrently only qu"litarit''e scientilic suPPorL Tlnre' 

of recommendãtions be viewed as tþ first sap in 

5.2.1. NASA,in iS capaciry as independent scien-tifrc resource. should be commissioned O 

gather addiúonal data on this lssue wirh rþ follorvrng pnoriùes; 

/ll

"Review of proposcd flight d-ury rc-qulaúons" 

ni nignt puty negubñon Scientific Srudy G'roup 

5. 2. l. l. 

and furr¡re rcgulaorY adjustmens' 

5.2.1.2. De¡erminarion of rtæ impæt of duty perid d¡¡¡ation o^q nerfo¡mance. inde- 

tttd;r;a slép dcpriüation a¡rd-circadian ptrasc qfffç Tlre impact of 

r.tytt t 

scsscd. 

percendges bf night tiroe wi¡hin r duty perid should dso be as- 

5.2.1.3. Dercrmination of rlr impa of vzrying *ortload. on pg{orma¡æ, with 

p.¡tutr auenüon o ¡hc-rolc of lurdings ¡¡¡d s¡¡stai¡rcd fligbr 

s.2.1.4. 8r,il: 

ly ex- 

tended. 

5.2.2. An indepcndenr scientific parc-l strould rcview tþ dan collected by NASA on a regular 

basis wirh tlrc inænr of proøAing a compreþnsiræ and detailed set of recommended 

revisions o rlre rcgulaúo'ns within ttree yizn from thc úme at which tl¡ese recommendaúons 

arc ultima¡elY imPhrnented 

t12

"Rcview of propccd flight dury rcgulaúors" 

The Flight Duty Regulation Scientifrc Study Crroup 

6. R,cfcrenccs 

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' u x-ézE Þ'úFU>

Remarks by Dr. William Dement to the ARAC Working Group Pilot 

Representatives on December 1, 1998 at ALPA HQ, Washington, D.C. 

I'm aery pleased to present Dr. William Dement of Stanford Uniaersity who's here to 

anstDer some of our questions regarding sleep science. Dr. Dement is considered the 

fnther of modern sleep medicine. He earned his M.D. and Ph.D. from the Uniaersity of 

Chicago where he first began to study sleep. ln L963 he became the director of Stnnford 

Uniuersity's Sleep Research and Clinical Programs and continues in that post today. He 

was Chairmnn of the National Commission on Sleep Disorders Research from 7990 - 

7992; a Commission chartered by Congress. He is the author of a definitipe textbook on 

the diagnosis and treatment of sleep disordqs and has written or co-authored more than 

500 scientific publications. Dr. Dement, welcome and thankyou for your time and being 

here today. 

Thank you. For many years, the people who were interested in circadian 

rhythms and the people who were interested in sleep were fairly separate. Now 

there's actually a scientific meeting going on ¡n Bethesda hosted by the National 

lnstitute of Health and the National Science Foundation in which circadian rhythm 

issues and sleep issues are considered to be complementary parts of one 

scientific discipline. This has been happening over the past 10-15 years. 

One of the things that I'm trying to deal with is the fact that the study of sleep, 

the scientific study, and the applications / operational situations coincided later 

than some of the other disciplines. To get really into the mainstream of the 

scientific knowledge and the applications, ...this has been what I've been most 

interested in trying to help accomplish during the past 20 years,... andlbe first 

effort was to try to create a federal agency that would really be responsible for 

sleep and circadian issues, research, applications and education. Our efforts to 

do this led to the response of Congress to create a Commission, not to create an 

agency but to create a commission. 

It turned out to be really a good thing because many of us had been in the ivory 

tower and this Commission really put us out in the field, hearing stories from 

people who have been involved in accidents, hearing what life is like in the 

trenches so to speak. That certainly made an enormous difference to me in 

appreciating, in a much more human way, the difficulties and the problems. We 

presented recommendations to Congress and it kind of coincided with the budget 

crisis, and dare I say, the Republican revolution so that only one key 

recommendation was passed. But there is now a federal agency - The National 

Center on Sleep Disorders Research - 

which, small, although it may be, is 

certainly a great start, and has on its plate some of the concerns that affect you. 

It also has the legislative mandate to interact with the Department of 

transportation and other agencies that are involved in these issues. I just wish it 

was much. much larqer, and we're still workinq in that direction.

I wanted to say three or four things about sleep. First of all, I'll preface this by 

saying last year when we changed to daylight savings time, there was a National 

Sleep Awareness Week sponsored by the National Sleep Foundation, which by 

the way, is a major resource in the education and is based in Washington, DC. lt 

created a sleep lQ test for the American public. The American public did more 

poorly than chance on this test. Not only then is there a pervasive lack of 

awareness by the general public, but there's also the presence of certain 

mythologies which then lead you to pick wrong answers rr¡ore frequently than by 

chance alone. A lot of those mythologies are still in the transportation industry. I 

think there is no question about that. 

The first thing that most people should be aware of is very simple: what is sleep? 

The fundamental difference between wake and sleep (and there's some very 

elegant research being presented about what actually goes on in the brain at that 

momentary transition) is that first, the transition is very rapid and can take place 

in less than a second. One moment you are awake and conscious of the outer 

world and then next moment you are asleep and unconscious of the outer world. 

When you're very fatigued, you can go to sleep instantly, and at that moment you 

don't see anything or hear anything. That's what makes falling asleep so very 

dangerous because you will not respond to a signal. The only thing that a 

stewardess could do is to wake you up. Often in a fatigued person, the 

awakening stimulus must be very, very intense. 

So, anyone who thinks that moving towards sleep is in the least little bit safe is 

completely wrong if you want a human being to function at any level at all. The 

transition is very, very rapid 

Then there's the period of fatigue that I like to call "fatal fatigue" which is 

approaching the moment of sleep and depending on the degree of fatigue, can 

be fairly rapid. But that's a period of great impairment where you miss signals, 

you misjudge, your memory is impaired, your reaction time is elevated, etc. You 

are now very close to the threshold of unconsciousness....the moment of sleep. 

There's a very dramatic study that I'd like to tell you about because it should stick 

in your memory. You have someone lying on a table with the eyelids taped open 

and a 50,000 power strobe light 6" from the nose. When that thing flashes, the 

table almost wiggles. He is supposed to press a little switch when it flashes, and 

you'll be making it flash and suddenly the person will not press the switch, 

apparently wide-awake. You ask him, "Why didn't you press the switch?" "Well, 

the light didn't flash." And if you look at the brain wave recording you'll see that 

there's a micro sleep right at the moment the light flashed. So that's how 

powedul that is. There's been a recent study in heavy trucks with brain wave 

recording in the cab as the drivers are driving, and yes indeed there are lots of 

micro sleeps there. They really do occur. 

¿

The second thing is that all sleep researchers now accept the concept of "sleep 

debt." Each individual needs a certain amount of sleep each day on the average 

to avoid accumulating a sleep debt. That sleep debt can accumulate over a long 

period of time. lt can accumulate in relatively small amounts so it's kind of 

insidious, or of course it can accumulate very rapidly. You find frequently that 

many people have been partially sleep deprived for long periods of time. They 

aren't aware of this as fully as they ought to be you would think. 

There's lots of evidence showing that you can get rid of that debt and how much 

extra sleep you have to have to get rid of it. The best type of research that 

demonstrates that is to show the increase in the tendency to fall asleep -- the 

power of the tendency to fall asleep - as you add hours to the sleep debt. 

Eventually, the person will finally fall asleep, no matter what. They can be 

walking and fall asleep. But if you put someone in an ad-lib situation, just take 

any one of you, and say, "Now you're in a situation where you have to sleep." 

You're going to be in a bedroom with no lights. All you can do is sleep. Then 

you will see all this extra sleep will take place. That's the debt....the amount of 

sleep that you should have received on a daily basis. That's usually astoundingly 

large. 

ln studies of this sort, you can show that a person thinks they're pedectly normal 

in terms of the way they feel. However, if they reduce the sleep debt, their 

pedormance will improve. The question is how much debt is anyone carrying at 

any parlicular time. The main thing is don't do anything that might increase it. 

That's my fundamental principle. 

Finally, the circadian rn¡n ñîfit that everyone has known that there is a 

biological clock. Since 1971, the location has been known in the brain, there 

have been a lot of electrodes and genetic studies, etc. Exactly how the clock 

functions to create a circadian rhythm of sleep and wakefulness has been 

understood relatively recently. This has been learned through the study of 

experimental animals. The best results are obtained with primates. So if you 

eliminate the primate biological clock, what's the result? They fall asleep all the 

time. They'll falt asleep, stay asleep, wake up, fall asleep, wake up, etc. The 

circadian rhythm of sleep is completely eliminated and you lose periods of 

sustained wakefulness. So that the concept today is that the clock participates in 

the daily regulation of sleep and wakefulness by alefting the brain at certain 

times. And you know those as, in other words, the forbidden zone for sleep,... 

the second wind that a lot of people get at the end of the day. But the clock does 

not put you to sleep. When the clock turns off in effect, when this aleñing 

influence ends, a person is left with this gigantic sleep debt. That's what I've 

heard you refer to as 'WOCL." That's the period where you find the least alerling 

of the activity clock, the most unopposed manifestation to the effects of 

accumulated sleep debt. and the greatest likelihood of falling asleep.

So those are the three main things. These are established facts. I don't think the 

scientific evidence is conclusive and those are the things we take into 

consideration when we try to apply the knowledge to the practical or operational 

situation. Any questions on that? 

People say, "Can you accumulate a debt for a year?" We don't know because 

those studies haven't been done. But there's no evidence whatsoever that says 

"No, it levels off," or "No, it changes." All the evidence says that you keep 

accumulating a debt as long as you keep losing sleep below your specific daily 

requirement. There's no evidence that you can change this. I suppose you 

could ski or play basketball as opposed to just sit in a hot room and that would 

make a little difference but that doesn't change your sleep requirement. 

Anybody got any questions? 

I've got a question. Napping: does that in any way alleviate the sleep debt? 

Let's say you have a 4O-hour sleep debt and you have a ten-minute nap. So now 

your sleep debt might be 39 hours and 50 minutes. lt wouldn't rnake any 

difference there. A lot of the napping is done after lunch. Most people, and 

especially younger people - and I don't know what the average age is in this 

group - 

but younger people have strong clock-dependent alerting late in the day. 

So you have sort of an illusion. You happen to take a nap just before the clock 

turns on. ls the alerting partly a result of the nap or not? Mostly not, but I would 

say until proven othenryise that a nap, if it is good sleep (which it usually isn't) is 

minute per_minute doing what sleep would do, but it's usually nowhere near the 

total añ'õffifttrat you require. 

Dr. Dement, I haae a list of questions tlnt pertain to our task of helpit:g to define flight 

time and duty time regulations and i.f I could just talce the liberty of asking these 

particular questions and open up the -floor.for nny otlrcr rentaining qurltons thnt other 

people may lut,e. One of the most basic tnsls is for us to ngree on n retLlntnrcndntion for ct 

sleeys opportunity,. . .. to afford euery reser?e pilot the opportunity of a ,-'rotected time 

period so that he or she is absolutely insulated from contact from ¡þs ¡"'7'=tator. Hott' 

many hours do yort recommend for a ntinimum fired sleeys opportunitv? 

I will start out by assuming that we would take 8 hours of sleep as the most 

common requirement. Then you need to add to that in order to be able to get the 

proper amount of sleep. ln your situation, I would think it would be a little larger 

than it might be for someone who really wasn't doing anything. Sc I'd add a 

couple of hours to get the proper amount of sleep. 

Are there anu.findings as far as the nntount o.f sleep /oss or the nhilitu :-' :leep during le:s 

tlrntt desirable times of the dnv nnd u'lt¡t n p¿rson coul,l erLtect?

Well, there's an ideal time to sleep and then everything else is less than ideal. 

Sometimes it's devastatingly less than ideal. 

WeII, how much so? If you had an opportwtity to sleep during the dny and you were 

giuen an 9-hour sleep opportunity, could you expect to get I hours of sleep during that 

opportunity? 

No, I'd say absolutely not. lf that happened, it would be an incredible exception. 

There's a ton of evidence on that also. 

Hoza about if you were getting a L0 hour sleep opportunity? 

No, I don't think so. There have been a lot of studies on sleep reversal. You 

simply reverse the sleep period and this is now a model of insomnia. lf you have 

to sleep in the daytime, you have insomnia in effect. The ideal time to sleep if 

you have a stable circadian rhythm is to stay near the circadian rhythm. 

The t hours of ideal sleep, is it possible from your studies Vou can nail down any specific 

9-hour period or is it aariable for indittiduals? 

Well, it may vary a little bit. Within a very narrow range I wouldn't say....l would 

say for most people, it's from 1 1 - 12 PM to 7 - 8 AM. For the vast majority, 

that's the ideal sleep period. People will ask why they are the exception, but 

you're not dealing with exceptions here. 

- When you're forced to haae to slerp if you're flying at night and you're sleeping in the 

day, I guess what you're really saying is that the chances are you're going to become 

somewhat sleep depriaed oaer time. 

That's right. 

And so the only zoay you correct that, no mntter hozu much time you are getting to sleep, 

Vou're still going to be somsu,hat sleep deprioed. So the only zaay you're going to break 

tlnt cucle is periodicnlly if yott haoe a certain amount o-f tinte o-ff and you sleep during 

zuhnt núght be considered your nornnl sleep period to restore that. 

Well, at the present time that really is the only effective way. I think that we take 

the position that there's never an adjustment to that type of schedule. You 

refened to night duty...and you would think that if a person did it all the time they 

ought to adjust, ..but all the studies always show impairment in sleep loss. 

Dr. Dettrct7t, . . . ,L,e're really at the point nozt, ultere ue're goirtg lta¡ond the ¡:ltilosophy 

nnd it'e're tn¡ing to pttt our finger on rutmeric -aalues. Our pos;!ion nt lenst _front tlrc 

¡tilots' stañ¡toittt , is tlnt lL'e see tl:r need for n l}-hour sleqt oprlort unity hntt,ing thnt 

tlrc o¡t¡:ctrttmitq nmr¡ not nltt,nvs be nt tlrc best time of tlrc ,1.u¡. I\-e're.fncing nt intlustnr 

¡tositiott thnt is lookirtg.for I hours its tlrc mininnnn. Our positiort is ¡tredicntetJ on tlrc

fact that t hours may be adequate if it oaeilaps the WKL. But since we don't know for 

sure when íue're goittg to haae that opportunity, zue beliroe that, or u,e think thnt hauing 

that extra 2 hours is going to gi-oe us a little more of a bu.ffer, especially u,hen it comes 

dttring the daytime. Would you consider that to be a conseroatiae and a justified 

position? 

Absolutely. I don't think you could possibly assurne someone is going to fall 

asleep instantly and then sleep continuously for I hours, not even under the most 


By the same tolcen, say that same indiuidual who was supposed to sleE had the perfect 

time during the day and u,as supposed to sleep during tlrc day, hadn't slept the preaious 

night and he had normal sleeping hours because he was not disturbed for any duty 

assignment. What effect does thnt haae on his subsequent rest period? 

ln the ideal situation if someone sleeps the normal amount at night, they can't 

sleep at all during the day. We are pretty much a sleep-deprived nat¡on so that 

we do have this mid day dip in alertness. Most people say they get drowsy after 

lunch. That's sleep deprivation. lf you were not dealing with someone who is 

enremely sleep deprived, then I would say sleeping a normal amount at night 

becomes very difficult, or it should become very difficult to sleep in the daytime. 

That is a fact if the carryover sleep debt isn't large, it's definitely more sensitive to 

stimuli, etc. and you're fighting the biological clock for much of the day. 

Have you ever conducted these tests when they're wearing a uniform? 

[Laughter] Well, we did some testing but I think they took them off when they 

went to bed. 

I ,flv nt night nll the time and onh¡ get rest during the lnt¡. I heard that if you sleep 

tlurinq the o¡ttimtrm time of day, vou renlly need to lu¡'e about n 7}-hour ¡seriod in u,hiclt 

' to getvotrTlzorSlnurso.f slee1t. Ifyottdonoteaerlaaetheopporttmitytosleepfor 7 

- 70 dnvs in a rous, Vou are nerer able to sleep dttring the optinntm time. I heard yolt sav 

tlnt vou nhtat¡s need ntore thnn 70lrcttrs to get el)en reasonable sleep eaen though yott 

probal.lv neoer will nchiet,e ndet\nte slee¡t. Can Vou Liut any kind of a nunùer on the 

trosS r?¡nor tnt of time uou could lnt,e atnilnble.for sleq' ttpt¡tortunity to tryl to restore 

sle4t7 

The problem is that there becomes inefficiency, You don't want to spend 16 

hours in bed to get I hours of sleep. There just isn't a good solution to be 

per{ectly honest. The main thing you need to know then is first, at what period of 

the day in your clock (God knows where your clock is) there is some period when 

it's the most ditficult to sleep. Hopefully you knor','that about yourself . Obviously 

you avoid that. lf you can schedule more than 10 hours, not at that time, then 

you yourself will need to determine if you can do ri in a minimum of 10 hours, or 

does it take 13. That would be a horrible life,. to spend all that time in bed. 

6

I'm typicallv so sleep depriaed that [can't understand rest of statement.] 

Years ago. just to make a dramatic point, we were approached before we knew 

about sleep debt, before we could measure sleepiness. lt was in the 60s we 

were approached by a company that had a billion-dollar bed (ceramic bead bed - 

billions of little beads. They use them now for burn patients. lt's supposed to be 

the most comfoñable su¡Jace ever. So we got a group of students. We had a 

regular bed, the cold concrete floor condition and the beaded bed. To our utter 

amazement, sleep was the same in all three conditions. The students who were 

doing this were on spring break, they probably had a 10O-hour sleep debt, they 

could probably sleep anywhere, and that to me is a symptom of grave concem. 

lf you could sleep an¡rwhere.. anytime you are very sleep deprived....that's not 

good. That's another mythology. People get so macho. Saying that they can 

sleep anywhere is like saying they were drunk or they could drive when they're 

drunk. People misunderstand that. That's a symptom of severe sleep 

deprivation. 

I haae a couple questions. First of ølI, if we consider u)e are dealing with an indiaidual 

who had no accrued sleep debt and that indiaidual azuoke in the morning, what does the 

science say about the amount of time awalce that indiaidual would haoe before, or is tltoe 

ant¡ kind o.f . ... 

Well, probably if he's getting up in the daytime, that person could not possibly 

sleep in the daytime. 

I'm not talking about sleeping. How long could he be awake beþre he..... 

Oh, well, maybe 16 hours would be the usual time he's awake. One of the things 

that we -- at least I and I think most of my colleagues -- agree on is that all 

wakefulness is sleep deprivation. ln the model of sleep regulation, you need that 

accumulated sleep debt of 16 hours to, in a sense, power the sleep of the night. 

I.f t¡ott didn't haae a sleep debt, hou many hours would you haae to be awalce beþre you 

could be nbi¿ to tnke a nap? ls there any mensurentent that has been done? 

First of all. it's so difficult to get a human being in a state of no sleep debt. I'm 

not sure that it has ever happened. The closest we've come are in the study I 

briefly alluded to where the people had to spend 14 hours in bed in the dark 

every night for 5 weeks. At the end of those last few weeks, we think they were 

getting up with 0 sleep debt. lt would take them 2 hours to fall asleep and they 

had terrible sleep because they tried to do it in 14 hours. lf you have a minimum 

sleep debt. then lwould say I don't think you could fall asleep....it would be the 

whole day I would think before you could really confidently fall asleep. One of 

the things lm not 100% sure is how much monotony and sensory isolation can 

7 

+-

you tolerate before you have a micro sleep? Two or three hours? Under 

ordinary circumstances, daytime sleep is difficult. 

ls there anything definitiue that *ys which of these two situations would be more 

fatigttirtg: an indiaidual who hns to stay up until 3:00 a.m. or an indiuidual who is forced 

to wnke up at 3:00 a.m.? 

That's a good question. I would think both would be fatigued and it's so the 

pattem might be a little different, but it would depend on how much sleep they 

had prior to that. I would think though that going into action at 3:00 a.m. for most 

people you'd be extremely impaired. On the other hand, some people, as you 

get after midnight, become extremely impaired also. I don't think they've ever 

been compared head to head, but those are the kinds that would impair 

performance. Period. There's a thought that people somehow get enough 

adrenaline. Certainly students in exam week somehow get so stressed and so 

anxious that they seem to be able to go a little longer. lt's obvious that they're 

paying a price when you look at them afterwards. That's not something to rely 

on. To me, it's only when you're trying to rescue people or something that you 

would want to do that sort of thing. 

Dr. Dement, after our reserre pilots receiue their sleep opportunity, they become aaailable 

for duty. We call the aaailability period the "resert-,e aaailability period" and that's 

basically the time they are aaailable for work, for flyirg. After the sleep opportunity, 

u,hnt zt,ould you consider to be a x.fe limit of time since atualce for a craunember? 

For the 1O-hour period? 

Yes. 

Fourteen hours. And I wouldn't say that's 100% safe but if you have a number, 

that adds up to the 24-hour day. lt ought to be reasonably safe. 

Where do you get your number from? 



the biological clock. lf you're getting outside the 24-hour cycle, then you're going 

to have periods of greater risk. I realize that operationally that's probably difficult, 

but.... 

Tltnt nssutnes tlnt the mdiuidunl:t'nkes up cts sootl as his protected time ¡s*iod is ooer. 

So in other words, you see n cott+tlintentary factor: 9 ltours of rest sltoultl Jictate a 75- 

l rcl t t r n t nil nb ili t y p erio d ? 

Yeah. I think most people u'ould agree that rr'ould be the ideal. 

-

Coing beyond that, what is probably the most greatæt points of contention right now - 

the debate between tlrc pilots and the industry opaators - Ls the _fact that the operators 

would like to extend this resense aaailability period in excess of ulut you say is 74 or 15 

or 76 hours, whatn,er the case may be, to a larger increment, ertending that resen,e 

auailability period based upon an adoance notice o_f n nap opportunity. In other r.uords, a 

pilot comes on call at 8:00 a.m. He is then told at 9:00 a.nt. that he is to report for duty 5 

hours later. The industry's position is that the notice constitutes an opporttmity for 

additional rest which then would be utilized to add more restoratioe energy, or analogous 

to ptttting more charge into a battery, to carry that pilot into more of an extended duty 

period with an additional amount of time.... up to in certain casæ 24 hours of duty. 

What is your feeling on that type of scenario? 

To me, that's a recipe for disaster because if you have a resporìsible, professional 

pilot -- who has a reasonable schedule, I guess - who is not horribly sleep 

deprived, and who has a fairly stable circadian rhythm, then the likelihood that 

he can get adequate sleep by trying to nap I think is relatively small. I would not 

depend on it at all. I would think also to have to do it sort of unexpectedly like 

this....Oh! Take a nap....Orly people who are very sleep deprived.... 

Cnn I ask that question a different way? 

Sure. 

Let's say I haue a TLhour slerp opportunity: 10 p.m. to 8 n.m. Tlat means I'm apdilnble 

Could I not get a cnll 

for 14 hours unless thrV fly nte into the next 10 p.nt. SlqL lgnight. 

say nt noon and say instead of you being off toniflîîl\TT'/.m., -LL.e want you to work 

until seaen tomorrow monting but you aren't going to go to tuork wttil 10:00 that night. 

So they caII me at noon, they giae a l}-hour notice that I'nt not going to haae to go to 

u'ork until 10 hours from noon, so at 2200 I report.for u:ork, and they want me to fly 

until 0800. So thnt u,ould be a total of 24 hours 

-front 

the t inte I theoretically zttoke up and 

l'',e had a T}Jtour notice that I was going to be flving this .fntigttirtg schedule. Wotild 

that be safe? 

l'Vell, I wouldn't be on your plane. No. I think that's almost insanity in the sense 

of saving that is safe. First of all, naps can't be depended on - even under ideal 

circumstances - to get you through this period n'hen the biological clock alerting 

is gone, when you're alone with your sleep debt so to speak, during the WOCL. 

There's no way that isn't going to be dangeroLLs. Yes, there mav be exceptions, 

but it's alrvavs going to be dangerous. The likelihood is not good that you would 

be able to have some kind of good luck that vou did sleep a lot, and that has 

.{otten vou through. First of all, you would not be at r-our peak performance. 

There is just no r1-ay. You cannot achieve peak performance during that period 

of time. N,favbe for 10 minutes. The notion.that vou can depend on getting 

adequate sleep I think is just wrong. You can go into a laboraton'and you can

do some studies and you can demonstrate that occasionally someone will 

perform prettv well, but that's not 1009â ever. It's never getting back to peak 

performance and it's under the luxurious circumstances of no interruptions, no 

noise, etc. I n'ouldn't ever think that napping could make it safe going through 

the night. 

How about that the flight is going to happen. There is going to be asery day in ,4tnerica, 

pilots that report to work at 2300 or whateaer and fly until0800 the next morning. 

Nout, what's different about the man who kttows a week, a month in adoance that this is 

going to be his schedule and the reserre pilot who finds out at noon after haaing wolcen 

up at 8 a.m.? Whnt wouldbe the difference? 


situation....You can never get to perfection, but the more practice, the more 

warning, the better you'll be able to handle it. Some people leam that there is a 

time when it's quiet and if I do this, I can preffy much depend that I will fall 

asleep. It's not 100% but you kind of learn that or you practice or whatever. But 


Dr. Dement, you'lse kind of led the discussion into another area of this nilemaking that 

has to do with an alternatiae method. Assuming that the pilots in this protected time 

period method uere depleted, the carriers then want to giue pilots aduance notice to coiter 

anv nússion or Rny assignment. They are looking at 70 hottrs as the criteria. l\'¿ don't 

belieae that to be adequate based upott. . .. 

Are you talking ro-nouiffigz - 

Ten-hour uanting, yes. To do anything. 

That would be 100% wrong. 

why? 

Well, because the 10 hours could fall sort of toward the beginning of what we call 

"clock dependent learning." There's no wa)'you could sleep. And then vou go 

into vour dufi-period at the h'orse possible time t'ou could have that situation. 

Whnt sort o.f tinte would you tltink zuoultT be ndequnte to giae a gry enough timt to get nn 

o¡tportwtity to rest so tlmt he would be snfer tltnn T0ltours? 

Twenty-four hours. At least a day before. Wouldn't you think? I don't see horv 

I'ou can get notified as the dav is beginning and feel you could depend on being 

able to take a nap. If it happened everv dav or somehou'vou knou'that vou 

10

could certainly get the probability up, but it's not something that you could ever 

really control. Again, there ought to be a better way. 

That's the problem: a better way. Understnndably, that's not desirable but tlæ question 

is: how do you best prepare for that? 

You're saying if the notice is given with the 10-hou¡ window? 

Management would like a L0-hour notice. 

It would seem to me that a better approach would be to have a 24-hour window 

or some longer period. Say you get notified the day before. I suppose there are 

emergencies and so on, and you would be called for those exceptions... and a 

pilot would have so many exceptions over such and such portions of time 

depending on the emergencies and whatever constraints.... 

Some types of operations operate without a schedule. 

That's the lvorst. 

I haae 2 qttestions, doctor. First, a person that hns adequate sleep wakes up non- sleep 

deprit,ed nt 8:00 a.m. Fourteen hours later it's 2200 and he's driaing home from dinner 

ztitlt his uife. Is he impaired? 

I have '¡gr¡itSlepends on his age probablv. The impairment is starting 

probably. You don't go straight down; you go down with an accelerating level of 

impairment. Most of the studies in the laboratory say depending upon where 

your mid day dip is, your performance will start decreasing in the late evening. 

We're not fantilinr zuith the mid-day dip. The late etening is .,..? 

I'm thinking 10:00. 

I_f n person u'ns to fly so as to stop flttittg nt 8:00 n.m. and he zttas to fly throughout the 

0200 - 0600 time ftame, zthat tinte shoultl he be ztnkitlg ttp in order to be best prepnred 

.for tlnt .fligltt thnt lands at 8:00 a.m.? 

I knou'you said he's flying. He's waking up? 

No. Wen slnuld he zt,ake up to be best prepnre;l.for n.fligltt tlnt zuotùd include lnnding 

nt 8:00 n.m.? I.f he stnrts nt núdnighf. Hcrit' do uou get prepnred for thnt a,en if (I'm not 

fnlking nbout reser-le or atn¡tltirtg)...lNlnt should n ¡tilot do, hoit, sltould lrc plnn lis dar¡ 

tù ,L'nke u¡s t! tlrc rigltt tinte tobe nrcst slert at E:00 a.m.? 

11

æ"- 

First of all, why does he have to wake up at 8:00? 

No, no. He's flying at 8:00. He's flving from midnight to 8:00. 

Oh, okay. But basically what should he do the day before if it's a midnight 

flight? I assume sleep as late as possible. 

On his norm.al sleep cycle like you frst said? 

Yeah. 

And then u:hat? 

And he's free all day? 

Yeah. He doesn't hnae to do anything.... 

If he knows that he has this post prandial period of diminished alertness , I 

would try to take a nap at that point in time. 

Iate afternoon? 

Yeah. 

I don't know what postprandial. . . . 

It means after lunch. Parenthetically, I've been working with students and I've 

been finding þecause I've been working with very small groups) that if they 

start by learning how much sleep they need as an individual, when is their time 

of peak learning, when is their circadian nadir, thev are able to make some 

choices in preparation for exams, etc. that are a great improvement over their 

previous situation where they didn't know these things. What you're trying to 

do is to get.your sleep debt as lorv as possible and utilize what you know about 

vourself to accomplish that. Part of it would be, as a responsible pilot, you 

n-ould do that as kind of a lifesh-le. Mavbe the lifeshle is changins a little bit but 

vou're alr+'avs trying to keep your sleep debt lorv so you never har-e to do 

something like when you are already really dangerous because your sleep debt 

may be -10 or 50 hours imperceptibly accumulated. Then again I'd tell vou the 

best preparation is to get as much sleep the night before. The pilots in this NASA 

lavover studv seem to be prettv good at taking naps. Not perfect, t'ut prettv 

good. lVe decided the reason for that is they lvere sleep deprived. Thev coulci 

take a nap. So there's that sort of tradeoff. Then the issue is whether or not the 

sleep closer to the duty period is necessarily better. I don't think it matters. 

\\;hen vou start that period, n'hat is vour sleep debt u'hen \-ou're going to go into 

12

that WOCL, if you will. Whether it's low because you naPPed or low because 

you got lots of sleep the night before doesn't matter. Both would be the best. 

Should you stay up until 3:00 a.m. so you can sleep l::er in the afternoon? 

Not necessarily, no. 

Should you stick with normal sleeping and then try to get a nap before you go to work? 

Yeah, I would say as much sleep as possible. But here again you need to know 

yourself a little bit. But that's not what rulemaking is all about. Rulemaking is 

what fits everybody. Because of the uncertainty of being able to take a nap, I 

mean it's uncertain for me and I think it's uncertain for pilots. Although again, 

since pilots are generally more sleep deprived, they are more able to nap. If you 

felt able to take a nap with absolute certainty, then you should take a nap. But 

also get your needed amount of sleep the night before. 

We're shooting around the subject. I hate to break anu of this up, but this question hns 

been plaguing this committee. The industry l

Along the same lines, hou much is the psttchological aspect of this preparation that we're 

talking about in the same situation that we're cunantly discussing play. In other words, 

the line holder as we know it, gets notice o-f his schedule a rteek, a month in adaance and 

cnn some'(Dhnt physically prepare himself. He knozts that three nights from now,l'ae got 

to fly this God-au:ful aII nighter trip so what yott said, he sleeps as late as he can (1-0:00, 

1.1:00 if he caù. The resmse on the other hnnd is ntentally unable to preTt:re himself. I 

know that I'ue got to go through this with 

But he knows that day. 

No. He might know a week or a month in adaance so he's had ... that's trlut I'm getting 

at. 

The reserve pilot or the regular pilot? 

I'm talking about the resmse now. On the other hand, he gets a caII at 8:00 a.m. or 9:00 

a.m. and they say, "Guess what, lohnT You'ae lost the lottery. You get to go fly 

tonight." lt's always, "Oh my God!" Now I'm tlrc unlucky one. He can only minimally 

physically prepare but how much psychologically does it affect him that lu's now 

ntrprised of the fact that he's got to go do this flight? Does this haae much to do with his 

ability to clear himself and be ready to go and fly this thing? 

No, I don't think it'd be negligible. I'm not quite sure. He could either be 

depressed, I suppose or angry. But I think that we don't feel that rerwing 

vourself up or being determine or anything else can really oppose a period of 

circadian nadir and.... 

So, it would be a minimalfactor.... 

Yeah, I r+'ould think so. Usually these are verv short lasting things. For example, 

I've been interested in when Stanford University gets a lot of Nobel Prizes and 

the call tends to come in the middle of the night because it's fiom Srveden. And 

it's interesting to me n'ho falls asleep immediately afterwards and rvho doesn't. 

Again, they tend to fall asleep rvith this incredible, exciting news t'ecause it's at 

that WOCL time. We have to tell them thev shouldn't call during the WOCL. 

One tlúng '(L1e LL)ere talking about . . . .Let's snt/ zLte nre in n cirumtstance ztl:ere we're in 

tltis situation ztlrcre ue're going to ha-c,e to denl zt,itlt this. You got notice Ltollre going tct 

hat,e to fIA the bnck side of tlrc clock, this tinte tlmt ¿tte don't zuant. ls it fa:, to say that 

based on the studies thnt limitittg the lengtlt o.f tlnt tinte, the slnrter the Ingth of time 

tlnt Vott opernte tlrc safer vou are, nnd the longer tloíre exposed to being -.n dutr¡ the 

u'orse off it is? 

Oh sure. Absolutelv. 

It seems lilce common sense. Fairly obz'ious. One other quick question.lt seems to be the 

waV yott rL,ere going is that hozu much notice you're giaen is not as important as when 

the notice falls. ln other words, uthen the opporttmity to rest based on this notice of 

assignment, is that a fair assumption? 

Well, the two aren't exactly the same. I don't mean to imply that when. ...I mean, 

the longer you have, the better. I guess I don't understand your question. 

Well, that's kind of what I'm getting at. I guess it is . . . . 

I mean, generally you don't get the notice in the middle of the night, do you? 

WeIl, it would kind of depend....u)e're denling with round-the-clock operations so we may 

haae situations where an indiaidual's protected time period this time he's supposed to be 

sleeping actually starts at 7:00 a.m. and goes to 3:00 in the afternoon. So he might get 

notice in the middle of the night for an øssignment that comes subsequent to that later on. 

So we're dealing with round-the-clock operations and no guarantees..... 

I would think notice in the middle of the night is useless. First of all, you disturb 

the sleep and secondly it doesn't really help you with the next day any more than 

notice at 8:00. 

Taking for a moment that you're not asleep, I menn that it's not your normal sleep time. 

I guess what yo{re saying is that 74 hours notice or 72 u,ould be better tly4nJ0 most 

Iikely . ... 

Yeah. All other things being equal. 

Did yott eaer.fly the midnight flights7 

No, not anymore. 

Especialh¡ after today, right? 

Doctor, I'd like to think zre'd be nble tc¡ negotiate sometlúng like r¡ott said: n '1}-hour rest 

period and a 74-hour maximum reserre aonilability period, but unfortunately, that's a 

rcnt high erpectntiort. WImt we uill b¿.fncing is longer periods of reserue aoailability. 

Bnsed on the fnct tlnt zue will be fncing potentially onerous, Iottg periods of tinte since 

nzt,nke, Iong resert,e aoailability ¡seriod:. do yott think that being ffirded a grenter 

antotmt of slee¡t opportunity tuill git,e :s ntore of a protectiott ngainst tlnt lotrger duty? 

Is tlrcre n r¿Intionsli¡: as fnr as tlrc antlintt of restoratiae sleep as prrparntion .for longtr 

¡serit'tt| of dutV? 

15

Yes. The less sleep you have the harder it is. period. 

so, in other words, if we zuere forced to accept by the rulemaking offæ these longn 

periods of duty in excess of 1.6 hours or 74 hours, then ¡t woull bîhooue the agency to 

Iook at p_roaiding pilots with as much rest as possible to prepare themseltes ¡oi tt "i typ, 

of duty? 

Absolutely- When you've been in this business as long as I have, to think that 

anyone could even think of the opposite is .... 

l'm-assuming that it's.mythology that if a person can't sleep, thnt the person tries to sleep 

and just lies thne and does nothing and stares at the ceiling and count sheep or 

whateaer, does thnt haae any type of restoratioe abilities? 

There's no evidence that anything but sleep has any restorative value. years and 

years ago people thought physical rest was important. But in a kind of normal 

range of human activities, only sleep is. Obviously you can get muscle strain and 

run 50 miles you're going to be in the hospital, bui iest is useless in terms of 

substituting for sleep. 

Dr. Dement, there's one area that touched ttpon at this point and I 

don't want to miss.. Tlæse are que he maintenance of circadian stabitity. 

In your opinion, why is maintaini lity so important? 

Well because usually... and by that you mean ygu¿Sþep opportunities and your 

lvake 

opportunities are in a period of stability,-then youhavè the best sleep ánd 

the best wake. If you get out of that cycle, then both-sleep and wake will be 

impaired. 

Well, u'hen I think about that in the context of uthnt we're trying to insttre in ottr 

reconmtettdations,.. T.þe're trying to insure that the protected titie period, the rest period, 

stayed the same from day to day, assuming the resei:nse 

that ntatter when he is called, he goes baci into his cyct 

hint bnck to as close to that original cucle and, mnintàin 

day ' NASA has findings on tlut. Their recomntendation zoas to maintnin that circarlin, 

stabilitr¡ ¡slus or minus 3 hours. Do vou agree or clisagree? 

i absolutely agree that's better than no stability. Obr-iously the smaller that 

number, the better. I think practicallv it couldn't be zero,but I think we tend to 

feel there's kind of a dailv flexibilitlv u'ithin that range, like 0 to 3 hours ,0 to 2 

To 

lrours go outside of that is, again, inviting u .or,äition of sleep deprivation. 

So deliberately creating a bad situation. 

Whnt lrap¡tens to the body as yott clunge n person's ct¡ck? 

16

All sorts of things happen, but the major thi.g of course is that you are now 

trying to sleep r+'hen the body wants to be awake and you're trying to be awake 

when the bodv n'ants to be asleep because you left the circadian stability that 

you talked about. 

[Question cannot be heard] 

No, I think in summary, ....science is really clariþing these issues that people 

have been struggling with for many years, and there is always a resistance to 

change. But I think one of the things that we confronted in our Congressional 

commission is that a lot of the bad effects of sleep loss and impaired performance 

are frequently not obvious because there has not been a history of really looking 

for them. One of the studies that impressed me the most in that regard was an 

anonymous survey of hospital house staff. I don't remember the exact question, 

but it was that 42"/' in this anonymous survey had killed a patient as a result of a 

fatigued-based error. Well, who knows that? IAIho wants to know it? If we had 

the power to really take a look at the price of fatigue, it would be enormous. I 

think these things are just beginning to emerge and they seem to threaten 

management, th¡eaten economic realities, but I think once there's this move 

toward help and peak performance and utilizing all this scientific knowledge 

that everyone rvill benefit. There will be ways to deal with these things and it 

will get better and better and the benefits will be recognized more and more. I 

think one of the problems in the trucking industry is the same kind of thing: 

what's the cause of all the crashes? Frequently, these causes aren't really 

assessed, and the pubüõe-sntî.".ognir" tné taUitity, but it's coming. i'* ,.rr" 

at some point it's better to be safe than to be sorry. Because sorry is lawsuits and 

lost lives, tremendous damage to property. Those things are going to be equated 

sooner or later. 

END TAPE 

17

X-ÕZtrJFú¡U.Þ

Fatigue, Alcohol and Perforrnance Impairment 

Nature, Volume 388, July-August 1997 

Reduced opportunity for sleep and reduced sleep quality are frequently 

related to accidents involving shift-workersr-s. Poor-quality sleep and 

inadequate recovery leads to increased fatigue, decreased alertness and 

impaired performance in a variety of cognitive psychomotor testsa. However, 

the risks associated with fatigue are not well quantified. Here we equate the 

performance impairment caused by faügue with that due to alcohol 

intoxication, and show that moderate levels of fatigue produce higher levels of 

impairment than tJee proscribed level of alcohol intoxication. 

Forty subjects participated in two counterbalanced experiments. In one 

tJrey were kept awake for 28 hours (from 8:O0 until l2:OO the following day), 

and in the other they were asked to consume lO-l5g alcohol at 3O-min 

intervals from 8:OO until their mean blood alcohol concentration reached 

0.100/0. We measured cognitive psychomotor perforrna.nce at half-hourly 

inten'als using a computer-administered test of hand-eye coordination (an 

unpredictable tracking task). Results ¿rre expressed as a percentage of 

performance at the start of the session. 

Performance decreased significantly in both conditions. Between the 

tenlh and twenty-sixth hours of wakefulness, mean relative performance on the 

tracking task decreased by O.74o/o per hour. Regression analysis in the 

sustained wakefulness condition revealed a linear correlation between mean 

relative performance and hours of wakeful¡ress that accounted for roughly 9Oo/o 

of the variance (Fig. f a). 

Regression analysis in the alcohol condition indicated a signÍficant linea¡ 

correlation between subject's mean blood alcohol concentration and mean 

relative performance that accounted for roughly 7Oo/o of the variance (Fig. fb). 

For each O.OLo/o increase in blood alcohol, performance decreased by I.160/o. 

Thus, at a mean blood alcohol concentration of O.100/0, mean relative 

performance on tl.e t¡acking task decreased, on average by Ll.60/o. 

Equating the two rates at which performance declined (percentage 

decline per hour of wakefulness and percentage decline with change in blood 

alcohol concentration), we calculated that the perforrnance decrement for each 

hour of wakefuhress between lO and 26 hours was equivalent to the 

performance decrement observed with a O.OO4o/o rise in blood alcohol 

concentration. Therefore, after l7 hours of sustained wakeful¡ress (3:00) 

cognitive psychomotor perfonnance decreased to a level equivalent to the 

performance impairment observed at a blood alcohol concentration of 0.05%. 

This is the proscribed level of alcohol intoxication in many western 

industrialized countries. After 24 hours of sustained wakefulness (8:00)

cognitive psychomotor perforrnance decreased to a level equivalent to the 

performance deficit observed at a blood alcohol concent¡ation of roughly 

O.lOolo. 

Plotting mean relative performance and blood alcohol concentration 

'equivalent' against hours of wakefulness (Fig. 2), it is clear that the effects of 

moderate sleep loss on performance are similar to moderate alcohol 

intoxication. As about 5Oo/o of shift-workers do not sleep on the day before the 

first night-shifts, and levels of fatigue on subsequent night-shifts can be even 

higher6, our data indicate that the performance impairment associated \Ã/'ith 

shift-work could be even greater than reported here. 

Our results underscore the fact that relatively moderate levels of fatigue 

impair performance to an extent equivalent to or greater than is currently 

acceptable for alcohol intoxication. By expressing fatigue-related impairment 

as a'blood-alcohol equivalent', we can provide policy-makers and the 

community with an easily grasped index of the relative impairment associated 

'ü/'ith fatigue. 

lNote: Retyped. Endnotes and Figures I artd 2 are illegible and have been 

omitted.l 

Drer,v Dawson 

The Centre for Sleep Resea¡ch 

The Queen Elizabeth Hospital 

Kathryn Reid 

DeparLment of Obstetrics and Gr¡recologr 

The Queen Elizabeth Hospital. : 

woodville, 50l I South Aust¡alia woodville, 50t I South Australia 

e-mail: ddawson@tqeh. smtp. tgeh. sa. gov. au 

2

taj X-VZFJ¡ÉFúÞ

stlultlARY 

The prcsent study systcmatically comparcd the effects of srxiarr¡¿'J ç¡keñ¡lnes anri alcohol 

inæxication on a ra¡Ee of netuobehavior¡al tasks. By doing so, it xzs possib,le to quanti4v ùe 

performance irapairment associaæd r¡ith sustained wakeñilness anC express it as a L,lood alcohol 

impairment eqúvalenr Twenty-twohcalthy subjects, aged 19to 26 years, panicipated in threc 

corurærbelanced condi¡ions. tn th€ s¡staincd waliefuincss conditioo, subjects werc kept au'ake 

for rweaty-cight hours. In rhe dcohol and placebo conditions, subjecs consum:d eirher an 

alcoholic or non-alcoholic beverage at 30 minute intervals. until their blood alcohol conccntralion 

re¿ched O.Wo. In each session, performance was measu¡cd at hou--þ intervals using four rasks 

Ëom a standardised computer-baseC tel baner,v. .{r:al;-si: indicaæd ¡trat the placeto bverage 

did not signl6cailÌ.v effect mer¡ relative perfomrance. In contrast. as blood alcohol 

concentration incrcÀted performancc on ail the ta-.ks, exrrpt fo: coe, signilìca"rtJv decr'^.ed 

Simila¡Þ, as hours of *akelulness i¡¡crea;ed pe:'formance levels ior :-.r¡ of th: s¡< Þararne:ers 

significantly decreased. More impcrantll'. equaring the perlonr-.ce imprirnenì in rhe tuio 

conditions ¡¡Cicated that. depending on tbe task meas.:¡ed- apprc\-:ne(ely 20 to 25 ncurs of 

'*'aliefulness produc:d perfoirnancc decrernenls eq'-¡valcnl to thos: ,'rs;n':J at a BAC of 0.10c,í' 

Ovcrall, thes: results suggest thar moderate lev¿l-r oisusratned wak:¡uLress produce pertbrmance 

equivalelr to or gteBier than tlose obsen'ed at Ìeveis of alcobol in'.cxcation deemed unacc:¡:able 

whcn driving, *orking and,'or oPeraung dangerous equipmenr. 

KEY \+'ORDS sustaincd r+'al¡eñ.rlnsss, alcohol r nloxicatjon. ¡erformance impai rment

TNTRODUCTION 

The rcgative ::-pa:i of sleep loss and fatigue on neurcttìlavioural pelformancc j5 *ell 

documentc¡l(G.:ltrerg et ol.. 1994: Vulla¡rey et a|..1983; Til.e,v and Wilkinson, 198¿). Studies 

have cieæly sho*rì rhar susrained waketulness signifìcantlç imPai¡s several ccnlponenrs of 

performance, iæluding responsc latency and variabllitv. speed and accurac) ' hand-eye 

coordrnatron, decisiæ-¡'nakurg ald mernory (Babkoff et ol., 1988; Lir¡de and Bergsuor+ 1992; 

Fiorica el af., l96t). Nevefheless, understa¡ding of the relalive perl'ormance decrernents 

produced by slecp loss a¡d fatigue ¿rmong policy-makers, and rvithin the community. is poor. 

By contrasl, rhe rmpairing etTecs of alcohol inioxication arc gencrdly well acceptcd by the 

commr.rnity urJ policy rnakes. rezulting in suong enfc.=ernent of lar¡'s mandating that 

individuals r¡.hos< btood alcchoi conoenuation exceeds a 33fain level be resuicted norn driving. 

u,orking anüc: ,aæral¡:tÈ Cangcr..us equipnenl Consequently, scveral studtes havc uscd alcohol 

as a standari b¡ which !o :c,:1;are impairnreni in ps.vcllcrcc:or perfcrmance caused by cther 

subsra¡:ses (Haùm"q et a!.,1989;Diclt e ¡ a/. 1984: Thapar :: ci..1995'.t. By rsing alcohoì as a 

refercnce po:;'- strh sruclics ruie provided lr¡ole eas:I1' grasp'ed :esults reguding the 

per forma-nce mpa-rrnent as sc c i ar e d urtb such subst¿nce s. 

ln an anempt :o Trovide poli:¡ m,¡ùters ar.d rhc comm':oitv with an easily understood i¡dcr of 

rhe rclative risb asso.-la¡çd with sleep ìoss and larrgu:. )eason a¡:d Reid (1997) equated the 

performance inpairm:nt of tatiguc and alcohol in:¡xicauoi: .sing a computer-basccl unpre:icrabte 

u-acking As¿ 31' dcing so, d:e authors den:onsua¡cd tnat one ntght of sìcep deprivatron 

produces perfr.:1]iance impairnenr greater than is currcntl)- acccptable for alcohe'¡l intoxicaticn.

Wlule ¡his ir¡rial stud;- cl:arly est¡blished that faugræ a¡d alcoirol inrcxie::n have 

quandrativell' simil¿r cffccts, it should bc noad that pet'orrrancc ùn ori¡' c:'.: :sk u'as 

rnvesdgated. Tbrs, it is u¡rclea¡ at present wtrethe¡ these results a¡e rÈstricled tc :ra,rci-eve 

coordir¿tioru or clraracte¡istic of the g=ncral cognitive effe;Ls of fatþræ. Wlile it :: gcnerally 

accepted trat sleep loss anC faúgue are a$ociatcd r¡'ith impured ncurobchsrioual pcbnnance, 

recent rescarch suggsts that tasks may diffcr substantially in thci¡ sensitiv¡tv to s,lcep loss. 

Studics addressi-og this issue luve suggesed that usks wtrich are cornplex, high ir rorkload, 

relativeiy mooctonous and *hich require conti¡ucus anendon a¡B toost rul¡erabþ to sleep 

depnv ation ( J oh¡son. I 9 t 2;'J/ilkrnscn, I 964). 

As conditions thst causc deterioration in one partrcula¡ fr.¡nc¡ion of perforrrance n¡¿ìy leavs s¡þs¡5 

ru¡aflicted, it is ur¡¡e¿sonable to assume that one :culd precrct all the eÎïècts of sleep lcss from a 

sl'rgìe perfonna¡ce lest. Tnus. the curent studl' soug!:: to :eplicate ar¡d exte¡:c' :--.: iniial 

f:ncrn5 of Da,¡'son a¡i Re;d 1199?ì'r¡' s¡s:era:icalì; ccnpariag rf,e eÏ#-ffi 

deprir-a:ion a¡¡d alcohol :rrioxication on a:ange cf :crforman:: tasks

}IETHOD 

Subjccts 

Tweuty-two participaats. aged I 9 to 26 years, were rccrui¡ed for rhe stuc¡' rsing advertisemenrs 

placed a¡ound læal univenuies. Volunteers were rcqu:red to complete a gøeral health 

qrælionnaire aad sleepwake diar¡' prior to the study. Subjccs wbc had a curenr hedrh 

problcrn, and/or a history of psychiaric or sleep disorde¡s weæ cxcluded- Subjecs who sn¡oked 

cigarenes or n'ho were taking medic¡¡ion knowu to inreract with alcobot were ajso excluded- 

Parlicipants rvc¡e social dri¡rken u/bo did not rcgululy coru¡¡rrn3 more tba¡ six sundard drinks 

pcr weck. 

Perform¡ncc Bettcry 

\euobehavioural performa¡ce Eas measr¡ed using a s¡andardised co:np'Jter based tes¡ 'oa¡ter)'. 

-l-te apparalus for rhe banery consisls of an IBI\{ compatib,e computel. micrcprccessor urur, 

:espolrss boxes a¡¡d computer mcn:ior. Bascd oo a3Éf,ñ"ãffiÀüce prcccssing model 

flVickens, l9te¡, the bane¡y sought to provide a broad sanpling of '.ar:ous cornponenrs cf 

neuobehav;oural pcrforn:a¡ce. Fot¡ of rwelve possible perfor=urce tests ìÀ'ere useC. such ihat 

¡þs lsvel cf cognitive cornplexrry ranged Ëom simplc tc morc complcx as listel 'relou). S¡¡re 

speed and acùurac)' scorÊs can bc cffecæd differentll' b¡ sleep deprivEtion (.{rrgus and 

HesìeEave, I9t5. rvVebb ald Lcv-v, l9t2), usks ùat assess:d both we¡e invcstigarcd.

The simpie scnsory cornparison task requircd panicipants to îbci-r on an arrentjo:r fuing spot 

displayed on the ¡nonitor for 750o¡s. Folio*ing this, a line of sr¡mulus charecrers, djriCed inro 

ùree block of eithcr rutmbers, leners ot a mixtr¡re ì*,as dispia¡cd Participants *erc then 

required 1o respond to ¡ visr.¡al cue, *'hich agpeared in rbc posiuon cf onc of the nimulus blocks- 

be naning tbc block uùich bad bccn theæ. Verbal resporu¡s were scored ¿rs conecl, parrrall¡- 

corlcct or inconec¡. 

The rxrpredictable uacking rask (tbree-miuute tials) was perfomec :sing a joystick tc control 

thc position of a tracking cutsot by ccnring i on a consranily moring rarÈet. Perccntage of rime 

on target was rhe performance measurc. 

Tne vigilance task (th¡ee and a balf minute trials) rcluLe¡i subjecrs io press cr.e of sü black 

br¡tlons or a single rcd button. depending on which ligJ:t rvas illun:ralci If a suæle -rgll rvas 

;ll'¿rninated, ubjccS rrere rê{uæËtæñ- conespondi:rg c.:ck buncn w¡icrn:a:h iL tf 

bowever, nlo ligha rvtre illurnnated simulta¡reousl.v, s':bjects ue.': reqiiired ro Frtss ¡he red 

brrtton. For th¡s report. ¡wo vigilarcc mcasrucs rverc cvaluaÞi I) tlre nr¡:lÞr c: conecr 

responses iaccuracl'), a;C 2) r.rcreases in the dura:ion of respons:s rr3sponse larcoc¡'). 

The grarnmatical rcasoning task requrred zubjects to indicate rie:her a logical s'atcmen¡- 

ùspla¡-.ed on the nooitor. \ùas -Jr.¡e or falsc Su'u;:cts were presenied r¡'rth 32 sa:ements pcr 

trial, and instructcd to concenl¡ate o¡r ac€Luacy. rather than speed Both accr¡¡acy (p3rcentagc o¡ 

conect responses) and response iaten:¡- were evaluated rn this r:p..n

Druing test sessions, subjects were seated in front of the workslation i¡ a¡¡ isolate,j roon¡ frcc of 

disrraction, and nære i¡srr¡cted o eomplete e¿ch t¡sk once (rasks rvete F¡esented in a randorn 

ordcr 1o Prevent order effects). Each tes¡ session lasterl approximately l5 rninutcs. Sub¡ects 

receiræd no fccdback drnng the study. in order ro avoid knowlodge of results affectin8 

pcrformnce levels. 

Proccdure 

Subjeas panicipsted in a ra¡domised cross-over design rnvorving ttuee cx¡rerimenral conditions: 

I ) an aJcohol intoxicarioo condiûon, 2) a placcbo condirion- and 3) a susùained wakefulncss 

condition. During the *'eek prior to corr¡mencement of the experimental cooditions, all 

participants were ind:r'iCuaily trained on the pcrformance 5anery'. ¡ familiarise themselves r¡-ith 

the tæks and to minimis: irnprovements il performance resulring ñcm ieuning. Subjecs *ve 

require'i to repeat cach tesr until their performance reacbed a plareau. 

The subjects reFìc'fld to the labo¡ator) at t:00pm on the nighr pncr ro each condition Pnc¡ ro 

rcriring ar I l:00pm. subjccts were rer¡uir:d to complete addiúonal pracrrce t¡ials on qach tasks. 

SubjecS wcrc wokEn a'. ?.CÉam. follo*ing a nigbr of sleep, and allcued ro breakfasr and shcrre¡ 

prior to a bas¿line tesling sssion, u'hich surted ar 8:00a.m. 

Alc oløl I nl ox ic g I tln C onùt i on 

Subiects completed a performance testing se=-sion horuly. Follou:ng tie 9.00am testing sessjorr 

each subject *as rcquired 1o consume an ai;oholic bcvera¡le, consistrng of ¿0 percent vodka a¡rd a

non'caffcinÂted softdrinl mlxer, at half hourly intcrvals. T'*'eng minures a.fter ¡hc consumpr:cn 

of eacb Crir¡)t. blood alcohol concenlrations (BAC) were csdrnared using a srandard calib:-.::d 

breathal¡"scr (Lion Alcohnetc¡ S-D2. Wales), acq.ûzue to 0.005% B.{C. \\,hen a B.AC of O.I tr ô 

was æached no fr-rther alcobol was given. Subjecs were Dor informed of thei¡ BAC at anyrir:e 

dwing tbe expcrimental period. 

Placebo Cotdition 

The proceCuue fot the placcbo condition ç?s essentialìy idcotical to the aJcohol condition. 

Subjccts ¡n tÌæ placebo condition had ùÊ rin of thcir glass dipped in ethanoj ro give rhc 

impression tba¡ it conl¿ined alcohol To e¡uurc that subjects rcmained blind to the 1¡earmcnr 

condition to *l¡icb they h¡d bcen aliocated, approximatcly equal numþrs of subjecS rc¡eiied 

alcohol or placebo iu aay givcn laboruory rsion 

Sus t ditu d fl o kefu I ne s s C ondt non 

--+- êcts \Àere deprived of slecp for one rigbr D-uing úris rime, ù:1' complereC a pe.rbrnar-ce 

lestìng session cveru hour. In bctu'ecn their tes'-rng sessions, subjeos ccuid rcad, urìle. wuch 

televtsron or coovers€ with other subjects, but rr:re not allowed to aercise, shower or bal¡. 

Food and drinks çe¡tîni¡g caffeine were prohibited :Ì:e nigbr before and Jruing rhe experimcnral 

conditions. 

St¡ti¡ticel A¡alysi¡ 

To conuol for ioter-indiridual variability on neu¡obehavior¡¡al pcrtbrnoncc, test scores for 3cå 

sub-:cct were expressed relæive lo the average tÊst scores they otrtained 3u.'ing the bæclue

(t:00em¡:esing sesslcn of each condicion. Relarire scores uji::n e¡ch inrcrval (boru of 

wakefulness or 0.C5?¡ BeC rntcrv'als) werc lhen averageC ro obtaj¡ the mearr ¡çjs¡jyg 

pcrformancc âcross s.rb.¡ccts. Na.uobehavioual perfoma¡:ce dau in tbe s,¡raine,c walcefulness 

and alcohol in¡oxica¡ioa conditioru were ùen coilap-d i¡ro two-hou br--:s ar¡d O.oztó BAc 

iaterva-ls, rcspecrively. 

Evaluation of sysæ-'ric cbanges Ín cach performance parameær across tioe (ho'rs of 

wakeñrlncss) or blood ¡lcohol coaccnt¡ation were asscsssd separatcty þ repeated-meåsures 

analysis oft'a¡'isncc (À\ovA)' wid: signirìcance tevels correcrcd for sphericir.v b). Greenho¡rse- 

Geisser epsilon. 

Lir¡ear rcgrcssion anal¡-sis r¡ns used ro determine rhe rclatjcnshrp bcnveen test perfonna¡rcc, 

hou¡s of uakefi¡lness ar.d alcohci il¡toxicaricr. Thc :etarionslup betìÀ.een ner¡obehaviou¡al 

performa:''cc 8nd boü bou¡s of *akefuh.ess a¡rd BAC are erpressed as a pcrcc¡tage Jrop rn 

pc'rforna:icc tbr each bcru of rraltefulaess or each Ferc3r:age rncreasc in B.qC, rcspectiyel¡,. For 

each perfanr¡i¿rre Pa¡-êrneler, the ç'ercen:age drop i¡ tcst per¡brrnance r¡r each of the tw.o 

condiijons was also egr:atcd, a¡rd tbc eflÞcs of su,s:arned wakcñ¡l¡ess on perforunnce expresseil 

qs a BAC aluiva.ler::

RESLLTS 

Alcohol Intoxic¡tion Cooditioa 

Table I displays the results of tùe .¡u\OVAs n¡r on each pcrforr:ance variablc as a t'u¡crion of 

BAC Five of the sixpcttbrmæce paranreters sig¡ifrcantlv (p - 0.0008-0.00C1) decrcased as 

BAC inc¡eascd, u'ith poorcst pcrformance resulring at a BAC of 0.10 or grearer. 

Thc liæa¡ relationship between increasing BAC a¡d perforurancc impairment u'as anal,vscJ b¡.' 

rcgessir€ mean relativc pcrformaacc agains BAC for eæh 0.027ô intcrval. As is er*lent in 

Table 2, tlere was a sgrificant (p - 0.0132-0.0001) liræa¡ con=letion bet\'æen BAC ¡¡id rnean 

rclctiye performance for all of the variables except one. It was found ¡hat for eacb O.0l% 

increase in B.{C, thc dccreasc ia performance relanve o bascline rar¡ge.d frorn 0.29 to 2.689'0. 

Pl¡cebo Condirion 

'fo ensue that differe¡rces in prlcmance reflccteC onl¡, rhe :ffects of aaual alc¿iol i¡i.rxicarion - + 

a placebo couditlon u'as incorporated into the stu

P€rformance pruErneter \Àas associated \+ith pooresr perfornrance r€s¡hing añer 25 to 27 hou¡s 

of r¡zkefulness 

Sincc rhere is a strong non-linca¡ component to the performa:rce data, u.h,rch Emai¡ed at a fairly 

srable level throughout the pcnod rvhich conodes uirh tbeu r:oro¡l uaking da¡,, the 

pcrfonnancc dccrement per hor.u of wakcfulness, was calculated usng a linear regressioo between 

the seventcenth (equivalenr to I l:00pm) and tn'cnty-seven¡h hor¡ of r¡,aksfulness. 

As indicated in Table 2, regression analyscs re¡¿ealed a signit-rcanr linea¡ sonctation (p - 0.001l- 

0.æ01) bctwcen mean relalive performance ærd hours of wakefulness fo¡ foru of tbe slx 

perfom:ance variables. Betwecn the sevcutcenth a¡rct lwenrv-sevenrh hor¡s of u'akefulness. the 

d"-cre¿se in performancc relative to baseline ranged fron 0.6i tc 3.35% pc: how C¡able 2). 

Surt¡ined \t¡kefulness ¡nd Atcohol lnto¡icrtion 

Tle ;i:::a-1' airrr 9f the cresent study was lo cxpress ùie effect-q of S\¡,;;ffi; oí# 

reurobehaviouri perfor:nani¿ l¡Lsks as a blood aicohol equivalent Figr^res l-6 iliusüare:hc 

cornparaire cffects of alcohol intoxtcal¡on and sustarneJ ç'akeñ¡l¡ess on the six performancc 

Pararneters 

\\t¡en comparcd ro ùr impzurment of performance cased by alcohol at a BAC of 

0 100/á, thc sarne degree aí impainnenl was produced after 20.3 (grarnmar:cal r:asoning responsc 

:atency),22.31r'igilancc accuacy) 2a.9 (vigilançc response latency) or 25.1 rtackint aucwac¡-) 

hci¡rs. Even aflc¡ 28 hotus of sustai¡red wakefulness, nei:he¡ of tlc rcrnaining two per.lonnance 

va¡iables (gran::rrdcal reasoning ùrcurac\ aod sirnple s3nsory corrparison) l:crc".ed to a lewl 

equivalent to the impairn¡enr ot'serred at a BAC oi0.l0%.

Dtscussror 

In the prescrl study moderalc let'els of alcohol intoxic¡uon had ¿ cl¿a.¡lv measuable effect on 

neu"rcbcturiowal pcrformance. \\re observed thar as blood alcohc. concentration inc¡e¡scd 

pcrforman;e on all tbe tasL-s, cxcept for one, significa-rtly decreasc.i. A simila¡ effec¡ was 

obsened i¡ the sustai¡ed watefulness condition. As hours of wakefulness i¡creas:.J 

pcrformanæ levels for for¡ of the six pa¡ameters signifuurrly dccreased- Comparison of tbe ¡wo 

effecls indicE::d tbu modcrarc level5 e¡ootsirrd wakefr¡lness produc: performance decresìents 

comparable o üose ob'served ar moderare levcls of alcotpl intoúcation L:i social drinkers. 

As previous resca¡ch has found th¡t sme individu"l< tend ro pcrfonrr in a nan¡er that is 

consisænt with the cxpectation th"¡ they :ue in¡oxicated due ro alcohol consump,jon 

(Brcchenridgea¡¡dDodd" l99l), aplacebo condiúon *'as rnclu.leti br this srudy. We found ¡har 

rhe placcbo beverage did nor slgnrficantiy eflècr mea¡. rulative perÍorrnancc. Tlrus, ir r¡.as 

assumed that ¡erformance decrements e''oserr':d drrnng rle alcohol co¡i:jcn u'e¡c causeC sclelv 

bi'incrcas:r3bloodalcoholconcenüa¡ion.\loreo'cr-Ño"lffirlepiaceuo 

ccndirion in nis study gcnereì-¡' dii not crcatc dìe perception ci ar:ohol consumprion. 

Furthermcre. lheu participants Ì:ad alread¡ o

irnpaircd by apprcx:raarely 6 87ó and l1.T/o Grún¡ner¡cal rcasoning Eccr¡ñL-w onc rcspcnse 

latcacy, respcctiveh | 2.-7% and 20 57o (vigilancr accuç¡ct and response latener.. respccrryelv) 

ot 2l.tyo (rækingi Overall. the decli¡e i¡ mcar: reìative pcrfornancc ra¡gcd from 

aPproximalely 0.29%to 2.68% p:r 0.01o,ó 8.4,C. These resuhs a¡e consisæ¡¡ ç'irh previors 

findings that suggel that alcohol produces a Cose-dependcor decrcasc in aeuobehariou¡al 

pet'ormancc @illings a al.,l99l). 

In contrasl, næan rclaive pcrformance in tbe susta¡De¡l *¡keñ¡lness cond.iúoo showed th¡ee 

distinct phases. Ncr¡robehavior.ual pcrformance rcrnained ar a reladvel¡r stable lcvel during thc 

period uhich coi¡cidcd with the nonn¡l *nking day (0 to 17 hous). ln rhe second phase. 

performance dccrcascd hnearly, with poorest pcrfornra¡cc geærally æcgrring aie¡ 25 ¡o 2? 

hours of wakefulncss h q'as obscrred that mea¡r rclative perfomrancc i¡creasei agarn añcr 26 ro 

28 hou¡s of wakeñ¡h.ess presumably ref,:.-ting eiù¡:r the well reporte¿ gi¡cqJran va¡iation i¡ 

neruobehaviour¿l p3rforma¡ce (Folk¡¡d a¡d Tonersdcll. 1993) or an enti of tesOag scssion effea. 

The linear decrease n performanc¿ cbecrved for fou¡ of the melsu¡es rn this s:uCy is consifent 

- 

r+ith previo¡rs studics docu.arc¡ri.g ner.ÃoÞhsvior:nl perrbnnance decrea_ses tbr pencds oi 

sustaincd ç'akeñ¡Jnes< ¡etween l2EDd E6 bou¡s Oiodc er al. 1992, Sro¡er sr ai.l9t9; Ficrrca e; 

a/. 1968). Bet*een tbc seventeentb a¡d lwentv-seventh horrrs of wakfuln€ss, mcE¡l rclar¡r,e 

performancc sigrrificurtiy decreased EL a rale of approúmetcll' 2.61.,'o (gt-a¡'.roancål rcasoning 

response latcnc)'), 0 6l and l.9t% (vigi¡aæc accuracy anC respoose laæncy, respcctivel¡-) ol 

3.36% (uacking) per horu.

't¡/lule thc resul¿s rn each of tbc experi¡¡entai coadirions a¡e rnteredog in themseþes. a¡¡ have 

been prerìousl¡" Þcn esablished,, thc primar-v a¡m of the prese;: study u'a.s ro conpa:e the 

effects of alcohcl inloxjcanon ud susrained u¡skefulness- Equaing rhe effects of rÌ¡e two 

conditioos i¡dica¡cd tha¡ l7 ¡o 27 bo¡¡s of sustained wakefulness (;om ?:00pm ro l0:(Oaat) urd 

uoderat3 dcohoÌ consumptron hsve quannbtively similar cûbc¡s on neu¡obehavbrual 

performance. Indccd, rhc findilgs of this study suggcst ùrar aftcr only 20 hows of sr¡stained 

wakeñ¡lness pcnbrmance impairment n¡¡y be oquivalenr to thar obscrvcd æ a BAC of 0.10%. 

Th,is study has conñ.rmed tbe suggcsrion madc b¡'Da*'son aDd Rcid (1997) rhar modcratc levels 

of sustained wakeñ¡l¡ess produce performancc decrerner¡ts equiralot to or g¡ca¡er tha¡ those 

obscn'ed at levels of alcohol intoxication d€cecd unâcceDrabl3 ¡:en d¡iving, rryorki¡g a¡d,o¡ 

operating dangercus cqulpment. More r.rrportantly, horlever. rÌ.:s slu{v '*'as designed to 

determi¡e s'he'.her tbc :csu.!ts of Dawso¡ ¿-rJ Reid (1997) 'rcr. an isolate.d fir.,Jr.g, or 

,+-..,- -...ë.--cha¡actcris'¡c 

o:- the gencrai cogniove effccs of sJeep de¡rivgccn. Using ûre dcg:e oÍ 

impairmee: caL¡sed by alcohol û:al produceC a BAC crf 0l0h as a sljndard. th;s sruciv 

systcmaticall¡' ccmpared the effeos of susra:ræd r¡alietulness c: a r¿ng:Ë of neuobeharrou-al 

rasks. R.esulrs rndicaæ tha: r*hilc, in gcncral, susta¡ned r¡,alefuln:ts had a derimental c¡Tcct on 

psycbomotor perforroance, the specific conponeûts of p:rfonnaæ diñìãed in theu dcE-e cf 

sensitiviç' to sleep deprivarion- 

The obsened diffc¡coccs bclween the performa-rrce tasks with respcct ro lhe nrlncra$liry ro 

sleep depiivation can be explaincd by their relative degreas of cor-:iexiry Tbat is to sar-. the

-+-.r 

more complex neurobcbsvior¡ral Parameters measwed i¡l rhe :-se::: srud¡. \À,3rc morc scnsitire 

to sleep deprivation thaa u'erc thc srmpler perlbrmance pe:-¿¡;erers. ñhile ".nl). 20.3 hor¡s of 

sustained r¡'akefulness was neccssaD'to Froduce a pcrformaru: decre'r¡cr¡r on :he most complcx 

rack(granllllaticat rcasoning) cguivalcnt ro thc impairment ohser-cc.l at a BAC of 0.109,e, it r+.as 

añer 22.3 a¡d 24.9 hours of susra¡ned wakefi:lness ¡ha: a smilar rÉ:ulr w.as seen in a ress 

complex task (vrgilancc æc¡¡tæy and response laæncy. reçccriveiy) Funhermorc, on Ìhe 

uapredictable tracking task, a slightly lcss complcx rask rhan rrg,lance, a decre'¡enr ul 

perforrnance cquivalontto that obscn'ed at a B.Ac of 0 10o,'o was producec añer 25.1 hor¡¡s of 

wakefi¡lness. 

It u'as obserr¡ed tbat, despire a sli¡ûrr downw.ard tend, pefc:uance o;: rhe sirnplest çf the fou 

usls did not significandy decrease, even folìowing twenr) -eigL: hcqrs of susra:ned r¡,aket-ulness. 

In contrasq perfomnnce on this t¿sk was significantl¡' irnpa:ed a-ñe¡ e dose .rf alcohol that 

produced a BAc of 0 l0% l'or 8-ater) These results ere i¡r h¡: rvrtb üe suggestion :hat slrrple 

Gsffileds ìensir¡r'¿ to sieep .lcpnvadon (Jobnson, 1982). iDdeåt ue bcljerc ir tilel¡. rhar 

impairmcnt of pcrformaucc on this rask may have occu¡red L- *e baC exendcJ rhe period oi 

sus¡uned wakefulness. Il is ¡nte¡Êsting o note tbat several stui::s (e ; Dinges et al., lggt) har,: 

reponcd that tasks similarly læking in complexity, such as sinpl: reacÞo¡ tinnc ìLc¡is. a.rr 

affcctcd carly aad proforudly by slccp ioss, thus srrongly- suggesting rhar rnonobny may 

increase sensitivitv to su5a¡ned wakeñ¡lness. Indeed. ¡hc facl drat ¡his :¡sk rras nor wlne¡abie 

!o sust¿r:'ned rvakefirlness may possibl¡' b,c explained by the :ntercsting a.nc :hall:nging :ropenres 

gf ¡ls t¡rk

It is also note'lonhy that, uhile we obsen'ccl a decreâsc in accwac.,r/ on rhe gram:naúcal 

reasoniugtask,imparrrrentof th:sperformurce parameter was not ccnparable to thar p;oducod 

by a BAC of 0.107â' \ltile this nray a¡ first cont¡adict u\e suggesrion thar in rhis srudv 

vulnerability to sustained wakefulncss was, [o E lârge degree, dercrmi¡:cd by rask compiexity. rr 

should bc notcd th¡t pa¡ticipa¡fs rr'ete insuucted to concentatc on a;curacy rather rhan speed 

when completing the grarnmalcal reasoning task. Thus, our partrcula¡ insrnrcdons ro 

puticipants may uplaiu- at least in pan rhis irrcgu.¡ariry. Alremadvely, rhis finding is in lir¡c 

with the suggesúon of a narnral 'speed-accuracy tade-off. Sirnil¡¡ resulLr have been obscrred in 

5sveral studies, ç'hich repoÍ a cecline i¡ speed of performance, but nor accurac)', when s,leep- 

deprived subjects arerequired to pcrform a logical-reasorung task (Ângus and Hcstegrave, 1985; 

Webb and Lcvy, 1982). 

lnreresunrl¡', this was not the c¡se '¡'ith the vigiJarce task. In rhis ies:rnc:, despite ir--\:ructtcn 

to cooccntrate pnmanll'on acct[acy, this componcnr \as shEhtly nore w.nerelle to sleep 

deprivation than r¡'as resp.ersc latency The absence of a tade-off on this rask na1, bc eçlaincd 

by the diffcrent propenies of the vigilancc and grammatical rcasorung tasks. In accordance u.:lh 

the distinction raiscd þ Broadbent (1953). :he laner oirhesc rasks cs be defìncd as arr u¡pêccd 

lask, in which the subject cetermi¡es thÈ ral.e Of stjmuli presenurlion In contras(, tbe rigjlsnsç 

task can be defined as a paced task, in which stunuli are presenteC a'. a spced controlled by the 

experineilcr. ln linc rrith this distrnction, our 6nClng. ar: consisteot r¡'irh thosc of B¡oaJbent 

(1953) who observed ùur while a paccd task raprdly detericrateC durin3 ùe exp:rimen'.al pcriod, 

in tcr¡ns of spccd, an unpaccd ve¡sio:: of t.re same t-k dr,l, nor

A rurth:r expla:ration for thc dtffe¡ences obscrved b:tweer L-.:sc :\vo tasks, may' ¡elatc ro the 

extremelv mono¡onous riErur€ of the vrgi.:rrcc usk. InCeei ue believe rr likely thar subjects 

\f,'e¡e rnore mouvatcd to perform wcll on tlre grarnmatical reascrung task. u.hich rvas senenllv 

considered more interesting and challenging. Hence degræ of motivarion rnay explain wh¡' 

rneasures of boù speed and accumcy decreascd on ¡hc vigildlcc usk, while on the t-orm ¡ask, 

accttacy remai¡eC relatively stable. This suggestion is in line r*'irh previous str.¡dies u.Ìich lrave 

for¡nd thz¡ mot¡vaüon ca¡L þ e degree, coru¡tcracl tbc effects cf slecp loss (Home and Pcrrirr, 

r e 85). 

Takcn togethei, ¡he resultsùom tbis study support tìe s-rggefl:e..r tàar eren ¡nodera¡e lo,eh o: 

sustaiæd u'akefulness produce performancc decrennents grealer :han is curre.:itly' acceg,able for 

alcohol intoxicat¡on. Furthennore. our îrrdings sugg:sl '-::: u'hile sleec Cepirva¡ion has a 

ger¡enJl;l detrimcnul cfi:ct ot neruobchaviou.al ç'erfonrance. spec:,fìc cùmpon3¡ìrs of 

performance difÈr in thei¡ sensrlivit¡ to su-

\\ìic lhe currenr siudy supForts thc idea rhat susrained wakefi,¡lness æa.v carr¡. a risk 

cocparable with moderate alcobol intoxicaùc:i. i: is difficult lo Lrou' ro u'ìra: degrec these 

rccrlts ca¡¡ be generaliæd to 'lc¿l-life" scttings Indeed, labcruori. measurËs a¡rd e¡r.ironm:nrs 

rrsully bear little ¡esemblance to acluai tasks and scttings. Fr¡rthrrmore. niule our study uscd a 

bt¡lery of ¡csts to evair¡atc Ùrc cffects of sr¡st¿i¡ed wakefi¡lness on performance, thei¡ is no 

F¡araalce that all the functions involved in .lcal-tife t¿sks", such as .Cnvrng, r¡ere utrlised and 

ase¡sed. An alternative approach '*'ould bc to si¡nutate rhe acrual rask, as accgrately as 

pocsit'le Givcn that, for practical and ctÞ.¡cal reasons, i¡ is difl¡cui¡ to experimenall¡. study the 

rclarionship b:rwccn susta¡ned',+'akcfi¡lness a¡ü actr¡al drrvrng, s;nularcrs of var,ring realiscr 

iure b:en used. Thus, protocols rsing simularors could be uscd ro model "rcal-Uli'. selings and 

es¡abllsh a more acculìBte cfirnåte of the BAC equivalence for Èrc perr'urr:rancc ,Jecremenr 

rss.r:iaæd *ith sleep loss and fatigue 

+-

REFERE]{CES 

Angus, R.G. and Heslegnlc, R.J. 

com¡nand and control siarrl¡tio¡. 

19t5, l?:55-67. 

Broadb,er.t. D E Noise, pa.-cd performancc. 

1953, 4a:195-303. 

Effects c:- sleep anci sutained cogn:rire performance dring a 

Behatiowal Research ]tlethodr !4siruments and Computers. 

Babkoff, H., Mikuiinccr, !t.. Casp.v. T., Kcrnpinski, D. and Sr-,e, H Tt¡e ropolog¡- of 

pcrformance culYcs ùlf:rìgn horrs of sl=ep loss: A memor.v and ;ea¡ch task. Iåe eørterl¡, 

Jownal of Experimento|Ps¡t\ologt . I98B, 3.24:73i-756. 

Brcchcnndge, R. a¡¡d Dod4 M. Locus of connol and alcohol placebo eiects on perfo:manc¡ i¡ a 

dri"iq8 simulator. Percef,¡ui and lvlotor Sb/Js, l99l, 72: ?Sl-756. 

a¡¡d vigila¡rcr. t¡sks 3¡:r-.å Jot,ncl of Ps;.claì,.-g,. 

Dalscn, D. u:d Reid, K Far:gue, alcohol aod pcrfornurce r.:rpairm e:;- |¡iøtw¿,1992, ltt: 235. 

Dick, RB., Serzcr, j.V , B'air, R.. Hayden, N{.8., Tavlor, B.J , Tolos. B. and puu-Ànderso:. v 

Effecs of acule exPosur" to toluerrc urC n:thyl elhyl ketone on pst cbomobr perforrnar:cc 

Archives of Occu¡ntiotuti qnl Environmcnlal Health, 1984, 5a: 9l -: 09

Drnges, D.F . Wlritehouse, W.G . Orne, E.C urd O-rc. il.T ltc benefis of a nap c.--;g 

prolonged r¡'ork and *akefulness. tlorkandSness,l96S.2; l3g-: j-? 

Fiorics' v.. Hisginsl E 4., Ianpieúo, P.F , hrcgota lrl.T. anc Daris, .q,.w physic.lcgia 

Íesponsesofmandruingslccpdeprivaaon,Joyrtulof.lppliedphynolog,,,lg6g,24(2): l69-j?5 

Folkud" S- Toncrdcll, P., MiDors, D. aod Vateri:ouse, J. Dissecung circadian perfom.an:c 

rh¡hms: Implications tbr shiftwork. Ergonomics, l99j- 36(1-3): ltj-t 

Gillberg, M', KcckJr¡nd, G. a¡d ¡'ke¡stedt, T. Rela¡iors bctr¡reo pcdormancc and subjær,;vc 

ra¡ings of sleepiness during a nighr arralæ. Sleep, 1994, I 7(3) : 236-t L 

Heishmar¡" S.-l , Slrser, trl L. and Bigelou', G.E. Alcchol an3 ;naril:an-a Comparative dose eiecr 

protìlcs in ht¡mans. Pharm¿colop, Eiuchemisrry and Behattour.'.çsg 3I :649-65s. 

Horne, J.A. and Penrn, A N Hi-eh i¡ceotive ciTects on ¡gilr,ce pcícrnance dru:ng 72 hor¡-. e: 

rotal sleep dcprivation. ,lcto ps¡'chologica, i 98S. 5t, l 23 I 3 9 

Johnson, L.C. Sleep

Mullaney, D.J., Kripkc, D.F., Flec&, P.q. and Joh¡rson, L.C. srecp loss urd nap effecls.rn 

strsta¡ned continuous pcrformaocc . Pslvhophy.siolop, 1983, 20: 643-ó51 

Storer. J.. Floyd. H., GilL W., Giusti, C. And Ginsberg, H. Effects of steep dçrivanon cn 

cognitrve ability and s¡ci[s of pacdiauic rcsidcnrs- Academic Lledicine,l989.64: Zg-32. 

Thapar. P.,7acny, J.P.. Thompson, W. and Apfelbaum, J.L. LÌsing alcohol as a sta¡rdarC ro 

assess the dcg¡ec of impairrnent induced by sedative and analges;c drugs used rn ambula¡orv 

su¡ger.v .1¡usthesiolog', 1993. E2(l): 53-59 

Tilley, A J. and $'ilkins¡, R.T. The effects of a iest¡ictcC sleep rcgrme cn th: con:posi:ion cf 

sieep arÉ on performancc Psychophysiolop, t9ti. 2l : a06412. 

WèltÙ:WlÏnd Levy, C. .+¡e. 3tëëfq'mùticn and p€rr-ornarlcc Pst:hophysiolog-v. t9SJ, 

19(3):7-¡2-2t6. 

Wickens C. Engnæering o:¡'cholop and lutman ¡xrformaôce. C.E. Ife;ill, Colr.¡¡nbræ. 19t4. 

Wtlk,nscn, R.T. Effects of up to 60 hows sleep deprivation on differeût Þ pes of '*orli. 

Ergonomte

.-

TABLE I Summary of li¡ea¡ rgession ar.aiysis of ne.,¡obchaviotu¿. performance r.¡-iables 

Petformance Psr¡meler DF F R2 9/oDecrcnse 

SW Condiúon 

GRG RespoDsc Latency 

GRG Accuracy 

VIO Response LatencY 

VIG Accuracy 

Unprcdicøble Tracking 

Simple Sensory 

Aìcohol Conditior 

GRG Response Latenc¡'b 

GRG.{ccruacv 

VIG Response I-atency 

VIG Accuracy I 

UnpreCrctable Trackrng' 

Simptc Scnsor¡ 

1,4 

l14 

1.4 

1,4 

1,4 

1,4 

70.61 

3.64 

98.54 

8! 79 

?0.93 

4.71 

74.30 

31.07 

t2 ê5 

2t2.37 

238.52 

s.37 

0.00t 1 

NS 

ù 00c6 

0 0008 

0.i,1l 

NS 

001i2 

0 Crl-< l 

0.ccù2 

0.00r)7 

c.æcó 

'Baseci on daa from 0.02?i-0.1truô BRC: b Bascd Lrn dat¿ ûom 0 C4?;.0 ltrzó B.¡rC 

NS 

0.95 

c96 

0.95 

0.95 

0.9? 

c89 

09E 

J.99 

0.99 

(pcr bour) 

7.69 

l.9t 

0.61 

3.36 

1¡ler0 0l% B.{C) 

)?1 

068 

205 

c.?9 

268

¡0 - 

5- 

3 

¡o 

Ê 

ë.r 

t) 

i'ror 

; -ts-.1 

3l 

_ -20 I 

at 

ut 

-30 

.15 

0 0 ) ü25 û.5 .0ó5 .085 .r0 

Blood .4lcohol Ccnccnùrtion (%) 

¡: t: ¡9 2! 

Houn -.f tÀ'akefulness 

FIG. l. V:rn :r.rtive prrfornranc: lcrels'.-o¡:lc respo:s: .arctc)' aou'¡pçne:: ;it-c s-amn¿lio¡l -asonin¿ 

t¡sk ln'.hc rlcchol ¡ntox¡c¡¡JoD (leflr end cust¡incd *arcL¡lness':¡ndi¡ion The eçivaleo; pc:fonnanc: 

dçcre¡¡clrr ¿l ¿ 8AC of C 05?å ar!l.le\ ¿¡e indrcated c: Èc rigl'.r ha:o ¡x's E¡ro¡ be.- inCìc¿te: or3 s,e.n 

a' 

o 

c IêG 

) 

t 

\. 

a\ 

+

e 

;U 

tr 

E.2 

I 

6 

o 

8.6 

¡u 

l 

z-¿ 

-1 

i 0a .03J .045 .065 CE5 -tc+ 

Bìacd Ahohol Ccncentr¿ticn (%) 

FlG. 2- ltlcs¡: rulrrive perforr:ancc levcls for rhc accw¡c),comh*îcr.: cf the ¿ra,r-esc¡l trsc¡rng tr!\ rn 

'àe alc¡..ùl r¡:cxtcation (le:) utd sust¡u:d x¡kefulness cofidr:Ìon ñe cq¡rra,:n: perienr.a-.- dccrc¡n:nr 

ata BÀ3 of t 05?z¡anC 0.10ú16 ¡n tnd¡cdcd ur thc right.r.urd r¡i: E¡rot ba¡s ¡.rdrcùtc 3 on€ ;.s m. 

-+-- 

0¡0 

e 

c- 

c 

o 

ç 

(: 

l: 

¡ 

s

5l 

e 0l 

9l 

el 

lf 

ã -5 I 

al õl 

g-l0l 

e.¡ 

Ðl 

y.r:l 

!l 

- -20 J, 

-25 

I 

I 

c oo 0?5 045 .065 .O¡f l0+ 

Btood Alcohcl Concent¡aion (%) 

ftG.J. VcurclUiv:pcrfc:nan;cle,rl¡forÜ:responsclatc:rc¡'aornpcn3:.:ofthevrtrlsnc:¡askinthc 

¡lcchol i¡1,¡xication ;l.fi) ¡J'l3 su3r!,nsJ wakefulness colüirio¡ Tþ cquivi::t pelona.lræ d:crcnen! lt 

! B.r\C of 0.05',ä ¡¡,,1 0 l0% a.'e rndrc¡tc: cn Úr: nght h¡nd axis !:o; ba¡s :-:dic¡tc ? o;1c: a m. 

t) 

2 

a 

E 

e 

ê. 

1) 

G 

C () 

'l I 

1 

-¡ -, 

I 

1 

.rJ 

1 

-5 - 

0 O0 üzj :r5 0ó! ,0t! .10+ 

Blcod Aìcoìrol C.rncentr¡tion (%) 

FIC ¿. Mc¡n rclS:rre p:rformance level¡ fo¡ ihe accuracy corE:poieût of tàe rìgiìur:e trsk in the 

alcohoì r¡roricarion i.:ftt ¡lr: sust¡:ncd waêc 

oro I 

e 

D

0) 

I 

É 

Ê 

E 

È 

L 

I 

e. 

l) 

I 

t) 

/ =I 

E 

20- 

l 

'o I 

.J 

_10 - 

I 

¡ 00 015 .o4t .055 .tl' l0+ 

Blood Alcohol Conccritra¡ion (%) 

' lt :5 l; 31 7i 

Hours of Sakeñ¡lness 

FlG. l. Mecl rtl¡tive perfgrm¡ncc lcvel¡ for ürc rrnprcdi;trble kukiag ¡¿¡k ¡n the aisohol 

'-toricotior (tçñ) ¡¡ìé srs:¡bed w¡kcfulners cor.dnioo, Tbc equrralcot pc:'fo:trrn:c dccæb.-rt rt a 

BACof0.05%¿nd0lf/slrernd¡c¡redonÛrcrightLa¡rd¡ris. Eno¡b¡¡r;nCrEsis+ones-cln. 

+ 

F 

+c 

e 

G 

t 

c 

s

I 

I 

äãË 

's.8 ¡ 

Zã¿ .- 

, ¡r â'B 

I q:l> 

I ""- 

áÊ 

I ëp t 

Ixgi 

= &3 

äÊH 

òoÕ 

ø¿-,s73 

rÍ,: 

'l ar O 

üú5- 

z*t 

rã: 

8,- I 

etË 

ó'f ø 

îtE 

nBo 

- l!¡ 

,t- i; 

c9 

tL 

et 

3lI 

E oÉ 

ßl 

u'l 

o 

4, 

çc 2' 

ôI 

5 ô8 

;- 

b g, 

ãå 

oú 

't 

-¡-l 

- , 

,l 

Mealt Rcle¡ivs Pcrformancc 

åti"êÞ:ù 

l- -¡--L-r L---I-¡ J-¡--t-r-l 

t'.{ 

-Ct 

o 

(9å) utx¡c¡¡ucruolt loqottv Puotq 

I 

I 

I 

I 

I

O X-éZlaJFÉFú>

Crev. tattgue tactors m a\nauon acçlot'lìr 

crew fatigue factors in the Guantanamo Bay aviation accident 

Mark R. Rosekind, PhD' 

NASA Ames Resea¡ch Center 

Kevin B. GregorY, Donna L' lvfiller 

Sterling Softwa¡e 

Elizabeth L. Co 

San Jose State Universþ Foundation 

J. Vrctor Lebacqa PttD' 

NASA A¡res Research Center 

Malcolm Brenn€r 

National Transportation Safety Board 

. time, a military contract flight crashe'd while 

on, Guantanamo BâY, Cuba- The aþlane, a 

il States government, conducted an official 

:cident and to make recornmendations to 

e NTSB, the NASA Ames Fatigue 

r fatigue factors to examine their potential 

role in the accident. Three principal sources of information were made available from the 

NTSB accident investigatión to NASA Ames for analysis: 1) Human Performance 

lnvestigator's Factual R"Pott' 

2) Opeiations Crroup Chairman's Factual Report, and 3) Flight 808 Crew Statements' 

Based on scientific data related to sleep and circadian rh¡hms, the NA-SA Ames Fatigue 

Countermeasures program identiñed ttr"" core physiological factors 1s s¡emine wheB 

rt oiaccident. These factors have subsequentþ 

a factor exnmined but not previously reported' 

ntlaccident investigations are: l) acute sleep 

urs of wakefulness, 3) time of day/circadian 

effects, and 4) pressnce of sleep disorder. These factors were examined and the 

sleep/wake histìries for the flight crew prior to the accident are presented in Figr[e l' 

hnp ://olias. afc.nasa. gov/publicationvrosekind/GB/GB. 

Abstraa -html 

1A27198

Cre\' laugue lactors ln avlatron acc¡uçIìl 

Cæt 

F/O 

FlE 

IIII 

tllllltl 

Figure I. Crevv Sleep/Wakc Histories 

The crew had been offduty up to 2 days pnor to the accident trip and then flora'n 

overnight cargo schedules for the two nights prior to the accident, and had been assigned 

the accident trip unexpectedly on the morning of August 18, shortly after b€ing released 

from duty. The e ctra trip involved segments from Atlanta to Norfolh VA to Guantanamo 

Bay back to Atlanta, approximately 12 hrs of flight time in 24 hrs of duty. The figrre 

provides information on the fatigue factors: l) the individual crelv members had an acute 

sleep loss (i.e., 5,6,8 hrs of daytrme sleep),2) were continuously awake 19,21, and 23.5 

hrs prior to the accident, and 3) the accident occu¡red just prior to 5 pm local time during 

the afternoonvindow of sleepiness (this did not represent a trme zone change for this US 

East coast crew). Upoo inquiry, there were no reported synptoms or signs of a sleep 

disorder. Therefore, all three of the rnitial fatigue factors rvere operating in this accident. 

Thsre were two principal sources of data available on flight crew performance in the 

accidsnt: cocþit voice recorder (CVR) and Captain's testimony at the NTSB public 

hearing. There e/sre four performance effects related to fatigue that significantly 

contrr-buted to the accident: I ) degraded decision-making, 2) visuaVcognitive fixation, 3) 

poor corlrmunication/coordi.tation, and 4) slowed reaction time. 

A complete description of flight operations, fatigue factors, performance effects, and 

accident investigation findings are available in the frrll NTSB accident report (1). Based on 

the findings, the NTSB determined that the probable cause of this accident included the 

impaired judgment, decision-making, and flying abilities of the caPtain and flightcrew due 

to the effects of fatigue. This was the first time in a major U.S. aviation accident that the 

NTSB cited fatigue in the probable cause. As a result of this investigation, the NTSB 

recogrmsnded that the Federal Aviation Administration (FAA) expedite the review and 

upgrade of Ftight/Duty Time Limitations of the Federal Aviation Regulations to ensure 

that they incorporate the results of the latest research on fatigue and sleep issues. The 

NTSB reiterated a recommendation to require U.S. air ca¡riers to include, as part of pilot 

training, a progrâm to educate pilots about the detrimental effects of fatigue and strategies 

trrp ://olias. arc. nasa. gov/publicationVrosekind/GB/GB. Abstract. html r2t27t98

Cre'., fattgue tactors tn auarlon acctoent 

for avoiding fatigue and countering its effects. This hfTSB investigation and the NASA 

guidelines to examine fatigue factors, provides a model for investigating and documenting 

the role of fatigue in operational incidents and accideng. 

(l) National Transportation Safety Board. Aircraft accident report: uncontrolled collision with tenain, 

e¡¡grir.tt International Airways Fhght 80E, Douglas DC-8-61, N8l4CK U.S. Naval Air Statioq 

Guantanano Bay, Cub4 Augr¡st 1E, 1993. WashingtorU DC: National Transportation Safety Boa¡d, 

1994; NTSB/AAR-%/04 

hnp ://otias. afc. nasa gov/pubb cationVrosekind/GB/GB. Abstraa. html t2127/98

AIR LINE PILOTS 

535 HERNDON PAtrKWA.Y tr 

ASSOCIATION, 

P.O. EIOX 1'1 69 tr 

TO: Captain Rich Rubin, ApA 

Captain Robert Landa, SWAPA 

Captain Don Kingery, IACP 

Captain Dave We11s, FpA 

Ms. Lauri Esposito, IpA 

Mr. Don Treichler. IBT 

¡NTERNATIONAL 

HERNDON, VtRGtNtA ?O17?_1 159 tr 7C3-689-2270 

FAX7O3-481 _?478 

February 19, 1999 

For your records, r enclose a copy of the Reserve Duty/Rest 

Requirements working Group submission regardingr reserve rest. 

The ARÀc working Group pilot Members Submission contarns the 

f inal Lamond/Dar^/son report which was produced as Àppendix F. 

You should discard che copy of the submission thac was mailed to 

you on or about Januarv 9. 

. ã\tr 

Enc losure 

Qi n¡ora'l rt 

v¿¿¡vv! v¿-Y , 

Legal Department

AIR CARRIER OPERATIONS ISSUES GROUP 

FAA AVIATION RULEMAKING ADVISORY 

COMMITTEE (ARAC) 

RESERVE DUTY/REST REQUIREMENTS 

WORKING GROUP 

Donald E. Hudson,l!I.D., Labor Co.Chairman 

H. Clayton Foushee, Ph.D., 

I nd ustry/lVlanagement Co-Chai rman 

Phil Harter. Moderator

LETTER FROM BILL EDMUNDS TO THOMAS MCSWEENEY. FEB. 'g.Iggg

L 

AIR LINE PILOTS 

535 HEFìNDON PAFII

y the FAA a¡ individual airlin:s for individual operations. The indusrn/labor represenrarives 

prefer a more stn¡ctured approa;h. 

After severalpublic meetings::¿o basic scheduling schemes were proposed for providin_e resene 

pilots the opportuniry for rest u-r limiting the duty day based upon the amounr of advance norice 

of flight assigrnænt: 

o d scheduled protected drne period for all reserve pilots with the use of advance 

notification to either ca¡cel a scheduled protected time period or ro utilize a reserve on a 

sliding scale where the length of the duty day would be dependenr on the amounr of 

advance notifrca¡ion. a¡d 

o Limiting the duty da1' based upon the arnount of advance notificarion for a flight 

assignnrenr. 

Consensus 

ARAC proposals are based on developing consensus within the working group. The services of 

Mr. Haner were used to assist in this regard. After a great deal of discussion and give-and-take 

on the part of all concerned, tbe working group realized that consensus r+'ould nor be possible. Ar 

that point, the labor and managen¡ent representatives were asked to derelop proposals that woutd 

address their individual concerns and issues. 

These proposals a¡e presented to provide the F.{'{ the various industrl concerns and the rationale 

for their respective positions. 

Industrv Prooosals 

The industrv/manasement reprrsentatives fìnal proposal for Pan l]l scheduled operarions 

proridesaminimumeighthou:::stperiodor l0hoursof adrrncenoril-;;¡rion.undermosr 

circumstances. pnor to a fltgh: .-rsignment. 

Industlv/manf,gerËnt represen'.tives (Helicopter .\ssocirtion lntern¡rir-nel ) propose e scheme ior 

Pan 135 on-dem¡nd airchaner -.perations *hich include scheduled res3f\È.¡nd ertended rÈser\e. 

u ith provisions for operation3i ¡ela-vs. 

Industry/managernent represen',:tives (Nationel Åir Transpon .{ssocirriurn and \ational Business 

Aircraft Association) also address such reserre-related issues as res[. oppùnunirl'time. duty, and 

standby in Pan 135 unscheduled operations. 

Industry/labor representatives propose a minimum prospecti!e protected rime penod of l0 hours 

during a 24

Economic Impact 

Industr.v/management represehtatives compiled economic data penaining to the cosr of their 

proposal for Pan l2l scheduled operations. They estimate there u'ould be approximately Sl00 

million in incremental costs to the ma1or operators that provided economic data. primarily Air 

Transport Assoc iation member airlines. 

No econo¡:nic data were provided by smaller Part l2l or Part 135 operators. 

The w'orking group was unable to provide additional economic analyses comparing the various 

proposals. 

Summary 

A great deal of honest effort and serious consideration ,*ent into developing these proposals. The 

working group engaged in an intense n¡eeting schedule. essentially monthly, and much work was 

performed preparing for meetings. The working group is to be commended for this dedicadon. 

Special thanks a¡e due to Dr. Foushee and Dr. Hudson for thei¡ dedication and sincere efforts on 

behalf of bringing this task to fruition. 

While the casual observer may see great differences among these proposals, it is essential to 

concentrate on the common elements The¡'can serve as a basis for ac¡ion by the F,{{ in the 

rulemakrng arena. 

Thank ¡ou for the opportunity to be of serrrce. 

Enclosure 

S incer:lr . 

uJ \o¿_'^ q) Îa* *o 

\\'illirm \\'. Edmunds. Jr.. Chrirma n 

,\R.{,C.\ir Camer Operetions Issues Group 

'Y

E 

Í|l 

i 

:' 

3- 

¡. 

aù 

-J 

¡t 

¡, 

- 

- 

tl 

MEMO FROM DR. HUDSON. FEB. I.Iggg

Daæ: Februarl' l, 1999 

To: Air Ca¡rier Operauons Group 

From: Donald E. Hudson, M.D. 

Labor Co-Chairman ARAC Resen'c Dur,v Working Group 

It was my privilege to again serve as Co-Chairrnan of anothcr ARAC V[orking 

Group, this tirne dealing with reserve rest issues for professional pilots. It u'as also 

rewading to again work with Dr. Clay Foushee, with whom I sha¡ed office space at 

NASA Ames Research Cenær in the mid-1980's. In addition, Phil Harrer did an 

adrnirable job moderating this sometimes contentious gathering. 

Tt¡e diversity of today's aviation environment was reflected in the representatives of 

the group and it was clear frorn the outs€t that there were a gfeat variety of 

operational schernes in use for schcduling resewe pilots. Most of the meeting rirne 

was sPent in anempting to reach agreernent on a general scheme for Part l2l 

Schcduled Operators, it being felt that consensus was more probable in that arena. 

However, I was disappointed and dismayed thaq once again, a general conssnsrs in 

the AR {C bctwecn labor and managcment representatives proved elusive deqpite 

good faith effons by rnury talentcd people on both sides of these issues. 

At ftc first mcenng, it was decidcd not to do a comprehcnsive review of the scientific 

li:crature on fatigue, despite the specific direction to do so in the Federal Regrsrer. 

The ntlonale at the time being that a deailed revieu' of üe sciendfic literarure was 

unneccssary and, indeed, might be an ac:ual impediment to reaching consensus 

recommendanons. It was felt by both Dr. Foushee and myselt thar the rwo sides were 

no: thar far apart and a discussron of the opcrational fatiguc research, especially that 

co¡ducted over the last l5 ycars, would lead to drsagreements over relarively mlnor 

Ports. In retrospect, thal was a senous eilor. As the discussions continued into the 

fall of I998, it became clear there werefwda¡nental misunderstandings and 

differences of opinion about thc resea¡ch data and it's applicabiliry to flight hrne/dury 

time regularions for pilots. Th¡s led þ assertions that thc scicnrific literarure can be 

inte¡preted in a variety of cqually plausible ,ways and rvas thus not vcry useful in 

providing guidance for drafting practicd regulations. That conclusion is nor shared 

by a¡:y of the reputable scicntlsts who bave conducted the operarional research and it 

is no: the vieu' of the labor representatives nor the Battelle Group ln their recent 

recom¡nendations to FAA.

To thcir crcdit, thc management group did acknowledge thc nccd to provrde an 

oppornniry for a pilot to obtain 8 hours of slccp in a24 fou penod but had great 

difïiculry coming to terms with the physiological fact tlnt where that opportuniry 

occurs in the circadian cyclc is as viøl a parameter as the number of hours available. 

The research data indicates tbat humans show sigruficant decrements in performance 

after prolonged penods of *akefulncss. .As wc all know, corrmercial aviation can be 

a vçry unforgiving atvironment and this pus a hcav¡'burden on FAA regulators who 

must try to eusure that safery is not unduly compromised. 

The labor submíssion to ARAC is bascd on the ava¡lable scientific data and research 

in this ficld - which continues in counties arou¡d the world. It is designed to make 

every effort to ensurc that, as rnuch as possible, only crcnmembers with opportuniry 

to reccive adcquate rest arc available for dury. It is also designed to prohibit 

operations that have the real potenhal to push the human operators to fly when 

physiologically impaired. Thc scientific basis for thæe reconmendarrons is 

referenced and includcd in the proposal. I would sugge$ the rnanagement side 

challengc themselves to similarly measure their proposal by the yardstick of rhe 

scientiñc da¡a as well. 

Any new regulanons w¡inen to add¡ess the pressing issue of pilot fatigue must be 

based on our knowledge of the deleterious effects of farrgue on human physiology. 

The only const¿nt in this discussion is the physiology of thc human operator - the 

pilot. All othe¡ considerations, including economics and eflclency are important but 

not decisive. 

It rs discouraging to note that it is now 5 years to the day since rhe last ARA.C Fatigue 

Working Group subrruned it's proposals to FAA - and we srill do not have a final 

rule on Flight Time Dury Time. New regulations dealing wirr Reserve Rest are a 

vital pan of any new rulemaking process urd I urge FAA to urcnsider the vanous 

proposals and the avallable scientiñc data - a¡d act swiftly ro add¡ess this pressing 

problem. 

,4-^ -tt P // / 

/^,/Or1 6,1¿4. r- foAkt- 

I -"* ' 

Donald E. Hudson, M.D. 

ARAC RDWG Labor Co-Charrna:r 

y* To-àL FÊûE.ø3 ¡.+

ARAC WORKING GROUP PILOT MEMBERS SUBMISSION, JAN.8, 1999

VIA OVERNIGHT DELIVERY 

Dr. Donald E. Hudson 

Aviation Medicine Advisory Group 

14701 East 2nd Avenue 

Suire 200 

Aurora. CO 8001I 

Gentlemen: 

ARAC WORKING GROUP 

PILOT MEMBERS SUBMISSION 

The 78,000 airline pilots who were represented at the ARAC Working Group welcome 

the opportunity to provide their unified position regarding a reserve rest re_sulation. We are 

pleased that the Working Group was able to reach a consensus that pilots who are assigned 

reserve duty should have a protected rest period during every 24 hours. However, we are very 

disappointed that we were unable to reach a consensus as to the "scheme" that would best 

provide the required rest. 

We believe that the efforts of the Working Group will prove helpful to rhe FAA in 

formulating a final regulation. The differing positions of the parties have been narrowed and 

clearly identified. It is now up to the FAA to timely promulgate a hnal regulation. 

Captain Rich Rubin 

Allied Pilots Association (APA) 

Captain Robert Landa 

Southwest Pilots Association (SWAPA) 

(,UIL 

,--\ t 

Captain Dave Wells 

Fedex Pilots Association (FPA) 

W>lL 

Don Treichler 

International Brotherhood of Teamsters (IBT) 

Respectfu I ly submitted, 

Dr. CIay Foushee 

Northwest Airlines 

901 l5th Street, N.W. 

Suite 310 

Washington, DC 20005 

Captain Frank Williamson 

Air Line Pilots Association (ALPA) 

Captain Don Kingery 

Independent Association of Continental Pilots (IACP) 

Lauri Esposito 

Independent Pilots Association (lPA)

Airline 

Air Wisconsin 

Alaska 

Allegheny 

AIoha 

Aloha Island Air 

America West 

American 

American Eagle 

Atlantic Coast 

Atlantic Southeast 

Business Express 

Carnival 

CCAir 

Comair 

Continental 

Continental Express 

Delta 

DHL 

Emery Worldwide 

Express 

Federal Express 

Hawaiian 

IBT 

Aviation Rulemaking Advisory Committee 

Reserve Rest Working Group 

Proposal of 77 ,955 Airline Pilors 


Pilots Airline 

240 

I 153 

354 

r92 

& 

r532 

9508 

2055 

694 

763 

372 

2t9 

172 

l 000 

4769 

1010 

9188 

395 

451 

329 

361 r 

285 

6000 

Mesa 

Mesaba 

Midway 

Midwest Express 

Northwest 

Piedmont 

Polar Air Cargo 

PSA 

Reeve 

Reno 

Ross 

Ryan lnternational 

Skyway 

Southwest 

Spirit 

Sun Country 

Tou'er Air 

Trans States 

TWA 

United 

UPS 

USAirways 

USAirways Shunle 


1095 

804 

174 

262 

6103 

368 

186 

254 

33 

302 

l9 

257 

I _ì2 

1735 

t 5-1 

2l -j 

206 

806 

25 r6 

962t 

2 r00 

5092 

t67

TABLE OF CONTENTS 

Preamble .............. l. 

Part I: Proposed Regulatory language ................... 5 

Part II: Pilots' Proposal with Intent, Examples. and Rationale........... -....--- j 

Scþntific Support ................ 16 

Principles and Guidelines for Duty and Rest Scheduling in Commercial Aviation, 

NASA Technical Mernorandum I10404 (May 1996) Appendix A 

An Overview of the Scientific Literature Concerning Fatigue, SleeP, and the 

Circadian Cycle, Battelle Mernorial Institute (January 1998) ....Appendix B 

A Scientific Review of hoposed Regulations Regarding Flight Crewrrpmber 

Dury Period Limitations, Docket #28081, The Flight Duty Regulation 

Scientif¡c Study Group ..........Appendix C 

Remarks by Dr. William Dement to the ARAC Working Group Pilot Representatives, 

December l, 1998 Appendix D 

Farigue, Alcohol and Performance Impairment, Nature, 

Vol. 338. July-August 1997 ..Appendix E 

Quantifying the Performance Impairment associated with 

Sustained Wakefulness. Nicole lâmond and Drew Dawson. The Centre for 

Sleep Research, The Queen Elizabeth Hospital, South Australia Appendix F 

Crew fatigue factors in the Guantanamo Bay aviation accident. NASA abstract......... Appendix G

AVIATION RULEMAKING ADVISORY CONÍMITTEE 

RLSERVE REST WORKING GROT.JP 

PROFOSAL OF 77,955 AIRLINE PILOTS 

Januar-r t, 1999 

PREAMBLE 

This document is submitted on behalf of approximately 78,000 commercial airline 

pilots. The proposal thar follows contains our necouunendations for Federal Aviation 

Regulations concerning rest requirements and duty limitations for reserve pilots. It is 

applicable to all Donpstic and International Part l2l oPerations under FAR Subparts Q, 

R, and S. Pa¡t 135 regulations should be revised to provide a þvel of safety equivalent to 

this proposal. 

Our proposal is presented in two parts. Part I is the proposed regulatory language. 

Part tr provides our intent, examples, and rationale. The scientific supPort for our 

proposal is included in the endnotes. 

We are pleased that both pilots and air ca¡riers were able to agree on the 

following elements of a proposed reserve rest rule: 

l. A pilot should be scheduled by the operator to receive a protected time period 

as an opportunity to sleep for every day of reserve duty. The op€rator lr¡ay not 

contact the pilot during this period- 

2. An operator should limit the rnovernent of a pilot's protected time period 

during consecutive days of res€rve duty to ensure circadian stability. 

3. A reserve pilor's availability for duty should be limited to Prevent pilot fatigue 

as a result of lengthy periods of time-since-awake.

4. Sufficient advance notice of a flight assignment can provide a reserve pilot 

with a sleep opportunity. 

We believe that it is incumbent upon the Federal Aviation Administration (FAA) 

to include time-of-day as a factor in designing duty and rest limitations. A substantial 

body of research and pilot reports shows that a decrease in performance frequently occurs 

during "back-side-of-the-clock" operations due to circadian factors. To address this 

issue, our proposal provides for a reduction in the reserve availability period when 

scheduled duty touches the 0200 - 

'lindow of circadian low." 

0600 time period, or what the scþntists rcfer to as the 

Our submission refers to several documents that have provided us with a 

foundation of scientific support. Prominent among them is NASA Technical 

Memorandum I l0t04, Principles and Guidelines for Duty and Rest Scheduling in 

Commercial Aviation, (May 1996)- This document, herein referred to as NASA TM. 

offers NASA's specific recorrrmendations on duty and rest limitations based on more than 

20 years of extensive research into the cause and prevention of pilot fatigue. It is 

anached hereto as Appendix.A. 

Another reference is An Overtiew of the Scientific Literature Concerning 

Fatigue, Sleep, and the Circadian Cycle, Battelle Memorial Institute Srudy (January 

1998). This study, herein referred to as the Battelle Study, commissioned by the FAA's 

Offìce of the Chief Scientific and Technical Advisor for Human Factors, provides an in- 

depth review of scientific research concerning sleep and fatigue. Drawing upon 165 

scientific references, the Banelle Report identifies major trends in the scientific literature, 

and has provided valuable information and conclusions. This study is attached as 

Appendix B.

Another reference is A Sci¿n¡ific Review'of Proposed Regulations Regarding 

Flight Crewmember Dur¡* Period Limitations, Docket #28081, The Flight Duty 

Regulation scientific Study Group. This study was sponsored by the Independent Pilots 

Association to provide a scientific review of NPRM 95- 18. It is referred to as the 

Scientific Study Group and is attached as Appendix C. 

The pilots net with sleep expert, Dr. William Dement, Director of Sleep Research 

and Clinical Programs at Stanford University. The transcript of that rneeting appears in 

Appendix D. 

We have attached an article titled Fatigue, Alcohol, and Perfomance Impairment 

that summarizes a study conducted by The Centre for Sleep Research at the Queen 

Elizabeth Hospital in South Australia in Appendix E. This study quantifies the 

performance impairment associated with sustained wakefulness in terms of equivalent 

p€rcent blood alcohol impairment. A subsequent study, titled Quntifiing the 

Perfonnance Impairment associated *'ith Sustained Wakefulness, by l:mond and 

Dawson replicates rhis study and extends the initial f,rndings. It is attached as Appendix 

F. 

The NTSB requested that the FA.A. conduct an expedited review of the FARs after 

pilot fatigue and continuous hours of wakefulness were found to be key frndings in the 

crash of a DC-8 u Guantanamo Bay, Cuba in 1993. A NASA/NTSB report titled Cr¿w 

fatigue factors in the Guantanamo Bav aviation accident is anached as Appendix G. 

Several airlines have switched to reserve pilot schernes very similar to the one we 

propose. These ca¡riers include Continental Airlines, UPS, Anrrica West, Alaska 

Airlines, and British Airways. The reserve pilots at these airlines have protected time 

periods of 8 to I2 hours with reserve availability periods of l4 to l8 hours.

\['e owe a debr of gratitude to rhe rnâny pilots who provided us with rePorts of their 

encounrers with pilot fatigue. These reporrs reveal that pilot fatigue typically occurs during 

back-side-of-the-clock operations and after long periods of time-since-awake' 

The pilors would like ro thank the FAA for providing this forum and the air 

carriers for conrributing to ttre debate. We hope that this ARAC has demonstrated to all 

interested parties how unregulated scheduling can lead to dangerously high levels of pilot 

fatigue for reserve pilots. 'We urge the FAA to quickly remedy this very serious safety 

problern 

4

l2l.xxx Reserve Rest 

PART I: PROPOSED REGULATORY LANGUAGE 

(a) Except as provided in paragraphs (b) and (d), no cenificate holder may schedule 

any flight crewmember and no flight crewrnember may:ìccept an assignment to 

reserye stafts unless a minimum prospective Protected Tirne Period (PTP) of l0 

hours during a 24-consecutive hour period is scheduled. The Protected Time 

Period must begin at the sanË time during any scheduled period of consecutive 

days of reserve status and the flight crewnpmber must be given no less than 24 

hours notice of the Protected Time Period. 

(b) 

(c) 

A certificue holder may reschedule a specific Protected Tirne Period during any 

scheduled period of consccutive days of reserve by the following: 

( I ) Rescheduling the beginning of a Protected Time Period a maximum of 

th¡ee hours later r*'ithout prior notification. 

(2) Rescheduling the beginning of a Protected Time Period a maximum of 

three hours earlier if the flight crewrnember is provided 6 hours notice 

prior to the beginning of the originally scheduled Protected Time Period. 

(3) Rescheduling the Protected Time Period by more than 3 hours once durin-s 

any 7 consecutive days by providing the flight crewrnember l0 hours 

notrce. 

A certificate holder may assign a flight crewrnember and a flight crewmember 

may accept an assignment for flight time in scheduled air transportation or other 

commercial flying if such assignment is permitted by this subpart; 

(l) If the assignrnent is scheduled to be completed wi¡hin l6 hours after the end 

of the preceding Protected Time Period; however. 

(2) If the flight crewrrrcmber is given a flight assignnrent for any part of the 

period of 020O to 0ó0O hours, any such flight assignment must be scheduled 

to be completed within l4 hours after the end of the preceding Protected 

Time Period. The operaror with the concurrence of the administrator and 

the pilot group rrny designate any 4-hour period for all operations between 

0000-0600 hours in place of 0200-0600 hours. 

These limitations rnay be extended up to 2 hours for operational delays.

(d) When there a¡e no other reserve pilots who have sufFrcient res€rve availability 

periods to complete an assignment, the cenificate holder may schedule a flight 

crew member for an assignrnent for flight tinp in scheduled air transportation or 

other flying permitted by this subpart, providcd that the crew Inember is given a 

minimum of 14 hours of advance notice and s released to protected time at the 

time of the notice. 

(e) Each certificate holder shall prospectively rclþve each flight crewrrpmber 

assigned to reserve for at least 24 consecuti\E hours during any 7 consecutive 

days. 

(Ð For augrrrnted International operations, a cettificate holder may assign a flight 

crewnpmber and a flight crewrrpmber may æept an assignrnent for flight time 

in scheduled air transportation or other comrærcial flyrng as follows: 

( I ) For single augmentation, the assignnrnt must be scheduled to be completed 

within 18 hours after the end of the preceding Protected Tirne Period; or 

(2) For double augmentation. the assignnrnt must be scheduled to be 

conpleted within 22 hours after the end of the preceding Protected Time 

Period. 

These limitations rrny be extended up to 2 hours for operational delays. 

DEFTNITIONS 

Operationd Delay - Any delay that would cause tÌrc Reserve Crewmember to be 

exrended beyond the applicable duty limit for up to rwo hours: except a delay caused by 

changing the Reserve's original flight assignment. 

Protected Time Period (PTP) - Sarne as l2l.47l(bX6), NPRM 95-18. except "has no 

responsibility for work" replaced by "has no responsibility for duty." 

Reserve Availability Period (RAP) - The period of time from the end of the PTP to the 

tirne that the reserve crewrrpmber must complete flight duty. 

Reserve Time - Sarne as l2l.47lOX7), NPRM 9t18, except "two hours" for report 

time versus "one hour." 

Standby Duty - Sarrp as 121.47(bX9), NPRM 9t18, except "less than two hours" to 

repon versus "one hour." 

6

Part II: Pilots' Proposal with IntenÇ Examples, and Rationale 

I2l.xxx R¿sene Rest 

(a) Ercept as provided in paragraphs (b) and (d), no certifuate houer may 

schcdule any flight crewmember and no flight crewmember may accept an 

assignment to reserye status unless a minimum prospective Protected Time 

P¿riod (nÐ of I0 houtt during a 2hconsecutive hour period is scheduled. 

The Protected Time Period must begin at the sane time during any scheduled 

pøiod of consecutive days of resert'e stotus and the tlight crewmember must be 

giæn no less than 24 houn notbe of the Protectcd Time Period- 

lntent: To ensure that all reserve pilots are sctpduled for and receive a Prosp€ctive, and 

predictable. lO-hour opportunity every reserve day to obtain 8 hours of sleep and to 

maintain cncadian stability. 

Example: 

Pilot - PTP 2OOO06OO 

10 hr PTP 

Rationale: The human body requires an avera-ee of 8 hours of unintemrpted, restorative 

sleep in a 2.4 hour period *'hen sleeping during normal sleeping hours. When attempting 

to sleep ourside of normal sleeping hours, 8 hours of sleep is still required. Ho*'ever, 

scienrific data indicates additional time is needed to obtain the required 8 hours of sleep. 

The l0 hour Prorected Time Period ([rfP) would. therefore, include an opportunity to 

prepare for and actually receive 8 hours of restorative sleep in all circumstances. 

Addnionally, a lO-hour PTP was selected with the assunption that the minimum required 

resr for all pilots would be l0 hours (See NPRM 95- l8). A lO-hour PTP would maintain 

consisrencv of rest for all pilots. Starting consecutive PTPs atthe same time is 

imperarire to maintaining circadian stability. The desired method of assigning PTP 

would be when the crewmember is assigned reserve. A minimum of 24 hours 

norifrcarion of a Protected Time Period will provide an opportunity to prepare for 

impendine reserve days. I

(b) A certificate holder may reschedulc a Prutccted Time Period during any 

scheduled period of consecutive fuys of resene by the following: 

Intent: To provide the reserve pilot with a predictable, prospective rest period and also 

give the operator scheduling flexibility to accomÍ¡odate unforeseen circumstances. 

Rescheduling a PTP +/- 3 hours is only applicable to thar PTP. Remaining res€rve days in 

a block would begin ar ttrc original start tinr. Shifting of a PTP does not extend a 

Reserve Availability Period (RAP). 

(t) Reschedaling lhe beginning of a Protected Time Period a 

naximum of tfuee houtt laer vithout prbr notifrcøtbn. 

Example: 

(In this example, under no circumstances ruy a PTP strt tirne be later than 2300) 

Day I 

PTP 2000 to 060O (original PTP) 

2mo 

2200 

Day 2 

PTP 2300 to 0900 

Ilay 3 

PTP 2000 to 060O 

Rationale: Delaying 

to circadian stability. 

l0 hr PTP 

a sleep opportunity, up to th¡ee hours, is not excessively disruptive 

In this c¿LSe, no prior notification is required.

(2) Rescheduling the beginning of a Prolected Time Period a marimum of 

3 hoan earlier if the flight crewmemba is provided 6 hours notice prior 

to the beginning of the originally scheduled Protected Time Period. 

Example: 

(In this example, under no circumstances may a PTP sõt time be ea¡lier than 1700) 

Day I 


Day 2 

PTP 1700 to 0300 

Da1'3 

PTP 2000 to 0600 

'I 0 hr PTP 

Rationaþ: Moving-a sleep oppornrnity earlier, up to three hours, is disruptive to 

circadian stabiliry. To accommodate and prepare for this rescheduled sleep opportunity 

additional notice is required.

(3) Rescheduling the Protected Time Period by more than 3 hours once 

during any 7 consecutive days by províding thetlight crewmember l0 

hourc notbe. 

Rationale: Changing a sleep oppomrnity more than +/- 3 hours is very disruptive to 

circadian stability. For extrene circumstances beyond tlre control of the operator (i.e., 

inclement weather, closed airports, etc.) an op€ra¡or has the ability to reschedule a PTP 

npre than 3 hours from the original sta¡t time. A minimum of l0 hours prior notification 

of the new PTP is required to allow the pilot a period of tirne to adjust for the rescheduled 

sleep opportunity. This provision is restricted to once in every 7 days because it is so 

deuinrental to circadian stability. This restriction also would preclude the operator from 

arbitrarily utilizing this provision and yet allows tlre certificate holder the flexibility to 

operate under extrenÊ circumstances.' 

l0

(c) A certiftcate holder may assign aflight crevmember and atlight 

crewmember ma! accept an assignmenrforflight timc in scheduled air 

transporTotion or other commercbltlying if such assigwnent is 

permitted by thís subpart; 

(l) If the assignment is scheduled to be compl-eted within 16 houn 

after the end of the preceding Prolcctcd Time Period; 

Inænt: To establish a "Reserve Availability Period" (RAP).3 

Example: 

22ú 2.00 oaoo 

lt

Examples: 

(2) If the flight crewmember is given a tlight assignment for any part of the 

períod of 0200 to 06ü) houtt, any suchtlight assignment must be 

scheduled to be complcted xithin 14 houn after the end of the preceding 

Protected Time Period- The operator with the concurtznce of the 

administrator and the píIot gmup may desígnate any hhour periodfor 

all operations between 0000-(M00 hoan in place of 0200-0600 hourc. 

2lr 

rlan¡ron 

14 hr RAP 

t0 hr PTP lf Duty Occurs Between 0200 - 0600 

t6 hr RAP 

l0 hr PTP ll Duly Occurs Outside 0200 - 0600 

These limitations may be extended up to 2 hours for operæional delays. 

Rationale: Time-since-awake contributes to fatigue. This section acknowledges timesince-awake 

by limiting the RAP to l6 hours if the pilot is afforded the opportunity to 

sleep during a normal sleep period. The soence further indicates fati_rue occurs sooner 

when given a sleep opponunit)- at a time othe r than normal sleeping hours. This section 

addresses that fact by reducing the R{P to l-l hours should duty occur during this normal 

sleep period.r 

t2

(d) When therc ore no olher resene pitoß who have sufftcient Ìesetlte availability 

periods to complete an assignment, the certiftcale holder may schedule aflight 

-crcw mcmberfor an assignmentforllight time in scheduled air transportation 

or otherflying permitted by this subpañ, provided that the crew member is given 

a minimum of 14 houts of advance notice and is released to protected time at 

the time of the notbe. 

Intent: All pilots are originally scheduled in a PTP systern Circadian stability is 

ensu¡ed by all pilots having a definitive, prospective sleep opportunity. When all such 

pilos havè been utilized, 14 hours notice rnay be used by the oPerator to assign a pilot to 

ä Rigttr. Once notified of a flight assignment a crewrrrmber is released from further 

responsibility until he reports for duty. TWhiþ this method of assigning reserve is less 

than desirable, it enables the certificate holder to continue oPerations as necessary. 

Rationale: While advance notice can pres€nt a sleep opportunity, scientific research is 

very clear that circadian factors make it very difflrcult and sometimes impossible to take 

advantage of it. For example, consider a pilot who fmishes his PTP at 0800 and is then 

contacted by the ca¡rier for an assignment thât rePorts aÎ2200. This would be an 

application of l4 hours advance notice. Circadian factors make it very difficult, if not 

impossible, for the pilot to sleep again until later, typically during the afternoon circadian 

low poinr (150O - 1800) or earlier if possible. However, by receiving the notice early, he 

can schedule his nnrning activity accordingly to best PrePare himself for the afternoon 

sleep opportunity (like a line-holder does). Typically, he would go to bed around l50O - 

l60O and ser the alarm clock for l gOO - 2000 to provide enough time to shower, dress, 

eat. and report for duty. Even with l4 hoursof advance notice. this pilot could only 

exp€cr to sleep 4 - 5 hours prior to reporting for a back-side-of-the-clock assignment that 

last until l20O the following day. It should be apparent that less than l4 hours 

"oul¿ 

norice could result in less than 4- 5 hours of sleep and raise the probability of serious 

pilot fatigue during the assignment- 

The above example was discussed during the Denver ARAC meeting. At one 

point,.Dr. Don Hudson was asked for his expert opinion re-earding what should be 

iequired for a minimum arnount of advance notice. Dr. Hudson's response was l3 to l4 

hours.t 

l3

(e) Each ceftiftcate holder shall prospcctively relicve cach tlight crewmember 

assigned to reserte for at least 24 consccutive houn during any 7 consecutive 

days. 

Intent: All reserve pilots must receive a prospective 24 hour period free from duty 

during ny 7 consecutive daYs. 

Rationale: Pilots assigned to reserve status must be continually prepared for any flight 

duty. These pilots should be relieved from this obligæion fo¡ 24 hours during any 7 

consecutive days. The pilot must be notificd prior to the beginning of that offduty 

period. 

l4

A 

Example: 

Example: 

For augmented International operotions, a certificate hoWer may assign a 

flight crewmember and aflight crewmember may accept an assignmentfor 

flight time in scheduled air transporlation or other commercialflying as 

follows: 

(l) For single augmentotion, the assignment must be scheduled to be 

completed within 18 houn after the end of the preceding Protected Time 

Period; or 

(2) For double augmentatioq the assignment must be scheduled to be 

completed within 22 houn after the end of the preceding Protected Time 

Period 

10 hr PTP 


lntent: To establish a Reserve Availability Period (RAP) for long-haul international 

reserve pilots. 

Rationale: L,ong-haul international flights necessarily involve back-side-of-the-clock 

flyin_e. Therefore. for a single pilot augnentation, we added 4 hours to the l4-hour backside-of-the-clock 

duty period and 8 hours for doubìe augmentation. This is in accord 

with the NASA TM. ó 

l5

I l2l.xxr Reserte Rest 

Scientific SuppoÉ 

(a) Except as provided in paragraphs (b) and (d), no cenificafe holder may 

schedule any tlight crewmember and no flight crewmember may æcept an 

assignment to reserte stotus unlcss a minimum prospective Protecled Time 

Period (nÐ of 10 houn dwing a 2Aconsecutive hour period ß scheduled- 

The Protected Time Period must begin at the same time during any schedul¿d 

period of consecutive days of reserte sbtus and the flight crewmember must bc 

given no bss tløn 24 houn notbe of the Protected Time Perbd 

Ssis¡tiñc zupport: 

(a) l0 hour Protected Time Period to provide an opportunity to obtain 8 hours of sleep. 

Each individual has a basic sleep requirement that provides for optimal levels of 

performance and physiological alertness during wakefulness. On average, this is 

8 hours of sleep in a 24-hour period, with a range of sleep needs greatet than and 

less than this amounr. Losing as little as 2 hours of sleep will result in acute sleep 

Ioss, which will induce fatigue and degrade subsequent waking performance and 

alertness. 

NASA TM, Í1. l.l, p.2. 

Off-duty period (acute sleep and awake-time-ofr requirements) - Therefore. 

the off-duty period should be a minimum of l0 hours unintemrpted within any 

24-hour period. to include an 8-hour sleep opportunity[.] 

NASA TM, t2.1.2. p. 5 

Standard Sleep Requirements and Off-Duty Period - Resea¡ch by Drs. Carskadon 

& Dement, l982and Weh¡ et al., 1993 support a minimum of 8 hours of sleep 

based upon a.range of studies that use several approaches includin-s: 

o Historical levels of sleep 

o Measures of daytime alenness 

. Sleep levels achieved when given the oppomrnity to sleep as long as 

desired 


. . . There appears to be substantial evidence that a minimum of eight hours of 

sleep is required for most people to achieve effective levels of alertness and 

performance. 


l6

. . . It is importanr to realize that an individual working nights is at risk for 

signifrcanr sleepiness for two distinct reasons: . . . an individual working 

successive nighrs is forced to obtain sleep during the daylight hours at a time 

when rhe circadian pre-disposition to sleep is minimal. . . . As mentioned, sleep 

under these circumstances is r¡rpically fragrnented, sleep state architecture is 

distorted, and the restorative nature of sleep - . . is reduced. 

A Scientific Revie*'of Proposed Regulations Regarding Flight Crewmember Dunn period 

Limitarions. The Flight Duty Regulation Scientific Study Group,12.6,p.5-6. 

Minimum rest periods should be adþsted upward for sleep periods that include 

tbe tin¡e of peak circadian alertness (4 - 6 PM.)- 

efFrcienc-v of sleep during that time. (Errphasis added.) 

Scientif,rc Study Group, tI 5.1 .2, 5.1-4, P- I l. 

Remarks of Dr. Dement: 

e: . - . One of the rmst basic tasks is for us to agree on a recolnrnendation for a sleep 

opportunity . . . to afford every reserve pilot the opportunity of a protected tirne 

period so that he or she is absolutely insulated from contact from the operuor. 

How many hours do you recomrnend for a minimum fixed sleep opportunity? 

A: I will start our by assuming that we would take 8 hours of sleep as the rnost 

corffnon requiremenr. Then you need to add to that in order to be able to get the 

proper arnounr of sleep. In y.our situation, I would think it w'ould be a little lar-ger 

rhan ir might be for sorneone who really wasn't doing anything. So. I'd add a 

couple of hours to -qet the proper alîount of sleep. 

Appendix D.p.4. 

Q: Dr. Derr¡ent, . . . we're really at the point now where we're going beyond the 

philosophy and we're trying to put our finger on nurneric values. Our position at 

least from the pilots' standpoint, is that we see the need for a lGhour sleep 

opportunity knowing that ttle opportunity may not always be at the best time of 

the day. We're facing an industry position that is Iooking for 8 hours as the 

minimurn Our position is predicated on ttre fact that 8 hours may be adequate if it 

overlaps the WOCL. But since we don't know for sure when we're going to have 

that opportunity. we believe that, or we think that having that extra 2 hours is 

going to give us a little more of a buffer, especially when it cornes during the 

daytime. Would you consider that to be a conservative and a justified position? 

A: Absolutely. I don't think you could possibly assulne solneone is going to fall 

asleep instantly and then sleep continuously for 8 hours, not even under the most 



t7


(a) Scheduling the Protected Time Period for the salr¡e time each day 

Time-of-day / Circadian Physiology Afiects Sleep and \{aking Performancr - 

. . . Tinre-of-day or circadian effects are important considerations in addressing 24 

hour operational requirements because circadian rhythms do not adjust rapidly to 

change. 

. . . Thus, circadian disruption can lead to acute sleep deficits, cumulative sleep 

loss, decreases in performance and alertness, and va¡ious health problems . . . 

Therefore, circadian stability is another consideration in duty and rest scheduling. 

NASA Feconunends a sleep opportunity that is predictable (24 hours notice 

re,coÍ[nended), does not vary rnore than 3 hours on subsequent days to ensure circadian 

srability, and is protected from intem¡ption. @mphasis added-) 

NASA TM, Il .3, p. 34;12.6.2, p. 8. 

Conclusion - 

hour cycle. 



Reserve assignments should anernpt to maintain a consistent 24 

Q: Dr. Dernent, there's one area that we really haven't touched upon at this point and 

I don't want to miss. These are questions re_sarding the maintenance of cr¡cadian 

stability. [n your opinion, why is maintaining circadian stability so important? 

A: Well because usuall.""... and b¡' that you mean your sleep opportunities and vour 

wake oppomrnities Íue in that period of stability, then you have the best sleep and 

the best walie. If you get out of that cycle, then both sleep and wake will be 

impaired. 

Q: What happens to the body as you change a person's cycle? 

A: All sorts of things happen, but the major thing of course is that you are now trving 

to sleep when the body wants to be awake and you're trying to be awake when the 

body wants to be asleep because you left the circadian stability that you talked 

about. 

Appendix D,pp. líl7. 

t8

t (3) Rescheduling the Protected Time Period by more than 3 houn once 

during any 7 consecutive days by providing the flight ctev'member I0 

houn notice. 

Scientific supoort: 

(b) Limiting rhe rnovement of the Protected Time Period to Plus or Minus 3 hours 

. . . the 8-hour sleep opportunity should not vary by nnre than 3 hours on 

subsequent days to erlsure circadian stability. . . . 

NASA TM,12.6.2, p. 8. 

Remarks of Dr. I)errent 

Q: . . . we're trying to insrre that the protected tirne period, the rest period, stayed the 

same from day to day, assuming the reserye crewmember is not called. Or for 

that maner when he is called, he goes back into his cycle. We're anenpting to try 

ro snap him back to as close to that original cycle and maintain that same rh¡hm 

from day ro day. NASA has findings on that. Their reconunendation wÍrs to 

maintain that circadian stability plus or minus 3 hours. Do you agree or disagree? 

A: I absolurely agree that's better than no stability. Obviously the smaller that 

number, the bener. I thlnk practically it couldn't be zero, but I think we tend to 

feel there's kind of a daily flexibility within that range, like 0 to 3 hours, 0 to 2 

hours. To go outside of that is, again. inviting a condition of sleep deprivation. 

So deliberately creatin-e a bad situation. 

Appe ndix D, pp. líl7. 

t9

' (c) A certiftcau holder may assign aflight crewmember and aflight 

crewmemba may accept an assignmenlfortlight time in scheduled air 

transportotion or other commetcialtlying if such assignment k 

permitted fo this subpan; 

(l) If úc øssignnent is scheduled to be compl¿ted within 16 houn 

afta the end of the preceding Protected Time Period; 


(c) l6 hour Reserve Availability Period Limitation 

Continuous Hor¡¡s of Wakefulness/Iluty Ca¡ Afiect AleÉness rnd 

Perforurance - Encnded wakefulness and prolonged perbds of continuous 

performance or vigilance will engender sleepiness and fatigue. 

Extended flight dutv period - 

An extended flight duty perircd should be limited 

to l2 hours within a 24-hour period to be accompanied by additional restrictions 

and compensatory off-dur¡* periods. This limit is based on scientific findings 

from a variety of sources, including data from aviation, that dermnstrate a 

significant incre¡ccd vr¡lnerability to performance-impairing fatigue af¡er 12 

hours. It is readill'æknowþdged that in current practice, flight duty periods 

extend to l4 hours m regular operations. However, the available scientific data 

support a guidelim different from current operational practice. The data indicate 

that performance-impairing fatigue does increase beyond the l2-hour limit and 

could reduce the sr-ety margin. 

NASA TM,ll 1.4,2.3.1. ¡p 4. 6 

NASA does not provide a saeciflc recorrrmendation for the duration of a Reserve 

Availability Period. Houerer, it follows that NASA'S recomrnended maximum duty limit 

of l2 hours plus 2 hours t'oroperarional delays (total - l4 hours)obviouslyrequires a 

pilot to be awake æ least rhet much time. By adding report tinp to NASA's 

recofiunended maximum 'ùrty limit, it is apparent that NASA's duty lim¡t is 

cornrnensurate with our proposed l6-hour reserve availability period lim¡t for unaugrnented 

flying. 

The results of an \TSB analysis of dornestic air ca¡rier accidents occurring from 

1978 to 1990 suggst that time since awake (TSA) was the dominant fatiguerelated 

factor rn tlrse accidents (NTSB, 1994). Perforrnance decrements of high 

time-since-awake crews tended to result from ineffective decision-making rather 

than deterioration oi ai¡craft handling skills. . . . There did appear to be two peaks 

in accidents: in ¡he morning when time since awake is low and the crew has been 

on duty for about tbree to four hours, and when time-since-awake was high, above 

l3 hours. Simila¡ æcident peaks in other modes of transportuion and industry 

have also been reported (Folkar4 1997). Akerstedt & Kecklund (1989) studied 

prior time awake tfour to l2 hours) and found a strong conelation of accidents 

20

with tirne since awake for all times of the day' Belenky et al' ( 1994) founð ihat 

flight time hours (workload) grearly increase and add to the linear decline in 

perforrnance associated with time since awake. 

Banelle Report, P. 13. 

Sorrp symptorns of fatigue are similar to other physiological conditions. For 

example, with fuigue one's ability to anend to auxiliary tasks becornes more 

narrow, very much analogous to the effects of alcohol (Huntley et al., 1973; 

Moskowitz, lg73), hypoxia (McFarland 1953), and heat stress (Bursill, 1958). 


Australian researclrers Drew Dawson and Karhryn Reid (1997) evaluated performance 

after l7 hours of wakefulness and found performance degraded to a level equal to that 

caused by a blood abohol concentration (BAC) of 0.05 Percent. At24 hours, 

performance decrerrpnts were equivalent to that of a 0.10 BAC. After ten hours of 

ileeplessness, the decline in performance averaged .74 percent per hour. Their study 

titled Fatiguc, Alcohot and Perfonrurnce Impairment appeared in Nature, Vol- 338, July- 

August lgg7. Gee Appendix E). These fîndings were replicated and extended by 

Nichoþ I-anrond and Drew Dawson in 1998- (See Appendix Ð' 

If an individual has þen awake for l6 to l8 hours, decrernents in alertness and 

performance are intensified. If time a'*'ake is extended to 20 to 24 hours. alertness 

can drop more than 40 percent (WRAIR, 1997: Morgan et al.. 1974: Weh¡, 1996). 

Battelle Report. P.25. 

The ¡{TSB cited pilot fatigue as the probable cause of the crash of a DC-8 at Guantanamo 

Bay in 1993. The individual crer¡'members \À'ere continuously awake for 19. 21. and 23-5 

hours prior to the accident. 

Mark R. Rosekind, et al., Crew,fatigue factors in the Guantanamo Bav av'iation accident. 

(See Appendix G). 

Rernarls of Dr. Dement 

e: Dr. Den¡ent, after our reserve pilots receive their sleep opportunily. they become 

available for duty. We call the availability period the "reserve availability period" 

and that's basically the tirne they are available for work, for flying. After the 

sleep opportunity, what n'ould you consider to b€ a safe limit of tirne since awake 

for a crewmember? 

For the lGhour (sleep oPPortunity) period? 

Yes. 

A- Fourteen hours. And I *ouldn't say that's IAOVo safe but if you have a number, 

that adds up ro rhe 24-hour day. It ought to be reasonably safe. 

ll

a 

A 

a 

A 

a 

A 

a 

Wt¡ere do you get your numþr from? 

Well, it conrcs mainly in my head from circadian rype 24-hour studþs to see the 

panern of the manifestation of the drive to sleep versus the awakening effect of 

the biological clock. If you're gening outside the 24-hour cycle, then you're 

going to have periods of greater risk. . . . 

That assurnes that the individual wakes up as soon as his protected tirne period is 

over. So in other words, you see a conplirrentary factor: t hours of rest should 

dictate a l5-hour availability period? 

Yes. I think nnst people would ag¡ee that would be the ideal. 

Going beyond that, what is probably the r¡pst geatest points of contention right 

is tÌte fact that 

now - the debate between the pilots and the industry operators - 

the operuors would like to extend this reserve availability period in excess of 

what you say is 14 or 15 or 16 hours, whatever the case may be, to a larger 

incrernent, extending that reserve availability period based upon an advarrce 

notice of a nap oppoftunity. In other words, a pilot corrìes on call al 8:00 am. He 

is then told at 9:0O a-rn that he is to report for duty 5 hours later. The industry's 

position is thu the notice constitutes an opportunity for additional rest which then 

would be utilized to add more restorative energy or analogous to Puning rnore 

charge into a banery, and then carry that pilot into more of an extended duty 

period with an additional arr¡ount of time-... up to in certain cas€s 24 hours of 

duty. What i-s your feeling on that t¡pe of scenario? 

To rne. that's a recipe for disaster because if you have a responsible. professional 

pilot - who has a reasonable schedule. - who is not horribly sleep deprived, and 

who has a fairly stable circadian rhythm, then the likelihood that he can get 

adequate sleep by trying to nap I think is relatively small. I would not depend on 

it at all. I would think also to have to do it sort of unexpectedly like this....Oh! 

Take a nap..-.Only people who are very sleep deprived.... 

[-et's say I have a lO-hour shep opportunity: l0 p.rn to 8 am. That rneans I'm 

available for l4 hours unless they fly rne into the next l0 p.rn slot tonight. Could 

I not get a call say at noon and say instead of you being off tonight at l0 p.rn, we 

want you to work until seven torþrrow rrnrning but you aren'l going to go to 

work until I0:00 that night. So they call rne at noon, they give a lGhour notice 

that I'm not going to have to go to work until l0 hours from noon, so at 2200 I 

report for work, and they want rr¡e to fly until 0800. So that would be a total of 24 

hours from the time I theoretically woke up and I've had a l0-hour notice that I 

was going to be flying this fatiguing schedule. Would that be safe? 

A: Well, I wouldn't be on your plane. No. I think that's alrnost insanity in the 

sense of saying that is safe. First of all, naps can't be depended on - even under 

ideal circumstances - to get you through this period when the biological clock 

22

alerting is gone. when you're alone with your sleep debt so to speak. during the 

WOCL. There's no way that isn't going to be dangerous. . . . 


23

' 

(2) If the tlight crewmember is given a flight assignment for any pan of the 

period of 0200 to 0600 hours, any suchflight assignment must be 

scheduled to be completed within 14 houn afier the end of the preceding 

Protected Time Perbd- The operator wilh the concunence of the 

a-dminßtrator and the pilot group may designale any $hour periodfor 

all operutions betveen 0000-06M houn in place of 0200-06(X) houn. 

Scientific zupport: 

(c ) Reducing the Rescrve Availability Period by two hours during Back-Side-Of-The- 

Clock Operations (0200 - 0600) 

Offduty perid (folbwing standard füght duty periods during window of 

circadian low) - Extensive scientific research, including aviation dat4 

dernonstrue that rnaintaining wakefulness during the window of circadian low is 

associated with higher levels of performance-impairing fatigue than during 

daytime wakefulness. . . . 

Ileñnition: "vvindow of circadian low" - The window of circadian lon' is best 

estimated by the hours between 020O and 06OO for individuals adapted to a usual 

day-wake/night-sleep schedule. This estimate of the widow is calculated from 

scientifrc data on the circadian low of performance, alenness, subjectiye repon 

(i.e. peak fatigue), and body temperan¡re. . . . 

NASA TM,1I2.1.4.2.3.2. PP. 5-6. 

The ingredient of day versus night long-haul flights ralses a second concern. the 

time-of-da,v departure. Because sleepiness and fatigue are strongly related to 

circadian rhythmicity, they should not be controlled by regulations. which ignore 

time-of-day in favor of elapsed time. . . . For the sake of efficiency and safety. it is 

incumbent upon regulatory authorities to include time-of-day as a factor in 

designing flight crew duty and rest hlrutattons. 

R. Curtis Graeber, et al., Aircrew'Sleep and Fatigue in l-ong-Haul Flight Operarions, 

. Tokyo. Japan (Octoþr 2G29,1987), P. 13. 

Back of the.Clock Operations, Circadian Rhythm and Performancc 

There is a substantial body of research that shows decreased performance during 

night shifts ¿Ls comp¿ìred with day shifts. The reasons for this decreased 

performance include: 

o Circadian pressure to sleep when the individual is attempting to work. 

. Circadian pressure to be awake when the individual is attempting to sleep. 

o Time since awake may be substantial if the individual is up all day before 

reporting for the night shift. 

o Cumulative sleep debt increase throughout the shift. 

Research conducted by Monk et al. ( 1989) indicates that subjective alertness is 

under the control of the endogenous circadian pacemaker and one's sleep-wake 

cycle (time since awake). r#hen tirne since awake is long and coincides with the 

24

circadian low there is a very sharp drop in alertness, a strong tendency to sleep 

and a significant drop in performance (Perelli, 1980). Alertness is relatively high 

when the circadian rh¡hm is near the acrophase and time since awake is small. 

Monk ( 1996) argues that this c¡'cle is consistent with the NTSB ( 1994) finding of 

a peak accident rate occulTing in the evening. . . . 

Battelle Report, P.23. 

Microsleeps have been shown to be a useful approach to asscssing the effects of 

tin¡e of day on sleepiness levels. EEG brain wave changes confirm that pilots 

experience greater sleepiness and decreased alertness betwecn 2:0O to 4:0O a-m- 

(Gundel, 1995). .. . 

Banelle Report, p. 9. 

. . .In determining maximum limits for extended duty periods, consideration also 

needs to be given to other fatigue-related factors that could contribute to excessive 

fatigue levels during extended duty periods, irrcluding number of legs, whethe¡ 

low time si 

awake. @mphasis added.) 

Banelle Report, P. 14. 

Night operations are physiologically different than day oPerations due to circadian 

trough and sleep loss. This carrþs a higher physiological cost and imposes 

grearer risks of accidents. One of the most established safety issues is working in 

the circadian trough between 020O and 0600. During this period workers 

experience considerable sleepiness. slower response times. increased errors and 

accidenrs (Mitler, 1991;Pack. 1994). Many recent accidents f¡om various 

rransporrarion modes have been associated with this circadian trough (l-auber & 

Kayten, 1988). Lyman and Orlady (l93l), in their analysis of the Aviation Safety 

Reporting System researcher stare that 3l percent of incidents occurring þtween 

2400 to 0ó00 hours were fatigue related. 

In Japan, 82.4 percent of drowsiness-related near accidents in electric rnotor 

locomotive drivers (Kogi & Ohta 1975) occur at night. Other landmark studies 

over the past several decades have docurnented the increase in accidents and error 

making. Klein et al. ( 1970) argue that their resea¡ch with simulators proves that 

night flights are a greater risk than day flights. Their resea¡ch found 75- to l0Opercenr 

mean performance efficiency decrernents in simulator flights during the 

early morning hours, regardless of external factor such as da¡kness or increasing 

night trafFrc or possible weather conditions. 

. . . A snrdy of naval watch keepers found that between M00 to 0600, resPons€ 

rates drop 33 percent, false reports rates 3l percent, and response speed eight 

percenr, compared with rates between 2000 to 220O hours (Smiley, 1996). 

Sameler al. (199ó) determined that many pilots begin night flights already having 

þen awake more than l5 hours. The study conltrms the occurrence of rls many 

as five micro-sleeps per hour per pilot after five hours into a night flight. . . . The 

aurhors concluded that 'During day time, fatigue-dependent vigilance decreases 

25

with task duration, and fatigue becornes critical after 12 hours of constant work. 

During night hours fatigue increases faster with ongoing duty. This led [o the 

conclusion that l0 hours of work should be the maximum for night flying-" 

[Note Sanpl's conclusion - Reduce the duty period from l2 to l0 hours'] 

Gander er al. ( l99l ) found in an air carrier setting that at least I I percent of pilots 

' srudied fell asleep for an average of 46 minutes. Similarly, Luna et al. ( 1997) 

found that U.S. Air Force air traffic controller [sic] fell asleep an average of 55 

minutes on night shift. A possible explanation for these sleep occurrences, in 

addition to circadian nadir, is the fmding of Samel et al. that many pilots begin 

tlreir night flights after being awake for as long as 15 hours. 

Battelle Report, PP. 

24'?5 - 

reduced. @nPhasis added-) 

Banelle Report, P.28- 

. . . flight duty regulations that adequately account for circadian nrodulation in 

the capacity of sleep and in human performance have been used in the United 

Kingdãm for 6 years . . . and by account appea¡ to be working well. The Study 

Group is aware of no qualitative reason why adjustments such as those 

incorporared in rhe UK regulations could not be used in the US as well- 

Scientific Study GrouP, t4.2, P- l0- 

Flight duty periods during window of circadian low' 

. . . Therefore, it is recorrrmended that in a 7-day period. there be no extended 

flight duty period rhar encroaches on any portion of the window of circadian low. 

[Note: a standard flighr duty period should not exceed l0 hours within a 24-hour period-] 

NASA TM, lI 2.3.5.8.:2-3-3. 

26

t (d) When lhere are no other resert'e pilots vho have sufftcient resen'e 

availability periods to complete an øssignmenl, the certificate holder may 

schedule aflight crew membertor an assignmentfortlight time in schedutcd 

air transportation or otherflying permined by this subpart, provided that the 

crew member is givcn a minimum of 14 houn of advance notice and is relcased 

to protectd time u the time of the notbe. 

Scientific zuppori: 

(d ) Minimum of 14 Hours Advance notice 

Considerable resea¡ch into other arenas has taught us that individuals are betrer 

abþ to cope with unusual or extended duty scheùrles when they can plan for them 

in advance. This forewarning allows them to dcrrclop time-linked performarrce 

goals and to schedule their rest and activity optimelly before reporting for dury. 

R. Curtis Graeber, et al., Aircrew Sleep and Fatigue in Long-Haul Flight Operatioru. 

Tokyo, Japan (October 2Ç29,1987), P.12. 

.. . [n other words. simply being off duty was not a sufficient condition for crew 

rnembers to be able to fall asleep. . . . 

Philippa N. Gander, et al., Crew Factors in Flight Operations: WII. Factors Influencing 

Sleep Timing and Subjecrive Sleep Quality in Commercial l-ong-Haul Flíght Crew's 

(December l99l), p.29. 

. . . In the limited time remaining, he attempts to sleep irrespective of his 

phl,siolo,eical readiness to sleep (circadian phase) and the local time, both of 

* hich may compromise the quality and quantitv of sleep he is able to obtain. 

Philippa N. Gander, et al.. Crew,Factors in Flight Operations: VIII. Factors Influencing 

Steep Timing anl Subjecrive Sleep Qualin' in Commercial l-ong-Haul Flight Crev's 

(December l99l ), p. 3 I . 

This reiriforces the importance of ensuring that adequare time is available for sleep. 

Conclusions -. 

. . Flight and duty time regulations can be interpreted as a rËans 

of ensuring that reåsonable minimum rest periods are respected. However. the 

p€rspective highlighted by this study is that the time available for sleep is less 

than the scheduled time off duty. . . . 

Philippa N. Gander, et al., Crew Factors in Flight Operations: WII. Factors Influencing 

Sleep Timing and Subjecrive Sleep Quali* in Commercial Long-Haul Flight Creus 

(December l99l ), p. 33. 

27


e: How about that the flight is going to happen. There is going to be every day in 

America, pilots that report to work at 2300 or *'hatever and fly until0800 the next 

nnrning. Now, what's different about the man who knows a week, a n¡onth in 

advance thar this is going to be his schedule and the reserve pilot who finds out at 

noon after having woken up aI 8 a.m.? WhU would be the difference? 

A: You know that the time you do all of the things you can to move toward a bener 

situation . . . You can never get to perfection, but the more practice, the rnore 

warning, the þtter you'll þ able to handle it. Sone people learn that there is a 

tirne when it's quiet and if I do this, I can pretty much depend that I will fall 

asleep. It's not læ% btrt you kind of lsam th,r or you practice or whatever' But 


e: Dr. Denpnt, you've kind of led the discussion into another area of this 

rulemaking that has to do with an alternative npthod. Assuming that the pilrots in 

this protected time period method were depleted, the carriers then want to give 

pilots advance notice to cover any mission or ¡rny assignment. They are looking 

at l0 hours as the criteria. We don't believe that to be adequate bas€d uPon . . . 

Are you talking lGhour warning? 

Ten-hour warning. yes. To do anything. 

A: That *'ould be 10O7c wrong. 

Q: tÃhy.) 

A: Well. because rhe l0 hours could fall sort of toward the beginning of what we call 

"clock depe ndent learning." There's no way you could sleep. And then you go 

into your duty period at the worse possible tirre you could have in that situation. 

Q: 

What sort of tirne would you think would be adequate to give a guy enough time 

ro ger an opportunity to rest so that he would be safer than l0 hours? 

A: Twenty-four hours. At least a day before. rJy'ouldn't you think? I don't see how 

you can ger norified as the day is beginning and feel you could depend on being 

able to take a nap. If it happened every day or sornehow you know that you could 

cerrainly ger rhe probability up, but it's not sonnthing that you could ever really 

control. Again, there ought to be a better way. 

Appendix D,pp. lGl l. 

28

Q: We're shooting a¡ound the subject. I hate to break any of this up. but this 

quesrion has been plaguing this committee. The industry keeps harping on the 

fact that there should be no difference between the schedule holder who knows 

he's got to fly from midnight to 8:00 a.m. If he can do it safely. why can't a 

reserve rhat wakes up al the same time in the morning (8:00 a.m. or 6:00 a.m.). 

Why is it not safe for this reserve pilot who does it with notice? 

A: I don't think it's safe for either pilot. Maybe a little less dangerous in the sense of 

performance, etc. But I think at least he has preparation, warning, etc. and knows 

his own strcngths and weaknesses whereas the other pilot I think is always 

without warning a¡rd has really no chance to prepare. I don't think the two groups 

a¡e the sa[re. 

Q: Are you implying that the preparation should actually start the previous night? 

A: Yes. If I was going to drive all night, I wouldn't want sonìeone to tell me that 

day. 

Q: They're really killing us for making that sarne argurnent. I rrean we make that 

¿ìrgurrrnt across the tabþ and we get smiles and nods of the head and shrugs of 

the shoulders from the other side. They say it's not a valid ¿ugulrrnt. That's 

always what they come up with. 

A: They say it's not a valid ¿ugurrnt? It is a supremely valid argument. I mean 

that's just like saying down is up. 


29

0 

For augmented International operations, a certiftcate holder may assígn 

attight crewmember ønd aflight crewmember may accept an 

time in scheduled air transportotbn or other 

assignment forllight 

c o mm ercial Ílying as follow 

Ø 

s : 

For singlc ougmcntdtion" the assignment must be scheduled to be 

complcted within IE houn after the end of the preceding 

hotected Time Perid; or 

(2) For double augmentation, the assígnment must be scheduled to 

be compbted vithirt 22 houn øftcr the end of tlu prcceding 

Prctected Time Perid- 

Thcse himítations may be extendcd up to 2 houn for operutional delays. 

Scientific zuoPort: 

(f) ( I ) and (2) augrnented crews 

Extended flight duty period: additiond flight cnew - Additional flight crew 

afford the opportunity for each flight crew nember to reduce the time at the 

conrrols and provide for sleep during a flight duty period. Consequently, with 

additional flight crew and an opporn¡nity for sleep, it would be expected that 

fatigue would accumulate more slowly. In such circumstances, flight duty 

periods can be increased beyond the recommended limit of l2 hours within each 

24-hour period. For each additional flight crew member who rotates into the 

flight deck positions, the flight duty period can be extended b-v- -l hours as long as 

the following requirements are met: l) each flight crew member be provided one 

or rnore on-duty sleep opportunities; and 2) when the extended flight duty period 

is l4 hours or longer, adequate sleep facilities (supine position) are provided that 

are separated and screened from the flight deck and passengers. Controlled rest 

on the flight deck is not a substitute for the sleep opportunities or facilities 

required for additional flight crew nrcmbers. 

NASA TM, I 2.3.6, P.7. 

30

a 

o 

a

NASA Technical Memorandum l1O4O4 


Duty and Rest Schedul¡ng in 

Comrnercial Aviat¡on 

David F. Dinges, University of Pennsy'vania Medical School, Philadelphia, Penr¡sytvanh 

R. Curtis Grâeber, Boeing Commerciai Airplane Group, Seattle, Washington 

Mark R. Rosekind, Arnes Research center, tvlotlett Field, calilomia 

Alexânder Samel, and Hans M. Wegmann, DLR'lnstiMe of Aerospace Medicine, 

Cologne, GermanY 

May 1996 

Nat'Kmal Aeroneullcs ano 

Space Adm¡n¡st¡atixt 

Ames Rcsearclr Cenþr 

Motlett Freld. Callornia 94ù3$1@0

Teblc of Contents 

1.0 -'i.iéi;;,t;¿i Gcncrat PrinciPles 

T'g3'Ofi, ütã Rcco"cry are Primary Corsidcrations-----.......-.- 

l.l.t SlccP 

t.l2 Arrfc dpc off ....- 

lute Solution 

ZO Spcciñc Prirriples Guidclines, rnd Rccom¡ær¡datioos """""" 

Zf -Ofi-DtY PGriod 

Z l. I Defiaition:'offdur¡f '.... -' ------ 

:---..-::-.::-.:-.:-:::*:::..-::-..:::....:.: 

lccp ¡nd Wrtin¡ Føfcoucc 

fFect Alcnness urd Fcrforma.e 

Ftigh¡ Ocw¡-....-. 

Ll 2 Otr 4¡¡ry pcfid (¡cr¡æ slecp and awatc-tiæotr rcquiræas) .. -........ -. 

' Ll.3 Ofid¡ty Pcriod 

(recovcry rcquirerænt).--""' 

zl.,t ofidury p.¡"¿ irouoøig såndltd flight dury pcnods duing wiodow of circedirn low)...... 

2-2 Dury PÉriods 

22.I Dcfinition: "dut¡f 

22 2 úÃttion: "dutY Period' 

2-23 Dt¡tY Pcrid 

23 Ftight Dt¡ry Periods 

2.3. I Dcfiûiti

PREFACE 

This documcnr is inrcndcd o povide scienrific inpur ro rhc issr¡c of dury ¡¡¡d rcst schcduting of flight crEws 

in commcrcial ¡viation. I¡ is r'railable ro ury inrcrestcd party thu is addressiog ùesc complex issr¡cs 

Scientific worting G 

rclevrnt 6 flitht sefcty. 

rrüÉr" oo sir¡ri6G d.r. 

To add¡css this 

dcryelop prirrþhs 

cd r¡e¡s of scieotific tnowlcd¡c 

d¡¡ wtre ¡vril¡He rnd dso ut¡s 

cat riæ¡iÉc bovldSBgæltPriDdflÉ q*tüy 

úËSd. Wilt ùc ¡æit FiDdPb¡ ¡ r b¡i¡ 

r rpecific rcco@Dd¡tbß TÞgury nccdttl 

rc¿ Uy ùe 2+boú dcost¿s of ûs ryi¡ti¡ 

pstc¿ o cæpleænt ùc drry ¡¡d resr shcanling 

cd Êoo iDdividuâls with cxtcasivc opcrationel 

scientific B¡ds for principlæ end Guldctines. Tbc scicotifæ worki¡8 srooP wls cÚPoscd of 

scientiss ætircfY i¡voþed i¡ ex 

dæ.wns bascd on their c/ûtconsideratior¡.s, 

a¡d to providc scicntific input o this r 

will providc óc Pccific scicntifrc rcfc¡c¡ccs that stp¡ 

sccor¿ dær¡ænt cdll bc looger ard u/iU fæus on ttp 

planncd ¡Ìrar a¡ inidat draft of rhis sccord docusrnr \¡/itl bc ava¡llabþ wiù¡¡ app'roxiroaËty 12 EDottths 

In atpbabcdcal ordcr, rhc scicntifrc workiog gouP 

}f¡tt R Rosckind,PhD, Atcx¡¡rdcrsaæl,Pb'D, 

this dær¡æot to the scientiEc working gottP, pleasc 

Y 

atioo of these principles and guidelines oay 

rs i¡¡cludc ccor¡omic, bgal, cost/bcnefiL and o¡hcr 

king got? þ rdd¡Êss ü¡csc isss, and thcy ¡¡e left 

: dcübcratioor 

ofr 

t sc thcc 

II¡DS M. Wegmann, Ìv{-D. 

DlRlnsd¡r¡æ of Acroepacc Mdiciræ 

LindcrIIæhÊ 

Þ51147 KæI¡ 

Crcrmany 

19 2]f¡3 æl I cxr 3667 (Officc) 

49 XN3 696372 (Fax) 

It'D' 

ü

- Ch¡.lleugç to Human Pbysiologr 

,INTRODUCTION 


Duty and Rest Scheduling in Commercial Aviation 

David F. Dinges, R,. C\¡nis Gracbeç Mark R' Rosckind, 

Alex¡r¡dcr SatJ' ¡¡d llans ]tl" Y/cgmana 

(¡¡oþlùcùtPl orb) 

Trclty-four Hour Requipænts of thc AYt¡t¡on Indgstry 

Tbe rvir¡io industry rcquires 24-horr ætivit¡ca þ æe¡ qcnnoo¡l dcod. CræTnü in Èbat boS' 

heut rcgion¡L ovcmigbt car3o, rnd 

rurDèóc'cbck requireænts Flith to 

æa Ëcse ind¡stry dcoa¡rds Boô dætic ¡d hæn¡ational avi¡ir¡n ca¡ dso rcqúE crcsing multiple 

riæ zmes Tbcrcfore, shift wcrlq ni$t uroút, ine$l¡r wo,rt rchcdr¡þs, unpredictrHc ulct schcdulcs, 

a¡d d'.- zæ c¡anges will continrrc o Þ moplacc componcas of ùc sviatioo iDd¡rstry. These 

t 

çøatioos. Utilizatiæ of s¡ch scicotific infcrmtiæ cen hclp ProtDote crcw perforææ and alcdness 

during flighr operations and ôcÍeby Esintain ud impro're üe safery EargfoL 

Tlu'or¡d¡g¡¡¡ Er¡iation histay, opcratio'ñal capatiliths and tcchrrcfog baræ etolved ùanoaticålly, uàib 

þurnan ph¡,siological capabilitics have mc Flight opcradors can engendcr fatigUe slecp losS and 

ci¡cadia¡r aisrrrytioo a¡¡d rbesc pbysiological faacrrs can rcsult in dccreascd pcrfcmaæ and rcdæcd 

¡lertncss d¡ring opcratioos Or¡er ùe pes a0 tlã:, scienrifrc klowlcdge rbout slecp, circEdia¡ 

È)6iobg/, 

sleepincs$ahnncss, ud ùc pcrfcrmaæ decremcas assia¡ed with thcsc facus has 

igcas.d sig¡iñcanüy. Scieotifrc rcscarcù has ereadcd is exa.minadon of úcsc fæ¡os o opcratiooal 

covirænts inclr¡ding 6eË a¡rd sirmrlator stldies Thsc studics have coofi¡rrtd ùep'rcscrrcc in 

¡viarcrs of pcrfømancc-;mpai¡int fatigue rashing Êoo the slecP loss, cirdian disuptioo, and 

c¡orkload ørgendered þ current flight and duty practiccs- 

fl,nnans a¡e ccntral to aviation opcrations a¡rd continue o pcrform criticel functiors Þ Ecct tbc 

2Á-horr requiremcns of the industry. Tlrrcfqq humrn pbysiological capabilities, a¡rd limi¡¡¡ie¡5, 

rEoain cn¡cial factcrs in Eaintaining safety Ed Foô¡ctivity in aviatiæ- 

Principles Based on Scientific Knowledgc 

Tbor¡gù ræcarcb on fatigue slcc,p and circad¡¡ pb¡tiology, a¡ld shiñ wort schedr¡lcs has gcncratcd 

an cxrcrisive body of scicntific howlcdge, thc rp'plbation of this information to tbc requircæns of 

cpcrarional scaings is relatively Dcur. V/hile æknowlcdgment of this scieotifc information is 

increasing, is tra¡sfer to opcrations (c.9., scbcduling, rcgulatory considcrations, pcrsonal sracgics, 

çgr¡nrcrDeåsures) ofren rhe greatest potential fcr is beileñr C\¡rrent fefuzd rcguluions and indusry 

scbeduling ¡racticcs rarely act¡owledge cr iDcorpfetc such knowledga The primary purposc of this

dær¡æ¡¡ is to outline scienrific¿Ily-bascd priæiples tlu¡ car¡ be epplied to Ûre dury and rcs scheduling 

rcquircæns of thc aviation indusuy. 

Shared ResPonsibilitY 

Tbcrc is no onc absoluæ orpcrfcct solutioo ro rbc dcm¡¡¡ds of duty and rcs¡ scheduling in aviatiott- It 

ryonsibiliry rmng rll üe indusryPútäP¡Dts 

N¡Dincd fc nænucs o incrporaæ sciead6' 

u will Eâximizc pcrfcoance ¡¡ld rløæ duing 

ling PrefücÊs, Pcrsorl¡t strategies' ud æchrnlogl 

ouH bc st¡bis o s¡cb ¡n cx¡mi¡¡b- 

'S¡fcl c¡n be Difficult to Qu¡ntifY 

oiquc chrllcages This dæræu i¡ foæod oo 

y rnd rcst scùcduling llowwe¡, it is Èorylcdgod 

srch æ leg¡L æooob, a¡d e¡rrerprcricc- It is 

troüioo bc coosllcrcd h ùc reg¡¡brydmd!" 

fcraft accidcns arc sr¡cü ralr; Gufierþæ rh¡t ¡!¡sJt 

a s¡fe qcrldoos. Thc aviatim i¡tdus¡ry ¡od ftyins 

rcy. Amng Eodcs of mryøafua óc ¡vi¡tio 

urany scgænts of ü¡e industry i¡creasc tbeir 

s ovcrall growttr cootinues, tlr challeags will bc o 

m¡inrain, a¡d wherc possiblc, improve Ûr 

prirciples 

czìn crea¡e a for dcc¡cmcns in 

mrgin' 

"r¡lnenbiüry 

Guidcfiocs designed ro spcciñcally addrcss tbcsc fac 

Objectives 

r.O GENERAL PRINCIPLES 

,empirically dcrivcd principles ard RútJcfines for 

he first scctiorl scicn¡ifically'bascd piæiplcs 

a¡e or¡tlincd I¡r tl¡e sccond scctiæ' ¡bc 

'dusry 

schcduling in commcrcial aviation, wiù qpccifics 

rd scction, a brief ovcwiew of otherpccntid 

d- 

1.1 steep, Awake Time off, and Recovery ¡re Primary considerations 

L Slecp is neccssary to maintain alerocss and 

urd well-bcing. Each idividuat has r hsic shcp 

prformance and ph¡rsiological alert¡ess during 

,p in a 24-bor¡¡ Pcrid, with a range of slcep needs 

s little as 2 hor¡rs of slecp will result in aan6 slecP 

scquent waking pcrformance and alcrhcss- Ovcr 

d,-u/in accrue in¡o a cumulativc slccp dcbc Tbe 

can only bc rcvcrstrd by stecp.An i¡¡dividual who

¡s ob¡ai¡rcd required sle+ *ill bc bcncr prepared to perform after long hou¡s awakc d ùãEd 

u¡ork schcdules th¡r¡ onc wbo is opcrating wirb r slccp deficir 

t.Ll Awake time off- FuigUe-rclatcd prføoance dccrcmcns arc uaditionally deñoed by 

dccli¡6 in pcrformencc ts r funcdon of tir- sPÊnt on e given ttd( Brcaks froo contin¡¡oss 

¡o maintain consistc¡t rd 

¡oó¡cod here o dcsc¡ibc tioc 

a¡c nccded to errsurroÉm¡E 

lstæbof pcrfanæ. 

Ll3 Recovcr¡- nccovcry Êom a¡¡ acutc dccp deñcit, cumulative decp debt, proloogcd 

pcûmæ ¡cqufot"t"El' 

osi¡lcr¡¡kn Opcttoo¡t 

rsr/Gry pcriod trtridÊ æ çpøtuniry 

pcrtæætd llcíDcsr. 

l2 Frcqueat RccoverT Pcriods arc Imporlent 

30 rcqu of 

troætÊ 

perfcnarrcc rnd alett¡ess Tbcse¡e 

¡cdpcriods of wkeful¡css Ge, dr¡ty) ar¡d dn¡dia¡ 

covcry is impcnant þ rcducc c¡¡muluivr cficds 

rforoancc a¡d ale¡mcss 

l¡16e Êeqgear recor¡ç¡y pcrbds rcdr¡ce ç¡¡6'l¡tivç htigllc rrrone etrcctiwly than less Êequcatæ. 

Fc exaryle, wee 

mothly rÊcovcny 

critical fcr rninirniziqg cu6¡¡tstive fadg6 cfferfs o 

lJ Time-of.Zftfe¡ñadia¡ Physiologl Affects Sleep and W¡king Performance 

Tbcre is a clæk in rhe human brain, as in otlcr crganisos that regulates 24-horu Pancrns of bdy 

ñrytigos This clæk cærrols æt only slecp and e¡alefulncss alternaring in panllel with thÊ 

cavi¡onmcnal ligh/dark cytle, but also the oscillaory na¡lre of æs phpiological, ps¡ahologba[ 

and bchvio¡al ñ¡nctions Tbc wide rangc of body ñ¡¡rctions conuolled by the 2¿l-hot¡r clæk includes 

body tsrñpcra¡Íe, bcæne scc¡Êtion, digestio+ physicat and mcnal pcrfommce' mo4 udmany 

dbcrs Oo a 24-trq¡r bosis, ôcsc ñ¡nctions flr¡c¡¡atc in a regular pattcro witb a hi$ lsvc¡ I æ tiæ 

ddey a¡d a low lcvrl u ambcr dmc. Thc ci¡cadian (circa = a¡rjun4 diu = day) pancr¡ of 

crakcñ¡krcss and slccp is progammca for wakefi¡loess during thc day a.od slecp at nitbl Tbc 

ci¡cedian clæk rcpcåls üris pancrn m a daily basis Ccnain horrs of ¡hc 2¿l-horr cydq ùat is (2ffi o 

Oúm, arc idcntified as a riæ when tlrc body is trog¿rrmcd to slecp and during which pcrfønancc 

is dcgredc¿ Trmc-ofday q circadian cfrecs æe imponan¡ consideradcns in addressing ?+hr 

requireæos bccausc circadian rhytìns do no¡ adjut rapidly to change. 

çcrational 

Fcr cxarryþ, ùr irdiviô¡al opcrating during the night is maintaining wakeñrlness in dirccr opcitim 

o pbysiological progranniDt Þ bc aslecp. Physiological, ps¡æhol,ogical, ar¡d bchavioral ñ¡mi

slccp loss, decrcascs in pcrforrrance-urd alertncss, ¡¡¡d va¡ious l¡calth problems (e'g'' gastroinæsdnal 

æøplainsl. nrcreiae,'"ir""di- srabiliry is urorher consideration in dury a¡rd rcst schcduling' 

1.4 continuor¡s Hours of wakefulnessr'Duty can AfTcct Alertness and Perfors¡ance 

ontinr¡ou 

usk will 

ods ttresc 

(he 

trccS is O 

ærs hor¡n 

¡n þ aeesscd ùrougb drily li¡nit'tions while 

¡iutions TbcrÊ is mt scicatific d¡¡¡ av¡llrHe o 

æ¡u¡tario of fr¡ig¡c cficcts 

l5 lluman Physiotogicat cepabtllties Extend to FllSbt crew¡ 

1.6 Flight Crews are Made Up of I¡dividuals 

Thcre arc conside¡able individuål difierer¡ces in ü 

ph¡,siological alcrtness" a¡rd subjective rçors of 

¡""p toss, nigbt \¡/6lq and coosider¿tions of reqt 

t¿iviau¿ difi.t nccs carì Yary as a furrtioo of a¡ 

other factcrs. Individuals can also Yary in their pa 

during a subecqucnt dury Pcrid (e'g'' commuun¡ 

a 4ury pcriod). 

rfama¡ræ dc6cis reflect ùcsc physiolo'giãt lirni¡a 

roo that of o¡þ þrrm¡n

spcciñc prirriptes and guidclincs elso ¡pply 1ry6s .ll n^yutg dury of flight crew ocobcç rcquhd o 

ptfor-Þ"n gt o¡ t"tilitary Oighr opøations bcforc a ¡ftcr schcduled commercial opcratioos 

In qdcr o provide spcciñc guidclincs, i¡ i5 ¡çccssary þ dcfuc thc tcros used in thesc guidcli"'s 

Alrering thcsc definitiors may invalidaæ rhe principles Öa¡ follow' 

2.1 Off.Duty Period 

LLI lÞfi¡itiou: .off-duty'- A conrinuors pcriod of unintcrn¡pted tiæ duing whicb l crew 

ocobcr is Êec of ¡¡l duties- 

LIJ Oflduty pcriod (rcr¡tc dcep ¡¡d ¡çrte-tÍme-olf rcquircmutsÞ Tþ ofduty 

s pcfroancc of rcquirod ¡ses Thc úird 

ing ro ofiduty pcriod- Tbcsc othcr æssrry 

r h¡ora accmodatisrs bæl cbcck iq/ú, Gt¡s' 

showcr, and pcrsooal hygieac. Thcrcforc, rhe otröy Pcriod sho¡¡ld þ ¡ rninimrrrn ef l0 bû¡rs 

r¡nintcrn¡Pt i *itio aoY Z+ 

and tiæ for othcr ncccssarY 

2.3-s.) 

2.lS Off-duty per¡d (recovery requiremeatÞ Tbe gencral principlcs outline ¡hc 

impøtancc of 

consccutive ni 

ury period fcr rccovc¡y sbold bc 

nighs of rccovery slecp, siËi¡ r 

74zy pcrid 

2.t.4 Off-duty period (fotlowing standard fiight duty periods during wÍndor of 

circadi¡¡ low'þ Extensive scientific rÊscå¡rch, incMing aviation da¡a, dcoonstraæ th-âl 

rnain¡¿i¡þg wakefulness druing ùc 

pcrforoancc-iropairin g fatiguc tban 

@ur drring tbc window of circediur low bave 

trEu¡ for recovcÐ¡. Jr is rccoærdcd tha¡ if two or tDore füght dury pcrio& wiüin t?drry Pcdod 

encroach on all ø ariy pation of üe window of ci¡cedia¡ low, tben rlre sa¡da¡d otr-dutypctiod (¡e 

continuous hor¡¡s u/ithin 7 days) be extended to 4t bours rccovery. 

2.2 Duty. Periods 

2.2.L Definition: 'duty'- Any rask a crçs, mbct is required by ¡hc oPcr¿tq to pcrføn, 

including füghr ri.Ee, a¿lministrative wort, tnining dcadheading, and airpct stardby rescrve. 

2.22 Definition: sduty period'- A continuors perioa of tims during which tasks a¡e 

pcrford fø rhc opc¡Írroç dercrmined from rcpcrt tiræ r¡ntil free from all rcquired tasls. 

' For dcfrni¡ic¡¡ of 'wir¡dæ of circ¡dien br.- se¿ scûiqt 23¿ 

5 

off'

225 Duty period- To rcduce vr¡t¡rcrabiliry to performar¡ce-impai¡int fatigue froo ex¡ended 

hor¡rs of conrinuous wakefulncss u¡d polonged pcrids d condnuous performancc requireænts, 

cr¡mut-dve dury pcr 24 hotrs should b limirc¿ h is ræomæ¡rded rhat this limi¡ nor c¡cccd 

14 hq¡rs wirhú . Z+tro- perid (In ôc casc of additional flight cnew, scc scction 2-3-6-) 

2J Flight DutY Periods 

23.r Dcfinition: .lligh3 duty perbd'- Thc pcfiod of tiæ rhat bcgins wbcn a crew æmbcf 

isrcqufuçdütbÊblæk-i¡ 

dæof ôc 

-0iÉtsivitics 

æd ffigÞt tirrç. 

2l,2 Dcllnitíon: .tvindoç of drcrd¡u lon'- The wiodow of circ¡dir¡ bw is bcst 

fc individrús ¡rpæ¿ o a r¡s¡l da¡wrkcrh[ttälcul¡¡Êd 

Êrm s¡eatific dan o úc ci¡crdro bw of 

¡eú fatig¡E), ¡Ddbody tcuPcrlnrL Frf,iÈtduty 

odow of circadi¡n low is csÉt"'t¿d to bc@O o 

lury pcriods ôr¡ c¡æ 4 q oac tirç zcncg tbc wi¡ôs 

dcirc ôa¡ lw is estimaÞd þ be O2m o 060 home-bascldooicilc tioc fa ùc firs ¿ft bours only. 

Aftcr r crÊw mbcr reolins mrtrç rhan ¿+t hor¡rs away froo boc-basddodicila thc wi¡dow of 

circadir¡ tw is cstinarcd to bc @0 o 06ü) rÊfefrEd o lqt tiæ u tbc point of dcprura 

233 StsDderd flight duty period- To redr¡cc vr¡l¡rerabiliry o pcrformancc-inpairing fuigttc 

Êom exænded ho,¡rs of conti¡r¡or¡s vakefulness and prolongcd pcnods of continuos pøforoancc 

or¡rs should bc limirc{ It is ¡ecomncnded üu fc 

psriod not exæcd l0 hor¡rs wi¡hin a 24bot¡¡ 

ght scgæns a¡rd daY or night flYiDg' 

23.4 Extended flight duty period- An extendç4t çrrrnsl¡tivc flight dury pcriod should bc 

lirnitcd to 12 hor¡rs *irfrin e Z+tnro pcriod ro bc accompatricd by additional rcs¡rktims dld 

scd on scicntific 6ndings frm a variety of sourccs' 

r significanrly increascd rdncrability fr 

t is readÍly æl¡owledged that in cr¡r¡e¡rt Practicc' 

r opcrations. Howevcr, the available scþntific daa 

donal practicc. Thc data indidc ürat pcrfcrmancefpu'lirnit 

and coutd redr¡cc ütc sfcty roagiD- 

Z3S Extended flight duty period: restrictions and compensatory off'duty periods- 

If rbe cr¡mularive nigñr dury pcnod is cxandcd o 12 hor¡rs ú¡ea tbe fotlowing rcsriaioos and 

cornperìsatory offdury pcrrods should bc applied' 

A. Cwü.Idtíve fiec's: ¡tøin)n ct¿tulaíve hows of øeæion. Ovcr timc, cxænded flight duty 

gue. To suPPorn opcrational flexibility and sill 

it is rccommendcd th"t cxtcnded flight d¡¡Ìy Pcriods 

or¡n within t 7 4zy Pcrio¿ Fcr example, Ûlcre could 

be two 2-hor¡r exrensions of rhe s¡anda¡d lGhotr¡ flight dury period (2 x2 = 4 br) or for¡¡ l-hou¡ 

extensions(4xl=4hr)- 

B. Flight dtuy periods dwing window of circadian bw.As describcd in Secdon 2.1.4, thc 

window of ci¡äoan low (asdcfined in Section2.3.2) is assæiated wirh highø levels of 

6

pcrformancc-impairing fatig.ß Tlpreforc, i¡ is recomrrçnded the¡ in e ?{ay Pefiod, there bc æ 

enqoæhes on eny ponbn d üre window of ci¡crdian !cw. 

exrc.dcd flighr dury frioa-tr., 

C. Resrict¿d wtùr $ taúngs during winfuw of circúion low. ff an extcr¡dcd flight duty 

grcatcr the¡ l0 hours thet 

it is ¡ecooær¡dcd tlrat Oigbtcrew 

fotlowiry ôe fütùt 

23.6 Extendcd R¡glt duty pcrioû ¡dditl 

Prwtc 

llcor/crY 6o6 funre fuigtr 

t¿Atiot ofrö¡tY ti* is rældcd' Thc 

tuld bc c¡ødcd by tþ tb drntitn dúÊ ñitb 

d f,itL ery Pc¡iod of ll5 bs wtld b? 

bcing cxæodcd to I 15 hilL 

c¡ew r¡d u opcurnitY fu dccPt 

. In s¡cü cùærc' flídt¡ ô¡ry 

dcd lir"it ú l2h¡rs wiü¡ eacù 2åhñ Pcrbd. 

aes ino ùc ftight dcck pcitiæs tbc fiight fuy 

; folloving rcquircæats ¡" tc l) crå a¡ilr 

,es reguired fr additional flightc¡lw ætr¡bcrl 

is i¡rcreascd accordi¡g o ùc above requiræÈr the ExiE¡E 

If an extendcd flight dury rrirrd 

ntg!, dury pcriod-finir sric''adc ùc l+hot¡f dury pcriod lirrri¡ (5¡ç[oo 12¡ 

23.7 Flight duty period (cr¡mulativeÞ A 24-hor¡r cr¡nulative fligbr dury period limi¡' r 

minimuaoffdury p""i.a rlaz4tlo'rs a¡¡d ¡ 

ffiå"ìy.ffiffiät*d3 

fæ¡¡s 

uce cxccssivç accunululn æ¡ols bngcrPcrilds 

rs ã! ¡Þcotr¡rrEfidcd- Tbcæ is æt srfficþat 

ris e¡ea- Howwc¡, the gcucnl piæiples +Pry' f'a 

2-weck limil sbû¡td atso b sct Also, thcsc 

adiustcd doqmc¡trd ec¡oss tbc longø tittp 

q¡mulatiræ fligbt duty pc¡iod timia¡isn to 

arrþunt shot¡Id bc dccrcascd I Ptræn4ge frm 

duty pcriod tí",iadon shor¡ld Uc ¿ccreascd r pcrccrirate frcm tbc 30day sDunL This wiu ñtrttE 

rçdu; thc porcntial for long-ærm acç¡gulaliot of fuigl¡c fætqs 

2.4 Exceptions Due to Unforeseen Operational Circumstances 

Exccp 

of the 

Tbcsc 

Srt 

spond to unfcresccn circumstariccs bcyond tbc control 

They are nor intended for r¡sc in rcgular PßcticÊ.

2.4.1Reduced off-duty period (exceptionÞ To suPPon opcrational flexibiliry' it is 

recognizld that dræ to circuEsranc6 bcyond the control of tl¡e oPcr¿lq' it may be ncccssary o 

rcd,r ur offdury pcriod ro 9 horrs This reduaion would occt¡r only in EsPoosc to r¡ 

unforcsccn operadonal rcquircnrenr In this siruadoo, ü¡e s¡bsequent offduty Pcriod should bc 

cxaodcd to ll bot¡¡s 

2.12 Ertended fligbt duty period (erceptionÞ To suPPon opcrarional flcxibiliry' ra 

o,.rn¿.¿ Oight ôtt-p..i"d on'u" incrcascd by r¡p þ a EüiEu"' of 2 hor¡¡s drp o r¡nfcescen 

circu'stl'ccs ùr"rå rhc coouol of rbÊ opcnrr. nc subccqræot required otrdrrty Pcriod shot¡td 

b" t".*"r.d by rú dæ by which tÞ ltiûr ô¡ryFiod b iseescd. 

2.5 Timc Differeocc¡ 

In ScDGraL 6c boger ¡ r1ìEhr c¡ps æobcr is 

d-".y tiæ is nccdcd fc readþænt back 

rccom;o¿ø thar frfligttt ù¡ty Pcriods that 

Eße away Êoo thÊ h@c-basc/domiciþ tiæ zorx 

rçhrrD to boæ bascÁdmiciþ tiæ. 

2.6 Reserve Statu 

eleæo¡ o opaatiooel f,cxibility ¡Dd b 

6¿¡ fiight crew æulbcrs 6 rËscr$e sn¡¡s 

2.6.1 Definition: ..airport standby r6erve'- A rescrve flight cflw membc¡ requi¡ed to bc 

available (on stardby) aì an airPon fcr assigrrmcor to a Oight dury pcriod- 

An airpon standby rcscrye flight crew mcmbcr should bc condrfged on duty ar¡d thc previous dury 

pcriod guidcl.ines applY. 

2.6.2 Def¡nition: .on-cau reserye"- A rcscrve flight crtw rDember requircd to be availablc 

þ an opsrator (away from the airpon) fcr assignænt to a fligh¡ duty pcriod 

On{a]] rescrve $an¡s should not bc considcr"l dury. Houævet, it is imponam ù¡¡ üc flight ctew 

æobcr h¡s an oppon'nitv .o obtain 'roP P"H# ilffii*å$$ffiäffi, 

c'indica¡æ Ûn¡ thc füght srçE' rrÉ'Íìhcr shq¡H bave 

Ddcd) as o wl¡cn tbc 8-hor¡¡ slecp oporruniry can bc 

n The &bor¡r slccp oppomrnity sbould oot vzry by 

ffie tl'ri 3 horrs on subsequent days o cr¡sure circadian sability- "A protccrcd t-horr slccp 

opportuniry-,-ñá u" pro,ir,ø from inrerrupdon by assignmcnt to a fli-tht drry pcrio¿ Aoy 

aiiroao rir.¡ *s thcþuireæns of thesc rwo principles could bc utilizcd.

2.? Summary Overview: Guidelines ¡nd Rccommendetions 

Frgure f prwidcs a sum¡Da¡y wcrvicw of rhe guidclines ar¡d rccooæodations discusscd in 

this docuæn¡- 

Þ -9tÞo() 

U) 

E I= 

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tn 

G 

Ofl-DutY Perlod Duty Perlod Fllght DUU Perlod 

ht Èr 

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lor.d 

ctor mafrü. 

¡rú br FDP¡ 

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bur* tæftt)r 

Extend.d 

FDP an b 

irucased by 

¡.pþ 2 tu¡ 

(srÈaeqwnl 

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pctird 

irsoas.d by 

an equC 

amount). 

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3.ü ÐTHER INDUSTRY STRATEGIES 

sbarÞd rÊsPonsibi¡ity, scver¿l otlrcr indutry 

bcd- Thcsc a¡e intendcd to cooPleocnt ùe 

e infuæd ¡bout tbc cxansive loowledge rcw 

æ it rcliares o pcrfcoaæ ¡nd rviuit¡o 

''dobg/ rd inÞ daily oecranons Tbc infcm¡dm ce¡ be 

crsúd sm¡cgies to E¡¡nage pcrfamance etrd 

g mdules to urect this rlecd ac arr¿ílable ¡¡d 

rsùy. 

uty t scñrl in guidbg ra¡iooal ard ph¡tsiologiåIyx 

a¡d multidcrermined præs Hor¡cvcr, it is 

hr¡ma¡r physiotogy as a factq for considc¡atioo' 

rst/be¡cfit considerations are aitical Therc a¡e 

rrmation on fatigue into schedule constn¡ction' 

33 Controlled Rest on tbe Flight Deck 

scieatific dera obrd!Ëd drring flight opcr¿rions t¡ave clearty demonstratcd ürc efrecdveness of a 

t a¡d alenncss in nonaugncotcd long-haul flight 

trarery and is not an arlswer ro all fatiguc 

rt inanded as a subsdn¡æ fcr addirional flight crcw' 

d dury. All possible srategics rlnt main¡ain c 

pcrations should be examined urd utilizc

REPORT DOCUMENTATION PAGE 

Fotn 49a6 

OMB No 07t OtU 

À¡ [FaDút Èry"aaâ E al, Ês¡cÞqì C nãñ¡¡IIì a armalé Þ aYa.a¡a l-lût F. [tagìaa, fËÉìc !l tL lq r¡.¡r.¡ ñGÉ¡gl. ra.Eññe Þ:- ¡ aârE¡. 

¡¡¡¡rd ¡g åãaæ a¡ aü¡ |t.,(¡.. arú csrqìg ytt ,rna-! ¡r c¡Er I rrc.ttf¡¡ût ¡aÚ cúítÛ n?¡ttl! t! Él 

-rra¡ 

! rt -ì. 

ãcãrar-t,¡sr-É|a¡ ¡JgEr¡rtìarr .tErãT ll3àtÜt E Ìltì.!E Ã.aJe¿"tt LrÚ.3uGtü t9 æ=r--ìarril trt tFl, 

È- ,tÊry. ¡¡¡ reO¡. r¡¡iør.-úe ,'Aeir¿,tIL r¡¡ ¡ ¡¡ q¡o I u.¡¡F.!rìl .tú ù.ó9r. t!.rut ¡¡¡rær ttetã OÈatla¡. Wrtü|¡ã\ æ õ- 

t. lGEraCY USE OflLY tL..v. Dt.âI) 2. iEPORT OATE I. iEPORI IYPC XO OAÍES C( 

H I tt 

¡¡r: 

May l9'9ó 

Tcchnical Memora¡ö¡n 

a. TtrLE Axo sulrlll-.c, 

XUIAERT 

hinciples a¡rd Guidelines for Duty and Rcst Schcduling in Commercid 

Avi¡rioo 

a. Ault{OR(S) 

t. 

Dryi.l F. Dinges R- Curtis Græbcc lvlart R- Rocckind, 

Atre¡andcr Saræ|. æd Hans!{-Wep444tEifoirlllo 

oncll.¡z^l¡ox tl^rE{3l Atl D ADOn€S S{E¡' 

ArË Rcsc¡¡cb Centct 

Moffcn Frcl4 CÂglO3Sl@O 

ço¡sor¡¡rarroi¡fon'lc ¡¡o€llcY x^rE(E) ArD ADDRESS{EII 

Natiooåt Aeronautics and Spacc Administation 

Wastringron" DC 20546ff1 

5ûL-Ár-(1 

tæoillÈo oiolE^Tþ¡ 

FOtlXUrlEi 

A-%t*U 

I 0. ttrollsoRltlorIorulolf O 

AC€¡'CY REPOFÎ N'IICÎ 

t{AsA TM-It0404 

rr. tu?PtErEXlAeY rolEs 

Point of Contacc Mark R. Rosckin4 A¡æs Resc¡rch Ccnær, MS 2624, Moffeu FÊld, CA 9403tt(re, 

(4t5) &392t 

t2a DISTRIBUTIOTUA Y ILA StLITY STAIEIET'1 

Uoclassified - Unlirni¡cd 

Subirt Catcgory 5l 

t¡- ABSTA gT (l¡ttisua 2æ aotét) 

r2Þ. ælRtBUftox coo€ 

Tlrc aviaúon industry reguires 2¿f-hor¡¡ activities to moet opcntiond demands. Cúowttr in global long-haul, 

t.. SUBJECT TERUS 

Fatigue, Circadian rhythrns, Duty and Resc Scheduling 

rr. sEcunrTY cL ssrFrcaTlox 

OF iEPORI 

Unclassiñed 

I¡. SECURTTY CI-ASS¡F|CATIqX 

oF 1t{rs P^GE 

Unclassified 

l l. sEcuñrTY cLAsstFrcaTx¡t 

o; gf 

^BsTñ 

T¡. IIUIBES OF P^GE3 

t5 

13. PFTCE COOC 

A03 

20. urff^Tto0{ of ^8sTR^Ct 

NSN 754æ1-?AO-55æ Srerìóaró Fofm 29E f R¿y 2-89ì 

!6---=s.r: S: -gF.:

a 

e 

a

I)teralure R¿r ¡e x 

An Ovcrvtew of tbc Schot6c Lltcr¡u¡re 

C-ooccrning Fetlguc, $*p, ¡¡d thc Circ¡dh¡ Cyclc 

Prepared for the Ofllce of tbe Chief Scieotific 

rnd Technlcd Advlso¡ fe¡ f,¡¡m¡n F¡ctors 

Fedenl Avl¡tloo Ad nl nlct¡¡tioo 

By 

Battelle Memorial lnstirute 

JIL lnforma tion SY:tems 

January l99t 

Page I

lntroductioo 

An Overt'iew of the Sc¡entif-¡c Literatr¡¡e 

Concerning Fatiguc. SleeP, ¡nd the Circadian C.r cle 

This docunrnr providcs a bricf rcvicw o{ tbc scicntific rcra¡ch rclating to issucs of piJa fatiguc 

arising from crew scbcduling practiccs. A oassivc ¡únounl of rcsca¡ch has bccn coodr¡cæd on 

c¡ch issrs ¡s thc covironræntd cooditions tbar cootribuæ to thc occtureocc of fatiguc. rq¡te and 

chrooic slccp dcbx and tbci¡ cffcctç oo pcrforrnancc, a¡rd tltc inflr¡cncc of thc ci¡cadiao cycle on 

rtcrbes. This papcr ancepts to idcotify nþr treods in this üæratr¡¡e that might bc of vd¡¡c i¡ 

ddressing scbcduling re¡uluory issls' 

Tbc 

proy 

cons 

sectioos. Tbc ñrst scaioo. -\Vhu is Fatigræ," attcmpts o 

f¿igræ ùa scrves to dcf¡¡c tbc scopc of issr.rcs thu nced to bc 

a¡ contributc to the occr,¡¡rencc of fatigrrc and nrcthodologies for 

asrssing the impact of fuiguc on huma¡ functionrng' 

Scctioo two, "Indicatioos and Etrccrs of Farigr.rc," bricfly revicws the hurnar¡ pcrformancc and 

pbysiologic¡l i¡dicaros of fuiguc. Tbc inaot is to idcntiÛ Possible de¡rccns in pcrfonrnncc 

that cor¡td bave a efe¡y irnpect. This scctioo also bricfly add¡esscs thc complexitics involved in 

rrrcasuring farigue levels. As this scctioo cxplains, fuigue is a complex cooc€P{ that does not 

aJuays produce erpected me¿surable dc¡rcrnenLs in pcrformancc 

Secrion tbrÊ€. 'lFauguc and tbc Aviatioo Envuonment." add¡esscs tbc issue of faugrr slthrn the 

avrarion enr.úonrr¡ent. Beforc changes a¡e madc to existrng rcgu,laltcrns. ùc qr.rcstioa of *hcthcr 

rherc rs a problem that ne¿ds to bc rcsolved should bc addrcsscd. Ata:lable rcsearcb on the exlent 

oI farrgue urth-tn the aviation envi¡oonrnt Ls rcvicr ed In addrtron. fa.-tors ùar compbcate the 

asscssrîenr of rhe extent of thc fatiguc problem in an operatlonal en\úonmcnt a¡e aJso descnbcd 

A pilor's lcr.el of alermess ar any tirrr dcpcnds upoo a complcx interactton be t*6¿¡ a numbcr of 

variables. For¡¡ va¡iablcs. i¡ particular, nccdtobc considcred: tinrc on task. ti¡nc sincc a*'ake. any 

existing slecp dcbt a¡d tbe pilot's own ci¡cadian cycle. Scclion'for¡¡. "St¿ndard Dury Period," 

dcscnbes the resc¿rcb rends pcrrairung to EtrE on tâsk and Ùnrc sLnce a'*alie *hile scction fir'e. 

"sranda¡d Slccp Rcquirerænts," sddræscs ¡rcutc and ch¡onic slecp dcbt, including 

recorur¡endations for stccp delx recovcry. Scction si¡, "The Cúcadiar¡ C¡cle and Farigue," r¡'hich 

looks at thc rcsca¡ch on ci¡cadia¡ cycles a¡d thci¡ implications for back-of-thc-clock and 

ransmcridian fìying. Finally, scction scye¡. "Augmented Crc*'s." looks at the limited data on the 

usc of augmented cnews to extcnd duty pcriods. 

Lite rature Reyiex 

Page 2

\t'h¡t ls Fatigue 

The ob¡ccti'e of ¡hc rcgularions proposed in the NPR\Í is ro idcntr[ scheduling constraints that 

will mini¡ruzc thc impact of pilot farigue rhar a¡iscs from duq'únr and slcep debt due to c¡er¡ 

schcdulcs. Thc rcnn "fariguc." has ya to bc dcñncd in ¡ concææ fashlon (Malrcr &, McPbcc, 

l99a); Ilendclson. Richa¡dson & Roth. 1996). Fatigrrc. æ addresscd in the human pcrforrnance 

tiæra¡r¡¡e. refcrs ro "dc¡erioruion in hurna¡¡ pcrformancc, uising as a conscqucncc of scveral 

potcntiel f¡cto¡l including slccpincss" 

dcfinitirn: -Slccpincss, æcordint to a.n 

cli¡icizr¡, is ¡ brsic physiotogical strc (like) hr dGtP 

i¡cre¡scs slccpirc r¡d rs hungcr or thirsr is revc¡siblc by ceting c drinking, nÊspcctively, slccp 

r'ycnecs shcpirc- G,oah ct r¡., t9t9, citcd by Mcnddson, Ricb¡¡dsoo ¿1, Roth. 1996, 9.2). 

tn kccping'with cunea3 thinlcing on tbc cooccf,t of fuigræ, M¡bcr aod McPhcc's ¡PPno¡ch ¡s t¡scd 

bcre: 

.Tariguc" must continue to bave tbc status of a hypolretic¿l constn¡ct, ar¡ eotiry 

uhosc existcncc and di¡ncnsions a¡e inferrcd from antcccdcot ar¡d conscqucnt 

evens or variablcs" (P. 34). 

This ræ¿ns rhar farigræ is trea¡ed as a coocc¡ that occurs in æsponsc to predcfincd conditioos 

a¡d bas physiological a¡¡d pcrformancc cons€gtrcnc¿s. Tbc antecedcot conditions of inærest bcre 

rncludc: 

o Trrrr on task. rncludlog flight ti¡r¡c and dury pnod dr¡¡a¡oo 

¡ Trmc sincc a*ale wbcn þgrno.ng the dury pcnd 

o Acute a¡d ch¡onic slccP debt 

. Cr¡cadia¡ drsruptron. multiple timc zooes. -¿ 5¡¡¡ * -'rrk 

The obje.-tit.esof this docurrrnt arc to rcr'iew the sctentlfic reseårs-h rn ordcr to: 

o Idcnrify thc impacr of thesc a¡ltc¡cdent va¡iable; on hum¡n pcrformance 

o Rclare ùcsc variables ro appropriate pbysiologicd rneasu¡es that have bccn derr¡onsrarcd 

to þ æcomPantd by dccrcrrrnts in huma¡ prformance 

Identify. to ¡hc ertent possiblc. limirarions and requirenËnts cooccrning dury* Pcrid durations. 

mirumum slecp re4uirenËnrs. etc. thar should bc rcfìecad in the regulatioos. 

I)teroture Revi¿v 

Page 3

lndicatioru and EfTects of Frtigue 

Thc massire literarure on fatigue has idcntif¡cd a numbcr of symptorns that indicate thc prescncc 

of farigue. includlng: incrcased anriet¡. dccre¡ccd shon ærrn r¡crþr¡. slowcd reaction tinrc. 

dccrcascd wort cfficiency. rcduccd nprivational drive. dccrcascd vigilancc. irrcrcascd variabiliry 

in work pcrformancc, increascd err

Sccrcury Ron Brown funher illustrares rhc rypc of inaction Dprcd of fatigue (Ne*man. 1996). 

.lJrhougir the pilots dcrccred an crror on apprcach a full m¡nute bcfore the crash. they rnadc no 

artcmpiro .o,'ç"r the enor-a coffur¡on cha¡actcristic of fatigue. This is due to a rcduccd lcvel of 

adhcrcnce to onc's normal s¡andard and a rcduced abiliry to cognttivcl¡ make a connecÙon 

bcrr¡ecn causc and efrccr. One rnay recognize a problcm but not tra¡rslaæ its effcct dr¡c to lack of 

full'comprchcnsion of thc siruation or simple failr¡¡e to initiatc en actioû- 

Relacd cvidcncc e¡ig,s rbrt f.tit¡¡cd worter: ¡¡e s¡ti¡ñcd with lower pcrforrnancc ¡¡¿ thrr 

n fu rbility of ôc worker to Pcrqe¡ve rod 

r un¡bþ to shifr qui

EfTecs of Fatigue and Sleep Loss on the Br¡in 

¡asks can bc determincd' 

nction. Horoc ( 199 I ) stålcs that thrs rcstoration ts 

tcr of tlre bra¡n. This is consisænt with thc 

tinrc since ¡*'ake signifrcantly increascd the 

9tl) for¡nd tha dominant EEG Êequcncics in 

gressive dÊclinc. with cach shifr bcgrnnint in ¡hc 

ihift croplo¡'ccs ¡hou¡ed EEG rc'di¡gs of l2-30 

duty during rhc oiSbt sbin' 2ó Il¿ Gcvens e¡ rl. 

bcrerrEß ere præcdcd by obocrnbþ EEG brain 

lcû¡ioorl fær¡s. Tbcsc EEG cåeo¡es rrc 

¡ncc dcc¡e¡mte ælu. Howia a d. (l9t) 

for¡nd th¡r undc¡ high wortload sin¡uions thc 

rf thoec disPlaYcd bY fresh Piloc- 

ecp is bnin glucosc levcls. All tissrc of thc body. 

: brain. worts clectrochcmic-lly, r¡d conforms to 

I uscd. Tbus. by æasuring glucoec utilization, 

n, üìe¡ls whicb ¡¡Ê very active duing va¡ior-s 

Tbornas et al ( l gg3). usr.ng posiuon effussron topography (PET) scan has providcd sÙong 

ph¡srological etidcnce uUat stccp loss is 

ft *"t ¡¡s5¡ i¡r'ol1'sd wcrÊ thc prcfro 

b'ile 

r^ ^- t! 

^t-;* 

- --^-. /-* 

r.n tbe a¡eas of higheiorder ¡hrnkrng declines ranged from l0 to l? pcrccnt (Tboro¡s' 199?)' 

.{Jr}.:ugh ther rclu.-rions scem relatirel¡- mrnor oYer a {t bour Pcnd' Gold ( 1995) rcccntl}' 

: 

fou¡J rhar com 

changes could significantJ;- erùancc cognirtr e 

hcaJthy yount adurs. erdcrry, and r'erc sr¡res of 

performance rn 

parhology such 

n"u"t tlop depnvation' t¡t orerall br 

ndronr Paticnu' 

pET scans of rccoveû slccp. aken sequenrially through thc nighr and synchronizcd with EEG 

changes. show that slow wave slecp apPears 

Uu Tbon¡as et al (1993. 1997) showed werc 

indicaæs rhat a¡eas of thc bnin i¡volved in der 

fncfh)ry. drive a¡d initiative. problem solving, complcr reasoning, and decision making a¡e tbe 

g".",.ri bcneñciarics of dccp sleep ([â'mbcrg' 1996)' 

since rhc fronr brain is rcsponsiblc for analysis of information. judgnrnt, planning' dccision 

ma\r'g. and rhc rniriation àf actions. it is not surprising thu NTSB found dccision making 

abilruis suffered with high time since a*'akc' 

Litetllure Rer lcx 

rsm' 

s 

Page 6

The orderly planning and sequencing of complex bcharrors. the abrltry to at¡end to 

rveral .o¡1ion.n,s simultaneousty. and then flexibl¡ altcr üre focus of 

conccnrrarion. rhe capac¡r) for grasping the contcxt a¡d est of a complex 

sirua¡ion. rcsis¡ancc ¡o drstraction and in¡crfcrcncc, the al'rlrry to follow multi'step 

instructions, tÞ inhib¡rion of im¡nediatc but inappropriarc rcsponsc ændcncies, 

and ¡hc ability ro sustain bchaviord outpt¡t... may eacb bccorrrc roarkedly 

disrupcd (Rcs¡t lgtt)- 

M¡ny of tbc ñ¡octions ¿os¡ibcd by Rcsak arc tbc sarnc functims æcssar! to e pilot's abiliry rc 

cornpctenttY flY r¡ rfucr¿ñ- 

Mcesurlry Fltþæ 

Alrlro'gh thc studics jus lisæd do show pcrforrnance decrenros ô.r to fatigue. othcr srudies 

have shov¿n no effeci(e.g.. Roscnrhal. 1993). particularly *hcn slccp loss þvels up to 24 hours, 

or small ch¡onic perria¡ slccp loss lcvels of only o¡ìc or two hor.¡¡s pcr day arc r¡scd. Tbe lack of 

dcñnitive resuls in parriat slccp dcprivation srudies rnay bc dtrc to difrcrcnccs in æsting 

proccd'res. Roscntb¡l tcsted on fou¡ scparate æcasions. where¿s oùc¡s tcsæd only oncc Pcr da) 

in.,o* scverc stccp deprivation srudy. Thornc (1983) madc t-bc rcsting i¡stn¡rncot tlte p.i-arl 

task. *.hich lastcd 30 rninutcs of each hou¡. As slecp loss bcc¿¡r ncreasingly trÊ¿¡c¡, subþts 

bccame slower. Thercforc. the drr¡c to complete thc sclf-paced t¿sk urcreascd about 70 pcrccnt. 

and at timcs doubled. 

frans er al (1991). in a rcvier*' of faugl.re rn comba( cTearty;st¿¡C ¡hat gr.¡dics ustng embcdded 

resrrng. such as Thorne (19t3). Angus and Heslegrave (1985). æd \fullancy et al. (l9tl). 

;cn:rsrenrlr sho* grcarer ettfecLs ol farrgue and slecp loss pcrfom¿rce dccrements tha¡ shon 

durarron isolared inrn¡srre resLs Belenky et d (1986) noles that --i:tlnuous emttcdded tcsting 

rereals targer pcrformance decremenls soonertha¡ dces interm:e¡t test¡Dt. Ln Angus and 

Hcslcgrare (19t5), ana.l¡srs oi rcsulrs found a ?t* de .-remcnt r:. :--'Ñrng,/dècoding performan;c 

anda43%decrerncnrinlogical rcåsorungafter2{hoursar*'ake H¡'sl¡m(19t2).usingnon' 

embcdded rcsdng. found no de¡rerncns and 29%. rcspectivel¡. 

Thc grearer scnsitiviry of cmbcdded asting is nor surprising gireo rla ùey rEasure pcrformance 

for a morc prolonged pnod. Brief. incnrsive psychomctric tesLs. In contrasl. a¡e novel and act as a 

rcst brc¿k, iistraaion. and remporary srimutus, thcrcby increasi-og shon ærm mobiliz^tion of 

effon rhus boosting pcrformance. Thc usc of such an inswrncn¡ * cxlld funcÙon similar to the 

effecr Chambcrs rrør) found in an indusrrial output study rrher o{rtPut remains highcr when a 

worker was switched to differcnt jobs pcriodically than to sta)' a¡ ooc jó' 

.\¡otherexplanation for the varling effects of prformance due t.', fati8ue is that pcrformance is. 

Lilerature Reyi¿r' 

Page i

in part. depcndent upon thc crrcad.ian physiology of the sub¡cct' subjects expcricncing cucadian 

dysrhythrru. o, op.äiing aunng thcu ciicadian trough ¿ue r¡!ìre lrkely to yrcld substandard 

pcrformancc. 

funcrion. 

ìf icrælee Ps 

uionship bc¡wcco fuigrre and perfonmncc' 

ìavc a targc imPæt oo ¡esuls' particulrrly rn the 

:ffccts are frequcntly most aPParcot æ¿r thc cnd 

orgiræls fo.lr¡d) but dso m¡y æcolü for thc 

5 sf slccp l6s" (BoDnGt' ¡9{' p' 50)' 

rs coosidcred ¡o iocre¡sc seositivity il æstiog for 

nctr¡dc cood¡r¡d¡t pcrfornaoca Proloogcd 

3 þ 3!6wa to wort i¡ dccre¡mt ôæonc¡is 

¡avc bccn rcportcd to bc lcss efrectêd by slccp 

ioo & Nritob. ln4). F¡tinp efræs nd to bc 

'roorivuint. and fccdback is givea' Oo thc uhcr 

nd ancndoo. the use of ncwly acquired skills' and 

,rt têrln rrrcrpry- This is bccausc wort-paccd tasks 

ereby dccreasing tbc rtscrre capacity of brai¡ 

ecrive tesing and the If SLT as good nrcesu¡es of 

y. McFarland (1953) considcred thc dccnoration 

)c srudy of farigrrc. Thls has rcccntJy bcco 

(lggl) rì¡ot¡gb tbc r¡sc of ftrgbt date rsordcrs for 

proccdure rDay bc thc bcst avenue ya for cruJy 

riond sening 

sscssing rÌ¡c.effects of fariguc urd slct¡relued 

rch. Microstccps *'erc fin¡ recognir:d by BiUs 

inrcnrcning yea¡s they bavc also bcco callcd 

ps." Tlc physiological drive to slccp can resul¡ in 

,itcs. Tbc lancr tcrminology is rlrc rcsult of EEG 

r forrnati on processi n g. subjecs monr nraril y s li p 

n a¡rd usually without ¡he blowledgc of thc 

:s (1929)- Bonnct and Moorc (1982) for¡nd that 

rnsciously a$'are of fdling aslecp, tbcy had bcen 

aps€s i n' "-n:lï ï:'.'ï1,*, jj"Ji: ot 

leadingtoeÍorsofomissiooduetomlssc4¡nlorroarion.Inrriajtasksthatarcwortpaced. 

Literature Retiew' 

Page E

mlcrosleeps can also lead to enor of commission and. if frcquent enough or long enough. can lc¿d' 

to loss of situationd ar¡'a¡cness. 

llcrosleeps have bccn shown to bc a uscful approach to asscsslng the effccts of tinrc of day on 

slecpirrcss tevels. EEG bnin wauc changes confirm that pilos cxpcnence gre.atcr slccpincss and 

decrcascd alertncss bcrwccn 2:0O to 4:00 a.m. (Gundcl. 1995). Alplu \Èaves in EEC¡s indica¡e 

micro cvcnts or micro slccps and have bccn for¡nd to bc th¡ec tinrcs grcacr during night than 

thc pbnirtogicd occr¡¡rcocc of microslccp ia cr 

narure of fatiguc in sucocssive nigbt opcratioos' 

The bcneficial effects of raking brÊåks havc dso bccn demonst¡ated by rrrasr.rriag microslccp. 

\f,'orkers pcrforming continuous tasks wi¡.hor¡t brÊels (Bills, l93l; Broadbcnt l95t) or suffcnag 

from stccp loss began ro dcmonst¡a¡e signs of micm slccps much soooet tha¡¡ thosc witb rest 

brcats or tcning adcquae rcsL resPectively (KlUbcrg. 1977b). 

Tbc rcsca¡ch ci¡ed in this scction sug,gesls that fuigr.rc rnay bc a factor i¡ thc aviation envi¡onnrnt 

duc ro dr¡ect performance decrcnrns a¡d. rndirectJ¡, th¡ou-eh m:;r.'slccps tba disrupt pilor 

funcrronrng The next secuon looks at data rclaung to the occurtence of fatiguc i¡ thc aviation 

eDVUoflf0cBt- 

Fatigue and The Aviation Enrìronment 

Tbc unrque cha¡actcristlcs.of the ariation envtroafirnt ma!'make p...rrs panicularl¡ susccptible rc 

farrguc Enrironrr¡e¡ral f¿ç¡s6 su\--h ¿Ls mo\enËnt restriction. Poor 3ú flou'. lo* lrght lcvels. 

frtiguer\fohicr. 196ó). Ioaddition.tìe 

backgroundnoisc.andvibrarionar€k¡o*¡caus.sof 

inuoduction of advanced automation into tlrc cockprt has changcd thc nan¡¡e of thc job for mur¡' 

pilos. Ha¡ds-on flying has bccn rcplaccd by grcatcr demands on tlìc crew to pcrform vigilant 

moruroring of thcsc systems, a rask which poplc ¡cod ¡o find trnng rf pcrforrocd for long Pcrids 

of ri¡r¡c. For example, Colquhoun ( t 97ó) found that monotonous t'igilancc tåsks could dccre¿sc 

alertncss by 80 percenr in one hor¡¡. which is conelated with increascd EEG theta activity or 

slccp-like stare. Si¡cc physical acuvity and.intcrest in thc task can hclp to minimizc thc dccline in 

pcrformancc due ro continuous r*'ork and slccp loss (Wilkinson. 1965: LiUe. 1979).lutomal¡on 

may conrribu¡e to incrcascd drowsiness in pilos srffcring from fatrgr.rc or slecp loss. Also, æ witl 

bc sho*.n be tou'. rhesc cognitire-based acuviticsrnåyþ susceptible to the effecs of fatiguc. 

IJIera:ure Reuiex' 

Poge 9

AJrhough these envi¡onrnentd cha¡actcristics a¡e sugtest¡\'e. thc acrud extent to'*hicb fatigruc is 

a safer¡,issue nccds to be asscsscd. A srudy of ASRS incident reportçsuggcsted rhar ll% of 

incrdenu rrere fatigue-related This figurc was challcnged b¡ Baker(199ó). whopornrcd our ¡har 

rhe daubase is a biased systcm dr¡c to sclf reponing, and the data werc fi¡¡tàcr biascd by thc 

rcsca¡chcrs' inrcrprctation of thc rcporu, Kirsch (1996) argues that thc actual ASRS esrima6 is 

for¡¡ to scven pcrc€nt. Græbc¡ (1985) clarifics ¡hc siruation as follows: 

An inirial analysis of NASA's Aviation Safety Reponing Sysæm (ASRS) iD l9t0 

rcvcaled th't 3.t petæot (77) of tbc 2006 rir trensport crcw lærnbcr errq rcporrr 

rcccivcd sincc 1976 rç¡e dircaly associa¡cd with faigræ (Lyo¡n ¿ì, Orl¡dy, 

l9t0). This rney sccrn lilc ¡ n¡hc¡ smrll poportioo. br¡t ¡s öc ¡uthort cqhasize, 

faiguc is Êcqæotly r pcrsonel e¡pcrftæ. Tb¡¡g whilc oæ ctts æEbcr rD¡y 

¡nribuæ an qlor to htittæ, r¡dcr mey rttributc it to . rærc ôrccdy pcrceircd 

czll¡sc such as inatæotioo or a miscommr¡nicetion. Wlren atl rtpori¡ which 

mcntior¡ed fætors directly or indirectly relaæd to fatigr.rc a¡e i¡cluded, thc 

pcrcentage incrcascs to 2l.l pcrccnt (426). Tlrcsc incidcns teodcd to occur rrþrc 

oftcn bcrwecn 0O:00 a¡d 06:0O flocal tirncJ and during thc desceol, approach or 

landing phases of fligbt- Fr¡¡tberr¡ore. e large rnajoriry of thc tcports corrld bc 

classificd "r s¡þ5t¡ntive, potcotially unsafe cnofs and not jr.rst mioor cno¡s. 

Ln a srudy of fligbtcrcw-involved rnajor accidcnts of donpstic ai¡ canicr: during thc 1970 rhroqgh 

1990 pcriod (NTSB. 1994). ooc conclusion pcrraincd directly to thc issr¡c of fatiguc: "Half the 

captains for *'hom data wcrc av ailablc had becn awake for morc than ll hours prior to thcir 

a.-cidenLs Half the first offic¡¡s bad þcn ar*'ake more üra¡ I I hor¡rs. Crtws comprising capraias 

a¡¡d frnr off¡cers rrhosc ti¡rr sr.ncc awalening was above tbc n¡cdia¡ for tåci¡ crcw positioo roadc 

¡¡¡gre errors overall. and sigmfrcantJy morc proccdr.rral and tacocal dccision errors" (p. 75). This 

fLnding suggesLs that fatigrrc rnay bc an imponant factor in the .-arrier accidens. Becausc tbe 

srudr rnrolred onJy donrcsDc c¿mer accidens. l( remå¡ns uncle¿r as to '¡hetherothcr fatiguerciared 

facrors. such as long fì.rght tirrrs and cr¡cadiaa drsruption due to multiple tr¡rr zones 

,¡ould aJso appcar as causative factors. On the basis of this srud¡. thc \-TSB recom¡rrnded tlrar 

¡hc F.{{ addrcss thê rssues of flight duty tinrcs and rest penods 

AJrlrough the rcsults of this study are suggestive. the acrual impact of fuigue has ya ro be 

dercrmi¡cd. Sincc no reel cfrort bas bcen madc to idcntrfy the effe¡s of fatigue in accidcnt and 

incidencc investigation, it is difñcult ¡o tsscss thc magnirude of thc problcm. ln addition. it is 

possible ¡hat sclf-rcponint syten$, such as ASRS, nray bc affectcd by the inabiliry of peoplc ro 

accuraæly ass€ss thei¡ own fatiguc levels (Sasaki et al.. 19861 Richa¡dsoo ct al.. l9t2; Dinges, 

1989). Subjcctive evaluatioos of slecpiness have not bccn found to bc rcliablc exc€pt in exuenrc 

slcepincss. Rosckind and Scbwa¡u (198t) notcd thar the scientific litenrure gcncrally 

demonst¡ates a discrcpancy bctwecn subjective rcporls and psychophysiological rpasu¡es, thc 

rcsult bcing underestimations of one's levcl of slccpincss (cf. Dement & C¿rskadon. l98l ). 

Derncnt et al. (197t) and Ruh et d. (1994) rcporred that some subjects.¡udged thcmsclves alerL 

Lite rature Ret iev Page l0

\Ahcn in fact thcy r¡'erc in t5c process of falling slecp' 

rhcir e¡'es and try to slccp This 

subjeccive alcnness in relaoon ¡ 

can bc rccordcd i¡ the sa-E cn\ 

¡trre effons t'et*een Europcan. Japanesc. and 

r haul at¡cre'* s. rePoncd that sub¡ectlre 

uc narure of thc psychophysiologicd staæ of 

cParate srudies by Derrrnt ct al' (t9tó) and 

found that subjccts subþctivcly fclt tlnt tltcy 

cn paired *'ith ar¡otbc¡ subþct' when io tcdiry it 

¡. Rosckind d al. (tgg¿) fou¡rd pilos un¡blc to 

ræ to ¡ shorr inftight nep. Alrhough pilots did 

ttrcy could not subjcctively ooticc ¡ dific¡eocc' 

pychophysiology cbanges ia higbcr ordcr 

r loss, thcsc changcs automarically precmpt oocs 

rccunrelY. 

c prescncc of ccrtai¡ fætors masks slccpiæss and 

. Envi¡onrncot¿l factors that have a maskjlg afÏe.,-: 

ne,lhi¡st, bungcr' e¡ciænpn¡. rrlking ¡bout 

tet al. (1978) fo{¡od tbet slccp dcprived pilots in 

occ ftigbt prcpalatioos werc undcr way rnd fligbt 

escarch that r¡scd tbc multiple slecp laæocy tcs 

:lnd et al.' 1994: RotÌ¡ er d.. 1994)' I¡ conr¡ast to 

cncy tcst asks subjects to quietJy lie do*n. closc 

rnasking factors' *hcreås 

e þrær corrclarioo bcca'¡¡sc bot'h 

' tl9t9) rcponcd thu slblecute 

slecprness rcsponses ro r-bc Sa¡rford Sleeprness 

cd sigrriñcance $ hen subjects 

,*ere entennt suge I slec; Tlus rt n¡ay tlc that rrhen EEG aJpha a.lld tìeta 3;t:\rry appcars therc 

rs trul) a fecLing of sleeP:

p€nÑ Srx factors that ma! nced to bc cons¡dcred are 

o 

a 

a 

o 

o 

a 

Trmc on task 

Time sincc aw'ake 

Task typc 

Duty period extension 

Cumutative duty tirrrs 

E¡vi¡onræntal factors. 

F¡ch of thcse factors is dirrsscd bclow. 

Tlne-On-Tlsk 

Ttrre appcårs to bc so¡nc conscnsus that thc efrecs of tirnc'on-task on pcrforrnancc a¡e diff¡cult 

ro asscss (c.g.. Maher & McPtrcc, 1994) a¡d a¡c ¡ffectcd by a nurnbcr of va¡iablcs, including tinrc 

of day. thc narurc of the task. ¡he subjcct's nrotivational lcvel. and if fatiguc or slccp loss a¡e 

already prescnt (Dingcs ll Kribbs, 199 I : Mahcr ll, McPhcc. 1994: Mendelson, Richa¡dsoo & 

Roú. 1996). Ln spiæ of this. pcrformancc on rnaoy labontorr- task follows a simila¡ cr¡rve 

(Vrþs{riever lÞ Meijnran. l9t?): relativcly low starting pcrformancc. followed by optinel 

pcrformance. whicb ¡lrcn dcclines drrc. prcsumably. to fatigue. Thc poins at which o¡inl 

pcrformance begins and then starls to ccgndrc varics with the task For sonrc cogniúve r¿sk. 

optirnal pcrformance is achreved afrcr about ñve bot¡¡s. thcn dechnes to its lo*'cst levels afier ll 

ro ló hor.¡¡s on t¡sk (Sçrnccr. 1987: Nicholson. l9t?l Sonrc t¿sks. such as moni¡orint ¡esks tha¡ 

requrre high lerels of vigiJance. shorv pcrformance dc¡rcrncns aier shoner du¡atioru. Coþuhoun 

I l9?6lfound rhar mono(onous vigilance tasks co

shift uorken (Colligan & Tepas. l9tó). nrght sfuft *orkcn (Rosa á! Collrgan. 1987). ra *atch 

r¡orkers lColquhoun. 1985). and truck dnvers (Hanrlin. l9t7). The laner srudv also found an 

lncre¡Lr tn the numbcr of accidents that a'cur *hen I l'hour shifts arc uscd- 

This increascd likelihood of accidcnt risk duc to long duty pcnods has bccn found in othcr 

s¡udics. Thc relarive risk of an accidcnt. ¡¡¡ l4 hot¡¡s of dury riscs to 2.5 tirnes tha of ütc lowest 

pornr in ¡lc f'rst eighr hor¡rs of duty. Askertedt (1995) rePons accidcot risks to bc th¡ecfold a¡ 16 

-hou¡5 

of dury. whiþ Harris and M¡ckie ( 1972) fo¡nd r ¡hrecfold nsk in jut over l0 bor¡rs of 

driving. TÌrcsc þvels of rist are simil¡r to ¡bat æsociarcd with b¡vi¡¡ oercolepsy or slccp rpæ¡ 

(L¡vþ et 1., l9t2), or I blood dcoùol level of 0.10 pcrccnt Wegrnann et al. (19t5), i¡ ¡ study of 

ai¡ carrie¡ pilots, rrgr¡cd for a duty pc¡iod of t0 bot¡¡s with t.5 bor¡r¡ or þss of f,ight ûry pc¡iod. 

Ti¡oc Sincc Aw¡ke 

The rcsults of an NTSB analysis of donrstic ai¡ ca¡rier accidcnts æo¡¡rint from l97t to 1990 

suggesr thar tirnc sincc arlale (TSA) was tlæ dominant fatiguc-rclaæd factor in ¡hcsc accidents 

(NTSB. 1p!4). Pcrforrna¡cc dccrerncns of high tiræ-siocc-awake crewr æodcd to result from 

ineffectivc dccision-m¡Þing ratlrcr tha¡¡ detcrior¡rion of ai¡crafr bandling skills. Tbcsc dccrcnæas 

werc nor felr ro be rcla¡cd to tinp zone crossings si¡rcc all ¡ccidcns i¡volved sbort bad flighs 

with a n¡a¡imum of two tinp zoncs crosscd. Thcre did appcar to bc rwo Pcåks in accidcos: in thc 

moming whcn rin¡c since awake is low a¡ld the crcw has bccn on duty for abor¡t th¡ec to four 

hou¡s. ¡"rd uhen tirnc-sincc-a*ale *as high. abore l3 hor¡¡s. Simila¡ accidcnt pcals in othcr 

modes of transp'onatron and indust-q hare also bccn rcponcd Gotkerd. 1997). Alerstedt & 

Keck1und (l9t9l srudied pnor trræ a*ale (fr-'ru¡to l2 hou¡s) and found astr-ong c_orrelation of 

accrden,.s urrh rrnr srnce a\Àake for all orrrs of tàe da¡ Bclenþ er al. (19ç¿l found that fìrghr 

trrne hours i,* L.r'idoad t greatlv tnr-reas€ a¡d ad'l to the linea¡ dccline rn performa¡ce associated 

r¡rth t¡lr st-nce ar¡al

emprricallr ascenalned. Ho*ever. it is clcar thar tlrcr activitics would ccnt¡ibute to fati¡ue in the 

lorm of turr since ag.ake. Consequcntl¡,. it ma¡ tr appropriate to limit tþsc activitics in e¡thcr of 

t \^ o \¡'a\ i 

o r,\'irh rcspccr to whcn tlrcy occur rclativc ro flight ti¡nc so s5 ¡e ¡rcid pilots achieving high 

tinr-since'awakc levcls during flight lin: pcriods' 

. hor.idc maximum lcvels for ¡lrçsc activitbs comparablc to duty PÊrid tirrr lcvels- 

othcr duç'Pcriod ætivi 

s¡ggcts iù p-pot"ft 

úrã sincc awake, wind 

ahcr bo¡r hþæ frcrors (c'g', 

duty pcrioû)Eey bc appropriare. 

The rclaiooship bctwecn task rype and fatigræ buildup i.o ùc avia¡ion dæain rcmains to be 

derermined. The demands plæcd on long-haut pilos are clcarly difrcæu Éom thosc of tbc 

:lþrdriven airplaæ wiù limitcd autoroation. 

Þ lcg of si¡ or rpre bq¡r Thc rnain task-rclaæd 

¡itive fatigrrc dr¡e to vigfúcc. Thc regiooal pilot. 

lr¡c to thc high wortload ilvolvcd in pcrforming 

sir or roore akeoffs and landings. For this ¡eason. it may prove nec€ssåry to develop scparatc 

re-Eulations that a¡e appropnare for each major tlPc of oPcra¡ion' 

DurY Period Extemions 

The re;:¡::h cired on dun FnùJ durarron sugtesls th¡l dut' pcnods a: -xabove ll houn a¡e 

assocraæJ *lrh a highcr nsk of eror This factor. together r¡lth thc tunc-s¡occ'a',r'a]

Environmentel Factots 

The phrsic¡l enrironrncnr of thc ccr'[ptr is a source of othcr factors tà¡ ca¡ contnbute to f¡tieue 

r\f ohler. l9óó). Fac¡on such es vibrar¡on. poor ventilation. ooir. a¡rd rhc availability of l¡rruad 

autornarion can con¡¡ibute ¡o rhc buildup of fatigue or accclentc its oort *'hcn coupled *ith tirnc 

sincc atr.ake. numbcr of tegs. and whethcr the flight involvcs thc WGI-. This may hare 

implications for rcgional c¿rrÈr pilots who fìy propcllcr{'riven ai¡cr¿fi' 

Concl¡¡sloos 

Tbc ¡esca¡ch circd suggests ¡¡ incrc¿sc io tttc liketihood of c¡ror as Óry Pcrids arc ertcodcd 

Þyood ¡2 hor¡rs. Thb ñndiry is espccirtly critical forcxæodcd dtrty Pcridl xtùich erc litcly to 

*.* under conditioos (c.g.. *car.bcr) tbat in and of tbcnsclvcs, rrt¡y incre¿sc tbc probtilþ of 

crew error. 

The interactions bctween multiple fariguc-rclued fætots mtl.st dso bc considered. Scpanrcly-, 

dury pcriod dr¡¡aúon. únp sr¡cc arvake. oumþr of hgs, and cnvi¡oom¡al factors contribuc to 

fatiguc buildup- Whcn any ooc of thesc factors reacbcs a high lcvel. coosideratioo sbould bc 

giv-n to reducing tþ rnarimum allowable lcvcls on tbcsc othcr faaas. Ti¡æ si¡cc awalc dso 

has obr.ious implications for rescñ'e assignnrens and for pilos who cmmutc. 

Standa rd Sletp Requirements 

Standard Stecp n*J,r.rn.nts ¡nd Ofr'Duty Period 

There is a generally,consisænr bod¡ of rese¿¡ch *hicb demonstratcs tà¡ nost people rcqulJ" an 

3\erase of t hours of slecp pr nrght to achieve normal levels of aleræss tfuou-shout dayrr-n 

hours r¡.ìrhour drowsiness a¡rd ro ar oid tÌrc buildup of slccp dcbt (C¿nt¡don & Demcnt. 1931. 

\\'eh¡ er al.. 1993). This frgre rs bascd upon a range of sR¡dies that used scveral approachcs. 

rncluding: 

o Historicd lcvels of slccp 

o }leasures of da¡iræ dertness 

. Slc€p tcvels achicvcd when givcn the oppornrniry to slecp as long as desi¡ed. 

Webb and Agne*' ( t9?5) reported ¡hat habirual sleep around the rr¡ro of ¡le cenrury r*'æ about 

nine hours. A l960 srudy of more than t00'000 Anrericans found tha l3 Frcrcent of nrcn a¡ú l5 

p€rcenr of *omen, ages 35ó5. slept less the scven hours wi¡h 48 PercÊnt of both obuininE less 

rhan eight hours of sleeppcrnighr ftl'oke IJp Americ¿. 1993). B¡ l9?7. onc incight Anrr':;ans 

Lileralure Rer ier* 

Page I5

eponed gen,ng si¡ or fewcr hours of stccp p'cr nighr (Schoenborn & Durchtk. l9t0) Br 198-1. 

,¡ust six "ian la¡.r. rhar numbcr had jumped ¡o one rn four (Schocnborn & Cohen. 198ól 

Thc ar.crage distriburion of habitual slcep rarìges bct*ccn 5.5 and 9.5 hor'fs pcr night. anJ 

includcs 95 pcrcenr of ttrc adult poputatio 

tt)' Ilost 

rcsca¡chers sccm to atrcc with this figurc 

l99l' Dinges 

et al.. 1996: Bonnet & A¡and. 1995). However. 

ir¡ditrdual 

differenccs in habirual stccp in e samplc of more ¡ha¡r 30,000 individt¡ds from I I ind¡rs¡nd 

countrics. t¡ this s¡udy rwo pcfc€nt wetË rcportcd ro slcep þss than frve bor¡¡s pcr nigbt rhile 

fivc perccor rcpo6cd ileeping rrlorc th¡¡n l0 hou¡s. Thcsc rvcrages bavc bcco llPoncd i¡ ¡imila¡ 

frndings ænost varior¡s populerion g¡ol¡pc. 

Moa rcscrrcbcr¡ .divo€te t¡r ¡vefatÊ rlccp rcquireffEd for aduls aÍ7 s to t.0 bours pcr d¡y 

ff."¡"t 

er rl.. lgtt: Carskedon, ¿1, Roù" t99l; Dingcs et d., 1996). Altbottgh e¡¡ly o. Derrcat 

àr d. (1986) indicaæd rha¡ t hours wts Écssary for oPdrnat dcrtness thrrughout tbc dey, Hornc 

considcred 6 hor¡¡s -cotË sleep" sufFrcicnt- Although Hor¡c's advocacy of 6 hor¡¡s core slccp has 

derracæd soræuåat from wha¡ nrost slccp rcsc¿¡chcn now fecl to be o¡imal slccp, it bas oot 

dislodged thc weigbt of evidcncc- 

Cenkadoo (l99l) r€po,ís the¡ t7 pcrcent of collcgc studcns babitually slccping scveo to 75 

hours per night had difñculty sraying awake in ¡hc efteroæo with 60 Pcrccnt rcponing roally 

falting aslccl. \*'hen compared with Hornc's advocaùng only 6 hot¡¡s of -corc slecp.- tbesc 

responscs scrm ro suBgesr rhar. although rhc subjccs spccrff a habirud arnount of slccp a.bove 

Horne's p.:uuve 'corc.' their slccp is rnsuffrcient The si¡-hou¡ core arnount does Do( s..{D to 

apply ro fr¡any. bascd upoo thc sclf-pcrceired adcquacy of slccp. 

Roel.r¡s er al tlgtg,sho'*ed that when short or long slecpers *ere requrrcd to stay in bcd ior ten 

houn. all ;ut'.¡ecr-i ;icpr abour an hour longer tlra¡ usual. Tbe result rastbal all sub,pcs i-rprored 

¡n rhelr alenncss. r i-grla¡ce. and rcacuon trme nccded for dnving or moruton¡g modcro coouol 

pancls. Dlr rded anentron performancc showed signrfrcant ur¡pro\ er¡cnt. and cent¡al task 

pcrformance sho*cd.somc*'har bcner improrerr¡cnl than pcnpheral task prformance Da.rt¡me 

slecpiness dccrcascd for both groups. bur ro a gratter ertcnt for thc indiv¡dualS *'ho prcriouslv 

reporred suffering from stecpiness. Sublccs s'þe *crÊ usuaLly slccpy trere more alcn. a¡d thosc 

.^housuallr functionedatahigblevelbecamccrcnsharpcr(Ca¡skadonetal.. l9?9). 

AJlo* ing jusr one hou¡ extra sleep pcr night over fou nigbt rcsulted in a progrcssit'e reduction in 

da¡,rimc sleepiness of nearly 30 pcrce nt w'hen mcasr¡¡ed by ttrc Multiple Slecp lâtency Tcst 

(MSLT). .{llo*.ing slecpcrs who q'picdly slept 7.5 hor¡ Pcr day to slccp ad libitum, otùrc'¡ 

rcsearchers found rhat slecp tinre increascd 28 pcrccnt from 7.5 to 9.6 boun. 1Taub. l9tl: \\'ebb 

& Agncr*.. 1975). Taub ( l9?6) srudied thc magnirudc of differcnces bcr*ecn rcgular (? to 8 

hours) slccpcrs and long (9.5 to 10.5 hours) slecpcrs whcn thei¡ slccp ræ Phasc shiñcd threc 

hours for,*.ard or backwa¡d. Tbey also cramined changcs when both groups had slecp pcriods 

Literature R¿ricx' 

Page l6

ex¡cnded or reduced. Although resulti shtrsed degrecs of impairmcn¡ from the acutc dterations in 

slecp panern b¡ borh slcep groups. the l-t..-t hour sleepc¡s consistently showed grcater 

imperrrrrnr CarskadonandDcnrcnr(lgtl.l9tllfound¡hate¡¡endrntthctotalt¡npinbedfrom 

crght hours ro rcn in l8 ro 20yeu old sub.¡ccs allo*ed thcm to incre¡sc thci¡tual slccptiræon 

more than onc hou¡. This resulrcd rn a significant irnProvcnrnt in da¡inr alcrùcs 

"".og" whrch only appcared afær tlrc sccond nigbt of extended slccP. suggcsing a repayiog of slccp dcbt. 

Thc rcsca¡chcrs fclt that ¡his improvcrrcnt supporrcd suggcstions thf cight horn of bcd tiræ roay 

rcpnescnr a ch¡onic slccp dcprivarioo condition in young adults. Scorcs on ¡Icrocss sho*çd r 

sair-step rcsponsc with tlrc lcogth of slccp per night as uæll ls witb tþ numbcr of nights. Thts 

scones for ¡lcrtncss wc¡e bcttcr for æo bo¡rs of slccp tbaa for e[!Ç eight weæ bcAcr tb¡¡ ñvc, 

r¡rd two nigbs with ñve bourl *cre baær thra scrca nights vith 6vt hou¡s wh¡cb scre bcacr 

than scores witt no slccP. 

In a stighrly difÏercnt rescarcb dcsigû.T/ehr (1993) for¡nd in e for¡¡-rek tcst thrt youog ¡ô¡lt¡ 

allowj to slccp as long .s tbcy dcsircd. slcpt in exoess of l0 bor¡r¡ e day ôuing tbc ñrst threc 

days- This was followcd by thrcc days of abor¡t 9 bo{¡rs. Thc rernai¡dcr of tbc 2t days þveled ofr 

ar an averagc of t.5 hours pcr night. Thcu habirual basc-linc slccp vrc7.2 bq¡rs. Tbc initially 

higtrcr levcl of slecp is inærpreted as rcpayrænt of chrooic slccp dcbL A similar slæp 

requirernent figure of t.4 hours was reporcd iDt¡¡.im 

repon. Tbus both slecp eræosion srudics and 

rcquirement aPPcars to bc be¡wcco t to 9 bor¡¡s 

considcrabll hrgher than habirual slecP ñgures. 

Thc bcncf ¡u of slecp are prerotl¡ considcrcd ro bc logarithmic in naru¡e. *ìth tbe initial boun 

sho,* ing signifìcantJy trcåter bcr¡cfrts riu diminish as ooc approacbcs his or hcr opcimal shep 

lcr.el This accounls for bow rna¡) can slccp less aod appç¿¡'to still fu¡ction nornrally Ho*erer 

rhe t-r nd rn _:- i o I Roh¡e ( 1989) urd Taub, and Bc rgcr t 197ó) indicate t-hat during tåc frrst si¡ houn 

of sleep. pr-,ormance is resrorcd tc a selrsi3s-tora lerel under normal conditions. although 

ajenness and vigor ma¡ suU bt drm¡nrshe3 In llc hr-rurs bc¡'ond sü houn of slccpthc rcstoration 

. pru-ess funher resrorcs alcrtncss aod vigor and the brarn's capaciry'to handle siruarions abovc 

that of normal and for longer priods 

An erample of rhis is besr iltr.rsr¡arcd b¡ Sarrrcl etd. (1997) wherc tlrc sccondof twonightflighs 

sho,*cd a considcrablc rcducuon rn toleran.'c ilìd an increasc in fatrgrr aftcr only threc hou¡: of 

flight *,hcreas on rhe ñnt nigbr fatigr.rc did oot sct r¡ unúl afrcr t bq¡rs. Tbr¡s. thc additioî¡¡ 

hou¡s scrved :Ls a rescrì'e capacity agains *orkload (Howin et al., l97t) or hours of dury (Sanæl 

et al-. 1997. Gundcl et al-, 199?) 

Lit¿rdture Ret ¡ex 

Page I7

Other Variables 

Individu¡l Differences ln Sleep Requiremen6. Many of thc srudics described above shoued 

rhar thcrc appears to bc a considcrable variability in individud slccp nceds. Thus. thc cighr-hou 

stccp rcquirenrnr rcprcsens thc averagc of slccp nccds. but dæs not take into account of thc 

nccds of thosc individuals who require additional slccp utd who rcprescnt a fai¡ pcrccnt of rhc 

populatioo. 

Age-Rehtcd Cleryes tn Shcp Rcqulrencats With ryc thcre is e si¡aiñcrat dccli¡c i¡ hsin¡at 

nigbrty slccp dræ to increascd nthttiræ ewelenirys (Devis-Shrns, l9t9; Wcbb e Cerapbeü 

l9t0; Ca¡skadoo ct ¡1., l9t2; Mitcs ¿l Dcræa¡, l9t0: C¿rsk¡doo ct tl.. l9t0). ln oldcr 

individuals. habirud nigbniræ slccp is æoqenict by increascd daytiÍE fetigræ, slecpircq 

dosing, rnd napping. This increasc in thc nunrbcr of slccp Pcrids approxirnatcs normal slccp 

qgandry and appcars to indicaa that slccp rcquirenrnts æmain thc sa¡æ oyer a pcrsoo's tdult 

Liferi¡nc Miles lÈ Denrcnt, l9t0; I{ahc-Gabr. l99l). Thcsc srudi{x e¡ttest that older crcw 

nrmbcrs may have particular difñcultics in æhþving nrfrrcieot slecp as part of a norrnal dury 

rhedule (cf. Ca¡skadon, Browa lÈ Denrcnt' l9t2). 

Logisticål Issues. A numbcr of srudies bave i¡vestigated the isnæ of thc a¡nount of slecp rhar is 

acrually achrered as a function of thc lcngrh of the off-dury pcrid. Tbcsc studics demonsuae 

r-bar off dury pcriods úrat appcar to pro\ ide an acccptablc slccp oppomrniry nray not. iD rcaliq . bc 

sufficrenr In onc srudy. reductions in slccp of ¡n'o to tb¡cc hours pcr 2¡f hou¡s occurrcd wbeo tbc 

rrrrr bcr*ecn sfufts or rrork '*as rcduccd to only ninc hours (K¡rauth. l9t3). I¡ the NASA sn¡dies 

of sh..n.haul pics (Ga¡der et d.. l99J: Cander & Graeber. 1994), pilos rcponed a¡¡ average of 

ll -5 hou.s off-duq t¡nr bct*ctn duty pcnods, but onJ¡ obtai¡cd ó l boun rcst 

Obsenauons of nurscs on ll hou¡ shifu workirg ll5 hou¡s uith ll 5 hours off bct*ecn shrfts 

obrarned a¡ a\eÉge of ó t houn slecp tllills et d.. ¡9t3). A¡rother srudy of long-haul and shon 

haul-rruck dnrers 1t*R{IR,. 199?15þs*'ed that shon-haul drivcts r¡'lt}¡ simjla¡rest pcnods 

bct*'e¡n shrfu obrained cvcn fewer slccp durarions. 

Com¡ncrcial rn¡ck driven' (FlfWA. 1996: Mitlc¡ e¡ d.. 1997) slecy'off duty schedulcs a¡c sbor¡n 

in Table l. tå/ben wckcrs (Cl-10) had 10.7 hor.¡rs off duty bct*'ecn l0 hour day shifts. slccp 

du¡arions of onJy 5.4 hours wcre achieved. On a I 3-hour day shift (C1- 13) with t.9 hours off 

ber*e¿n dut¡' pcriods. slecp du¡ations averaged 5.1 houn. On l0-hon¡ routing shifu (C2-10) u irh 

8.7 houn off dur¡ . thc sleep tirnc '*'as 4.8 hours a¡¡d aficr a l3-hour night shift (C3- 13) with t.ó 

hours off. the rcsulting slecp diminished to only 3.8 hours. In quick changcovcrs *'ith t hor.¡n off 

ber,¡een shifu. Toncrdcll (19901 found that r*'orkem only acquued 5.1{ hours sleep. Kurumatan¡ 

( 199{) found a ccnelauon (¡=.95) bctwecn thc hours bct*een shift and slecpduration. The¡' 

Literalure Rer t¿x Poge I E

conclu,Jed rhar at lcast l6 hor¡n off duty tinr *ere ncedcd bc¡*ecn shifu to ensure ì'S hou¡ 

,rc.p r conclusion reitcrated i¡ a recent review (KecUund &. Nrerstcdt. 1995). 

Table I . Truck drivers shift tl Pe and off dut¡* hou¡s in rclauon to time sPcnt itr bed and 

slccP 6¡6' (1996) 

R,educed Rest 

ilecp bctwecn quick shi-ft cbangeovcls may bc tbe 

orsrall a¡d Akerstdt (198t) sho*ed that ships' 

tecreascd qualiry of slecp *tucb tlr¡ annbuted 

sicians i¡ smallcr bospirals and appars to bc 

)-*rng day (Alenredt & GiUbcrg. ¡990)' 

hler:d ls due to rle other a'-tir ities ùat must bc 

on ia¡o\ers, these acúr rties ¡,n;ludÈ tcnlng to 

Thesc actir ities ;learly t¡ke au ar from the unrc 

Rese¿¡ch on rhe efrects of slccp reduction on physiological and rask pcrformance has failed to 

o,* much sleap ma¡'bc rcduccd bcfore a signifrcant impact on 

c rÊasons for this uerc dcscribcd previously in the scction cntitled 

n and Dcment (1981) rcduccd subjecS'slecp to onl¡'Írre hours 

dngina60pcrccnrincrcascinslccptcndcncy.Bascdonthis 

j Rorh (199i) conclude rhat as linle as two hor¡¡s of slccp loss ca¡l 

errÉnrs and reducrions in alertness. Wilki¡son ( l9ó8) r'aricd slecp 

..L:^L.^ -l--^ Qianifi¡ant ¿{¿¡rp¡c¡t in 

quanlir).by allowing subjecs0. 1.2.3.5. or ?'5 hours in *'hich to slecp' Sigruficanr dccreascs in 

I)leralure Reyi¿t+' 

Cl-10 deY 

Hours off'dutY 

= , " ' poiZii

.igilance pcrformance $ere found the follo,¡ing d.ry uhen sleep rras rcduced bclo*'th¡ec hours 

for one night or fener than f¡r'e hours for tuo con-tutive nl-shLs. C¿¡sk¡don. Harvey and Den¡cnt 

(l98l)found rncre¡sed daltrnr sleepiness. f,s nrriured bythe IfSLT. afreronc night of slecp 

reduced ro four hours in a group oÍ l2-yeu-olds. dthough pcrformancc decrcnrnLs r¡'ere Do( 

found. 

Rcstriction of slecp in young adults to just 5 hor¡rs increascs slecpiness on the MSLT thc rrc¡t dar 

by 25 pcrccnr and by 6O pcrccnt tlrc scvcnth day rCankadoo &, Dcr¡cnt. l9tl). l¡/ha slccp was 

rcdr¡ccd to ñve hor¡¡s or lcss. performara ¡¡rd dcnncss sr¡frercd aad slccpiæss significently 

irrcrcascd (V/ilkinsoo e¡ rl.. t96ó; Jotrasoo, l9t2: C¡¡skadoo ll Roth, l99l: Giübery ll. Atcrstedr. 

l9g{; Taub lÞ Bcrger, lÍl3',C¡rskadoo ll Deræo¡. l9tl). A ¡ecent srudy of Ar¡sualiü tnrtcrs 

fou¡d th¡ 20 Frccnt of driver: stcep 6 hor¡rs o¡ lcss üd æcor¡nt for ¡lO Pcrceot of tbc b¡zå¡dons 

evenrs ¡çporrÊd (Arootd d rl.. 1997). During Opcratioo Descrt Storu. ùÊ PiloG of tbe lfilitrry 

Airlift Com¡na¡¡d flighs obtrining only I I bours slccp in ¡tt honrs wcre for¡¡d to bc in denger of 

expcriencing difficulries in concentrari¡g urd sul ing awake (NevilÞ el d.. 1992). Furtber pilot 

obscrvarions indicared ¡hat ro prevent fatigrrc in ¡besc Pilots. a¡ lcast l7 bours of slccP iD 4t hours 

(?.5 hou¡V 24 hours) werc required. 

Dingcs (199?) showed sigoiñcant cumulative efrecs of slccp dcbt oo waking functioos wbcn 

subþs werc rcs¡¡icæd from thei¡ usual 7.¡11 hor¡¡s slccp to only 4.9t bours (sd .57 hrs) of rsual 

sleep (67 pcrcenr). Across ¡!¡¿ 5¿ven or eigbt da¡s of slecp rcstrictioo subjecs showed iDcrc¡srnt 

lcvcls of subjective slecpincss. fatiguc. confusioo. ænsion. nrntal ex-baustion indicators. sùEss. 

and lapscs rn;reasing ih frcquency and duration These eselating cbangcs provide stron8 

eviden.-e r}at panial slecp rcstncÚon similar to t-bat cxpericnced b.'" piJos has cumulative cffects 

sim¡lar to thosc found rn total or F¡ore exCrcrr Paf¡d rcstnction. 

In conuasr. H..'cke)"s r1936) analrsis of plrid sleep Cepnration srudr fin,Jrngs rcrealed minimal 

performance;henges bur rherc *ere srgrufi.'¡rrt rcJu;tlons in rteüan;e. efitc¡encv. and incrcased 

sub.¡ectirc sleepiness w¡th a¡rd mood detenorauoo 

These resulrs suggesr rhat rcducint rcst b¡ an hotu should hare linle impa;t on a pilot's 

performan.-e ii rhe pilor is rr.ell rcsted prior to tlrc reduced rcst. lf the pilot rs suffering from slccp 

dcbt pnor ro rhe reduced rÊst. thcrc ma¡ Þ ¡rn rmF 3ct on the pilu's pcrforrnancc. If so. a reduced 

duq pcnod should follow r}rc reduced rcsr pcnod m order to comPcnsate for thc possibiliry that 

the pilot may be more susceptible to Ùnrc-s¡ncc-auake effccs. 

Required RecoverY Time 

Complcre recovery from a slccp dcbt may Dot oc.-ur afier a single slecp pcriod (Carskadon & 

Denrenr. 1979: Roscntha¡ et d.. l99l). Typicall)'. r\r'o nighs of recoverl are required (Carskadon 

& Dcmcnt, l9?9: Kalcs er d.. l9?0), although tbe required necover)'Pcriod may depcnd on thc 

lcngrh of prior waltefulncss (Ca¡skadon &, Denrot. 1982). For cxamplc. Kales et al. (1970 found 

I)terature Rel ier, 

Pogc 2,)

that re:tnctrng slecp to 5 hou¡s pcr nighr for 7 

f",,.rnt. rcqurred onlv- a singlecrtendcd night 

t 199ól foun,J fatigue resultiig from the loss of 

. l97l ). Thcsc results s'crc obscn'cd cvcn though 

rhe rcsc¡rcb ¡lso sustests tb¡t rtoep * 

"u:;ro,tåffi"tljîiffitr Sl*g" 

Tbc quantity of slccp Sli¡tcd dcpcods Dlt uPoo 

ilÚtcr rhrn Úlc lca$h of pri

Thc oscillarions appcar as saves. and thc tirnc to complcte one full $a\e !-ycle'is callcd a 

"p€nd." Thc¡ are dirided rnto tfuce groups b¡ lcngrh of ¡he rh.rrhm. l-ltradian are rh¡rhms of 20 

hours or lcss. Crrcadran encompasscs rh¡rhms bc¡seen l0-:S hor¡n. urd lnfndiarì arÊ rhrrhrns 

gre¡rcr rhan lt hours. Thc lancr includc rhythms callcd circascptan (7 da¡s, t 3 days). 

circadisepan (14 days t 3 days). circavigintan (21 days. :3 days). circauigintan (30 days. t 5 

days) and circaannud (onc yea¡. r 3 months). According to Har¡s & Tor¡itor¡ (1994) tbcre is 

cvidcnce of 7 day. 30 day and annual rh¡hms in humanr as well as tlr cúcadian and ultradian 

rh¡hms. 

Ci¡cadia¡r rhythrns b¡ve bcco rccognizcd for dccadcs. Yct tbc biologicel çl6t th¡r regulecs rbe ' 

z4-bcrrr ptysiologicel eod bcbavioral rhythms wrs not idcotificd r¡otil üc l97os. Tbcsc trc 

bitucrally locarcd nræþi crllcd thc supræhircmiç a¡¡cþi (SCI\Ð r¡e læ¿cd ¡bove ùÊ optic 

chiasm in thc ütcrior bypotheh¡rr¡s. TbcsÊ nælci r¡e osidc¡cd thc circedirn pcn¡¡|cr1 

Destrucrion of tl¡csc nr¡clei producc an arräytbmia and scvere disnt¡io bdu¡cca behavior urd 

physiologicd paranrtcrs i¡rcluding the timing of food i¡take and slecp. TÞy appcar Dot ro 

regulatc ¡hc anrcunt of eithcr of thcsc bchaviors (Tu¡ek ¿1, Rccrà. 19961. 

Signals produccd by ttrc SCN arc botb bormood u¡d ncurd. Gr¿ñcd nr¡clci without ncr¡nl 

coûrctioos restorc circadian rbythms of cating and activiry. Melrtoni¡ rcrctions, howeve¡, a¡e 

not rcstorcd. $gges¡i¡g ncuron cootrol. Melaronin r€ccptors bave boco for¡od in thc SC.I\I rDd 

appcar ro bc parr of a fecdback rncchaoism thal causcs shifu in tþ ci¡cadi¡¡ clock. Tbe SCI.I has 

bccn found to posscss is own built-in rh¡hm. Evidencc gatbered thus fa¡ indicarcs rha¡ SC.¡{ 

receive i¡formation about thc hght-dark cycle viatrlo ncural patbways fromthc optic ner\e. one 

from rhe retinohypothala¡nic tract and thc othcr through t-be geruculohypotåalamic trztct. TÞ taner 

parh*'ay appcå¡s to pro\ rde rnfo¡mati_on or signals that bclp witb ¡ecorra¡¡¡ænt afrcr a shifi rn tbc 

iigl',r-a"rk c¡cle. Bur rccent rc-s¿a¡ch appca¡s to ind¡care tbat othcr phoro re.-eptors ma)' also be 

inrol.ed n the ent¡a:nmcnt process lCampbcll & \l,rrph¡. 1993' 

Peak leicls of ph¡srolo_eical functroning occur dunng thc Lght phase of ûre lighr/dark c¡'cle This 

sy'nchronÍzatron o[ph¡srologicd rh¡'thrns enhances *ork pcrfornrancc dr.urng the da¡irrr urd 

suppons slccp at rught b¡ nurunt do* n ¡ìc rrr¡abolrc tlrcrmo;ut The in¡croal synchronizauon of 

rhc ra¡¡ablc np¡ebolic p:ìra¡Tìctcrs *'ith the light/dark cyclc are runed for opumal functioning. 

Ovcr l0O biological rh¡rhrns are gcnctically gerrcratcd within thc human body, then eouai¡cd or 

synchronized to bener *'ork in conccrt 1-Wchr. 199ó:TaÌabasi. 1996). Tlr greatcr the 

synchronization bctrrecn hormonc production. nre¡abolic rate. enzyn¡c a¡d ocu¡ot¡ansmicc¡ 

s¡'nthesis. rlrc higher thc amplirude of the rb¡hm and thc tÌe¿ter thc communicarion bcn¡eco the 

body's cclls. Thus, the maintenancc of a stront circadian rhythm c¿rrics *itl it considcrablc 

ramifications for good health. *cU-bcing. and functioning Cw-eh¡. 19961. 

The suprachiasrruc nuclei. togctìcr w'ith the pineal gland. function as nrubolic and bchauioral 

concen conduc¡ors in cue *'ith cnr'ûonmcntal factors such as tight/duk. nral timing. social 

interaction. and physical activiry. This syncfuonization of in¡ernal and behaviord r*'irh rhc 

Lilerature Reyie¡ Page 22

errernsl en\rronrEnt afound rhe 24 hour day (circa=about: dies-4l¡ t rs cdled ci¡cad¡an rh-rrhm 

entrilnfr¡cnt. 

AJrhough orhcr inrernal and ertcrnal factors do play a role' thc Itghr'dark cycle is the major 

cn¡¡ainnrnr facror for most of ¡hc animal kingdom. For humans. rlrough. thc Light'dark cycle is 

felt to Þ a rclarivcly weak synchronizaiion of tlre human circadian rh¡rhm for two ¡easons. 

Compared ro orhcr ani^¡t. itr. tigttt scnsitivity th¡eshold as a synchronizing faaor is 

-.rri¿.r.uly elcvucd. For comparisoo rhc ti¡ht inænsity rcquired for 91ryt'iut s¡æcbronization 

in . t.*"cr is only .5 lr¡¡. u¡bcrcas fq hunrans estimatcs raoge froo l2G256ltu (Reinbcrg ¡l' 

srnorcnsry, l9g4):This niscs qwstioos eboü rbc adcquæy of indoor ligbting. sccoo4 ma¡ is 

rbc only rþi'' rhat livcs q'¡sidc of tþ daylnigbt cycle. 

socia¡ eavfuon¡æot appcå¡s to play e fætìe ir8pofr¡st ¡oþ in e¡tnin¡æ¡u Sæi¡l f¡aors thu crn 

n rà¡hms iacludc ùcmpc¡¡¡¡¡¡. flight duty, sress. 

el it Wegmann. t9t7). Excrcisc or activity dso 

rpion. Ferrer ct d. (1995) ci¡c evidcncc that 

pts to shifr work changes rcgardless of is 

;icdly fit ¡¡d cxcrcisc rcgularly have highcr 

¡ds, and ¡bosc with Ugh ci¡cadian rhythm 

rcr et d., lfs). This belps to explain s'hy age' 

i to increascd slecp diffrcultics. poor adjustræot tc 

night *ork and t¡a¡rsrrrridian flighs in ¡-ho- over 50 

- FacF oT the Clock Ope rations Circ¡dian Rh¡ thm and Perforrn¡¡cl 

ñere rs a subsr¿¡rtiaJ bod¡ of rcsca¡ch rh¡r sho*s de;reascd p

* 

'1989 ) a¡-;ues that. up to 2.1 hours *'ithout slccp. cr¡cad¡a¡ rnfluenccs probabl¡ have greater 

circcts th¡¡ trmc since a*'ale. 

ln Japan. tl { percen¡ of d¡o*sincss-rclared nea¡accidens rn elccrnc motor locomotire dnrcrs 

r Kogi & Obt¡. 1975) occut at night. Orhcr la¡rdrna¡t srudics ovcr tbe past scveral dccadcs 

bave documntcd the increasc in accidcns a¡¡d crror making. Kleia er d. (1970) argue rhar thci¡ 

resca¡ch uitlr simulalors Prov6 that night flighs ¡rE a g¡cåtcr risk tha¡ day flighs. Thcir resca¡ch 

fq¡nd 75- to 100-pcrcent rEåtì pcrforrneacc efficþæy dccrcnrcnrs i¡ simula¡or fligbrs dnring thc 

cerly nrorning bours, rcierdbss of e¡tc¡¡d fæta sæh as da¡lcncss or i¡cæasing nigbt uafñc-or 

poesible sc¿tbcr conditioos. 

Task pcrfonnancc in e vuicty of nigbtllùc hes bæo comparcd wi¡h perform¡ace of their d¡niræ 

co.¡ntcrparts. rod rcsults coosistcotly sàow dctc¡iorarioa of perfonnane oo tþ night shifr. 

Brownc (1949) studicd tclcphooc opcfitotls' rÊspoos€ ti¡æ in urs*rring incoming ç¡n< i¡ ¡elaioo 

ro thc bor¡r of thc day and fo¡nd tbc loges rc.spoose ti¡rrs occurred be¡wccn 03æ a¡rd O46p 

bours. Bixær et ¡1. ( 1955) erami¡cd tas company horly lcdgcr corlFrtarions of gas prodgccd 

æd gas uscd over an lt-year pcrid a¡d for¡nd tba rccording error werc highesr u 03@ bou¡s 

sirh a smallcr sccondary pcak at l5OO bor¡¡s. Hildcbrar¡dt e¡ d. (1971). investigating automatic 

úain br¿krng and acorstical warai¡g signal alarrm sct-offs, dso for¡¡d rwo peats ¡r O36p ¡¡rd 

l5O0 bor¡n in thcsc safety-rclatcd eveDÈ¡. Simila¡ 6nding have bcca rcponcd in tn¡ck accidco¿s 

tTlarris, 1977) and in Ai¡ Forcc ai¡crañ æcidcots (R.ibak e¡ d., l9t3). Orbcr accidenr analyscs of 

unr of da¡ and hours of wort show thu both ci¡cadian ràyttr¡n a¡d bor.¡¡s of dury ptay I 

srgrul-rc¿¡r role rn the ct-currence of accidenrs (Folþ¡d, 1997:L¡noee¡ al.. 1997). tn addirion. the 

rncidencc of accrdental lDJury nea¡lv dor¡bles dunog the nrght shrft compared ro morning shjfr- 

*blc tbc screnty of in.¡ury i¡crascs 23 pcrccot (Sro¡th ct al.. 1994). .\rghr nu.rses mate ocarly 

¡¡ice the pancnt mcdicauon enors as da-r'Du¡ses a.od expcncnce nca¡h ùrec urrrs the auto 

¡ccrdenrs,-ornmutins to a¡¡d from *'ork (Gold et al . 19931 

\Ìerstedr,l9tElrevie'*ed the effects of slecpincss riom nr_ehr shfr nork and found rha¡ rhe 

¡.æntrallr 

hazardous srrualron rcsulting from i¡cre¡-çcd slceprness durug rught shift is real a¡¡d 

rrnderestrma¡ed. Akerstcdt (l98tl dso rcports rhar faugue rn sh¡fr *orters s h:gtrcr than io day 

trorkers. hrghest in night workers. follorred by mornmg workers. OvenJl. stccprncss ¿unont rughr 

sorkers is estLmated to bc a¡ound 8O to 9O pcrcent Roth er d. (1991) i¡dicarc tha¡ rates for 

r¡orkers falLng aslecp on the job 

'rhiJe oo night sluft havc bccn rcponal ro bc as high as 20 

Pcrcent. 

Sight operarions are physiologicalJy different than day opcraùons due to ci¡cadian trough and 

slccp loss. This ca¡rics a higher pbysiologic^l cost and impors grcårcr risks of accidcnts. One of 

thc most est¡blished safety issues is working in thc cúcadian ¡roueh bcr*'ecn 0200 and 0600. 

h.rring thx priod worken cxpcriencc considerable sleepiness. sloner rcsponsc ti¡nes. increascd 

errors a¡¡d accidcnu (Mitler. l99l: Pack. 1994) Ilan¡'recent accidens from va¡ious 

uansporution modes hare bccn associa¡ed '*'ith thjs cr¡cadian trough (L¿ubcr & Karren. l98t). 

Literature R¿r'i¿x Page 24

L¡m- e¡¡,J orlad) ( lggl). in rher¡ anal-rsis of rhe Aviation Safetl Rc¡'r.rng S¡'stem rese3f\'her 

st¡re r--,¡r 3l pcrs-enr of incidenrs occurring bctscen 2{00 ro 0ó00 hr-'rurr uere farigue relared 

hor¡rs a-fter bcginning rhc shifi' 

pilos erhibi¡cd panrrJ ad,aPtation to nrght uork 

Ëy tcmpcrarure. rr irh subþtive fatiguc and 

is. pilos stilt experienccd a th¡cc-fold incrcasc in 

:rcent) and a 1.2 hour slccp dch per night 

7 be dræ to tiræ sincc ôc l¡st slæp- Pokorny a d. 

þyear pcrid rnd fot¡Dd th¡. dtbol¡gh tbc ti¡rp of 

poísnt færors ia driw¡ æcidc¡ts *rs bow carly 

*'oen 05æ4óOO had ¡bcrr si¡ timcs rs muy thc 

)- A Peåf in æcidcns also æcr¡¡red two to four 

¡rr, dccrcrncnts in alertncss and pcrformance :¡¡Ê 

4 hot¡¡s. alcrtness can drop morc tha¡ 4O pcrccnt 

)6). A srudy of navd ua¡.-b kccpers for¡od tha¡ 

crccDt. falsc reports rares 3l Pcrccnt. and responsc 

spccd eighr pcrsenr. compared with raæs bct'*cen 20oo to 22æ hours {Smiley' 1996)' 

Sarrrl e¡ al. (1996) dctermined tbat many Pilots bcgin nighr flights al¡e¿dr haring bccn ar¡ale 

morc rhan l5 ho'¡s. Thc srud1'coof-rrrns rìe æcurrencc of as many as fire micro-slceps pcr hour 

¡' aJso found thar 62 Pcr'-.ot of dlgilots sn¡died 

fli' a¡) longer after tleu ught flight This 

ht flights that shoued sr-nficant ph¡stu'lrrs:'-rJ 

rase afier fly ing trro rugbl tlights (outboun.j and 

. Although fìights rancJ Íom nonh-south and 

4.5 days. slecp debt a¡pared similu' East-r¡'est 

tlighrs had srgnifìcantly' longer layovcrs but *erc disruptive ¡o circ¡dru rtryrhms' Thc authors 

concruded thar.-Durini o.y,*., fariguc-depcndcnr vigirance decreascs \¡irh rask durarion- a¡d 

fatigue bccomes cririci aftcr l2 hours of constant work' During nighr barrs fatiguc increats 

fastcr r'irh ongoing dury. Th¡s le,d ro rhe conctusion that l0 hours of '¡ori should bc the marimum 

for mght flYing'" 

Ga¡r,Jcr ct al. ( 199 I ) found in an ai¡ carrier scning ¡hat at least I I perccnt of pilots srudied fell 

asretp for an a\.erage of 46 minures. Similarly. Luna er aI. ( 199? ¡ found ùa¡ u.S. Au Force air 

t¡afñc conuoller fell astccp anavcrage of 55 minutes on night shift-.{ ¡ossible explanation for 

rhe- slecp occr¡rrences. in addirion ro ci¡cadian nadi¡, is thc Frnding of Sanrcl et al. that many 

pilour bcgi¡ rheir nigbr flights afier t'eing a*'ake for as long as l5 houn 

Litcrolure Rette¡, 

Page 25

The effect of unr srnce ¡he last slctp rs c\en grceter ¡f a slccp debr alrc¿d.r e\rsLs. A¡ NTSB 

hcavy trucks accident ana.lysis (NTSB. 199ó) clearly shou s that "back of rhe ctock" dnr ing u.irh 

a slecp debr caries a very high nsk Of 107 singlc-rehrclc tnrck a.'cidenrs. l- dnrers.r..i.J.d 

rhc horlrs of dury. lrinery-two pcrccDt rló) of thcsc had fatrgue-relared acc¡denrs The .¡-TSB 

rcpon also shows that 67 pcrccnt of m¡ck drivc¡s with irregular dur¡' or slecp pencrns had farigucrclaed 

æcidcnts compared to 3t pcrcent in drivcrs with regular dury or slæp panerns. 

trregularity resulted in a dccreasc of 1.6 bor¡¡s on averate in slccp wirh a rotal of onty 6. I hor¡¡s 

compared ao7.7 bor¡rs ia regular petlcro drivers. Thc IiTSB report indicacd thar tlrcy could oot 

dctcrmiæ wh.lbcr irregular dury/slccp Peltcros pc¡ se lcd to fetigue but rcræ erpcrirænrå¡ da¡a 

e¡ppon ùb Dotioo. Tbe 6ndings of fu NTSB oot only fouod shiñod slccp p.r¡crDs but rhis shiñ 

*rs couplod witb slccp lc. Tr¡¡b æd B€ger (1974), whiþ rnai¡¡einint s¡ccp leogth, shiftcd 

slæp rirrrçs ¡od fqnd thrt pcrfornæ o vigileoc+ cjcr¡t¡tioo r-d¡r, ¡¡d mæd ¡æ¡e 

sigÊific¡dy uryr1ea. R¡nhsuaq Nlúolson ct d. (19t3) shonæd thu inegutar slccy'wort 

rcsultcd i¡ increasing pcrforrnanca inpdræots wfiich clas ñ¡Íùcr increascd by tinr on task. 

cumulative slecp loss. a¡d working througb tbc ci¡cadia¡ nadi¡. 

Perforrna¡cc c¿¡ dso bc affedcd b¡'curoulaive fadgue buildup across multiple days. Gundel 

( 1995) for¡nd that pilots flying rwo coosccutive nighs wirå 24 hor¡rs bc¡u,cca fligbs stepr abour 

rwo and a half bot¡rs þss dr¡ring tÞir deytirrE layovcrs (t.66 hor¡¡s yensus 6.15 bours), and 

erperieoccd a signiñcant dcclinc i¡ elcræss oo the sccood night ftight. Alerocss d'ring tþ fi¡st 

sü bou¡s i¡ boû flights appeared lo bc thc saæ. Tbc laucr part of thc sccood flighr shoied 

increascd dcsylchronizatioo of EEG dpba wave activit-v. indicating lowcr lcvcls of alersress. 

Spontancotrs dozing indicared a¡ i¡cre¿scd surc¡ibihq slecp Subjecùvel¡. pilos fclr grearer 

fatigue on the sccood night. Tbercfore. wrtb trrrr slnce auake berng the sarnc. slecp qualiq,a¡d 

quantir,v duriog tbc da¡irnc layovcr resuJtcd i¡ incre¿scd fa-riguc. 

Sarncl et al. (1997) monitorcd I I rusbt fìight rotatrons hom Fra¡rkfon ro.\la}e/Se',chelles 

crosslng tì¡ec tiræ zones Pilos slc¡ oo ayerage ergbt hu.rn on b¡scbne rught5 On laror.er. 

slecp *as reduccd to ó.3 bours. Prle\s arnved a SFZ aficr ll hor¡rs of Þmg ar¡.ake (crccpr fcr 

approxirnatc L5 hou¡ nap prior to dcpernrre;. Fatrgue s*-oîes increased orcr borh outbounà anC 

rnbound flighrs with 12..1 micro-slccps pcr pi.lot outbouod au;'d2a.1 on rerurn. hior ro r11c 

outbor¡nd FR A'-SU flight t5 pcrccot of pilos felt rcstcd n hereas on reruÍn onJy 30 pcrcenr 

rcported fccling so. Tt¡csc str¡dics dæurænt t-hat nighr fì.¡-shs a¡e associarcd * ith reduccd slecc 

quantity and qualiry, alrd are accorDpanicd by cumula¡ire sleep debr. 

Boro*'sþ and t#all (19t3) found t-ba flight-rclated accidcnts in \avy agcrafr *ere significanrly 

higher in flighu originating bct*cca 240O a¡d 0ó00 houn. The higher m,ishap incidencc was feir 

to bc the rcsult of ci¡cadia¡l dcsynchrooiz¡ûon and disruprcd slecp-uake c¡-cte. Sharppcll urd 

Neri ( 1993) divided the opcrationd day of navy pilos in Desen Shield and Descn Srorm 

opcrations i¡ to for¡¡ quartiles bcgrnÃing u 06O I - 1200 uirh 0001 ro 06O0 bcin_e rhe fou¡rh 

quartile. Thcy found that therc $as a progrÊssive [¡ç¡ç¿5. in pilou' sublccúr'e need for resr 

bctr+een fligbts as flighs originated later a¡d la¡er in rhc dar from quanile I ¡o qua¡ile 4. In 

Literature Rer iex 

Poe¿ 26

addiúon multiplc missions and cumula¡ive days fl¡ing also in.'reascd thc pilos subjecÙre necd 

for addirionar resr u.i"..n rnissions. Tre l¡nir cffcct is rhe .-umurarrre cffe.-r of fatigue As slecp 

tirrrincrc"s¿ucrorcaflightrhcsubjccr¡rerestnctdedteforc¡hencrtfìrghtde..rcased 

SleeP P¡ttems DudnS Tbc DeY 

*ith tbc rapid drop in body EmPcrarure 

N 

rcst during rbc day ro¡y rlot be sufficicnt ¡o 

worters bave bctn sbo*l to slæp oo ¡YeratÊ 

¡ht 

tcr¡ CUinors & lVrtctùot¡sc, l9t4). Depcoding oo 

rs th¡ec bot¡rs slccp dcficit- Czeisle¡ ct d. (t9t0) 

p ci¡cadia¡r pbasc. Thrs da¡ilæ slccp wrs 

æP. 

l*&Tepas.lgtó¡Inqulckcharrgeorers 

\À 

Tra rsmerid ian OPerations 

¡od low during thc day.But thcre is a gradicnt 

rsake. sleepincss in coot¡ol s.rbjccs i¡crr¡scd 

perccnt (Mi¡or & \\'aterùor¡r. l9t?: Minor et d ' 

fi.h¡os-horroonal' sccr€lory, tcmPc ra¡ur€-rhat 

i*iog rhc day and for rest u night- Tbc cfrcct of 

i! thc findings of a slccp dcprivation srudy on 

pins out tha¡ dertncss and pcrformancc would 

'ake, exccpt u'ben corplcd to the ci¡cadia¡ risc io 

vel.'- stabrJe through most of the waking bours' Tbe 

'ou¡ hours pnor to normd bcdunr' At bcdtinr 

in p

zonc fì¡thcs is thc rimc requrred forrbc body to ad.¡ust to ¡hc ncr¡ tllr¡c zonc Tlepcnod of 

adjustrncnrappcarsrodcpcndonttrduectionoft¡arcl AdjustmenlaPFatstobefasteraftcr 

o.r,rârd flighrs than casrward fligbu (Klcin ft t*'egrnann. l9t0). Adjustnrnr follos'ing 

wcstç'a¡d flighrs appcars to occur e¡ a rate of about I -( hours pcr da;" rr hile e^st* ard-fÙght 

adjustnrcnt occurs at about I hor¡r Ft 

day. This ma¡' bc due lo the bod.'-'s i¡thcrcn¡ tcndency to 

lcngthen is pcnod bcyond 24 hor¡¡s. which coincidcs sith wcs¡*'ard flighs. Thesc data dso 

,rgg.t, rha phasc shifu bclow si¡ bor¡rs can have a signifrcant impact (Ascboff et al.. 19751. 

Asidc frorg tb obvior¡s iruplicaioos for ua¡rsræridian ogcraions. tbasc'lrt'¡lso apply to rqssre 

pilo(s whosc pfotÊclcd slccp oppornnity nr¡y vafy ss lo its oc¡cu¡reoc/e ælGs essignnrcnts. Evca 

if I prorcctca tiræ pcriod is paaicottc, unþst it i¡clr¡dcs thc night boun, it may nor providc rn' 

cfrcctive opporg¡¡fy for slæp rod tbt¡s fil¡y Dot lcsscn fatigtæ. 

Conch¡sloos 

The follo*iog conclusioos ca¡r bc dr¿wn from thc rcsca¡ch cited abot'e: 

o A¡ i.odividr¡el's WOCL sbould bc deñDcd on thc basis of the ti¡rr zoæ *herc hc/shc 

rcsides, which n¡ey bc difrcrcar from thc horr domicile' 

. D,¡ry pcrids conducrcd during WOCL atready carry a fatiguc Pcnalty due to the ci¡cadia¡ 

cycle. Consc4uently. duty priods involving WOCL should bc reduced. 

. The number of dur.v pcrids r¡r'olvin_q WOCL thu must bc pcrfonrr,j **itbout tin¡e off 

sbot¡ld bc limitcd. 

o Becar.sc tbc ci¡cadian cyck is longer tha¡ l{ hrrlils. each duq Pcnd should sun la¡er 

rha¡r tËc prcvious duç- Pcnd. 

.. Rese n c assignments should atierìrF( ¡o mainta:n a !-onsisten: l:-hou¡ ;i cle 

. Dua-ooo of rotauon for bo¡.h ba.-k-oi-¡hc-cl¡-ii fì¡ing a¡J .j.¡ect¡cn r'f !r3-íìsme ndla¡¡ 

opcrauons should bc consrdcrcd Grren the boJi'; preferencc forcrtendins thc da,r'. 

backr*ard rotatioo should b. uscd *hen possible 

o Tra¡snrndran opcrations shor:ld bc scheduled ln accorda¡ce u i¡å c¡tåer of t'*o 

approachcs. 

. For shon pcriods, it may rnake scnsc to anemPt to kecp t}e piJot on hornc-domicile 

È.rrE. 

o For longer pcriods, reducing tìe dury perid and providing morc opponunities to slccp 

rnay þ the bcst aPProacb 

Literature Rn'i¿x 

Page 2E

.\ugrnented Crews 

Linlc resca¡ch has been pcrforrncd rsr .LSSCSS thc effe..-r¡\eness of managrng irugue through the use 

NAS.{ Pro;ec¡'s hatc bccn ¡¡rua¡cd to srudy loog' 

1.. l99tl. Thc first project r¡scd a sun'cy to 

r slccp rn cre\r qu¿utcrs insrdled on ai¡craft' 

analy-s are prcscntly bcing condr¡ocd' 

Cooclr¡sion 

: *rrr mbcrs from th¡ec ParÙciPating U. S' ai¡l incs' 

Itics *cre nolÊd' fligbt cærumbc¡s werc ablc to 

rtàiþ re*ing in on-boa¡d h¡ts. Fr¡¡tbcr, tbc 

lnDqss rad pcrforrnancc. This srudy elso 

rnægics to ôtai.o oPtùnrl dccP' 

Dcd ôc qua¡tity and qr¡ztity of slcep obtai¡cd i¡ 

gbs. Dara were collcctcd tom two ai¡lincs 

etions. rnd a corporate oPcfi¡¡or. hel'iminary 

6{ qrr¡n¡l¡y and quality of slccp. Additiond 

A rcr.ie,*. of rhc scicntific literarurc Dcrtårrung to fatizuc. slecp. and cúc¿diro physiology *'as 

tssues tbar nced ro bc considercd ra dcveloping a 

pcrforrncd 

rc¡rrrlaor;-slecpdcbt.The;..n..lusionsderelcFrdfore¿chtssue 

rcflect arc 

¡uooal FAA consrderation' 

R efe re nces 

Àkersredt.T.(I9t9)Arcvie,*ofslecp/xa}icdisrurt'¿InJÈjlnconnectlcnurÛrdrsplaccd'*ork 

bours rn fìight op.rat¡ons Srress Reseorch Repons' \c ll3' \ational Ins::rute for Psychologrca') 

F".,or, "r, J g.i,l. Dept. Stress Rcsca¡ch. K a¡ol rnska I nst rtute' S r¡ ede n 

¡ftgrstedr. T. ( 1995). \r/ork injurics a¡d ¡i¡oc of day-\auonal !¿¡2 proceedings of a consetsus 

Developmeru Sy,rrpo,si-r, ent¡íkd "Work Hours. Shepiness and Accidents-' Stockholrn' S'*'edcn' 

t_ t0 Sc¡. lgg4:tbo. c¡rc¿ by Rosa R.. R. (lgg5). E.rrcndcd workshifu anJ exccssive faûgue. 

Journal of Slecp Rcseorch' 4' 51'5ó' 

Alerstedt. T.. Gillbcrg. M (lgg0r Subþcrir.e and objecur'e sleepiness in rbc acúve i¡dividual. 

Internarional !ounal of Neurosc:¿nce' 52' 29-37 ' 

I¿le rature Rei rex 

Page 29

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Conrputers. l - -{-i'ó7. 

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Shappcll. S A. & Ncn. D. F. (1993). Effecr of combat cn ai¡crc,¡'sub.¡cctire readr.ness during 

Opcrations Desen Sbreld a¡d De-n Storm. In¡ernation'¡! Jourw¿l of .4riation-P¡'chologt 3,231- 

25. 

Sh.¡n_eeldecker. C. A. & Holding. D. H. (197{l Risk and cffon rnc¿srue of farigue. Journol o-f 

-ll ot o r Behat ior. 6. I 7-15. 

Smilc¡'. A. (199ó. Norembcr). Interpretarion of Operorrv Perfornwnce Data. In: Operator 

Pe rfonnance.\lecs¿r,'ment: Derelopin-e Co¡runonalin.{.''oss Tronsponatton.Ilçt/¿5 - 

I)terature Rer i¿r. Poge 1l'

p,oceedtngs o-f o Septrntber l99J ll'orkslrop DOT Hum¡'r¡ F¡ctors Coordinatins Cornmjnec Frnd 

Rcpon 

Sm¡rh. L.. Fotka¡d. S.. Poolc. c J \f ' (1991)' lncrcascd rnJunci on nrsht shift' L¿nc¿¡' 3+l' 

n37'1139. 

spcncer. M. B. r lgt? l. Thc influcnce of inegurarity of resr and acrir-ir;- on pcrfofroance: a modcr 

bascd on rimc rr..,rc"p -¿,¡tt of day. Ergonomiæ.30. 1275-lltó' 

Takahåsi.J'S.(1y96).T}rcbiologi.calclock:It.sallinthcgenes.tnR.M.Buijo.A.K¡Isbcck'H. 

J. Romijn, C. M. p.nia¡t¿ ¿l M- if¡-ti'* (Eds')' H¡-prlnlomic-lntegration'of Circadian 

Rh¡-thms. 

Taub, J. Il. (l9tl) Bchavioral and Psychobiological Effca Of Ad-tibirum Extendcddelaycd 

Srccp. tn t. Ikrac- iÈ¿.1. pslci_.,phísiorogicar aspects of sreep. park Ridge. l'i- J.: Noyes 

Medicd h¡blicadons' 

Taub. J. lvr.. & Bcrgcr. R. J (rgr_¡l..pcrfofnìancc 

urd Timing of Slcei' Pstchopht siologt'' t0' 559'570' 

and lfood Fo'o'*ing'a¡iarions in the tcngr' 

Taub. J. M.. & Bcrger. R. J. ( l9;ó) The effecs of changing the phar and du¡atioo of sleep' 

J6arnal of fupenÃenral P¡'chobg\' l. 30-41' 

Thomas. \l L.,199?l Br¿tn cr: Beløt:rcral Efects of Proloneed ll'ake'fulness tn Hu¡tuns' A 

pt,stîron E^rr9on'fo,*g'oplrr 5':iJ¡ o.f B'o'n-Gl¡r"se '\lenboltsm During Task Pcrform¿nc€ 

.\ner 1t hours n,, sirrpóri u"¡,:blr'heJ drr^.l"nl drsxn¡rron ccor-ee \lason Lnirersitl-' 

Tlomes. \f L . 5rng. H C . BcIcnþ.C . et al r 199: Cer:br:] Clu;ose L.ttltz¡tl..n Dunng Ta'\ 

. perlormance ¡nl Ërîtong.,J Sle:: Loss '/ou rn¿t o'f Cerebro! B:c'¡o'! FIo* ¿nd \l¿:¿boltsnt' 

,l3rSuPPl ll. Sj-tl 

Thornc. D.,Censcr. s. Srng. H. c Hcg-ee' F r l9t-ì' Plumbrng hur':'¡¡t çerformancelimltsdunng 

-lhou¡sofhrgb,"rf fo"¿ -Proc¿¿dtng\-of rhe:t^DRG,Semtrarç't"TheHuntan'ls'1 Limilng 

Elcmen¡ In Ililircn5.\sre¡ns. l'c-tmel Totonto' Ca¡ada' Ifal' )J 

Torsvall,L.,&.{kerstedt.T.(l9tt)'Drsru¡bcdsleepuhilet"erngon'call:'\r¡EEGsrudyofships' 

enginecrs. SIeeP' Il' 35-38' 

Tonerdell. P.. & Folka¡d. S. r lF')l The Effccs ot changrne From a \\'eekl! Routing to a 

RaprdlrRouringShlftsche.Ju]:lnG.CostatEd.l.ShiftuorkHealrh.Sleep.andPerforman..e 

Itte ral ure Ret lcr' 

Page J'

Turek.F \\.&\'¡nRccth.O tl99ó Crrcad¡anrhrthns ln\f J Re-el-r&C If Bl¿neistEdsl. 

!'landbt,rr\ o.f PhtJt

A SCMTSTTHC Rg\ÆW OF PNOPOSSP RTCULATIONS REGARDNG 

FLtCrr Cn¡wUrluBER Dury PsnrOp LnnrlTIO¡iS 

Docxer #2t0t I 

The Fligbt Duty Reguletion Scientific Study Group' 

Preperetion of this docurrcnt w¡s supported by e grent from the 

Independent Pilots Associ¡tion 

Rr¡gr.rrng t;rle: Review of propo--d fìrght duty æSuJauons 

Corresoondence to : Cary S fuchudson. MD 

Endæn ne - H ypcræ nsion Divisi on 

Brigham and Women's HosPiul 

221 Longwood Avenue 

Boston, MA 021 l5 

'Co-Chai¡s: Wallace A.Mendelson. MD. Cleveland Cli¡ic Foundatjon; Gar)'S. Richa¡dson. MD. 

Bngham & \\'omen's Hospiral a¡¡d Han'ard Medicd School:Thomas Rotlr, PhD. Henry Ford 

Hospiul.

"Rcúew of proposcd ftighr d-ury rcqule-uons" 

Tfrc night pury ncguhtan Scicntif¡c Srudy Grroup 

Tm FLlCrr Dtrry RTCUI TTION SCu¡¡nr¡C Sn¡ov GnOUp 

orders. 

board of rlre Sleep Rescarch Society. 

: Di¡cctor of rlc Slecp Rescarch l:boratory and 

'ersiÌy of ChrcaSo' He is. ar¡ internationally. toogrrticuiarly 

insomni¡. ¿r¡d o.n tlrc phTmTology.d 

r an ofIìi-¡ oo tþ e¡ecutir¡e boards of both ür 

tcri{åri S¡ccD Disordcrs Assæiation, and part¡clolicy 

on rbc-diegnosis urd uea¡nre¡rt of slcep.dis- 

rt Brigham ¡nd Wornco's Hos- 

I,lcdicine, and ¡r¡ Inst¡r¡c¡or b 

tiooetly r€coglizÊd authoriry oo 

consr¡lunt to ¡Ìr 

k and sbcp dep 

on tlre exccutiw 

Thom¡s Roth, PhD. is Di¡ector of Resc¿¡ch for tlr Henry Ford Health Sysarn rn 

rhe Na¡ional lnsúrures of Heal¡h. Dr. Rorì has scnæd æ a corsult¡nt o tl¡e Department 

of Transporuúon. Naúonal Highway Trafl¡c Safe¡y Associauon and NASA. 

\lemben: Ruth Benca. MD. PhD 

U ru r'ers tty of W isconsr n/H ad:son 

Madrson. W¡ 53792 

Cynthia DorscY. PhD 

Mcl-e¿¡¡ HosPiuJ 

Belmont- MA 02178 

Ba¡ba¡a PhilliPs. MD. MSPH 

Cood Samanren HosPru.) 

lexingon, KY 40508 

Imoùy Ræhrs, PhD 

Henry Ford Hospitat 

De¡¡oit MI4t202 

Ma¡y A.Cank¡don. PhD 

Bradley HospruJ 

Easr Prov¡dence. RI 02915 

Mark Malrowald, MD 

Hen¡rcprn County Medicd Center 

Minrrapoüs. MN 554 l5 

Jame.s Wdsh. PhD 

St. L¡ke's Hospinl 

Chcscr{]eld. MO 630¡7 

Gary Zammit" PhrD 

S r- l-¡¡le' s-Rooscvel t H ospi tal 

New York. lfl 10025

"Review of proposcd ftiSht d-ury trryI?tiotls" 

riã errirti drü Reguraùør Scicndñc Snrdy Grroup 

l. Int¡oduction 

uorls. It is our hope that many of the rmporunt.ar 

oroduced by thls'effon. whe re¿s other issr¡¿s cle 

bas¿. f¡esè wil requirc add:úon¡l rese¿¡ch aru 

malung effons. 

The goal of providing safc.tot=l 24 hours a 

at aliumes. Slr,ce human den¡rcss is hrghly 

ro beuer address tlresc lssr¡cs wlrl tÌrc goal of op 

os of fuigrr ¡¡rd slcep dc-privation 4 ltghl crew. 

izc ev¡ilablc scbnri6c informaúoa. boü that ex' 

of sckntific'lirer¡¡¡rc ægarding tb ongru of hu' 

by rcgulaory effons in otlrer induscrrs and by 

r is soluuon. However, tlre Stud¡' C:oup [eels 

allocate...J rest rime should not reUeve =gulatoq 

Jequare Lurre Ls provrded for resu 

tl

'i:îíäî'Jüffi ,['Ë*gm.oJ":å"r'crro'p 

Figurc 2.1: Sclcm¡tk rcprcscoletioa of tbc plysiol4ic f¡ctor¡ 

contributio3 to bum¡n htiguc la ¡¡¡st¡ i¡rcd opcrrtions 

2, Scientific Brckground 

2.1. A workrng delinition of faúgue 

(Figurc 2-l). 

-Slccpurcss. æcnrding b ¡¡ crsging corls€¡lst¡s ¡¡norì8 s 

pòysrobgicz,l s¡¡c 0ilc) bunga a ôi¡st' Dcprtvaloo cr 

ard es bunger s thi¡s¡ is revcn¡blc by caung a drint'u3' 

rcscd modificatiors to tlæ FAA regulatioru r'aria' 

descnbe the physiolopcal condition arising from 

rccurs when wakefulness is forced during phases 

nplrcarron of this usåEe is -tlt¡t tÌrcsc lerrns ar€ I'n' 

:aies tlut ¡Ìrey a¡e nou and confusion of Ùr rwo 

basis of performa¡rce errors and Ù¡e aPpropnac 

dcfiniuon: 

orænts which ¡ts¡ become the target for inte¡venbr 

¡lr teneral condiúon in which performurce is 

p cont¡ibutors to human faÙgue. the control and 

ion ol performa¡ce of crew members in air fìighu 

' Frcsr Ro{b, T., ¿r at.. Da},r¡-sr slcrpnncss and a.lcm¡css .lt Pnnciplcs atd Prættce of Slcep Mcdicitu, M H Kf}'' 

gcf.T.Roù, üd w.c. DcrrnL Eds 19t9, W.B.Saundcrs: Philadclphia, p l+13

"Rernew of proposcd flight dury rcgulauors" 

The Fbghr Dury Regulaton Scicntific Srudy Group 

2.2. Horneost¿tic rcgulation of slccp 

¿lca'ecs of fetigræ is ¡ dcclinc in human derûrc

,i'iîíä,i'dffi ,f,É*giff#.ii:ö'.,-* 

üon a¡rd tightdark .y.lq have progresscd ro tÌ¡c noint wb¡c it ls now possiblc to makc rcasor¡ablc 

;-ñ-.r*-õr rrr. efféi ói mnsritcr¡-¿ian rrevel, w¡r¡ rtr consogucftt altc¡aooru in light-drrl gxpo 

sur!, on ínamal .,,c.dñ "*"¡arion a¡d üE dependerrt rtryrtrns rn ¡þrt¡lcss and Pcrformance 

(l l)' 

concl'sions rclcvant to e¡¡ended-dury paradi¡rns 

r nccds of thÊ boræosta¡ic system will not rcsult in 

1.4 Time on t^

ff îíä?'effi ,trslågr'f#J"iTö'Group 

2.6. Shift'work 

impæt of r given shifr schedulc. or t"g¡ 5pccl 

n.L. ot oùri human factors ¡rrc not always ava 

.ióãi-t resc¿¡ch result-s rcgardrng a sPecific g 

n rnd sbcp dcpriratioo (horneosutic) infÌ¡'rr¡c¿s.o 

r ærformåd. Écnaing collec¡ion of such data idc' 

- 

"fü,È 

t-.-on- t¡sk -¿ara noné theless nis¿ si g ni-fi' 

siw rsPect of ¡úuion. 

l¡¡c thc physiologic conributors to fa¡¡gæ il F 

¡d imporr¡¡tce: foiexample' how mr¡ch tþ? ú1lti- 

¡? Wirl¡out more d,t¡ on thls issue. ttr only efÏec' 

reæh of rhe three ares as completely as psible. 

$t crcws occurs rn tþ co{ìExt of g9rrt"l- corrcern 

int slæp depnvadon in a large number of æcupa' 

'owing number of US. workers a¡e calþd upqn 

!o 

. It is-esumated ¡Ìrat some rwelve mill¡on popb in 

of shifrworker (19). A number of stratcgÈs have 

Jne coveragc of the growing variety of scrvice and 

s suffing. TIE m6t common of tbcsc is thc 

Lcrs work-successive shifs for one or mce wecks 

/)

"Revicw of proposcd flight ¿û'y ryFguo¡rsrÈ 

rîärti úiün.g.,bù'on ScÉnüÍ¡c Sudv Gmup 

ent measure. 

3. SummarY of ProPosed Suidelines 

rivatim. 

tþ i&nrif¡cation of ourcûne meåsr¡nes to bc uscd 

Whiþ available rncesuÉs haræ a@uatcJy docu' 

e rlrat can be used o effæuvely monitor thc impcct 

ansuophic ourcomes as r-hc onJy acceptcd depcnd' 

Jum "Pnnciples and CuldeLine for Dury. a¡rd-Rest 

E pnrnary óurcc rn r}rc pæparaúon of ùe NPRM 

etweerì Ùte NASA recommcndations and ÛE f¡r¡Âl 

ss dury pend. fìight. Ùnrc' a¡rd rest re4uiremens' 

vcll asiumulauve-dut¡' periods lor a week a¡d a 

month. . t 

The¡e arÊ two mpon¡nt tgneral fearu5s 9[ t]" Pro.ry1! 8":1t]Ti ].,ff^'^r¡ Prl:d'fi:ÎL:: 

å,ö'rñ: ñ ;*" fi ' äå " 1'-,v -i^,c"-r q. l Y T EII 1i1," :: lm,l:, : t**":, "i .1,'," 1I.0 f i:ff 

ÏËoiåiäË""nËr-*i;'þF"t!:'¡."*:,f*::',ii:;,,ï. n*,:i"*;'l;^:*å'i# 

ìffi i t #i,ifi,"'uïã i ó' l* ¿ u t y * g'¡íl P -y 

li';'åiähii;-;'"ili;i;*-;íp.i;iän¡,,pry1::T :1:*1-t:.t*il^t:?::îit^*ltrl'å 

:,11 ï ¡.", 3i' f.îË9 î l î',s: :'" i:"'^g,llfl." 

ffi iå'rii;ffi;rï nigrriãryäug$J -ä ir,'itr"rron or dirrerences Þween rclevant pcrts of ûre 

Pan l2l rcgulatio* ;í,r"'P," l3s '=j:l'^:.:Îil:I:::q ::TTl::"Td.,,o*.ot'-d fìighs)' 

rt'ù å"llii'iiiì'pî'r[.r* -¿ e."",1y irñproved corsisænc¡'in fìrghI reguJatiors.

'*îïä?'Jüffi ,['å3å'üitr#.i"":ö"o-"0 

T¡¡rs ll: Sur'rnA¡Y oP Proroseo Rscu¡'rnoxs 

l. Fllgbt dulY drretloa Crcr ¡l¡c M ¡r,d rr¡tlon 

(duty/fll¡ll) 

lul 

ta/l0 

t6/'2 

tM6 

2. Ml¡lnun rrd dunllo¡ Crcç ¡l¡¡ Ml¡" Jrntlo¡ 

(lorrr) 

3. Fti3bt timc limits Timc fnmc M¡¡, lliSbt 

tl¡nc (Lourr) 

3. l. Rerìsed Flrght'Dury Durauors 

f .2. Rest Period 

hou rs. 

I 

2 

3 

3' 

al 

t 

) 

3 

3' 

al 

Pcr rÆÊt 

Pe¡ ocotb 

Per 

Dcstpix 

operational delaY. 

t0 

¡0 

la 

It 

a, 

n 

ræ 

fl

"Review of proposcd flight dury rcgulatiolls" 

Thc Flighr Dury Regul¡úon ScÈntilic Sudy G'roup 

3.3. Sund'ByAssiSnmens 

Rescrvc time in this 

not on dury but 

nonetlpless musr be 

dury pcriod. Thc 

suideti¡Es cxOLicitly it 

' 

rclaqs ¡Irool¡¡lt 

ãf Uro" of advance -n period. Witì less 

d is ¡llourcd- As Dotificetion pcnod gocs to En or 

pcodi¡t oo circumst¡¡Ees, Ls allowablc. A¡ dæ¡onst¿nt 

6 bour protcctcd time (by reqæst) for cæh 

nif¡c¡tc bolde¡ E¡y Dot cont¡lct tþ cæw ræmbcr 

bÊ ¡ssipcd beforc tlr qtw membc¡ bcgl¡rs ¡hc 

bc coopletcd in lt hor¡¡s within tþ rescrrr tinr 

rli¡rcs 

3.4. Cumuluiræ Limis 

Tlp cumr¡l¡tiræ limis fa flight hor¡rs ¡¡r€ set ¡t 32 bours fr any 7 &y period, end l0 houn for 

ury calendar month. Ttr f¿rty pcriod is set by multiplþg ttrc monthly requircment by 12 (i.a. 

1200 hours). 

4. Evdu¡tion of proposcd rcgulations 

It is importanr to rcitcrate and ernphasize ttr.Study Group's. posirion tlu¡ tÌÉ proposed rcgulations 

as dehned in û¡e currcnt NPRM on tþ whole reprcscnt ut important advance over existing nightdury 

regr¡l¡úons. Tt¡e principal improvement lies in thc æw dependenæ of thc ægulations m oal 

dury time. ratÌ¡er than jrst fligtrt úme. in scaing. limis on rnatdrDum work duration. As rcvþ,¡ed 

above. ¡l¡is is ¡ m¡.ch morc physologically sound appmæh, rcflecting tÞ importancc tlut all work 

time has in tÞ generarion of fatigrc. 

Tþ Study Group did. however, oPosed regulatiors that 

should be improved upon andor a inæntion "...to incorpo 

raa (wtrnever possible) scicnrif¡c physiology into rcgulaüors 

on flight crew rheduling." (l). Adjusuncn should address each of 

rÌ¡c rssr.¡es ldentif¡cd bclow. 

ln companng ùE proposcd rcgulaúgns to tl¡c suæd goals outJrned in tlr inuoduction o ¡l¡c ll?RM 

and ro ãvailable data rn tle scicnúfrc lierarurc. thc Study Group identified two imponant gernral 

rssues. 

4. l. Exccssive dury duration 

duraúoru in exccss ol 12 hou¡s ¡¡e rssæiåtcd w: 

r slcç v¡tc history (13. 23), the¡e ca¡r be bde 

; of 14 hours, ler alorrc the greatcr duraúoru pcrpecific 

duty ard tirnc limitations ¡¡re thc same as 

2), dtlough tlre¡e arc polentielly important difÍertu 

NPRM in the definition of flight úmc \Àlhile 

thc NASA docunrcnt rççeg¡1irrs thc imporuncc of limiting marimum shift duration (Section I.4; p 

4). ir provides no evidencc in supporr of the stalcrncnt üû l4 hours within a 24-our perid is sufficienr 

li¡nir¡üon (Scction 2.2.3). nor was the Srudy Group able to identify resea¡ch to suggest ù¡t 

rhesc shifr durariors might bc "cctpuble in the unþw ¡vi¡tion s€túng. I¡ this regard. it is importånt 

ro noe ùar rhesc dury perids are significantly longcr tl¡an ¡hose being applied in a range otler 

work seuings wherc rcgulaory arænúon has been fæuscd on tþ problem of faúgue-related prforma¡ce 

decrement-s. includrng most other transpon¡uon s€ctors. 

/t

"Review of proposcd flighr dury regulatioas" 

î," nigh, Oury Reguleuon Scicntific Surdy Crroup 

Absc¡rr resc¿¡ch dara to tÞ contrary. thc only rcjry¡¡ findings.suggcst that pcrformancc dctcrio 

- 

an 12 boun. ù¡d th¿ tæqamendcd I'imis for dury 

efTcct- 

tioos mr¡s¡ await erupirical confrmarion of sr¡ch an 

'cirçumstarces wlæ¡c c¡srr nu¡nber is augmented 

lli.sh¿d srudies luve not yet shown that tìls tmion 

o allow a signifrcantly slcc¡deprived crcw 

s corrern is thet scræral studies in otlpr concxts 

pporurnity for slecp in Ûtc exænded-duty scning 

C obui¡¡ed. Without express stipulation about tlrc 

d by crcw members. it is ou¡ concerì that thc re' 

rter¡èd duty arrangemenls wiÙrout providrng uty 

oh¡¡¡rd. 

dêquæ ¡o compen$te for tlre clearly l¡eroic dc' 

t alkr*a¡ces are adjrsed for ¡l¡e rest penods fiolccdr¡g 

rt- Thus for crewmembcrs movrng among 

be called upon to work very long shift dunrions 

"re¡Lr¿d rest"), witlr no stipulation th¡t t}rts u¡ne 

be prorndcd ¡t a circadian phasc condr¡cive to slcep. 

rp dø r¡ot foel ¡Ìrcrc is ¿dcqr¡aa scientific justifr- 

\,lor is rlrc Study Group conlident that compensa- 

:n b fìight. and exænded rest provide adequaæ 

itl very long work schedules permitted under tl¡e 

4.2. No rdjrstme¡¡t for "bæk side of thc clæk" 

Ou¡ sccond rnaþr concern is that rÞ propord rcgubuors-malce no effort,to adjus¡ prescribed.lim' 

¡o on wort duårion or resr dr¡ration bascd on the ü¡rr of day u which thosc activitie's a¡e sched' 

ut"¿. tt¡ iç rlr mosr disappointing omission, a¡rd panrcularly diff¡cult.o r¡ndersta¡rd in light 9f 9" 

.ror""r predic¿ion of rlre Ë"isc¿ rcgularians on tlc NASA-Arnes datebase. a body. of resea¡ch ¡ìat 

t,"l ø"ä m¡rch o clra¡actc¡izc rhc dèpcndence of sleep and prformancg in tlp aviation sening on 

\ srudies a¡rd tle larger body of scientilic evidencc 

abour ûre importancc urd rcleva¡rce of circadian 

ance a¡d tlre ænder¡cy o human error, and to thc 

crrna¡¡cc decremen$ arising as a corLs€quer¡ce of 

sleep depnvauon. 

ß

ff îíäî'*ffi,f;S* tli,lifl*iö "-* 

1'3' Intcrætio¡s 

c¡dorr¡ of rhc 

¡s ¡pvicuæd 

and no cq¡well 

or¡tsidc 

hout adjusunc¡rs of rcst pcnod du¡aúon for cir' 

le to Ìui,c a rourine 14 hour night shifu follo*td 

) PM. i.¿. preciçely coirridcnt with tÌ¡c circadian 

orbiddc¡ zöne'). followed by r 2ó hour strift 

n of in-night timc for slecp can not bc assumcd rc 

ncnls th¡t ma¡athon dury of this kind will i¡pvi¡r 

ion sæms frorn the ebscrrce of any adjustment of 

s could dcmorurrac that a succcssion of 14 hor¡¡ 

rablc pcrfonnarlcÊ limis. it is very unlikcly that a 

ly validaad. Unless maximum shift du¡ations a¡t 

keor well within hurnanpcrfonnance limir-s. i.c. less tl¡anJlhous'. somc adjustment for tþ com' 

polnding cffccs of Úmeof'day nccds to be includcd' 

na¡iæ ¡Ire not likely to bc rcprescntative of rypical 

on of tlrc Study Group h¡t no rcliable protectioo 

:Þduling can bc lud withor¡t express adjusmens 

ci¡c¿dian clæk, urd signifrcant reductiors in thc 

4.4. Rescrve Trnr 

Thc Srudy Group has separarc bur rcla.red concerrLs abort.rhe.proposcd.regulaúoru rcgatq¡Í¡g R.e- 

;,-,,- Ti-fr..-li rirr.*ed'above, rwo dlsdrrct approachcs.for tlr pmrecûon of rest time within ttte 

¡i{ "variable noùcc". tþ ma¡imum length of a dury 

perid- Tlr window is ttre sa¡ne during cach succ¿ssive day on reserve. 

Thc Study Group is conccrrrd that ùrc vúi¡bb notice a¡ran8erDcnt is based on,t'l't"_TPPYÍ^ ju.l 

p"rid tÍrt stejp Oe6"arion resr¡lting from a shorr-noticc call cen bc adcquaæly compensated tor 

. Twelvc boufs is fclt o bc t-bc manunr¡-rr safc sbift dr¡¡zrion in many sbifrwort satunS\ c.g. nursinS. Howerc¡. 

ùcrÊ '-e d¡r. dcsrcnsua¡ng ur irrrcasc i¡ frfcrs¡¡¡¡c¿ errrs betwæn t ar¡d ¡ 2 bû¡rs of shift d¡¡ndql. sttggcsting o 

sorne the¡ rÀc approçrrac mårrmu!ì shiñ d¡¡rarx¡o io safery-rnsitivc shifrwcrk ruings sbou¡d bG t bot¡rs (17)' 

/10

'l,cview of propæcd ftight d-ury ryqultiotls" 

frtc nrght fiury n.3ut ù'on Sciênriñc Sody Crroup 

5. Rccommend¡tions 

c¡ttËrDe. this rrrangeocot would dlow ¡ pikr o 

cc, d.c. ¡dv¡¡s notice equivabtt to thc unr rc' 

m¡geo€aL es spccifrcally dcf¡ncd in ùc NPRM, 

iy¡Éõo is ¡iniÊri o lt bours (Pres¡¡m¡S ù¡l ôÊ 

r pruccrcd vi¡dows dnring tl! d.y' ud panbr 

¡ni¡l ¡¡c¡-css. six bor¡rs would not rgpeer n be 

¡s. 

lin tb cuÍcal NPRM Eserve ¡¡r¡rngements is üc 

iræd- 

5.1. Recommended revisions to thc proposed rcguhtiors: 

5. 1, 1. 

tightduty rcgulations rÊPrescnt an important ad' 

rd Lmirs û¡at minimize fatigtæ and optimize flight 

of tlp specilic regulations æviewed above ¡æ not 

iltHú åHf;ffi ¡J:ilf,roup 

u rses expdicnt 

slcepincss(4-64À{). 

5.1.2. Minimr¡m rcst pcriods should bc dlns_red upward for sleep perids ¡Ì¡¡ inclu& he 

tirrrc of pcâL circ¡dirn ¡lcrtncss (4 - ó PM)' 

5. 1.3. Thc provision allowing ertcrsion of dury maximums. uP.to 24. hours (2ó yiù opcra' 

uon"l delay) in augnrnrcd crcws end rn assignrncns tìat include fæ.tljties for rn-fì.ight 

slecp shouid not É impÞmcntcd ur¡r¡l scþntific cvidenct is available dcmorscnung 

thar'in flighr arrengrmens pres€n't alcn¡rcss at æccptabþ levels. i.¿. at le rtls equiva- 

þnt to rhit on Ûre roudrr shift duraÚons 

5.1.4. Rescrtc tirrr rrraogs'rrs should bc djuscd so tlrat Protcctci windowsiuf-tng futimc 

otpcal circadi-an alcrr¡rss a¡e cxenðcd to comPcrts¿rc for dccr€åscd clÍrcirry of 

slecp during tlut unr. 

5.2. Recommendations for fut¡¡¡e rcvisiors: 

Sewral of tlrcsc issr¡cs illurarc fu Dced for addiüonal dat¿ a¡¡d even wiÚt adjrstmens reDom' 

I minimum rest duntion will represcnt quantiutive 

urrently only qualitatiræ scientilic suPPort TÌÉrÊ' 

l[ recomrnerËaúons þ viewed as tþ lint stcp in 

5.2. l. NASA. in ir-s capaciry as rndependent scientific resource. should þ commLsioncd o 

gather additional dau on this issue wirlr ûæ followrng pnorities; 

/u

"Revicw of pmposcd ft'ighr dûry rc.gule-tions" 

ff,c n gnt fiury negrtl¡È'on ScËnúiic Sordy Group 

S.Z.Z. 

5.2. t.l. Idcoti6cetion ¡¡rd cl¡¡ræreriz¡ti 

tlrr¡ c¡¡ subsdrua for æo¡l 

rDc¡sl¡t€ of fatigrr in fligfit cn 

rsscd to continuoslY oonitor 

a¡rd furr¡re rcgulaory adjustmens' 

5.2.1.2. De¡crmin¡rioo of rtr impæt of dury perigd dr¡ration o¡ nerfo¡mancc' indcp""d""r 

;a sleep acpriration ¡¡d-ci¡cadi¡¡.ptrasc qffff Tlæ impact of 

r.ry.nt pcrccndgcs 'of nigfrr dræ within r duty period should also bc esscsscd. 

5.2. t.3. Dcrcrmin¡¡im of rtr impeg of vrrying rc+loed. on çr.form¡¡p, with 

panrcut¡t ¡lenrio to thc- rolc of hndings ¡¡rd srs¡ai¡¡cd füghr 

5.2.1.4. Asscssecnt of rlp proræivc PPI' 

sioo of fæilitics fc irnight of dc' 

rcroining tþ excat to w-hich ¿ ly er- 

a¡dcd. 

^2 

view tþ data collectcd by NASA on a rcgu.lar 

pæhensiræ and de¡ailed sct of recomrncndcd 

e¿¡s from thc time at which thesc recommer¡'

"Rcview of proposcd flight duty rcgulaüors" 

Tlrc Flight Dury Regr¡l¡tion Scicntifrc S¡udy Cnoup 

6. Refcrenccs 

l. US Govt kal Aviatim Adminisratioo Rigfit Crenr¡eç¡¡¡r' Dury Period Limi¡¿rions. 

Right Time limiutiors and Rcsr-Rcqui¡e¡ne¡¡s. Notxæ of propord rulemaking (MRM). 

Fc ù ral Re gisu r 195:60(2U):6595 I {0. 

2. Srerrb I, l -hm¡¡ul D, Sleep deprivation: efrecr 

in man El¿ctoc¡ccy'ubgraphy &. Clinicat 

3. C¡rskadon lrlA Bro*'r¡ ED,' Den¡cTt.lVC, S]fq fragmcnurioql! qre clderl¡ rclarimship 

to da¡ime slccp rcndcncy. Neurotiology of Aging l9t2;3(4):321-7. 

1. C¡rskadon lvlÀDcme¡¡t WC, Effccs of ¡p¡¡l sbep loss oo sbcp tendency. Pcrcepul l&, 

M o o r Sb r¿r lÍl 9 :a8Q):49S506. 

5. Roscnth¡l L ì{erloui L Ræ}trs TÀ_Roth T, Eaforced 21-bour æcovery following slccp 

deprivation Sleep I 99 I ; I a(5):44t-53. 

6. g.Fly.AA. Bddeær G. Trachscl L Tobler I, Efræt of mi.l"olam urd sleep deprivarion 

on day-tinrc slecp propensiry. Ara¿imincl-Forschung 198535(l l):169G9. ' 

7 . Moore-Edc MC. Czcislcr CA Riche¡dson GS, Ci¡cadian ti¡nckeeping in heåtrh and diseasc. 

l/. hgL J. Med l9t3:309:469-7ó & 530-6. 

t. Ri

"Review of proposcd flight d_ury rcgula_uns" 

The Flighr Dury Regulatim Scientif¡c Sudy G'roup 

19. Mellor EF. Shift work and flcridme: How prevalent ¡¡rË thcy? Monthlv Labr Rcvie* 

1986(Nov/86):PP l+21. 

ZO. Akersrcdr T, Sleepiness ¿s ¡ corisequencc of shifr work Sle ep l9tt: I I ( I ): I7-3a. 

2L. Rosekind MR, Gandcr Pl[ Mitþr DL, et rL, Fatigrr in operaüond sctongs; examples 

from thc aviation cavi¡onment Hunøn Fæørs l99a;36(2):327'3t' 

22. Rosekind M. Wegrourn H. Din¡rs D, Graebc¡ R. Sa¡æ_l À Principles ¡nd Guidelines for 

Dury urd Rest Schcduling in Com¡¡ercid Avi¡tion ¡fÁ^9t Teclnical Menorandum 

1995;in press. 

23. Unitcd Statcs Cæst Guard Al¿rùvss atú Fatigue Re- 

ßäi"#"i:k 

tnfoencc oÍilu Mø'Mochirc Inurface 

24. Rosckind M, Gr¡cbcr R Dingcs D, et ¡1., Crew Fæors in Flight Opcntiors D(: Effecs 

of planrrcd cocþir rÊst on crcw Frformancc ¡¡rd eþrt¡pss in long-haul opcrations. /V/tS^ 

Teêtnical M c nøratúun 1994; l0tt39: I ó4. 

t'l .

Remarks by Dr. William Dement to the ARAC Working Group Pilot 

Representatives on December 1,1998 at ALPA HQ, Washington, D.C. 

I'm L,ery plensed to presat Dr. Williant Denrcnt sf $tnnford Unit'er:itt/ ¿tlto's lrcre to 

ansluer some of our questions regarding slerp science. Dr. Denrcnt ts considered tlrc 

fatlrcr of nrodern sleep medicine. He earned his M.D. and Ph.D. front tlrc Unioersity o.f 

Chicago where he first began to study sleep. ln 7963 he became the director of Stanford 

Uni''ersity's Sleep Research and Clinical Programs and continues in tlut post today. He 

was Chairman of the National Commission on Sleep Disorders Rexarch from 7990 - 

1992; a Contmission chnrlered by Congress. He is the author of a defnitiue textbook on 

the diagnosis and treatment of sleep disorders and lus u¡ritten or ctauthored more than 

500 scientifc publications. Dr. Demmt, welcome and tlunk you þr your time and being 

here today. 

Thank you. For many years, the people who were interested in circadian 

rhythms and the people who were interested in sleep were fairly separate. Now 

there's actually a scientific meeting going on in Bethesda hosted by the National 

lnstitute of Health and the National Science Foundation in wl¡ich circadian rhythm 

issues and sleep issues are considered to be complementary pañs of one 

scientific discipline. This has been happening over the past 10-15 years. 

One of the things that l'm trying to deal with is the fact that the study of sleep, 

the scientific study, and the applications / operational situations coincided later 

than some of the other Cisciplines. To get really into the mainstream of the 

scientific knowledge a"C the applications, ...this has been v,'hat l've been most 

interested in trying to help accomplish during the past 20 years,... and the first 

efforl was to try to create a federal agency that would really be responsible for 

sleep and circadian issues, research, applications and education. Our efforts to 

do this led to the response of Congress to create a Commisslon, not to create an 

. agency but to create a commission. 

It turned out to be really a good thing because many of us had been in the ivory 

tower and this Commrssion really put us out in the field, hearing stories from 

people who have been rnvolved in accidents, heanng what life is like in the 

trenches so to speak. That certainly made an enorrnous difference to me in 

appreciating, in a much more human way, the difficulties and the problems. We 

presented recommendations to Congress and it kind of coincided with the budget 

crisis, and dare I say. the Republican revolution so that only one key 

recommendation was passed. But there is now a f ederal agency - The National 

Center on Sleep Disorders Research - which, small, although it may be, is 

certainly a great start. and has on its plate some of the concerns that affect you. 

It also has the legislative mandate to interact with the Department of 

transportation and other agencies that are involved in these issues. I just wish it 

was much, much larger, and we're still working in that direction,

The second thing is that all sleep researchers now accept the concept of ''5leep 

debt." Each individual needs a certain amount of sleep each day on the average 

to avoid accumulating a sleep debt. That sleep debt can accumulate over a long 

period of time, lt can accumulate in relatively small amounts so it's kind of 

insidious, or of course it can accumulate very rapidly. You find frequently that 

many people have been partally sleep deprived for long periods of time, They 

arên't aware of this as fully as they ought to be you would think. 

There's lots of evidence showing that you can get rid of that debt and how much 

extra sleep you have to have to get rid of it. The best type of research that 

demonstrates that is to show the increase in the tendency to fall asleep -- the 

power of the tendency to fall asleep - as you add hours to the sleep debt. 

Eventually, the person will finally fall asleep, no matter what. They can be 

walking and fall asleep. But if you put someone in an ad-lib situation, iust take 

any one of you, and say, "Now you're in a situation where you have to sleep." 

You're going to be in a bedroom with no lights. All you can do is sleep. Then 

you will see all this extra sleep will take place. That's the debt....the amount of 

sleep that you should have received on a daily basis. That's usually astoundingly 

large. 

ln studies of this sort, you can show that a person thinks they're perfectly normal 

in terms of the way they feel. However, if they reduce the sleep debt, their 

performance will improve, The question is how much debt is anyone carrying at 

any parlicular time. The main thing is don't do anything that might increase it. 

That's my fundamental PrincrPle. 

Finally, the circadian rhythm - I think that everyone has known that there is a 

biological clock. Since 1971. the location has been known in the brain, there 

have been a lot of electrodes and genetic studies, etc. Exactly how the clock 

functions to create a circadian rhythm of sleep and wakefulness has been 

understood relatively recently. This has been learned through the study of 

experimental animals. The best results are obtained with primates. So if you 

eliminate the primate biological clock, what's the result? They fall asleep all the 

time. They'll fall asleep, stay asleep, wake up, fall asleep, wake up, etc. The 

circadian rhythm of sleep is completely eliminated and you lose periods of 

sustained wakefulness. So hat the concept today is that the clock pailicipates in 

the daily regulation of sleep and wakefulness by alerting the brain at certain 

times, And you know those as, in other words, the forbidden zone for sleep,.., 

the second wind that a lot of people get at the end of the day. But the clock does 

not put you to sleep. When the clock turns off in effect, when this alerling 

influence ends, a person is left with this gigantic sleep debt. That's what I've 

heard you refer to as'WOCL." That's the period where you find the least aleriing 

of the activity clock, the most unopposed manifestation to the effects of 

accumulated sleep debt, and the greatest likelihood of falling asleep. 

3

Well, there's an ideal time to sleep and then everything else is less than ideal. 

Sometimes it's devastatingly less than ideal. 

W'¿ll, lnzr much so? lf vou had an opportunitv to sleep during the dnu .tnd uou îL'ere 

gi,,en an S{nur sleep opportunity, could uou etpect to get S ltours o.f slery during tlnt 

opportunitv? 

No, I'd say absolutely not. lf that happened, it would be an incredible exception. 

There's a ton of evidence on that also. 

How about ,f you were getting a L0 hour sleep opportunity? 

No, I don't think so. There have been a lot of studies on sleep reversal. You 

simply reverse the sleep period and this is now a model of insomnia. lf you have 

to sleep in the daytime, you have insomnia in effect. The ideal time to sleep if 

you have a stable circadian rhythm is to stay near the circadian rhythm. 

The t hours of ideal sleep, is it possible from vour studies you can nail aoltnt any specific 

|-hour period or is it aariable for indiuiduals? 

Well, it may vary a little bit. Within a very narrow range I wouldn't say....l would 

sayfor most people, it'sfrom 11- 12 PM to 7 -8 AM. Forthe vast majority, 

that's the ideal sleep period. People will ask why they are the exception, but 

you're not dealing with exceptions here. 

l\'il,'l l/t.r:( l'a.riìr'ú¿',? fo /i.;:'c to s/e4r i.f vr.:i rt.flvittg ttt ttigltt L1n;l uLlu 'r'r :.iq:;r1ç ln l/¡¡ 

dnv I1'rri-.-.;i'/r.?l vLitt rt renlltt -snvillg ls jllal tlrc clnttces nre vou'rctf:':_\- fur b¿'L(rlr¡c 

(' 

-i 

r? ¡ c'. ¿'/t ¡t : ; i i n, tl nt r i:' t'.r, t1ï e r t i û I t' 

That's nght. 

Andsotheonlvl.1'nVvlitcorrectthnt,nt ttntterlnzt,muchtinteuou:tr:gettirtgtoslerp, 

ttou're still going tòbe somanhat sleep tl7trit'ed.. So the onlv it'nv yott'r.:-going to brenk 

tltnt cycle ts ¡teriodicnllu i.f vou hat,e a certnin amount of time o.ff and vL1:t slee7 during 

tlnt ntigltt be considered your nornnl slee¡: ¡:eriod to restore tlnt. 

Well, at the present time that really is the only effective way. I think that we take 

the position that there's never an adjustment to that type of schedule. You 

referred to night duty...and you would think that if a person did it all the time they 

ought to adjust, ..but all the studies always show impairment in sleep loss. 

Dr. Dent¿nt, . ..u,e're really at the ¡toirrt t'tozt, tchere u,e're going beyortd the ¡thiloso¡slty 

nnd tte'r€ trying to pttt our finger on nunteric !,alues. Our position nt lenst .front tlrc 

pilots' stnnd¡toirrt, is thnt zle see the need -for n l}Jrcur slee¡t o¡:portun:lrtknozting thnt 

tlrc opporttutity may not always be nt the best time of the day. We're.fncing an industry 

position that is looking for I hours as the ntinimum. Our positiort is predicated on the 

5

I'm tv¡ticnlly so sleep deprit,ed that Icnn't wtderstand rest of statenient.] 

Years ago, just to make a dramatic point, we were approached before we knew 

about sleep debt, before we could measure sleepiness. lt was in the 60s we 

were approached by a company that had a billion-dollar bed (ceramic bead bed - 

billions of little beads. They use them now for burn patients. lt's supposed to be 

the most comfortable surface ever. So we got a group of students. We had a 

regular bed, the cold concrete floor condition and the beaded bed. To our utter 

amazement, sleep was the same in all three conditions. The students who were 

doing this were on spring break, they probably had a 10O-hour sleep debt, they 

could probably sleep anyrvhere, and that to me is a symptom of grave concem. 

lf you could sleep anywhere.. anytime you are very sleep deprived....that's not 

good. That's another mythology. People get so macho. Saying that they can 

sleep an¡rwhere is like saying they were drunk or they could drive when they're 

drunk. People misunderstand that. That's a symptom of severe sleep 

deprivation. 

I ha¿e a couple questions. First of all, i-f u,e consider we are dealing with an indiaidual 

u,ho lud no nccrued ;leep debt and tLnt indiuidual autoke in the nrcrning, u,hat does tlrc 

science snv ahout the amount of tinte azt,ake tlnt indiuidual would lwae before, or is there 

anv kini o.f . 

Well. probably if he s getting up in the daytime. that person could not possibly 

sleep rn the daytime. 

I'tttnctti.zli::':i'?¿r0rr;-i/cr'l)urç. l/1r;¿'ion¡r:olr/,ilrcbcntt,nkebefor;ite..... 

Oh. well. maybe 16 hours would be the usual time he's awake. One of the things 

that we -- at least I and I think most of my colleagues -- agree on is that all 

wakefulness is sleep deprivation. ln the model of sleep regulation, you need that 

accumulated sleep debt of 16 hours to, in a sense, power the sleep of the night. 

I.f uou ,ù,ln t ì:'¡t,e a sleep debt, hot ntattv ltours zt'ould vou hn¿e tt"'be n¡t'ake beþrt vott 

coulrl b¿' tthb to tnl

I wanted to say three or four things about sleep. First of all, I'll preface this by 

saying last year when we changed to daylight savings time, there was a National 

Sleep Awareness Week sponsored by the National Sleep Foundation, which by 

the way, is a major resource in the education and is based in Washington. DC. lt 

created a sleep lQ test for the American public. The American public did more 

poorly than chance on this test. Not only then is there a pervasive lack of 

awareness by the general public, but there's also the presence of cerlain 

mythologies which then lead you to'pick wrong answers more frequently than by 

chance alone. A lot of those mythologies are still in the transportation industry. I 

think there is no question about that. 

The first thing that most people should be aware of is very simple: what is sleep? 

The fundamental difference between wake and sleep (and there's some very 

elegant research being presented about what actually goes on in the brain at that 

momentary transition) is that first, the transition is very rapid and can take place 

in less than a second. One moment you are awake and conscious of the outer 

world and then next moment you are asleep and unconscious of the outer world. 

When you're very fatigued, you can go to sleep instantly, and at that moment you 

don't see anything or hear anything. That's what makes falling asleep so very 

dangerous because you will not respond to a signal. The only thing that a 

stewardess could do is to wake you up. Often in a fatigued person, the 

awakening stimulus must be very, very intense. 

So, anyone who thinks that moving towards sleep is in the least little bit safe is 

completely wrong if you want a human being to function at any level at all. The 

transition is very. very rapid. 

Then there's the period of fatigue that I like to call "fatal fatigue" which is 

approaching the moment of sleep and depending on the degree of fatigue. can 

be fairly rapid. But that's a penod of great impairment where you miss signals. 

you misjudge, your memory is impaired. your reaction time is elevated, etc. You 

are now very close to the threshold of unconsciousness....the moment of sleep. 

There's a very dramatic study that I'd like to tell you about because it should stick 

in your memory. You have someone lying on a table with the eyelids taped open 

and a 50,000 power strobe light 6" from the nose. When that thing flashes. the 

table almost wiggles. He is supposed to press a little switch when it flashes, and 

you'll be making it flash and suddenly the person will not press the switch. 

apparently wide-awake. You ask him, "Why didn't you press the switch?" -Well. 

the light didn'1 flash." And if you look at the brain wave recording you'll see that 

there's a micro sleep right at the moment the light flashed. So that's how 

powedul that is. There's been a recent study in heavy trucks with brain wave 

recording in the cab as the drivers are driving, and yes indeed there are lots of 

micro sleeps there. They really do occur. 

2

Going beVond tl.,r.t, u,hat is probably the ntost greatest points o_f contention right n(r¡¿' - 

the debate bet¿uen the pilots and tlrc industry operators - is the fact tlnt the operntors 

would like to extend this reser',e atailability period in excess of zthat vou sßv is 71or 75 

or 16lnurs,u'hatrc,er the case may be, to a Inrger incranent, ertending that reser¿¿ 

auailability period based upon an adttance notice qf a nap opportunity. ln other t'ords, a 

pilot comes on call at 8:00 a.m. He is then told at 9:00 a.m. that he is to rrport for duty 5 

hours later. The industry's position is that the notice constitutes an opportunity.for 

additional rest a'hich then would be utilized to add more restoratiae energy, or analogotts 

to putting more charge into a batten¡, to carry tlut pilot into more of an extended duty 

period zuith nn additional amount of time. . .. up to in ceñain cases 24 hours of dutv. 

What is your feeling on that type of scenario? 

To me, that's a recipe for disaster because if you have a responsible, professional 

pilot -- who has a reasonable schedule, I guess - rvho is not horribly sleep 

deprived, and who has a fairly stable circadian rhvthm, then the likelihood that 

he can get adequate sleep by trying to nap I think is relatively smalt. I would not 

depend on it at all. I would think also to have to do it sort of unexpectedlv like 

this....Oh! Take a nap....Only people who are ven'sleep deprived.... 

Can I nsk that qtestiott a different t,ay? 

Sure. 

Let':;,ztt I lnt¿.; i)-lrcur sltqt t't¡t¡tsytttntt'g: 70 pr.rtt 1.. S a.pl. Thnt ntenns l'm.¡.-.iilnbl¿ 

.ft-¡r7-i /ior¿rs¡¿r:.:s:tlte,t.r7tt nttit'tto t/¡¿n¿i't 10¡r,r'..,':toirig/rf. C¡:¡1,?/ncrf r-¡:.;;n// 

Sou il! rlrrrrll fl)'lr ;.ty tttsteatl o.f vou beittg crff folriÀ'/¡l i! 10 p.nt., z¿'c i¿'¡znf :/o¡t Ícl;¿'r.rk 

until ;c¡,¿n frrrT;-'.ro¡¿' ntonlnt? but vott nrcn't grrirrg 1.. ¡o to i.L,ùrkuntll l0:00 tluti rtight 

So tltn cnli nt¿.1: noon, tlvy gi7,¿ n 7)-lnur notic¿ tiu¡! I'nt not going tohn,,t fo€cr fo 

¡t'ork until 70 Jt,^ws front noon, so ni 2200 I rEtor! .ic.r ,L,c)rk, nnd thzu icutt nte tc. flv 

ttntil 0800. 5o :;i,¡t ,t'otúd he a totnl of 21 lnurs front lit¿ titttt I theoriticallu ,cokt iti, nnit 

l'te hatl h 7}-hc.i¿r notice that I itns goittg to be.flutnq tlti:.fntigttirrg -.che,?ri/e lfì.¡rid 

thnt bc safe? 

lVell, I u'ouìdn't be on vour plane. No. I think that's almost insanity in the sense 

of saving that is safe. First of all, naps can't be depended on - even under ideal 

circumstances - to get vou through this period rçhen the biological clock alerting 

is gone, n'hen r-ou're alone rvith vour sleep debt so to speak, during the \\-oCL. 

There's no \\'a\- that isn't going to be dangerous. l'es, there mar- be exceptions, 

but it's alrvar-s going to be dangerous. The likelihood is not good that vou rtould 

be able to have some kind of good luck that vou did sleep a lot, and that has 

gotten vou through. First of all, vou lvould not be at your peak performance. 

There is just no way. You cannot achieve peak performance during that period 

of time. lr{avbe for 10 minutes. The notion that vou can depend on getting 

adequate sleep I think is just wrong. You can go into a laboratory and you can 

9

So those are the three main things. These are established facts. I don't think the 

scientific evidence is conclusive and those are the things we take into 

consideration when we try to apply the knowledge to the practical or operational 

situation. Any questions on that? 

People say, "Can you accumulate a debt for a year?" We don't know because 

those studies haven't been done. But there's no evidence whatsoever that says 

"No, it levels off," or "No, it changes." All the evidence says that you keep 

accumulating a debt as long as you keep losing sleep below your specific daily 

requirement. There's no evidence that you can change this. I suppose you 

could ski or play basketball as opposed to just sit in a hot room and that would 

make a little difference but that doesn't change your sleep requirement. 

Anybody got any questions? 

l've got a question. Napping: does that in any way alleviate the sleep debt? 

Let's say you have a 4O-hour sleep debt and you have a ten-minute nap. So now 

your sleep debt might be 39 hours and 50 minutes. lt wouldn't make any 

difference there. A lot of the napping is done after lunch. Most people, and 

especially younger people - and I don't know what the average age is in this 

group - but younger people have strong clock-dependent alerting late in the day. 

So you have sort of an illusion. You happen to take a nap just before the clock 

turns on. ls the alerting partly a result of the nap or not? Mostly not, but I would 

say until proven otherwise that a nap, if it is good sleep (which it usually isn't) is 

minute per minute doing what sleep would do, but it's usually nowhere near the 

total amount that you require. 

Dr. Denrcnt , I lt,z,,e a list o_i quesf ion-ç tlnt pertain to our task of l;al¡tirtg to de.fine flight 

ttme and dutv ttnte regulntiorts nnd i.f I could just take the libertv o.t asking these 

¡tarttcular questiorts and opn up the .floor.ior any other rennining questions that other 

people may hat'e. One o_f the most basic tasl

could certainiv get the probabilitv up, but it's not something that you could ever 

really control. Ågain, there ought to be a better war'. 

Tluzt's the problem: a better tav. Understnndably, tl:rr.t': not desirable l¡ut the questiort 

is: how do vott best prepnre .for tlnt? 

You're saving if the notice is given with the 10-hou¡ rvindow? 

Mnnagement u'ould like a 7}-hour notice. 

It r.r'ould seem to me that a better approach would be to have a 24-hour window 

or some longer period. Say you get notified the dav before. I suppose there are 

emergencies and so on, and you would be called for those exceptions... and a 

pilot would have so manv exceptions over such and such portions of time 

depending on the emergencies and whatever constraints.... 

Some types o.f operations operatt u'ithout a schedule. 

That's the rr'orst. 

l1:.t.'e 2 qrrisfrr-'r:-., doctor. First. a person thnt has ndequile sleep itakes upt rnn- slerp 

,i¿,.'ri,,ed at E:0(t -i t¡t. Fourt¿¿n ht'lurs later it's 2200 nni |w's ¡lri',ing:lnnte front dínner 

.r'::jr hi-ç r¿';t I: !rc inrytntrt,l? 

I heve to sar it Cepends on h¡s aee probablr'. The r:.pairment is starting 

probabir'. \'ou Con't go straight don'n; \'ou go dorrn n'ith an accelerating level of 

rmpairment. \lost of the studies in the laboraton'sav depending upon n'here 

vour mid dar iip is, r'our performance will start de,-reasing in the late evening. 

I'm thinking ltì:00. 

I.f t7 persotl ¡¿'n-r jo.flr¡ -so ns f rr stLlD _flvùlg nt 8:00 n.nt. an,i he ¡t'as to flv tltrottglnut the 

0:00 - 0600 ttn:¿ frnnte, ir.'!ut! !:,ne sltould he be zt'nkinq :¿p in ortier to be best prepared 

i¡, llnt fliglú tl:-tt Innds nt 6:00 :t.nt.? 

I know vou said he's flr-ing. He's rvaking up? 

\o Wrcn slro¡r/d lrc u,nke up to be best prepared for a.t't:Eht tlmt zuottld include Innding 

nf 8:00 n.nt ? li he starts at ntidnight. Hozt, do you Set ¡tr¿p¡¡rrd for tlnt e-aen if (I'nt not 

ttzlking about re:er,'e or anvtltir¡ql.. .Wlnt should a pilot '7o,ltozt, sltould he plan his day 

tt.t iLlale up nt the right tinte to be nnst alert at 8:00 a.nt.? 

11

-fact thnt t hours nny be adequate if it ot,erlaps the WOCL. But since î.te ¿on'¡ ¡çns7u for 

sure zcltnt ,t'e're goirtg to lnt'e tlut opportunity, we beline that, or ue think that luaing 

that ertra 2 hours is goirrg fo g::'e us a little more of a buffer, especiallv ¡t'hen it conrcs 

during tlrc dnr¡tinrc. Would uoit consider tJnt to be a conser¡tatit,e and n iustifted 

position? 

Absolutely. I don't think you could poss¡bly assume someone is going to fall 

asleep instantly and then sleep continuously for I hours, not even under the most 


By the *me tolcen, say that sam.e indiuidual who was supposed to sleep had the perfect 

time during the day and utas supposed to slerp during the day, hndn't slept the preoious 

night and he had normal sleeping hours because he was not disturbed.for any duty 

assignment. What effect does that haae on his subsequent rest period? 

ln the ideal situation if someone sleeps the normal amount at night, they can't 

sleep at all during the day. We are pretty much a sleep-deprived nation so that 

we do have this mid day dip in alertness. Most people say they get drowsy after 

lunch. That's sleep deprivation. lf you were not dealing with someone who is 

extremely sleep deprived. then I would say sleeping a normal amount at night 

becomes very difficult, or it should become very difficult to sleep in the da¡ime. 

That is a fact if the carryover sleep debt isn't large, it's definitely more sensitive to 

stimuli. etc. and you're fighting the biological clock for much of the day. 

Have you ever conducted these tests when they're wearing a uniform? 

[Laughter] Well, we did some testing but I think they took them off when they 

went to bed. 

I .flv a! nigltt all tltc tinte nnd crlv get rest dtring tlv tlny . I henrd tlni i.f vott sleep 

during the o¡ttimum tinte o.f d¡v vou reallv need to ltnt,e about a 7}-hour period in zthiclt 

l¡-t get uottr 7 V: or I |rcurs of -.,';+' I.f you do not e-L,er hnLte the opporttntity to sleep for 7 

- 10 d,lvs in a ro¡t', L/ou dr€ ne'¿r nble to slee¡s during the optinntm tim¿. I heard you sn7 

tlnt uott ali.t'nys need nrcre thnt: 70 hours to get el,en reasonnble sleT, e .'en though yott 

¡srobnblv nerer icill acltir¿e ai,¿.¡unte sleep. C'm you lut any kind o_f t ntmtber on the 

gros-ç tTntount o_f tinte Vou coul.ì ltaxe n,,ailnble .for sleeyt op¡tortwtittt to tn/ to restore 

sle4t? 

The problem is that there becomes inefficiency. You don't want to spend 16 

hours in bed to get I hours of sleep. There just isn't a good solution to be 

perfectly honest. The main thing you need to know then is first, at what period of 

the day in your clock (God knows where your clock is) there is some period when 

it's the most difficult to sleep. Hopefully you know that about yourself. Obviously 

you avoid that. lf you can schedule more than 10 hours, not at that time, then 

you yourself will need to determine if you can do it in a minimum of 10 hours, or 

does it take 13. That would be a horrible life.. to spend all that time in bed.

that h'OCL, if you will. \4hether it's low because vou napped or lorv because 

you got lots of sleep the night beiore doesn't matter. Both would be the best. 

Shotild vou stay up ttntil 3:00 ,2.m. so yott can sleep later in tlæ aftentr'tvt? 

Not necessarily, no. 

Shotild vou stick with normal sleeping and then try to get a nap befort vott 8o to u,ork? 

Yeah, I would say as much sleep as possible. But here again you need to know 

yourself a little bit. But that's not what rulemaking is aX about. Rulemaking is 

what fits everybody. Because of the uncertainty of being able to take a nap, I 

mean it's uncertain for me and I think it's uncertain for pilots. Although again, 

since pilots are generally more sleep deprived, they are more able to nap. If vou 

felt able to take a nap with absolute certainV, then you should take a nap. But 

also get vour needed amount of sleep the night before. 

Wdre shooting around the sub.iect. I hate to break any of this up, but this question has 

been plaguing this committee. The industry lcerps harping on the fnct that there should 

be rn difference bet'r.teen the schedule holder who knou,s he's gttt to _fly _fron, nidnight to 

8:00 a.nt I.f he cnn do it sa.felv . zuhv can't a r€s€r'c1€ that u,alce: up nt llte snnte time in the 

ntorninl (6:00 n.m. or 6:00 a nr.) WAnl is it not safe for this reserce'-'!!ot ¡cl:¡ does it 

¡t'itlt r -':ice? 

I dor. : :hink it's safe for er:her ¡ilot. 

perfornance, etc. But I tfr-ink at least he has preparahon. l\'alTrng, etc. and 

knorss his on'n strengths and u'eaknesses n'hereas the trther p:.r-rt I think is 

alrçar-s n'ithout u'arning ánd has reallv no chance to prenare. I don't think the 

t\\'o EToups are the same. 

Ìvf avbe a little less CangeÍtìuS in the sense of 

Are vtri inrytluing that the preparntion should ncttnlly stnrt tltt preT':''tt; r:ighf ? 

Yes. Ir I rçere going to drive all night, I rvouldn't rvant someone to tell me that 

dar' 

Thru'r¿ renllV killittg us .for ntnktng thnt stune argttnrcnt. I n:¿.ttt ¡¿'i "lnkc tint argurrtent 

nrrpss :he tnble nntl îte get sntiles nnd nods o.f the lrcn,l nnd sl:rugs o.; tlte slnulders.front 

fh¿ollr.-rsi,ic. TJrcvsnv if '-< rlcrl nt'nlidnrguntent' Tlnt's n/;¿'¡vs zcii-'¿t tltat cotneuP 

¡¿'if/r. 

Ther--v it's not a valid argument? It is a supremelv r-alid argument. I mean 

that's iust like saving dou-n is up- 

13

you tolerate before you have a micro sleep? Two or three hours? Under 

ordinary circumstances, daytime sleep is difficult. 

l: there anything definitit,e tlut says u,hich o_f these tu,o situatiotts ztould be more 

.fatiguing: an indi-',idtnl tho hns to stay up until 3:00 a.m. or an indbidual who is forced 

to ztake up nt 3:00 a.nt.? 

That's a good question. I would think both would be fatigued and it's so the 

pattern might be a little different, but it would depend on how much sleep they 

had prior to that. I would think though that going into action at 3:00 a.m. for most 

people you'd be extremely impaired. On the other hand, some people, as you 

get after midnight, become extremely impaired also. I don't think they've ever 

been compared head to head, but those are the kinds that would impair 

per{ormance. Period. There's a thought that people somehow get enough 

adrenaline. Certainly students in exam week somehow get so stressed and so 

anxious that they seem to be able to go a little longer. lt's obvious that they're 

paying a price when you look at them aftenryards. That's not something to rely 

on. To me, it's only when you're trying to rescue people or something that you 

would want to do that sori of thing. 

Dr. Dement, after our reserùe pilots receiz'e their sleep opportunity, tlrct¡ become az:nilable 

.for dutv. We call the dt'ailability period the "reser,'e at,ailabilitv period" and that's 

b.t:tcnlltt the time tlrcu .tre a.'ailable.for ¡t'ork, _for.flving. A.fter tlrc slerp opportunity, 

:.'i;.rf ¡¿'crr¿/d vou ccln-i¡r/ir to be a safe lintit L1f tinrc since ait,nke iùr a cr¿';ctnemberT 

For the 10-hour period? 

\ '--: 

Fourteen hours. And I wouldn't say that's 1009'" safe but if you have a number, 

that adds up to the 24-hour day. lt ought to be reasonably safe. 

l\here do yott get vour ttuntber from? 



the biological clock. lf you're getting outside the 24-hour cycle. then you're going 

to have periods of greater risk. I realize that operationally that's probably difficult, 

but.... 

Tltnt assuntes tlut the indit'itlunl it'akes up as soLlrl as hi-s protected tinte period is ot,er. 

Sc'' in otlrcr zu,ords, vou see a contplimentary -factor: t hours of rest should dictate a 75- 

I: r. u r a ¿ailabil ity p erio d ? 

Yeah. I think most people rvould agree that would be the ideal. 

I

It seems likc contnton sense. Fntrlv oht,ious. One other quick tyuestiott. /l s¿c'n¡s tct be the 

îL1nV Vou zt'ere goirtg is that hoiu ntuch notice Vou're giten is not as importnnt as i¿,hen 

tlrc notice.falls. In other uords, then the opportunity to rest based on this notice of 

assignment, is that a fair assun+ttion? 

Well, the h+'o aren't exactly the same. I don't mean to implv that r+'hen....I mean, 

the longer vou have, the better. I guess I don't understand your question. 

WelI, that's kind of itlat I'm gettirtg at. I guess it is.... 

I mean, generally you don't get the notice in the middle of the night, do you? 

WeII, it would kind of depend....-,De're dealing with round-the-clock operations so ute may 

laae situations where nn indiuidual's protected time period this time he's strpposed to be 

sleeping actually starts at 7:00 a.m. and goes to 3:00 in the afternoon. So he might get 

notice in the middle o.f the night -for an assignmnt that comes xùsequent to thnt later on. 

So we're dealing ztith round-tlrc-clock operations and no guarantees..... 

I rvould think notice in the middle of the night is useless. First of all, you disturb 

the sleep and secondly it doesn't reallv help r-ou with the next dav any more than 

notice at 6:00. 

'.i nlltlt¿nt tlnt ut¡u r'¡ r¡of t:le4t,l nt¿.¡,t thnt it's t1t'¡t ut''ur nonn,zl sleeTt fi¡yls. 

:.ìj vr'l¿'rc'-i,?r/il7g i-ç f l:-ij lJ i:rrllrs l¡crl:.j tr 7) iL,ottld bt !',etter th,ln 70 itt'tst 

Yeah. .{Ì1 other things being equal 

Dd qou et'er _flr¡ tlrc núclniglrf .fl;ghts? 

No, not anvmore. 

Especiallv a.fter todntt, right? 

Doctor,l,llike tt'¡ tlút:Jzt'e'db¿ .zble tc¡ negotintt:ontetlting |iltt vt',tt said: a 7}-hc'ur rest 

¡teriod ani n T[-lrcur ntañntunÌ rescrL'c attnilabtl:lv period, hut un.fortttnntelv, thnt's n 

,'ery high ¿rpectntion. Wnt r¿'¿ ¿'i// be facing ts itln1€r perit'tds ¡.f reserre n',nilahility. 

Bnsed on tlrc 

-fnct thnt ¡.t,e ztill h¿ _fncing potentinliu onerous, Iong ¡teriods o_f tinte since 

ttiL'ak€,lt'tng r€s€fcte amilnbilitu periods, do yott tltink that being afforded n greater 

nnrcunt o.f slee¡t opportunity zcill gioe us ntore o.f 

't ¡trotection agninst that longer dutyT 

Is tltere a relationship as far as the antouttt of restorntiae sleep ns preparation for longer 

period of dutv? 

15

do some studies and vou can demonstrate that occasionally someone r+'ill. 

perform prett]'well, but that's not 100oo er-er. It's never Eetting back to peak 

performance and it's under the luxuriou-. circumstances of no interruptions, no 

noise, etc. I u'ouldn't ever think that napping could make it safe going through 

the night. 

How about that the flight is going to happen. There is going to be eæry day in America, 

pilots thnt report to work at 2300 or whatr;er and fly until0800 the next morning. 

No'u, what's different about the man who htm.us A tueek, a month in adaance that this is 

going to be his schedule and the reseroe pilot -,tho finds out at noon after haaing woken 

up at 8 a.m.? Whnt would be the difference? 


situation. . ..You can never get to perfection, but the more practice, the more 

warning, the better you'll be able to handle it. Some people learn that there is a 

time when it's quiet and if I do this,I ca¡r pretty much depend that I will fall 

asleep. It's not 100o'o but vou kind of leam that or you practice or whatever. But 

if it's r,r'ithout warning, all bets are off. 

Dr. Demerit, vou' ¿e kind of led the discusstc'n into another area of this rulentaking tlnt 

has to do zt,ith an altnnatit,e method. Assuniing that the pilots in this protected tintc' 

period method ¡t,ere depleted, tlrc carriers ti'¿tt u,nnt to gile pilots ad?ßnce notice f o co¿'er 

nnvntissionLlrnnv rl-.s;-gnntertf . Tlrcuare,,--'

All sorts of things happen, but the major thing of course is that vou are norv 

trying to sleep when the body wants to be awake and you're t -ving to be as-ake 

*'h"r, the body n'ants to be asleep because vou left the circadian stabilih' that 

vou talked about. 

[Question cannot be heard] 

No, I think in summary, ....science is really clarifying these issues that people 

have been struggting with for many years, and there is always a resistance to 

change. But I think one of the things that we confronted in our Congressional 

commission is that a lot of the bad effects of sleep loss and impaired performance 

are frequently not obvious because there has not been a history of really looking 

for them. One of the studies that impressed me the most in that regard was an 

anonymous survey of hospital house staff. I don't remember the exact question, 

but ii was that 42% rn this anonymous survey had killed a patient as a result of a 

fahgued-based error. Well, who knor¡'s that? Who wants to know it? If we had 

the por.r'er to really take a look at the price of fatigue, it would be enormous. I 

think these things are just beginmng to emerge and thev seem to threaten 

management, threaten economic realities, but I think once there's this move 

torvard help and peak performance and utilizing all this scientific knorvledge 

that even-one r.r'ill benefit. There rtill be \\'avs to deal with these things and it 

rvill get t'etter and better and the benefits rvill be recognized more and more. I 

think one of the problems in the trucking industn'is the same kind of thins: 

rvhat's the cause of all the crashes? Frequentlr', these causes aren't reallrassessed, 

and the public doesn't recog¡ize the liabilitt', but it's cominq. I'm sure 

at some point it's better to be safe than to be sorn-. Because sorrv is lau'surts and 

lost lir.es, tremendous damage to properfr'. Those things are going to be equated 

sooner or later. 

END TAPE 

17

First of all, why does he have to rvake up at 8:00? 

No, no. He's flying at 8:00. H{s flving from midnight to g:00 

oh, okav. But basicallv what should he do the day before if it,s a midnight 

flight? I assume sleep as late as possible. 

On his normal sleep cvcle lilce you first said? 

Yeah. 

And then what? 

And he's free all day? 

Yeah. He doesn't haise to do anything.... 

If he knows that he has this post prandial period of diminished alertness , I 

would tT'to take a nap at that point in time. 

Late aftentoon? 

Yeah. 

I tlon't knr'.¿' ttlnt lto:!t rnntii,zl . .. 

It means after lunch. Parentheticallr', I'r'e been rvorking rr-ith students and l,r.e 

been finding þecau-se I'r'e t'een n'orking rvith .'"r,,- ,*ulll groups) that if the,v. 

start bv learning hors much sleep thev need as an indiçidual, when is their iime 

of peak learning, rvhen is their circadian nadir, thev are able to make some 

choices in preparation for exams, etc. that are a great improvement over their 

previous situation rr-here thev didn't know these things. lVhat vou're trying to 

do is to get your sleep debt "t lo*' as possible and utilize ¡,hat \.ou kno*, about 

vourself to accomplish that. Part of it rçould be, as a responsibie pilot, you 

rvould do that as kind of a lifestvle. Mavbe the lifesh le is changr"g u tittt" bit b,ut 

vou're alrçavs trving to keep vour sìeep debt lor+' so \-ou ne\-er have to do 

üï:' iåi"ï'å'"iï;:,ïÍï:ï:;ï:'"ff:, 

best pre night before. Tie pilots in ihis NASA 

lavover naps. Not perfect, but pretty 

good. We decided the rea ere sleep dåpriyed. Thäy could 

take a nap. So there's that n the issue is lvhether or not the 

sleep closer to the duh-pe rily better. I don't think it matters. 

when you start that period, rvhat is your sleep debt r.r,hen you,re going to go into 

12

Fatigue, Alcohol and Perforrnance Impairment 

Nature. Volume 388, July-August 1997 

Reduced opportunitv for sleep and reduced sleep qualiqv are frequently 

related to accidenls involving shift-workersr'3. Poor-qualiry sleep and 

inadequate recovery leads to increased fatigue, decreased alertness and 

impairìd performance in a variety of cognitive psychomotor testsa. However. 

the risks associated with fatigue a¡e not well quantified. Here we equate the 

performance impairment caused by fatigue with that due to alcohol 

intoxicauon, aná show that moderate levels of fatigue produce trigher levels of 

impairment than the proscribed level of alcohol intoxication. 

Forty subjects participated in two counterbala¡lced oçeriments. ln one 

they were irept áwake for 28 hours (from 8:0O until l2:AO tl.e following day)' 

rtrá itt the other they were asked to consume lO-l5g alcohol at 3O-min 

intervals from 8:OO until their mean blood alcohol concentration reached 

O.lOo/0. We measured cognitive psychomotor perfolrnance at half-hourly 

inten'als using a computer-administered test of hand-eye coordination (an 

unpredictablekacking task). Results are expressed as a percentage of 

performance at the start of the session. 

performance decreased significantly in both conditjons. Between the 

tenth and twenty-sixth hours of wakefubress, mean relative performance on the 

tracking task decreased bl'O.71o/o per hour. Regression analvsis in the 

sustainéd wakefulness condition revealed a linear correlation betrveen meart 

relatir-e performance and hours of rvakefulness that accounted for roughlv 90% 

of the variance (Fig. ta). 

Regression analvsis in the alcohol condition indicated a significant linea¡ 

correlation between subject's mean blood a-lcohol concenlration and mean 

relatiçe performance tfrat accounted for roughlv 7Oo/o of the variance (Fig. lb). 

For each O.Ololo increase in blood alcohol. performance decreased by 1.1602ô. 

Thus. at a mean blood alcohol concentration of 0.100/0. mean relative 

performance on tJ.e tracking task decreased. on average b]- I L'60lo' 

Equating the two rates at which performance declined (percentage 

decline per hour of wakefulness and percentage decline rvith change in blood 

alcohol concentration), rve calculated t-Ìrat the performance decrement for each 

hour of wakefulness behveen i O and 26 hours was equivalent to the 

performance decrement obsen'ed with a O.OO4o/o rise in blood alcohol 

concentration. Therefore. after I7 hours of sustained rvakefulness (3:OO) 


p.kor-*cè impairment observed at a blood alcohol concentration of 0.050,0. 

This is the proscribed level of alcohol intoxication in marl\- rvestern 

industrializèd countries. After 24 hours of sustained rvakefulness (8:00)


performance deficit observed at a blood alcohol concentration of roughly 

O.l0o/0. 

Plotting mean relative performance and blood alcohol concentration 

'equivalent' against hours of wakefulness (Fig. 2), it is clea¡ that the effects of 

moderate sleep loss on performance are simila¡ to moderate alcohol 

intoxication. As about 5Oo/o of shift.-workers do not sleep on the day before the 

fìrst night-shifts, and levels of fatigue on subsequent night-shifts can be even 

highef. our data indicate that the performance impaiment associated with 

shift.-work could be even greater tha¡r reported here. 

Our results underscore the fact that relatively moderate levels of fatigue 

impair performance to an extent equivalent to or greater than is currently 

acceptable for alcohol intoxication. By expressing fatigue-related impairment 

as a'blood-alcohol equivalent', we can provide policy-makers and the 

communit-v with an easily grasped index of the relative impairment associated 

with faugue. 

[Note: Refvped. Endnotes and Figures I and 2 are illegible and have been 

omitted.l 

Dreu'Dau'son 

The Cenrre for Sleep Resea¡ch 

The Queen Elizabeth Hospital 

Kathnn Reid 

Departrnent of Obstetrics and Gynecolog,' 

The Queen Elizabeth.Hospital 

Woodrille. 501I South Australia Woodville. 5011 South Australia 

e-mail : ddarvson @ tqeh. smtp. tgeh. sa. qo\'. au 

2

ng the Performance Impairment associated 

with Sustained Wakefulness 

Nicole Lamond and Drew Dawson 

The Centre for Sleep Research, The Queen Elizabeth Hospital, South Australia 

March / April 1998 

S ustai ned lV.akefulness and Performance 

Address allcorrespondence to Drew Dawson, The Centre for Sleep Research, The Queen Elizabeth 

Hospital, Woodville Rd, Woodville SA 501l- Australia. 

Phone: +61 8 82226624. Fax: +61 8 822?6623. 

Acknowledgments: Research supported by the Australian Research Council.

SUMMARY 

The present study systematically compared the effects of sustained wakefulness' and alcohol 

intoxication on a range of neurobehavioural tasks. By' doin,e so, it was possible to quantify the 

performance impairment associated with sustained wakefulness and express it as a blood alcohol 

impairment equivalent. Twenty-two healthy subjects. aged l9 to 26 years. participated in three 

counterbalanced conditions. In the sustained wakefulness condition, subjects were kept awake 

for twenty-eight hours. In the alcohol and placebo conditions, subjects consumed either an 

alcoholic or non-alcoholic beverase at 30 minute intervals, until their blood alcohol concentration 

reached 0.1OVo. In each session, performance was measured at hourly intervals using four tasks 

from a standardised computer-based test battery. Analysis indicated that the placebo beverage 

did not significantly effect mean relative performance. In contrast, as blood alcoholconcentration 

increased performance on all the tasks, except for one. significantl¡' decreased. Similarly. as 

hours of wakefulness increased performance levels for four of the six parameters si_enificantly 

decreased. More importantlr'. equating the performance impairment in the two conditions 

indicated that. dependin-s on the task measured. approximately 20 to 25 hours of wakefulness 

produced performance decrements equivalent to those observed at a BAC of 0.l0Vc. Overall. 

these results suggest that moderate levels of sustained wakefulness produce performance 

equivalent to or greater than those observed at Ievels of alcohol intoxication deemed 

unacceptable rvhen driving. working and/or operatin_s dangerous equipment. 

KEY WORDS sustained wakefu lness, alcohol intoxication, performance impairment

INTRODUCTION 

The negative impact of sleep loss and fatigue on neurobehavioural performance is *'ell 

documented (Gillberg et al., 1994; Mullaney et al., 1983: Tilley and Wilkinson, 1984). Studies 

have clearly shown that sustained wakefulness significantly impairs several components of 

performance, including response latency and variability'. speed and accuracy, hand-eye 

coordination, decision-making and memory @abkoff et al.. 1988; Linde and Bergstrom, 1992; 

Fiorica et al-, 1968). Nevertheless, understanding of the relative performance decrernents 

produced by sleep loss and fatigue among policy-makers, and within the community, is poor. 

By contrast, the impairing effects of alcohol intoxication are generall,"- well accepted by the 

community and policy makers, resulting in strong enforcement of laws mandating that individuals 

whose blood alcohol concentration exceeds a certain level be restricted from driving, working 

and/or operatin-q dangerous equipment. Consequently, several studies have used alcohol as a 

standard by which to compare impairment in psychomoror performance caused by other 

substances (Heishman et a\..1989: Dick et al. 1984: Thapar et a\..1995). By usin_e alcohol as a 

reference point, such studies have provided more easiJy grasped results regarding the 

performance impairment associated with such substances. 

In an attempt to provide policy makers and the community $ ith an easily understood index of the 

relative risks associated with sleep loss and fatigue, Das'son and Reid (1997) equated the 

performance impairment of fatigue and alcohol intoxication using a computer-based unpredictable 

tracking task. By doing so. the authors demonstrated rhat one night of sleep deprivation 

produces performance impairment greater than is currently acceptable for alcohol intoxication.

t, 

While this initial study clearly established that fatigue and alcohol intoxication has quanrirarively 

similar effects, it should be noted that performance on only one task was investigated. Thus, it is 

unclear at present whether these results are restricted to hand-eye coordination, or characteristic 

of the general cognitive effects of fatigue. While it is generally accepted that sleep loss and 

fatigue a¡e associated with impaired neurobehavioural performance, recent research suggests that 

tasks ma¡'differ substantially in their sensitivity to sleep loss. Studies addressing this issue have 

suggested that tasks which are complex, high in workload, relatively monotonous and which 

require continuous attention are most vulnerable to sleep deprivation (Johnson, 1982, Wilkinson, 

t9&). 

As conditions that cause deterioration in one particular function of performance may leave others 

unaffected. it is unreasonable lo a-ssume that one could predict all the effects of sleep loss from a 

sin-ele perlbrmance test. Thus, the current study sou-eht to replicate and exrend the initial f,rndings 

of Dawson and Reid (1997) by s¡,stematically comparing the effects of sleep deprivation and 

alcohol intoxication on a ran_se of performance tasks. 

4

I\fETHOD 

Subjects 

Twenty-two participants, aged 19 to 26 years, were recruited for the study using advertisements 

placed around local universities. Volunteers were requi¡ed to complete a general health 

questionnaire and sleep/wake diary prior to the study. Subjects who had a currenr health 

problem, and./or a history of psychiatric or sleep disorders were excluded. Subjects who smoked 

cigarettes or who were taking medication known to interact with alcohol were also excluded. 

Participants were social drinkers who did not regularly consume more than six standard drinks 

per week. 

Performance Battery 

Neurobehavioural performance was measured using a standardised computer based test battery. 

The apparatus for the batten' consists of an IBM compatible compurer. microprocessor unit. 

response boxes and computer monitor. Based on a standard information processing model 

(Wickens, 1984). the batten sought to provide a broad samplin_e of various components of 

neurobehavioural performance. Four of twelve possible performance tests were used, such that 

the level of cognitive complexity ranged from simple to more complex (as listed below). Since 

speed and accuracy scores can be effected differently by sleep deprivation (Angus and 

Heslegrave. 1985; Webb and Levy, 1982). tasks that assessed both were investigated.

The simple sensory comparison task required participants to focus on an attention fxing spot 

displayed on the monitor for 750ms. Following this, a line of stimulus characters, divided into 

three blocks of either numbers, letters or a mixture was displaved. Participants were then required 

to respond to a visual cue, which appeared in the position of one of the stimulus blocks, by 

naming the block, which had been there. Verbal responses were scored as correct. partially 

correct or incorrect. 

The unpredictable tracking task (three-minute 

the position of a tracking cursor by centering 

time on target was the performance measure. 

trials) 

it on 

was performed using a joystick to control 

a constantly moving target. Percentage of 

The vigilance task (three and a half minute trials) required subjects to press one of six black 

buttons or a sin-sle red button. dependine on which lieht 'À'a-s illuminared. If a single lieht was 

ilìuminated. subjects rvere required to press the corresponding black button underneath it. If 

hou'ever. two li-ehts were illuminated simultaneously'. subjects were required to press rhe red 

button. For this report. two vigilance measures '*'ere er aluated: I ) the number of correct 

responses (accuracy). and 2) increases in the duration of responses (response latency). 

The grammatical reasoning task required subjects to indicate u'hether a logical srarement. 

displayed on ¡he monitor, was tn¡e or false. Subjects \\ ere presented with 32 statements per trìal, 

and instructed to concentrate on accuracy. rather than speed. Both accuracy (percentage of 

correct responses) and response latency were evaluated in this report. 

6

During test sessions, subjects were seated in front of the workstation in an isolated room, free of 

distraction. and were instructed to complete each task once (tasks were presented in a random 

order to prevent order effects). Each test session lasted approximately l5 minutes. Subjects 

received no feedback during the study, in order to avoid knowledge of results affecting 

performance levels. 

Procedure 

Subjects participated in a randomised cross-over design involving three experimental conditions: 

l) an alcohol intoxication condition.2) a placebo condition. and 3) a sustained wakefulness 

condition. During the week prior to corrrmencement of the experirnental conditions, all 

participants were individually trained on the performance battery, to familia¡ise themselves with 

the tasks and to minimise improvements in performance resulting from learning. Subjects were 

required to repeat each test until their performance reached a plateau. 

The subjects reported to the laboratory at 8:00pm on the night prior to each condition. Prior to 

retfing at I l:00pm, subjects were required to complete additional practice rrials on each tasks. 

Subjects were woken dt 7:00am, following a night of sleep, and allowed to breakfast and shower 

prior to a baseline testins session. which started at 8:00am. 

Alcoltol I n¡ orication C onditiott 

Subjects completed a performance testing session hourly. FolJowing the 9:00am testing session, 

each subject was required to consume an alcoholic beverage, consisting of -10 percent vodka and 

a non-caffeinated softdrink mixer, at half hourly intervals. Twenty minutes after the consumption 

of each drink, blood alcohol concentrations (BAC) were estimated using a standard calibrated

eathalyser (Lion Alcolrneter S-D2, Wales). accurate to 0.0057o BAC. When a BAC of O.lOVa 

was reached no further alcohol was given. Subjects were not informed of their BAC at anytime 

during the experimental period. 

Placebo Condition 

The procedure for the placebo condition was essentially identical to the alcohol condition. 

Subjects in the placebo condition had the rim of their glass dipped in ethanol to give the 

impression that it contained alcohol. To ensure that subjects remained blind to the treatment 

condition to which they had been allocated. approximately equal numbers of subjects received 

alcohol or placebo in any given laboratory session. 

S us t aine d W akefulne s s C ondit i on 

Subjects u'ere deprived of sleep for one ni-eht. During this time, they completed a performance 

testin-e session every hour. In between their testing sessions, subjects could read. write, watch 

television or converse with other subjects. but were not allowed to exercise. shower or bath. 

Food and drinks containing caffeine were prohibited the ni-eht before and during rhe experimental 

conditions. 

Statistical Analysis 

To control for inter-individual variability' on neurobehavioural performance, test scores for each 

subject \À'ere expressed relative to the average test scores they obrained during the baseline 

(8:00am) testing session of each condition. Relative scores within each interval (hour of 

wakefulness or 0.017c BAC intervals) were then averaged to obtain the mean relative 

performance across subjects. Neurobehavioural performance data in the sustained wakefulness

and alcohol intoxication conditions were then collapsed into two-hour bins and 0.027c BAC 

intervals. respectively. 

Evaluation of systematic changes in each performance parameter across time (hours of 

wakefulness) or blood alcohol concentration were assessed separately by repeated-rneasures 

analysis of variance (ANOVA). with significance levels corrected for sphericity by Greenhouse- 

Geisser epsilon. 

Linear regression analysis was used to determine the relationship between test performance, 

hours of wakefulness and alcohol intoxication. The relationship between neurobehavioural 

performance and both hours of wakefulness and BAC a¡e expressed as a percentage drop in 

performance for each hour of wakefulness or each percenta-qe increase in BAC, respectively. For 

each perforrnance parameter. the percentage drop in test performance in each of the two 

conditions was also equated. and the effects of sustained waliefulness on performance expressed 

as a BAC equivalent.

RESULTS 

Alcohol Intoxication Condition 

Table I displays the results of the ANOVAs run on each perforrnance variable as a function of 

BAC. Five of the six performance pararneters significantly (p = 0.0008-0.0001) decreased as 

BAC increased, with poorest performance resulting at a BAC of 0.10 or greater. 

The linear relationship between increasing BAC and performance impairment was analysed by 

regressing mean relative performance against BÅC for each O.OZVo interval. As is evident in 

Table 2, there was a si_enificant (p = 0.0132-0.0002) linear correlation between BAC and mean 

relative performance for all of the variables except one. It was found that for each 0.017c 

increase in BAC, the decrease in performance relative to baseline ran.sed from 0.29 to 2.68%. 

Placebo Condition 

To ensure that differences in performance reflected only the effects of actual alcohol intoxicarion 

a placebo condition w'as incorporated into the study. As indicated in Table l, mean relative 

performance in the placebo condition did not si_enrt-rcantly varv. 

Sustained Wakefulness Condition 

Table I displays the results of the ANOVAs for each performance variable as a function of hours 

of wakefulness. Four of the six performance parameters showed statistically significant (p = 

0.0001) variation by hours of wakefulness. In -general, the hours-of-wakefulness effect on each 

performance parameter was associated with poorest performance resulting after 25 to 27 hours of 

wakefulness. 

l0

Since there is a strong non-linear component to the performance data. which remained at a fairly 

stable level throughout the period *'hich coincides with their normal waliing day, the performance 

decrement per hour of wakefulness. was calculated using a linear regression between the 

seventeenth (equivalent to I l:00pm) and twenty-seventh hour of wakefulness. 

As indicated in Table 2, regression analyses revealed a significant linear correlation (p = 0.00tt- 

0.OO0l) between mean relative performance and hours of wakefulness for four of the six 

performance variables. Between the seventeenth and twenty-seventh hours of waliefulness, the 

decrease in performance relative to baseline ranged from 0.61 to 3.35Vc per hour (Table 2). 

Sustained Wakefulness and Alcohol Intoxication 

The primary aim of the present study 'Å'as to express the effects of SW on a range of 

neurobehavioural performance tasks as a blood alcohol equivalent. Figures I -6 illustrate the 

comparative effects of alcohol intorication and sustained wakefulness on the six performance 

parameters. \lhen compared to the impairment of performance caused by alcohol at a BAC of 

O.l}Vc. the same degree of impairment was produced after 20.3 (-erammatical reasoning response 

latency). 22.3 (r:i-eilance accuracy). l-1.9 (vi_eilance response latency) or 25.1 (tracking accuracy) 

hours. Even after 28 hours of sustained wakefulness. neither of the remaining two performance 

variables (grammatical reasoning accuracy and simple sensory comparison) decreased to a level 

equivalent to the impairment observed at a BAC of 0.lÙVo. 

ll

DISCUSSION 

In the present study moderate levels of alcohol intoxication had a clearly measurable effect on 

neurobehavioural performance. We observed that as blood alcohol concentration increased 

performance on all the tasks. except for one, significantly decreased. A similar effect was 

observed in the sustained wakefulness condition. As hours of wakefulness increased performance 

levels for four of the six pararneters significantly decreased. Comparison of the two effects 

indicated that moderate levels of sustained wakefulness produce performance decrements 

comparable to those observed at moderate levels of alcohol intoxication in social drinkers. 

As previous research has found that some individuals tend to perform in a manner that is 

consistent with the expectation that they are intoxicated due to alcohol consumption 

(Brechenridge and Dodd, l99l). a placebo condition *'as included in this study. We found that 

the placebo beverage did not signifrcantll effect mean relative performance. Thus. it was 

assumed that performance decrements obsen'ed during the alcohol condition were caused solell' 

by increasing blood alcohol concentration. tor.ol.r. it is worth noting that the placebo 

condition in this study generally did not create the perception of alcohol consumption. 

Furthermore, when participants had already experienced the alcohol condition, and thus the 

efiects of alcohol on their subsequent behaviour and performance, placebo beverages were even 

less convincing. suggestin-s that inclusion of a placebo condition is not necessary in future studies 

of a similar nature. 

In general, increasing blood alcohol concentrations r.r'ere associated with a significant linear 

decrease in neurobehavioural perf,ormance. At a BAC of 0.lOVo mean relative performance was 

impaired by approximately 6.87c and 14.2Vo (grammatical reasoning accuracy and response 

t2

latency. respectively),2.3Vo and 20.5Vo (vigilance accuracy and response latency, respectiveh'r or 

2l.4Vo (tracking). Overall, the decline in mean relative performance ranged from'approximarely 

0.29Va ¡o 2.68Vo per 0.0lVo BAC. These results are consistent with previous frndings that 

suggest that alcohol produces a dose-dependent decrease in neurobehavioural performance 

(Billings et al., l99l). 

In contrast, mean relative performance in the sustained wakefulness condition showed three 

distinct phases. Neurobehavioural performance remained at a relatively stable level during the 

period which coincided with the normal waking day (0 to 17 hours). In the second phase, 

performance decreased linearly. with poorest performance generally occurring after 25 to 27 

hours of wakefulness. It was observed that mean relative performance increased again after 26 to 

28 hours of wakefulness presumably reflectin-s either the well reported circadian variation in 

neurobehavioural performance (Folkard and Tottersdell. 1993) or an end of testing session effect. 

The linear decrease in performance observed for four of the measures in this study is consisrent 

rvith previous studies documenting neurobehavioural performance decreases for periods of 

sustained wakefulnesS between ll and 86 hours (Linde et al. 1992: Storer et al. 1989: Fiorica ¿¡ 

¿/. 1968). Between the seventeenth and twenty-seventh hours of wakefulness, mean relarive 

performance significantly decreased at a rate of approximately 2.61% (-erammatical reasoning 

response latency).0.61 and 1.98% (vi-eilance accuracy and response latency, respectiveh'r or 

3.36Vo (tracking) per hour. 

While the results in each of the experimental conditions are interesting in themselves, and have 

been previously established. the primary aim of the present study was to compare the effects of 

l3

alcohol intoxication and sustained wakefulness. Equating the effects of the two condirions 

indicated that l7 to 27 hours of sustained wakefulness (from l2:00am to l0:00am) and moderate 

alcohol consumption have quantitatively similar effects on neurobehavioural performance. 

Indeed, the findings of this study suggest that after only 20 hours of susrained wakefulness 

performance impairment may be equivalent to thar observed at a BAC of Q1OVa. 

This stud¡' has confirmed the suggestion made by Dawson and Reid (1997) that moderate levels 

of sustained wakefulness produce performance decrements equivalent to or greater than those 

observed at levels of alcohol intoxication deemed unacceptable when driving, working andTor 

operatin-s dangerous equipment. More importantly, however, this study was desi-qned to 

determine whether the results of Dawson and Reid (1991) were an isolated finding. or 

characterlstic of the general cognitive effects of sleep deprivation. Using the degree of 

impairment caused by alcohol that produced a BAC of O.lOVo as a standard, this study 

svstematicelly compared the effects of sustained *aliefulness on a range of neurobehar.ioural 

tasks. Results indicate that *'hile. in general. sustained wakefulness had a detrimental effect on 

psychomotor performance. the specifrc components of performance differed in their degree of 

sensitivitr to sleep deprivation. 

The obsened differences betu'een the performance tasks with respect to the lulnerability to sleep 

deprivation can be explained by their relative de-srees of complexity. That is to say, the more 

complex neurobehavioural Parameters measured in the present study were more sensitive to sleep 

deprivation than were the simpler performance parameters. While only 20.3 hours of susrained 

wakefulness was necessary to produce a performance decrement on the most complex task 

(grammatical reasoning) equivalent to the impairment observed at aBAC of 0.lOVo. it was after 

l-t

22.3 and 24.9 hours of sustained wakefulness that a similar result was s€en in a less complex task 

(vigilance accuracy and response latency. respectively). Furthermore, on the unpredictable 

trackin-s task, a slightly less complex task than vigilance, a decrement in performance equivalent 

to that observed at a BAC of 0.10Vo was produced after 25.1 hours of wakefulness. 

It was observed that, despite a slight downwa¡d trend, performance on the simplest of the four 

tasks did not significantly decrease, even following twenty-eight hours of sustained wakefulness. 

In contrast, performance on this task was significantly impaired after a dose of alcohol that 

produced aBAC of 0.10% (or greater). These results are in line with the suggestion that simple 

tasks are less sensitive to sleep deprivation (Johnson, 1982). Indeed. we believe it likely that 

impairment of performance on this task may have occurred if we had extended the period of 

sustained wakefulness. It is interestin-e to note that several studies (e.g. Dinges et a1..1988) have 

reported that tasks similarlr lackin-e in complexitv. such as simple reaction time tasks. are affected 

earll' and profoundly br sleep loss. thus strongly suggesting that monotony ma¡ increase 

sensitivity to sustained rrakefulness. Indeed. the fact that this task was not vulnerable to 

sustained wakefulness mav possibly be explained by the interesting and challengin,e properties of 

the task. 

It is also noteworthy that. while we obsen'ed a decrease in accuracy on the grammatical 

reasoning task. impairrnent of this performance parameter was not comparable to that produced 

by a BAC of 0.l0Vc. While this may at f,¡¡st contradict the su,egestion that in this study 

to sustained wakefulness was. to a large degree, determined 

"ulnerability 

by task complexity, it 

should be noted that panicipants were instructed to concentrate on accuracy rather than speed 

when completing the gramrnatical reasoning task. Thus, our particular instructions to 

l5

Participants may explain, at least in part, this irregularity. Alternatively. this finding is in line with 

the suggestion of a natural 'speed-accuracy trade-offl. Simila¡ results have been observed in 

several studies, which report a decline in speed of performance. but not accuracy, when sleep- 

deprived subjects are required to perform a logical-reasoning task (An_eus and Heslegrave. 1985; 

Webb and Levy, 1982). 

Interestingly, this was not the case with the vigilance task. In this instance, despite instruction to 

concentrate primarily on accuracy, this component w¿ts slightly more vulnerable to sleep 

deprivation than was response latency. The absence of a trade-off on this task may be explained 

by the different properties of the vigilance and grammatical reasoning tasks. In accordance with 

the distinction raised by Broadbent (1953). the latter of these tasks can be defrned as an unpaced 

task, in which the subject determines the rate of stimuli presentation. In contrast, the r-igilance 

task can be defined as a paced task, in ç'hich stimuli are presenred at a speed controlled by the 

experimenter. In line with this distinction. our findings are consistenr with those of Broadbent 

(1953) who obser"'ed that while a paced task rapidl¡'deteriorated durin_e the experimentalperiod. 

in terms of speed. an unpaced version of the same task did not. 

A further explanation for the differences observed between these two tasks, may relare to the 

extremely monotonous nature of the vieilance task. Indeed. we believe it likely that subjects 

were more motivated to perform well on the grammatical reasoning task, which was generalìy 

considered more interesting and challen-eing. Hence degree of motivation may explain why 

measures of both speed and accuracy decreased on the vigilance task, while on the forrner task, 

accuracy remained relatively stable. This suggestion is in line with previous studies that have 

l6

found that motivation can. to a degree. counteract the effects of sleep loss (Horne and pettitt, 

1985). 

Taken together, the results from this study support the suggestion that even moderate levels of 

sustained wakefulness produce performance decrements greater than is cumently acceptable for 

alcohol intoxication. Furthermore, our findings suggest that while sleep deprivation has a 

generally detrimental effect on neurobehavioural performance, specific components of 

performance differ in their sensitivity to sustained wakefulness. 

Since approximately 50 percent of shiftworkers typically spend at 1east twenty-four hours awake 

on the first night shift in a roster (Tepas et aI.,l98l). these findings have important implications 

within the shiftwork industry. Indeed, the results of this study. if generalized to an applied 

setting. suggest that on the hrst night shift. on a number of rasks, a shiftworker would shou. a 

neurobehavioural performance decrement similar to or greater than is acceptable for alcohol 

intoxication. 

'Wirile the cunent study supports the idea that sustained w'aliefulness may carry a risk comparable 

with moderate alc.ohol intoxication. it is difficult to know to what degree these results can be 

generalized to "real-life" settings. Indeed, laboratorl' measures and environments usually bear 

little resemblance to actual tasks and settings. Furthermore, while our stud¡- used a battery of 

tests to evaluate the effects of sustained wakefulness on performance, their is no guarantee that 

all the functions involved in "real-life tasks", such as driving, were utilized and assessed. An 

alternative approach would be to simulate the actual task. as accurately as possible. Given that, 

for practical and ethical reasons, it is difFrcult to experimentally study the relationship between 

t7

sustained wakefulness and actual driving" simulators of varying realism have been used. Thus, 

protocols using simulators could be used to model "real-life" settings and establish a more 

accurate estimate of the BAC equivalence for the performance decrement associated with sleep 

loss and fatigue.

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Brechenrid-ee, R. and Dodd. M. Locus of control and alcohol placebo effects on performance in a 

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Effects of acute exposure to toluene and methyl ethyl ketone on psl'chomotor performance. 

Archives of Occupational and Ent'ironntental Health, 1984,54: 9l-109. 

Dinges, D.F., Whitehouse, W.G.. Orne, E.C. and Orne, M.T. The benefits of a nap during 

prolonged work and wakefulness. Work and Stress, 1988, 2: 139-153. 

l9

Fiorica, V., Higgins. E.4.. Iampietro, P.F., Latesola, M.T. and Davis, A.W.'Physiological 

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Folkard, S., Totterdell, P.. Minors, D. and Waterhouse, J. Dissecting circadian performance 

rhrthms: Implications for shiftw ork. Ergonomics. I 993, 36( I -3): 283-8. 

Gillberg, M., Kecklund, G. and Akerstedt, T. Relations between performance and subjective 

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Heishman, S.J., Stitzer, M.L. and Bigelow. G.E. Alcohol and marijuana: Comparative dose effect 

profiles in humans. Pharmacologr, Biochentistrv and Behaviour. 1989. 3l: 649-655. 

Horne. J.A. and Pettitt. A. N. High incentive effects on vi-eiìance performance during 72 hours of 

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Johnson. L.C. Sleep deprivation and performance. In: W. B. Webb (Ed.) Biological rhvhms, 

Sleeo and Peformanc¿. Wiley, New York. 1982. 

Linde, L. and Ber_sstrom. M. The effect of one night without sleep on problem-solving and 

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\lullaney. D.J., Kripke, D.F., Fleck, P.A. and Johnson, L.C. Sleep loss and nap effects on 

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20

Storer, J., Floyd. H., Gill, W., Giusti. C. And Ginsberg- H. Effects of sleep deprivation on 

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Thapar, P..Zacn¡'. J.P., Thompson, W. anfl Apfelbaum, J.L. Using alcoholas a sranda¡d ro assess 

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Webb, W. and Levy, C. Age, sleep deprivation and performance. Psvchophtsiolog_r., 1982, 

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Ergonornics. 196J. 7: 175-186. 

2l

TABLE f . Summary of ANOVA results for neurobehavioural performance variables 

Performance Variable 

GRG Response Latency 

GRG Accuracy 

VIG Response Latency 

VIG Accuracy 

Unpredictable Tracking 

Simple Sensory Comparison 

Placebo Alcohol Intoxication Sustained ryVakefulness 

Fr. rr 

' 

P" Fs.tos P" Fr¡.:z¡ P^ 

0.82 NS 4.96 0.0021 t3.77 0.0001 

0.63 

2.r9 

2.02 

2.63b 

0.78 

GRG. grammatical reasoning: VIG, vi_eilance 

NS 

NS 

NS 

NS 

NS 

6.88 0.0001 

43.09 0.0001 

7.99 0.0008 

5.32 0.0008 

l.88 NS 

u corrected by Greenhouse-Geisser epsiìon: b based on data from twenty subjects. 

2.20 NS 

33.74 0.0001 

I1.04 0.0001 

10.09 0.0001 

1.47 NS 

22

TABLE 1. Summary of linear regression analysis of neurobehavioural performance variables 

Performance Parameter DF F P R2 ToDecrease 

SW Condition 

GRG Response Latency 

GRG Accuracy 

VIG Response Latency 

VIG Accuracy 

Unpredictable Tracking 


Alcohol Condition 

GRG Response Latency o 

GRG Accuracy 

VIG Response Latencv 

VIG Accuracy o 

Unpredictable Trackin-e " 


1,4 

1,4 

1,4 

1,4 

1.4 

1,4 

1) 

1.4 

1.4 

l-J 

l.J 

1,1 

l.l 

70.61 

3.& 

98.54 

8t.79 

70.93 

4.71 

74.30 

31.07 

t2.65 

212.37 

238.52 

5.37 

0.001l 

NS 

0.0006 

0.0008 

0.011 

NS 

0.0132 

0.0051 

0.0002 

0.0007 

0.0006 

' Based on data from O.02Vc-0.10% BACI o Based on data from 0.04Vc -0.l\Vo BAC 

NS 

0.9s 

0.96 

0.95 

0.95 

0.97 

0.89 

0.98 

0.99 

0.99 

(per hour) 

2.69 

1.98 

0.61 

3.36 

(per0.0l Vo BACt 

2.37 

0.68 

2.05 

0.29 

2.68 

23

.l) 

H^ 

.o -5 

q, 

R -to 

It 

E .I.5 

ax 

É -"v 

4 

oá 

-2s 

Blood Alcohol Concent¡æion (%) 

ll 15 tg 23 

Houn of Wakefulness 

FIG. f . IHean rclative pcrformance levcls for the response latency componenr of ¡he grammarical reasoning 

task in the alcohol inroxication (lefit and sustained waksfulncss condiúon. The equiv¿iç¡¡ psrformance 

decrement at a BAC of 0.05Va a¡d O.l07c are indicarcd on ûre right hand ¿ris. Error ba¡s indicare + one s.e,m- 

tú 

ã- 

0.0-< &Þtí 

o 

o.r0 g Õo,DD5 

tt 

I 

\é 

24

a 

Q 

f- 

,o 

e 

E 

.f 

I 

ã -.ó 

J 

E 

.0:5 .045 .0ó5 0E5 .to+ 

Blood Alcohol Concentration (9ä) 

FIG. 2. Mean relative performa¡ce lerels for the accuracy' component of the gramrnatical re¿sonins nsk in 

thealcoholintoricedon(left)andsustarnedwaliefulnesscondition. Theequivalentperfoimancedecr:¡rpnt 

¡t a BAC of 0.057c utd O.lMc are indicated on the righr hand a.ris. Error ba¡s indicaæ i one s.e-!E 

tÍ 

õ- 

'o Ê. 

Þ 

o.o5 I Ef) 

o 

ã 

o 

0.10 ä u 

õ' 

5 

s 

25

o0 

c 

.ð -5 

o 

P -10 

..A 

ã e 

o1 -t5 

f6 

o 

=- -20 

0.00 .025 .045 .0ó5 .0E5 .10+ 

Blood Alcohol Concentration (%) 

Il t_< t9 23 

Hours of Wakefulness 

FIG. 3. Mean relarive performance levcls for thc response latency componear of the vigilance rrsk in the 

alcohol intoxication (ieft) and sus¡ained *ahefulness condition. The equivalcnr performance decrement at 

a BAC of 0.05% and 0 l0% are indicated on the right hand axis. Error ba¡s :ndicare¡ one s.e.m. 

ID 

õ" 

o 

9. 

Þ 

ño 

6 

0.05 ã o 

Ëì 

x 

I 

0.t0 : \o 

€) 

26

ü-r 

g 

€ õ-3 

À g 

6- 

É 

ã o 

E-:. 

Blsod Alcohol Concentration (%) 

FIG. 4, Mean relative performance levels for the accuracy component of the vigilance task in the 

alcohol intoxicauon (left) and susrained wakefulness condi¡ion. The equiralent performance decrement 

at a BAC øf 0.05Vc and 0.10!t are indica¿ed on ¡he risht hand axis- Error bars indicatÈ + one s.e.m- 

27

Êro 

.l 

Ë 

€ rn 

o- 

À 

IÞ 

-( -ro q¡ 

É 

Eo0, 

E -20 

7ll151923Z7 

Hours of Wakefulness 

FIG. 5. N{eari relaúve performance levels for the unpredicuble racking tssk ir the ålcohol 

inloxication (lefi) and sustained wakefulness condition. The equivalent performance decrernent at a 

BAC of 0.057o and 0.107q are indicated on the right hand. axis. E¡ror bars indicate ! one s.e.m. 

l! 

Eo 

ê. 

Þ 

Ènfì{ 

g 6 

Õ 

o 

ã 

.D 

0.ro äI ã 

\à

o 

Q 

ã. 

ti 

,o 

-l!rì 

!t¡ 

À 

ä.: 

16 

Ë{ 

á 

at- 

=-o 

- 

trt 

E' 

o 

9. 

Þ 

ñ 

o 

r 

.¡ 

o 

B 

lD 

x 

I' 

ö' 

ã 

ö

'. rev, ¡atlguc Iaclot> úr dv¡ô!.¡L,lr êvv¡g!^r' 

Crew fatigue factors in the Guantanamo Bay aviation accident 

Mark R. Rosekind, PhD. 

NASA Ames Research Center 

Kevin B. GregorY, Donna L. lvfiller 

Sterling Software 

Etizabeth L. Co 

Sæ Jose State Universþ Fou¡d¡tion 

J. Vrctor l-ebacqa PtiD. 

NASA Ames Research Center 

Malcolm Brenner 

National Transportation Safety Boa¡d 

, f'me, ¿ military contract fltght crashed while 

on, Guantanamo Bay, Cuba. The airplane, a 

'impact forces and fire. The three flight 

National Transportation Safetv Board 

(NTSB), an indøpendent agenry of the united States goverDment, conducted an official 

ùvestrganon to áetermine the cause of the accident and to make recommendations to 

pre!'enr a recufrence ( I ). At the request of the NTSB, the NASA Ames Fangue 

Countermeasures program anzly?ßd the crerr fatigue factors to examine ther¡ potentral 

role in the accideot. Tbr." principal sources of information *'ere made available from the 

\TSB accident inrestigation to NASA Ames for analysis: 1) Hrman Perforrnance 

Investigator's Factual RePort, 

2¡ Opeiauons Group Chairman's Factual Report, and 3) Flight 808 Crew Statements. 

Based on scientific data r.elated to sleep and crcadian rh¡hms, the NASA Ames Fangue 

Countermeasures program idcntified three core physiological factors to ex¡mirre when 

investiganng the role óf f"tigue in an incident or accidsnt. These factors have zubsequently 

been eipanã.¿ to four, to explicitly include a factor examined but not previously' reported- 

The for¡¡ fatigue factors 1s sxemine in rncident/accident investigatiorls are: l) acute sleep 

loss/cumulative sleep debt, 2) continuous hor¡rs of wakefulness, 3) time of dayrç¡cadian 

effects, and 4) pr.r"o* of sleep disorder. These factors were e¡amined and the 

sleep/wake histories for the flight crew prior to the accident are presented in Figure l. 

hnp ://olias af c. nas. gov/publicationVrosekind/GB/GB. Abstraa.html 

ra27lgE

L rer lauSue lagtors tn a\]¿tuu¡r .¡\ie r\¡ç¡¡. 

C?t 

F/O 

FIE 

¡IIII 

llrillt 

Figwe I. CreY' Sleep/Takc Histories 

The crew hed been offdqy up to 2 days priot to the accident trip and then flown 

overnigbt cargo schedules for the two nights ptiot to the accident, and had been assigned 

the accident trip uneryectedly on the morning of August 18, shortly after being released 

from duty. The erctra trip involved segments from Atlanta to Norfolk, VA to Gr¡antan¡mo 

Bay back to Atlanta, approximately 12 hrs of fl.ight time in 24 hrs of duty. The figure 

ptór.id"t information on the fatigue factors: I ) the individual crew members had an acute 

il""p loss (i.e., 5,6,8 hrs of daytme sleep). 2) were continuousl¡' awake 19.21, and 23.5 

hrs prior to the accident, and 3) the accident occured just prior to 5 pm local time during 

the afternoonwindow of sleepiness (this did not rePresent a time zone change for this US 

E¿st coast crew). Upon inquiry, there were no rsPorted symptoms or signs of a sleep 

d.isorder. Therefore, all three of the initial fatigue factors were operating in this accident. 

There were two principal sources of data available on fhgbt crew perfonnance in the 

accidsnt: cocþit voice recorder (CVR) and Captain's testimony at the NTSB publ-rc 

hearing. There were four performance effects related to fatigue that significantly 

contrr-buted to the accident: I ) degraded decision-making, 2) visuaVcognrtive fixation, 3) 

poor çps1¡armication/coordittation, and 4) slowed reaction time. 

A complete description of flight operations, fatigue factors, perfonnance effects, a¡ld 

accident investigation findings a¡e available in the full NTSB accident report ( I ). Based on 

the findinp, the NTSB determined that the probable cause of tlus accident included the 

impaired judgment decision-making, and flying abilities of the captain and flightcrew due 

to the effects of fatigue. This was the fi¡st time in a major U.S. aviation accident that the 

NTSB cited fatigue in the probable cause. As a result of this investigation, the NTSB 

recourmended that the Federal Aviation Administration (FAA) expedite the revier*'and 

upgrade of Ftight/Duty Time Limitations of the Federal Aviation Regulations to ensure 

that they incorporate the results of the latest resea¡ch on fatigue and sleep issues. The 

NTSB reiterated a recorrrmendation to require U.S. air ca¡riers to include, as part of pilot 

training a prognm to educate pilots about the detrimental effects of fatigue and strategies 

http://oli¡s.arc.n¡ìs¿t.gov/publicationJrosekind/GB/GB.Abstract.html 

ra27t98

Cre t lattgue laflors m allatlon accloeni 

for avoiding fatigue and countering its effects. This I'{TSB invesngation and the NASA 

gurdelines 1e ç¡amine fatigue factors, provides a model for invesngating and documenting 

the role of fatigue in operational incidents and accidents. 

(l) National Transportation Safay Boa¡d. Aircraft accident report unconuolled collision with terraiÂ 

n-ericao International Airways night 80t, Douglas DC-tó1, N8l4CK U.S. Naval Ai¡ StatiorL 

Crtu¡tanamo Bay, Cub4 August 18, 1993. WashingorL DC: Natiooal Transportation Safety Boa¡d, 

1994; NTSB/AAR-94/04. 

hnp ://olias.arc.n¿rsa. gov/publicarionVrosekind/CB/GB Abstract. htmJ t2/77/98

IBT PROPOSAL, JAN. 6,1999

INTERNATIONAL 

BROTHERHOOD OF TEAMSTERS 

AFr-CtO 

R{Y W EENNINC, lR.. Direcror 

Airl¡ne Divrsron 

6l¡l Westchester Parkwav. Suite 150 

Los Angeles, CA 90045 

Mr. Donald E. Hudson 

Aviation Medical Advisory GrouP 

14707 East 2d Avenue 

Suite 200 

Aurora, CO 80011 

Gentlemen: 

TEL: rll0ì 6¡15-9Eæ 

FAX: rJ ¡ Or 645-9869 


Mr. Clay Foushee 


901 15h Street, NW 

Suite 310 

Washingrton, DC 20005 

The undersigned (FPA, IACP, lPA, SWAPA, and IBT representing approximately 

20,000 crewmembers) concur with the basic document submitted by the entire 

labor group concerning the issue of Reserve and Reserve Rest. This submission 

is supplementary to that document and it addresses additional methodology 

applicable to the Part 135 and non-scheduled carriers (non-scheduled as used 

herein applies to carriers currently operating under Part 121, Subpart S 

(supplemental rules) excluding such carriers as FEDEX. UPS, etc. that may 

operate under supplemental rules, but do so with a known published operating 

schedule). 

It is recommended that the basic labor document, addressing a Protected Time 

Period (PTP) and Reserve Availability Period (RAP) methodology, apply to all 

carriers, i.e., scheduled, non-scheduled (as herein defined), and Part 135. 

Additionally, it is recommended that non-scheduled and Part 135 carriers be 

provided an alternative method for reserve assignments where it can be 

validated that the PTP-RAP methodology cannot be applied. An example 

requiring this alternative means would be an aircraft with one crew at a station 

with a prospective duty to operate the aircraft at an undetermined time. 

The underlying rationale of the Flight and Duty Time ARAC working groups over 

the past seven years has been to ensure that crews are provided a reasonable 

sleep opportun¡ty. The most eflective means of rest is to provide a sleep 

opportunity at the same time each night. Recognizing that this is not always 

possible in the air transpoñ industry, the PTP-RAP methodology and a reduced 

duty time, based on predetermined notice periods, represent two means of 

satisfying the underlying rationale of ensuring a reasonable sleep opportunity. 

This alternative methodology greatly reduces the economic impact of regulatory 

reform on the non-scheduled and Part 135 segment of the air transport industry. 

2: LOUISIANAAVENU= NW WASHINGTO\ DC 2OOOr. (202\ :2¿.58:,3

We believe that this submission should be helpful to the FAA in formulating a 

new rule that balances safety, economics, and the public interest. We are 

pleased that the FAA has addressed this issue and we are supportive of 

constructive change arising from the etfort put forth by the respective gioups and 

the Agency. 

Dave Wells //s 

FPA, CAPA 

D.R. Treichler 

IBT, CAPA 

Don Kingery //s 

IACP (non-CAPA) 

Lauri Esposito //s 

IPA, CAPA 

Bob Landa //s 

SWAPA, CAPA

PROPOSED REGULATORY LANGUAGE 

121.xxx Alternative Means of Obtaining Reserve Rest for Non-scheduled 

Operators (without a known schedule) and Part 135 Operators (separate 

subpart) 

(a) Non-scheduled operators and Part 135 operators may schedule a flight 

crewmember and that flight crewm€mber may accept a reserve assignment as 

follows: 

(1)The operator first must assign a PTP period, discussed elsewhere in this 

rule, provided the operator's flight assignments haye a known departure time 

(schedule), and the operator may then schedule and a crewmember may accept 

any assignment provided elsewhere in this rule excluding (2) and (3) below; 

(2) lf unable to comply with (1) above, and an advance notice before 

departure of not less than 14 hours is provided the crewmember, an operator 

may schedule and a crewmember may accept any assignment provided 

elsewhere in this rule excluding (3) below; or 

(3) lf unable to comply with (1) and (2) above, an operator may assign and a 

crewmember may accept a reduced duty period as set forth below: 

(a) With I to 13:59 hours advance notice, the scheduled duty period is 

limited to 12 hours, but may be extended to 14 hours for operational délays; or 

(b) With 6 to 7:59 hours advance notice, the scheduled duty period is 

limited to 1 0 hours, but may be exlended to 12 hours for operational delays; or 

(c) With 4 to 5:59 hours advance notice, the scheduled duty period is 

limited to I hours, but may be extended to 10 hours for operational delays; or 

(d) With less than 4 hours advance notice, the scheduled duty period is 

limited to 7 hours, but may be extended t hour for operational delays. 

(e) For assignments in paragraph (2) and (3) (a) through (d) above, the 

operator must relieve the crewmember from all further responsibilities between 

advance notice and report time. 

(f) Advance notice, as used in paragraphs (a) through (d) above, means 

the time from when a crewmember is alerted for an assignment until 

transportalion local in nature is available at that hotel to transport that 

crewmember to his place of assignment. The duty period thereby commences 

with hotel pick up.

Appendlr I 

Reference Data Furnished by the IBT 

1. Normal dally sleep - References vary trom 7 hours and 20 minutes to 

approximately 8 hours and 10 minutes. 

Coren, S., S/eep Thieves, (Toronto: Free Press, 1996) pp.251-253 

(7 to I hours and 10 minutes.) 

Dinges, D. and R. Broughton, S/eep and alertness: Chronobiolqical, behavioral 

and múical aspects of napping, (New York: Raven Press, 1989) 

(Average sleep for N. American and European adults were around 7 hours and 

20 minutes.) 

Wojtczak-Jaroszowâ, J., Physiologiæl and Psychological Aspcts of Night and 

Shift Work, USDEW (N¡OSH) 1977 

('During normal night sleep, lasting about 7/a hours....") 

2. Napping - 

Op. Cit., Coren, S., pp. 222-223 

(Naps before and during a shift have shown "modest success.") 

Nicholson, A. and B. Stone, Circadian Rhythms and Disturbed Sleeo: /ts 

Relevance to Transport Operations. IJAS 1/3-D (Unknown publication date in 

approximately 1982 

("...naps, sleeps of 3-4 hours and very long periods of sleep are all attempts to 

adapt to the irregularity of duty hours and time zone changes, and to ensure 

adequate rest before the next duty period. lt would be reasonable to assume 

that the natural requirements for sleep are met in this way-even though the timing 

and duration of the sleep periods are radically changed.") 

Nicholson, 4., Sleep and Wakefulness of the Airline P/ot Stewart Memorial 

Lecture presented February 11, 1986 at the Royal Aeronautical Society 

("...with a 4 hour period of sleep during the evening, there was a sustained 

improvement in performance overnight' .....'...recent studies show how (naps) 

can improve alertness...There was a distinct improvement in their alertness 

during the day when a nap of t hour was taken in the morning. The effect was 

evident in the afternoon, as the nap seemed to encourage the rise in alertness, 

which normally occurs during the day. The duration of a nap may be critical if it 

is to be beneficial, and its effects may last for several hours.")

ARAC RESERVE DUTY WORKING GROUP INDUSTRY/IVIANAGEMENT REPORT

ARAc Rescne Dury workrng crrurp Industry/lvfanagement Repon (t/15/99) 

Backsround end Introduction 

ARAC Reserve Duty Time 

Working Group 

Industry/Ìf anagement R.eport 

The RD!ü/G was asked to rcport on six specific tasks ¿¡d to complete the report by 

December l, 1998. That daie was subs{uently extended roJ;ï¡ary rs, i*B. - 

scheduled, FAR Part 121 vs. 135, on-demand, supplesls¡ral, etc.). Thus, the rqslç 

assignment drafæd by the FAA also included-.a-próvision for the nbWC té p-"i¿" 

recommendations that accommodated these diffèrences in a rearcnable fashiïn. 

The first publi-c meeting YT hJId on Augu1 l2-l3,l9lB, an-d subsequent public meetings 

were held on September l-2, October I-2, October 2930, and Decemær à-5. Numeror,-. 

were resolved by the final public meeting. 

ere pres€nt at one or more meetings druing 

.l as the *ATA position," the proposal therein was developed by the entire RDWG 

r ncustry/management group. 

ussions, 

between 

i,Ëi*"å¿", 

In addition. a consensus industry/management proposal was reached for Part l2l, nonscheduled 

operations, which recognized that certaià types of operations could not iunction

ARAC Reserve Duty' Worbng Group Indusrry/lvlanagemenr Repon ( l/15/99) 

uled operations. At least scveral 

despiæ the lack of an overall 

It was also generally agreed by the industry/management group that the Part l2l, scheduled 

reseryc relt ProPosat should not apply !o Fhrt 135 operations for many of the same 

Feaso¡Ls..Tw-o proposals werc submitted for Pa¡t 135 operations, one by the Helicopter 

Association Inærnati_onal (Attachment 3) and onc fq Part 1.35, non-schéduled opera-tions 

by tbc National Air Tranportation Association and tbe National Business Aircrafì 

Assæiation (Anachment 4). 

Natiooal Business Aviation Association, and 

the members of these organizations. 

IndustrJr/-lVlsnagerrent Resgonses to SDeciñc Tssks 

Task 1: Review of current scientific dat¡ on the eflects of fatigue in 

reserve duty. Coneider conflicting opinions. 

The l¡¡s public meeting included an extensive disc¡rssion of the relevant scientific literai,rrc, 

and whether any new data pertaining to this issue h¡d emerged since the issuance of NIRM 

9418. It was generally agreed that there wer€ no signifrcant new scientific studies relevant 

to the rcsewe duty question published since that time. 

It was frequently pointed out by the indrstry/management group that there bave been no 

known accidents where the probable cause was deemed to be pilot fatigue associated with 

reserve duty assiguments. In the minds of many RDWG members, this was relevant to the 

question of whether changes to the existing rules should be a regulatory priority. 

Extensive discr¡ssions ensued th¡t illusuated the fact that the scientifrc literature pertaining 

to this issue can be inærpreted in a variety of ways. As a result, many different and 

sometimes inconsistent conch¡sions can be d¡awn, and thus, there a¡e no clear ansìyers 

from the body of scientific liæran¡re ^s to appropriaæ rcgulatory policy 

The RDtl/G did agree that there are two very broad scientific principles specifically rclevant 

to res€rye duty. Frnt, it was agred that humans generally need the oppo(uniry to acquire 

approximately 8 hours of sleep per V+ hour period Second, it was agreed that fatigueis 

more probable during the period of time encompassing approximately 02OO to 060, whicb 

rougbly corresponds to the low point in an "averaç" (across the population) human 

circadian cycle. 

However, it was also noted that the scientific literarure demonstrates that humans, in 

general and piloa in particular, arc highly variable in their slecp habits, lifestyles, and 

circadian cycles. This phenomenon poses significant a¡d diffic¡¡lt complications for FAA 

rcgulatory policy on flight and duty time. An appropriate rest opportunity (no matter how 

long) cannot guarantec that a particular res€rve pila will obtain appropriate sleep. In 

addition, because of the high degree of variability in individual sleep habits and lifestyles, it 

is difficult to know the natu¡e and timing of a paìticula¡ individual's circadian cycle. For 

example, since a large percentage of pilos commute across multiple time-zones to both 

2

ARAC Rescrvc Duty Workrng Group Indusrry/hlanagemenr Rcpon ( l/1999) 

rcs€rve and scheduled duty assignments, it is diflìcult to assess the particular timing of an 

individr¡al's circadian cycle vis ã vis a particular flight assignment. 

The rnajoriry 

opportunity i 

hours during 

also acknowledged that the PTP should not c 

the next- Consensus was rcached that this is I 

ranâgem€nt proposal is rb¡, at best, rcserye 

appropriate rest opporrunity. They cannot 

ryriately rested" prior to a flight assignment. 

rccept personal respo,nsi tility for obtaining 

i provided for resl 

m routine 

method is 

ry to 

In addition, it was recognized 

difficult, if not impossible, to 

and/or Part 135 operations (sc rs of 

crcws involved in sucå operatio_ns. Thus, an alærnative was deemed to be necessary for 

non-scheduled and other Part 135 operations. 

nce rqserves are frequently not called for 

fligbt assignmens 

operations, if at all 

"snowball effect," 

course of a normal 

assiguments to utilize all available opportunities for rcst. 

RDWG discussioos of the scientific literatu¡e also included resea¡ch by the National 

Aeronautics and-Space Administratiog (l,lASA) which demonstrated rhrt gys¡ brief naps 

(approximately 45 minutes) can significantly enhençs alerhess and scrve as an effectivì 

countermeasure to faúgue. This underscores the responsibility res€rve pilos have to utilize 

all available r€st opportunities during RAh. 

Task 2: Analysis of current reserve schemes and operational situations 

Extensive discr¡ssions of current practices illustrated that there is a wide variety of reserve 

conclusion that a single rule would not be in the public intercst. 

It was fu¡ther demonstrated by the management group that the majorir¡- of major airlines 

(affecting the vast majority of U.S. professional pilots) had negotìated work-rules 

governing nes€rve assignments that had factored in the cha¡acterisúcs of a particular 

tc.

AR,{'C Rescn'e Dutv Work¡ng Group Indusrry/lvlanatemcnl Repon ( l/lS/99) 

grganization's.oPeration. Thus, it was asscrted that any rule change must be broad and 

flcxible glough to take these negotiaæd work-rules and- operationai diflercnces into account 

without disproportionate impact on a particula¡ ca¡rier. 

As a rcsult of these discussions, industry/management members proposed that the þst 

alter¡ative for rescrye flight and duty time rulemaking would be to ailow individual 

operators to develcp detai led, indi vidually-tai 

rcserve duty by.each 

Offìce. This the way 

specificatiou tions, trz 

this aPP'roach. 

T¡sk 3: Recommendations on stand¡rds end criteri¡ 

Á¡f.ter several public meetings, nv9 basic schemes were proposed for providing reserve 

ptlgts op-portunities for rest or limi¡i¡g the duty day basà u-pon tle arnomt ofãdvance 

notice of-a fligþt assi8nment. Tbe first scheme involved providing a scheduled PTP for all 

Feserve pilots, but also allowed tbe r¡se of advance notificãtion to ãither cancel a scheduled 

second scheme simply limited the dury day 

based uPgg +l3¡1ount of advance notification. The latter is very similar to regulaûoni 

proposed in NPRM 9t18. 

Afær extensive discussions, the RDWG agreed to attempt to reach a consensus for Part 

121, scheduled operations on the first scheme, where most pilots would receive a PTP, 

with an appropriate mechanism for the urilizafe¡ of advancè nodfication in lieu of PTPs 

under circumsrânces associated with deviations from normal operations. The second 

scheme was proposed as an alter¡aúve for Part l2l, non-scheduled and part 135 

oPerauons. 

The industry/management proposal for Part l2l, scheduled operations is presented in 

with the amount of time devoted to PTPs, length of R.,ôrPs, and the amount of advance 

notification necessary to cancel tTh, modify RAPs, as well as how advance notification 

should aflect the amount of allowable dutv time. 

to complete a flight assignment safely and legr 

industry/management-proposal is far more restrictive with rcspect to rules governing 

reserve assignments than either those proposed by the FAA in NPRM 9t18 or current 

rules, neither of which have provisions for PTPs covering the vast majority of rcserve 

pilots in U.S. domestic service.

ARAC Rescn'e Duty Workrng Group lndusry/lvlanagement Repon ( l/ lt99) 

The fìnal labor proposal(s) included longer PTPs, longer and more extensive advance 

notilìcation rcquirements, shorter RAR, and restrictions on allowable duty time bas€d 

upon time of day. The indnstry/management RD\tt/G memþrs maintain that the benefits 

which might possibly be derived from the labor proposal(s)' more rcstrictive parameters are 

susp€ct, at best, and not supporæd either by the scientific literan¡re or by the safety rccord, 

in ligbt of the substantial additional burden that would bc placed up the indrxtry and the 

U.S. air transportation system (see task 5 below). 

Task 4: Recommendations on how FAA witl Eeasure compliance 

With regard to the industry/managemeut proposals, tåere was no disagreement within the 

RDWG that the FAA would be able ûo measure compliance in the same $,ay it currently 

assesses flight and duty time regulatory compliance. It was noted that most automated 

rccord keeping systems could be modihed ¡o accommodate the proposed shnnges within S 

to 12 montbs from the date of publication, depending upon the complexity of a new rule. 

Task 5: Economic Impact 

Industry/management represenøtives compiled the available ec-onomic data pertaining to the 

costs of the proposal provided in Auachment 1. It was estimated that the cost of that rule 

çh¡nge would be approximately $10 million in incremental costs to the major operators 

thet provided economic data (primarily ATA member airtines). Mæt of these costs a¡e 

necessitated by the requiremeut to hire additiooal Fes€rye pllots and the associaæd c.¡sts of 

training both the additional new pilots required and part of the exising pilot populadon 

because of the "upward bumping" phenomenon created by most conmct-imposed seniority 

systems during perids when new pilots are being hired 

No economic data were provided by sm¡ller Part 12l operators, hrt 135 operations, or 

other types of operations, but it is probable that the total cost to industry would be 

significantly greâter th¡n $100 million. [n addition, it was maintâined that some smaller 

unscheduled operators might have to ceas€ opentions under some of the labor proposals. 

It was also asserted that these proposals would substantially alter the nature of manl' 

collecti ve bargaining agreements. 

The RDWG was unable to perform additional detailed economic ¡nalyses comparing the 

va¡ious proposals. This was due to the fact tbau t) these analys€s are very complex and 

time-consuming,and 2) it was difhcult to ascertain how to conduct comparative analys¿5 s¡ 

competing labor proposals, because a single labor proposal had lot emerged by the 

deadline associated with the final public meeting and the task assignment. 

However, exploratory analyses did indicate that very small increases in PTPs, advance 

noúfìcation requircments, and corrcsponding decrcases in RAPs (as outlined in the labor 

proposal closeit to the ind 

- in the 

iurñUer of reserves requir 

this 

dramatic incrcase occurs. 

serve 

positions becar.rse it and has multiple crew bases. 

îhese circumstance 

. the number of resewe 

positions equals the of ryat 

positions in each baseðaptain 

vs. hrst officer vs. second officer--times the number of aircrafr types operating in 

eaèh base). In most cases, there are only a handful of reserves in each category (often as 

few as I 

million in salarY, 

benefits 

s it initiallY hires. 

For this 

nding reductions 

5

AR.AC Resen e Dut¡' Workrng Group I ndustry'/N4anaSemeot Repon ( | I I fl 99) 

in RAh from the industryimanagement proposal would require it to add at least one 

res€rve ùo every category. As a rcsult, the minimum incremental cost for this single airline 

would be $G7 million, assuming only one reserve is necessary in each category. These 

incremental costs over and above the final industryimanagement proposal are expecæd to be 

similar for each major airline. Thus, the potential incremental costs of competing labor 

proposal(s) could be perhaps double (in the'best'case) or significantly more (in the 

"worst" case) than the cost estimates associaæd with the industry/management proposal. 

l{lærnatively, a carrier could choose not to saff the additional reserves that would be 

required to cover contingencies imposed by more stringent rcserve rest requi¡ements. Of 

course, this would cause significantly more fligbt cancellations than a¡e common under 

current rules and a resulting negative impact on the U.S. air transportâtion system. 

In summary, even small (1 or 2 hr.) increases in advance notification requirements, PTPs, 

or conesponding reductions in RAP, or duty day would cause an operator to add additional 

reserves in each reserve category to provide at least minimal coverage. The associaæd 

incremental costs would be substantial over and above the final RDWG indr¡strv/ 

rrìanageme nt proposal. 

Reserve pilos, by definition, are ne,cessary because an operaûor never knows when or if 

they will be required. In normal operations many, if not most, res€rve pilots are never 

cålled for an assignment. [n short, the economic consequences of the industry/management 

proposal are significant, but all competing labor proposals are significantly more cosly. 

Thus, the argr:ably questionable benefits of any rule change must be carefully considered in 

ligbt of the large additional economic burden imposed upon air tansportation providers. 

Task 6: Assessment of record-keeping burden 

The RDWG was unable to ass€ss the specific additional rccord-keeping burden since a 

cons€nsus was not reached on a proposed rule. However, as previously reported, any rule 

chaage would require each operator to make changes to it's record-keeping system, which 

wor¡ld reslt in some incremental cost. 

ln addition- it is expected that FAA would need to either add additional inspectors to 

monitor compliance with more complex rules th¡n those prcsently in place, or alternatively, 

FAA would be required to reduce surveillance in other areas. The RDWG was not in a 

position to advise the ARAC or the FAA on this internal policy matter. 

H. Clayton Fqbshee 

ARAC RDWG Industry/Management CoChairman

N&. H. Clayton Foushee 

Vice President-Regulatory Affairs 


901 l5ô Süeet, N.W. Suite 310 

Washington, DC 20005 

Dear Clay: 

Dece!îber 30, 1998 

.ìttachrent I 

As co-chairman of the Aviation Rulemaking Advisory Committee (ARAC) 

Working Group on Pilot Reserve Rest, you are aware that the final meeting of that grouP 

was helã on Dècember 2, 1998. The working group was originally given a task deadline 

of October, but that date was extended r¡ntil December. Non¡¡ithstanding the extension 

and despite a good-faith effort from all xào participated, a consensus position was not 

reached. 

The ATA reserve rest proposal, discussed at length during the ARAC Worki¡'g 

Group meetings, effectively addresses the issue of prospective rest for pilots in reserve 

statu;. Attached is the final ATA proposal. which represents the collective position of ou¡ 

member airlines. Our proposal calls for a Protected Time Period (PTP) for each reserve 

pilot of a minimum oleight consecutive hours. This period of pre-scheduled rest is time 

when a pilot is free from all duty and has no present responsibilir¡ for work. ATA 

operators anticipate that the majoriry of reserve pilots will fall into this category. 

By definition, reserve pilots a¡e needed to protect schedule integrity when 

unpredictable events occr¡¡. To account for these inegularities, ATA oPerators require 

greater flexibiliry than is afforded by simply scheduling reserve pilots with protected rest 

periods. Therefore, a system is needed that provides both the flexibility necessary to 

maintain a reliable operation that meets consumer needs, and that also provides reserve 

pilots an oppornrnity for rest. 

FAA inrerpretations have consistently stated that if the time between notification 

for a flight assignment and reporting for duty were of sufficient length to meet existing 

rest requirements, then that period would qualify as an opportunitv for rest. The ATA 

Ai¡ Ïr¡mporl Associ¡lior¡ of Amcric¡ 

I l0l Pennsrlv¡nr¿ Ave.. Nw - 5U'te I l0O W.rshrnglon, DC 20OOJ-.l707 

(lcr 6¿6-.¡000

proposal includes a provision that provides the pilot u'ith a minimum ten-hou¡'adva.nce 

notification. Once notified, the pilot would be free from reserve status and all 

responsibility for work. Notification under the advance notice concept would permit the 

pilot to be utilized for any legal flight assignment becar¡se the pilot has an opportuniqv for 

full rest prior to reporting for the assignment. 

It is worth noting that the advance notice proposal is not without additional 

complexity or cost. As stated earlier, ou¡ members have indicated that that most reserve 

pilots will be provided with pre-scheduled or protected rest periods (PTP). A review of 

historical reserve utilization app€ars to support this hypothesis. 

In order to provide a limit to the time, in which a pilot may be utilized in a 

specific reserve or duty assignment, a concept called Reserve Availability Period (RAP) 

is included in the ATA proposal. This limits the pilot's assîgnment to nineteen hours 

from the end of the previous protected rest period. 

Note: The 19 hour proposed møimum Reserve Availability Period (MP) is 

consistent with the l6 hour period beween consectttive Protected Time Periods 

efP) plus the ability to reschedule the subsequenl PTP by 3 hours. Any 

maximum PAP of less than 19 hours cannot be justífied and will have 

considerable economic impact on operators. 

In summary, the ATA Reserve Rest proposal satisfies the ARAC task assignment 

as it appeared in the July 9, Federal Register. Reserve pilots are provided with an 

oppornrnity for prospective rest that is not available to them under the cu¡rent rule. This 

proposal also provides a solution to reserve rest that is consistent with a long list of FAA 

interpretations. In developing this proposal. ATA member ai¡lines considered many 

'factors including safety, effectiveness. flexibility, cost, administation, compliance and 

FAA enforcement. 

Encl. 

ftr, 

Sincerely, 

.,.'>)= t/ 

/ .'f 7'É-

ARAC Reserve Duty and Rest Requirements Working Group 

DEFINITIONS 

The following definitions îo¡ ¡æt and duty apply to Subparts Q, & and S and are identical to existinq 

deflrnitions in Subpart P. 

Duty Period - The period of elapsed time between reporting for an assignment involving 

flight time and release from that assignment by the certificate holder conducting 

domestic, flag or supplemental operations. The time is calculated using either 

Coordinated Universal Time or local time to reflect the total elapsed time. 

Protected Time Period (PTP) - A period of time during a reserve assigrrment that 

provides a flight crewmember with an opportunity to rest. A certificate holder may nor 

contact a flight crewmember during his or her PTP, and a crewmember may not have 

responsibility for work during hisåer PTP. 

Reserrye Availability Period (RAP) - The period of time from the end of one protected 

time period to the time that the reserve flight crewmember must complete resen¡e or 

flight dutv and sta¡t hiVtrer next PTP. 

Reserve Flight Crewmember - A flight crewmember that does not have a flight duty 

assignment and has a present responsibiliry for flight duty if c¡úl:d, but who is nct on 

standby dury 

Rest Period - The period free of all restraint or duty for a certificate holder conducting 

domestic, flag or supplemental operations and free of all respc.sibility for work or duÇ 

should the occasion arise. 

Standby Duty - A period of time when a flight crewmember is required to report for a 

flight assignment in less than I hou¡ from the time of notification. It also includes time 

when a flight crewmember is required to report to and remain at a specific facility (e.g. 

airport, crew lounge) designated by the certificate holder. Standby dury is considered 

part of a duty period. Standby dury ends when the flight crewmember is relieved from 

dury associated with an actual flight, or is otherwise relieved from duty.

Rest Period: 

ARAC Reserve Duty and Rest Requirements Working Group 

RESER\¡E REST PROPOSAL 

PART I21, SCIÍÐ(ILEÐ 

Each flight crewmember assigned to reserve duty will be provided with a scheduled rest 

period of at least eight consecutive hor¡¡s during each reserve day, free of all duty with the 

carrier, so that the flight crewmember will have an oppornrniqv to resr. 

o The ca¡rier may reschedule the rest period by as much as th¡ee hor¡rs ea¡lier or later 

than the beginning time of the preceding rest period provided that notice is given 

prior to commencement of the next scheduled rest period. 

o The carrier may rcschedt¡Ie the rest period with at least ten hours advance notice prior 

to the commencement of the ne:ct scheduled rest period. 

Advance Notice: 

Advance notice to a reserve flight creçmember of a flight assignment by the air carrier 

provides the flight crewmember an opportunity for rest. 

. If the resçrve flight crcwmember is provided with l0 or more hours advance notice, 

that flight crewmember may be assigned any legal flight assignment. 

. Contact may not be made with the reserve flight crewmember during a scheduled rest 

period for the purpose of providing advance notice. 

Reserve Availabilitv Period : 

The Reserve Availability Period is the period of time from the end of the rest period to 

thè time that the reserye flight crewmember must complete reserve or flight duty. 

The reserve flight crewmembe/s reserve availability period may not exceed l9 horus 

except as permined below. Actual flight dury time may be extended an additional two 

hou¡s for reasons beyond the control of the air carrier such as weather, ATC, or 

mechanical delays. With advance notice of less than ten hou¡s. the reserve availabiliry 

period may be adjusted as t'ollows, allo'*'ing for an opportunity for rest in preparation for 

the assignment: 

. If at least 8 hor.rs notice is given, the scheduled reserve availabiliry period may not 

exceed 24 hours, except that the actual reserve availability period may be extended an 

additional 2 hours due to operational circumstances beyond the control of the 

oPerator.

' [f at least 6 hor¡¡s notice is given, the scheduled reserve availabiliry period may nor 

exceed 22 horus, except that the acrual reserve availabiliqv period may be extended an 

additional 2 horus due to operational circumstances beyond the control of the 

opeËtor. 

o If at least 4 hor¡rs notice is given, the scheduled reserve availability period may not 

exceed 20 hours, except that the actr.¡al reserve availability period may be extended a¡r 

additional 2 hor¡rs due to operational circumstances beyond the control of the 

operator. 

The above reserve Availability Rules apply to international flights except where the 

reserve flight crewmember is assigned to an augmented crew, in which case, the flight 

and duty time rules of $121.a83 and $121.485 apply forthe enti¡e flight duty assignment. 

ttt

Attachment 2 

Alternative Reserve Duty and Rest proposat 

for Non-Scheduled Operations 

(a) A certificate holder may apply the following reserve scheme for nonscheduled 

operations in lieu of the protected time reserve scheduling 

requirements for domestic or flag operations.. 

(b) Each flight crewmember must be given a 1O-hour rest per¡od before any 

reserve time assignment. 

(c) lf the reserve f light crewmember is provided with 10 or more hours 

advance notice, that flight crewmember may be assigned any legal flight 

assignment. 

(d) The certificate holder may provide advance notice of 

duty involving flight and provide an additional time of not 

to report with the following limitations. 

an assignment to 

less than one hour 

(1) lf at least I hours advance notice is given, the scheduled duty 

period is limited to 12 hours, but may be extended to 14 hours for 

operational delays. 

(21 lt at least 6 hours notice is given, the scheduled duty period is 

limited to 1o hours, but may be extended to 1 2 tor operational delays. 

(3) lf at least 4 hours notice is given, the scheduled duty period is 

limited to 8 hours, bút may be extended to'10 for operational delays. 

(41 lf less than 4 hours notice is given, the scheduled duty period is 

limited to 7 hours, but may be extended to 8 for operational delays. 

(e) The certificate holder must relieve the crewmember from all further 

responsibilities between advance notice and report time. tEndl

1635 Prrnce Streel Alexandrra Vrrqrnta 22314-2818 


Dr. H. Clayton Foushee 

Vice President-Regulatory Affairs 


901 l5'Street. NW. Suite 310 

Washineton. DC 20005 

Re: ARAC Flighr Crev' Reserve Time Working Group: 

HAI Proposalfor a Rule Applicable to Pan 135 On-Demand Air Charter 

Dear Clay: 

]ri:chm¡f ? 

Telephone. (703 I 6E3-4646 Fax (703) 683-4745 

On August 5. 1998. F.\A invited Helicopter Association lnternational (HAI) to serve on a working group of the 

Aviation Rulemaking Advisory Committee (ARAC) to consider flight crew resen'e time requiremenrs. H,\I 

herewith tenders its proposal for the structure and content of a Flight Crew Reserve Time regulation applicable 

to on-demand air chaner operations conducted under 14 CFR Part 135. 

HAI's proposal reflects many hours of thou-eht. discussion and negotiation focused on optimizing flight safery. 

flight crew lifesty'le concerns and operational flexibility in the context of the unique demands of Part 135 air 

charter operations. .\s y'ou k¡ow'. HAI fulll supports the proposal for scheduled domestic operarions conducted 

under l-l CFR Part lll described elsewhere in your repon. FIAI believes that proposal is an appropriare 

balancingofconcernsinPartl2ldomesticscheduledaircarrieroperations. Hou'ever.HAlalsobelievesrhar 

the proposed Pan Ill solution will not work in the Part 135 context. in particular because the advance norice 

provlsions of the Pan l2l proposal are inconsistent with the ondemand nature of part 135 air charter 

operatlons. 

HAI also suppons ¡he substance of the "Special Provisions for Air Ambulance Operations" proposed by the 

National Air Transponarion Association (NATA) and National Business Aviaúon Association (NBAA). 

However. we beliere that the approach outlined there is appropriate for allpan 135 on-dèmand air charter 

oPeratlons. 

Finally. HAI thanks;-ou and Dr. Don Hudson for your very capable, even-handed. and very patient leadership 

of the Working Group. Your efforts as co-chairs have been greatly appreciated. 

Sincerely,l 

President 

Oe'7,cated to the advancement of lhe ctvtl heltc-^cler tnd-slry

ARAC Flight Crew Reserve Time Workin_s Group 

FIAI Proposal for a Rule Applicable to Part 135 on-Demand Air charter 

HAI proposes a rule on Part 135 Flight Crew Reserve Time srrucrured in three parts: 

l. Scheduled Reserve 

Under 14 CFR pan 135, an on-demand air charter operator may assign a pilot to 

"scheduled reserve." 

. No period of scheduled reserve may exceed 14 hours in any 24 hour period. 

o Each period of scheduled reserve must be preceded by a "protecred time 

period" of at least l0 consecutive hours in length. 

o No combination of "scheduled reserve" and assigned duty may exceed 20 

consecutive hours. 

o Under "scheduled reserve," the pilot's duty period begins when the pilot 

receives a call from the operator to report for work. 

2. Extended Reserve 

,{n operator may assign a qualifying pilot to a penod of "exrended reserve." 

Under exrended reserve. a pilot mav be assisned to hold herself: 

o Able to be contacted bv the ooerator: 

r Remain fit to fly (to the extent that this is within the control of the pilot): and 

o Remain within a reasonable response time of the alrc¡aft. 

all without triggering the start of any period of "duty" under the Parr 135 flight 

cre\,\' dutv time regulations. 

a. Dutv under Extended Reserve 

. Under "extended reserve," the pilot's duty period begins when the pilot 

receives a call from the operator to report for work. 

o When a pilot completes a period of duty under extended reserl'e, that pilot 

shall enter a protected time period of at least l0 consecutive hours before next 

being available for contact by the'operator.

ARAC Flight Crew Reserve Time Working Group OIlL3tgg 

HAI Prcìposal for a Rule Applicable ro Pan 135 On-Demand Air Chaner paee l 

b. Limitation on Extended Reserve 

. Assignment to extended reserve may not exceed l5 consecutive days. 

o If assignment to extended reserve is for a perid of not more than six 

consecutive days, the flight crew member shall enter a protected time penod 

of at least 24 consecutive hours before next being available for contacr by the 

operator. 

o If assignment to extended reserve is for a perid of more than six consecutive 

days, one additional period of 24 consecutive hours shall be added ro rhe 

protected time period for each 3 days, or any porrion of three days, of 

extended reserve assignment over six davs. 

3. Operational Delay 

o The limitations stated in paragraphs I and 2 above may be extended by a 

maximum of 2 houn to meet operational delavs. 

o The limitations stated in paragraphs I and 2 above may be extended by air 

medical service op€rators as reasonable and necessar_v to complete a medical 

transport oPeratlon.

NATIONAL AIR 

TRANSPORTATION 

ASSOCIATION 

Mr. H. Clayton Foushee 

Vice President, Regulatory Affairs 

Northu'est Airlines 

901 15'Street, NtvIy' 

Suite 310 

Washingron, DC 20005 

Dea¡ Clav, 

Janua¡y 15. 1999 

At-sachr€nt -; 

4226 < ^3 Sîree' 

Alexondrio, Virgrnro 22302 

(703) 845-9000 FAX (703) 845-8r7ó 

Enclosed, you will find the National Air Transportation Association (NATA) 

and Na¡onal Business Aviation Association (NBAA) proposal for the Aviation 

Rulemakjng Advisory Committee Reserve Duty/Rest Working Group. 

This concept paper reflects the issues unique to the on-demand air charter 

industrl. and explains the operator and pilot relationship where reserve concepts are 

concerned. While the proposal articulates the manner in which both NATA and 

ì\BA.'\ believe reserve-related issues for Part 135 unscheduled operators should be 

handlec- this proposal should not be vie*'ed as suggested regulatory language. Please 

for'*'a¡i this proposal to the ARAC Executive Committee for submission to the 

Federaì -\viation Administration. 

Thank you for all your hard work as we addressed this complex issue. 

Enclosu¡e 

cc: Phil Harte¡. The Mediation Consortium 

SERVING AVIATIC.. SEIIVICE COMPANIES 

t"¿"&L 

Sincerely, 

An&o¡á. Cebula 

Vice P¡esident


NIIrOXI¡, ATR TRANSPORTATIOT{ ASSOCIATIOT 

& 

N¡,noxlr Busnvnss AvIATToN AssocIATIo\ 

Pnoposg Fon Rrsnnvs-RElArno Isstns Ix FAR P.rnr 135 

Uxscmolrr-ED Opnn lrons 

THE concept: 

Under FAR Part 135, a flight crewmember's reserve issues consist of: 

l. Rest 

o required rest þer current regulations) 

2. Opporunity Time 

. can be contacted for a possible duty assignment 

3. Dury 

' flYrng time 

o time required to prepare/conclude a flight 

4. Standby 

o time required to wait for dury assignments 

The purpose of this proposal is to define the elements of 'Standby' and 'Oppornrnity 

Time.' This clarification will provide the Part 135 certificate holde¡ with the versatility 

to comply with the on-demand nature of unscheduled FAR Part 135 operations by having 

a pool of crewmembers who are on their or*n time, and free of all present duties of a 

certificate holder, unless the crewmember is contacted and the crer+member accepts a 

dury assignment. At the same time, this clarifies the crewmember's responsibilities to the 

Part 135 certificate holder and ensu¡es adequate rest and fitness for dutl' assignments. 

OPPORTUNITY STANDBY 

TIME 

DUTY 

\[hat was the 

Previous Rest? l0 consecutive hou¡s l0 consecutive hou¡s l0 consecunve hou¡s 

after a dury assignmeur after a dury assignmeut after a duty assignment 

Is this Rest? 

is this Duty? 

Can the Certiñcate 

Holder Contact 

Crewmember? 

Is This Part of l4HR no 

Duty Period?+ 

yes yes 

yes yes nJa 

yes yes 

*Sp¡crnL PRovlstoNs APPLY Fon Arn ArvrguleNcE FLIcHT Op¡n¡loNs, 

SEE PAGE 3


Pnrlrous REsr 

Following a duty assignment, the crewmember must have received at least l0 

consecutive hours of Rest before assignment to 'Opportuniry,' 'Standby,' or 'Duty' can 

occur. 

REsr oR DurY? 

Opportunity Time: Opporruniry time is not to be considered a duty assignment and 

does not fall under the duty time limitations. However, Opporunity Time is not Rest as 

defined by the regulations. It is an assignment unique to Part 135 unscheduled operators. 

When in Opportunity Time, the crewmember has no specific duties to the certificate 

holder until a duty assignment is accepted. Example of Opporrunity Time: The 

certificate holder has no current duty or Standby assignment for the crewmember; 

however, should one arise, the certificate holder can contact the crewmember to 

determine if the crewmember can report for that duty. 

Standby: Standby is considered a dufy assignment. Upon being assigned to Standby, 

the l4-hour duty clock begins. Thrs duty period ends when the crewmember is released 

b-v- the certificate holder or the 14-hou¡ duty period expires, whichever occurs first. 

Example of a Standby assignment: Crewmember is directed to wait at the airport for 

contact for a dury assignment and must report to that assi_mment within a reasonable time 

penod. 

Dutl': Dury is the time a certificate holder has assigned a creumember to specific duties 

and responsibilities. Dury time begins when a crewmember reports and ends when 

released or the duty period expires. Examples of dury are: flying, pre-flight and postflight 

activities, training for the certificate holder. 

OgUcaTIoN To REPoRT 

Opportunity Time: Druing Oppornmiry Time, the flight crer¡member has no specific 

duties to the certificate holder; however, the certificate holder can contact the flight 

crewmember for a duly assignment should one arise. There is a responsibility on the 

crewmember to be fit for a duty assignment unless the fli*eht crewmember is not capable 

of accepting a dury assignment based on an inability to meet the following, for example: 

¡ Adequately rested for the planned dufy ¿tsslgnment, 

o No immediate physical impediments that would affect abiliry to perform the dury 

assignment, i.e., sprained ankle or broken arm, etc., 

o Not being detrimentally affected by a major life stress, i.e. death in the family, or 

divorce, etc., that would affect abiliry to perform the duty assignment, and 

. Ability to report for duty within a reasonable ¿rmount of time as defined by the 

certifrcate holder. 

Standby: The duty period begins when Standby is assigned. A crewmember in Standby 

must be able to complete any duty assignment within the original duty period. 

Dut-v: Reporting is not applicable as the crewmember is presently on duty.


Penr oF DurY Pnn¡oo? 

Opportunitv Time: Oppornrniry Time is not considered part of the duty period,and, 

therefore, does not count against the l4-hour dury clock. 

Standby: This assignment is part of duty and can only'continue for the duration of the 

normal duty period. 

Sppcmr PnolrsroNs FoR Arn A¡vtsuLANcE Opnn¡noxs 

To accommodate the unique and critical flight operations conducted by Air Ambulance 

operators, these Part 135 on-demand air cha¡ter operators could operate under the 

following standby provisions without triggering duty time: 

. an operator may contact the pilot for a duty assignment 

o the pilot may be expected to remain fit for flight (to the extent that this is 

within the control of the pilot) 

o the pilot may be expected to remain within a reasonable response time to the 

aircraft 

o when operating under these provisions a dury period begins when the pilot is 

contacted and accepts an assignment 

Such operations would be subject to the following constraints: 

. following completion of a duty assigned during a period of extended reserve. 

the pilot will be provided at least l0 consecutive hou¡s of rest before next 

being available for contact by the operator 

. assignment to extended standby can consist of up to six consecutive days 

which shall be followed by a period of at least 24 hours of consecutive rest 

before next being available for contact by the operator 

. ExtensionProvisions: 

The six-day period may be extended by the operator under the following 

conditions: 

t. Th¡ee additional days of extended standby may be assigned.with the 

addition of another 24-hour period of rest. 

2. The ma,ximum amount of extended standby will be l5 days followed by a 

mandatory 4 days of consecutive rest during which the operator may not 

contact the pilot. 

¡ The duty period may be extended by Air Ambulance operators as reasonable 

and necessary to complete a medical hansport operation.

t4910-131 

DEPARÍÌ{ENT OF TRAI{SPORTATION 

Federal Aviation Adninistration 

FJ.ight Crervmenber F1íght Time Linitations and Rest 

Requirements 

AGENCY: I'ederal Aviation Administration, DOT. 

ACTION: Notlce. 

SITMMARY: This notice announces to the public the Federal- 

Aviation Administration's intent to rigorously enforce the 

r rarrrl uv ufu al i ons cônr:erni no F'l i oht- time limitations and rest 

! rêr^rriremenls- v\auf ! Thcsc reollations have been under review for 

Some time, and the FAA has stated with respect to reserve 

time assignments that if new rules \^/ere not adopted' the FAA 

intended to enSure that the current rules, âS interpreted' 

:ra kraina ¡nrror-t'l rz imnlcmented. No new rufes with regard 

oIç vçfrrY 9vrrvuurJ 

to feserve time have been adopted. Therefore, the FAA ís 

ro ì1_ar:l- i nrr jf - Innaorrnrlì ¡n inlornrcl-aliOn Of itS 

-Lò -L\r1I9ÒLArrufll\j Lrruç!yrçLuu 

regulations on this issue and is giving affected certificate 

holders and fÌiqht crewmembers notice of its intent to 

enforce its rules in accordance with this interpretation. 

This notice is beinq given so that those affected witl have 

ãñ nnnart rrn'i 1_r¡ l_n ror¡i ow l_ þai r nr:,^l i r-oq and i f nor-o5SAfyt 

dI.L UpPUr LL.,ll.l-L Ly LU rE v fUvv Llrçrr y Lqv sfrvt 

come into fuft regulatory compliance. 

DATES: This notice is effective on June 15, 7999-

FOR ET'RTHER INFORMATION CONTACT: 

Atberta Brown, Aír Transportation Division' AFS-200, 

B O O Independence Avenue , SVü. , Vüashington, DC 2059I , 

Telephone (2A2J 267-832I.

Admlnístrator finds necesSary for safety in air Commerce and 

national security." 49 U.S.C. S 4410I (a) (5). 

The current rules specify flight time limitations and 

rest requirements for aír carriers certificated to operate 

under part I2L (domestic: subpart Q; flag: subpart R; and 

supplemental: subpart s) and part 135 (subpart F). The FAA 

has consistentlv interpreted the term rest to mean that a 

flight crewmemb'er is free from actual work for the air 

carríer or from the present responsibLliLy for work should 

the occasion aríse. Thus, the FAA previously has determined 

that a flight crewmember on reserve hras not at rest if the 

f I i oh1_ .rcu¡merhnr l-,rÄ 1 ñrôqênl II resnonsi biÌitV for work in 

L\-,1 11L U!çvvrLLUrlLUUI tlÕLt A yrçÐçr1u rçJI/vrru L 

that the flight crewmember had to be availabfe for the 

carrier to notify of a flight assignment- 

The FAA| s current rules at L4 cFR S I2L.4'7I set forth 

flight time timitations and rest requirements for domestic 

operations. Subsections (b) and (c) of this section have 

^^ñ^r¡r_nr.l ñ,rñôrôlls inlernref :l'inn rorrrrasfg ffOm indUStfy. 

9U.LI.EId.LUU ItUILLE!VUO f¡iLç!yrvLqufvir 

These sections províde that: 

section 72L.477 FLiqht time limitations and test requirements: 

AJJ fTight crewmembers. 

(b) Except as provided in paragraph (c) of this section, no 

certif icate hol der conductirlgJþnLestic operations may scheduJe 

flight crewmember and no flight crewmember may accept an 

.-ôi ã^m^nf far f l iahf f jme r-lüy j ¡a fho ?4 aançar-tttiVe hOUf S 

d.Þö t gtttIICttL LvL t!!9!t L L Lfr.u vuLJtt9

precedinq the scheduJed compfetion 

scheduled rest period during that 

foJJowing: 

(1) 9 consecutive hours 

sr-herlttl erl fl ioht tjne. 


hours of scheduJed flight 


schedufed flight time. 

wL atty LttvrtL 

24 hours of at 

aanmanf ¡^¡i f hnttf 

feast the 

of rest for -less than B hours of 

of rest for B or more but fess than 9 

time. 

of rest for 9 or more hours of 

(c) A certlficate hoLder may schedufe a flight crewmember for 

less than t.he rest required 1n paragraph (b) of this section or 

may reduce a schedul-ed rest under the foffowing conditions: 

(1) A rest required under paragraph (b) (1) of this section may be 

scheduLed for or reduced to a minimum of B hours if the fllght 

crewmember is given a rest period of at feast 70 hours that 

must begln no later than 24 houts after the commencement of 

the reduced rest period. 

(2) A rest required under paragrdph (b) (2) of this section may be 

schedufed for or reduced to a minimum of B hours if the fJiqht 

crewmember 1s qiven a rest perlod of at Least 77 hours that 

must begin no fater than 24 hours after the commencement of 

the reduced rest period. 

(3) A rest required under paragraph (b) (3) of this section may be 

schedufed for or reduced to a minimum of t hours if the fJight 

crewmember is given a rest petiod of at Least 72 hours that 

must begin no later than 24 hours after the commencement of 

the reduced rest period.

similar language is contained in Sections I35.265 (b) and 

(c). Also note the "l-ook back" requirement in Section 

r35.267 (d) . 

The EAA has consistently interpreted Section L2I.471(b) 

and the correspondinq Section I35.265(b) to mean that the 

certificate holder and the flight crewmember must be able to 

look back over the 24 consecutive hours preceding the 

scheduled completion of the flight segment and find the 

required scheduled rest period. This interpretation of rest 

also has been applied to pilots On "reserve time." Reserve 

time wh1le not defined in 14 CFR 1s general-Iy understood to 

be a period of time when a ffight crewmember is not on duty 

but must b'e available to report upon notice for a duty 

period. Thus, a flight crewmember on reserve could not take 

- €l -i 

d I-LIL¡llL ^Lr- crD>JVIIItLvllLt --oi ¡¡1¡p¡1_ _ ancl arru the ur CertifiCate hOlder COufd nOt 

schedule that crewmember for a flight assignment, unless the 

flight crewmember had a scheduled rest period such that at 

the end of the fliqht segment one could fook back 24 hours 

and find the required amount of rest. 

Compliance and Enforce¡nent PIan 

Flight crewmembers and their unions have raised 

Concerns that scheduling procesSeS used by Some certificate 

holders may not ensure compliance wíth flight time 

restrictions and rest requirements when a ftight crewmember

and expects to deal stringently with any vioÌations 

discovered. 

Issued in Washington, DC on June 10, 1999 

/s/ 

L. Nicholas LaceY 

Director, Ftight Standards Service

Rest Period: 

ATA Proposed Reserve Rest Regulation 

Each flight crewmember member assig uty will be provided with a 

scheduled rest period ¡eriod of at lea tive hours during each reserve day, 

frge_of all ith the carrier ght crewmember will have an 

. The carrier may reschedule the rest period by as much as three hours earlier 

or later than the beginning time of the preceding rest period provided that 

of the next scheduled rest period. 

riod with at least ten hours advance 

e next scheduled rest period. 

Advance Notice: 

Advance notice to a reserve flight crewmember of a flight duty assignment by the 

air carrier provides the flight crewmember an opportunity for rest. 

. lf the reserve flight crewmember is provid eawitdto g) ror" hours of advance 

notice, that flight crewmember may be assigneffi legal flight assignment. 

o Contact may not be made with the reserve flight crewmember during a 

scheduled rest period for the purpose of providing advance notice. 

Reserve Availability Period: 

The Reserve Availability Period is the period of time from the end of the rest 

period to the time that the reserve flight crewmember must complete reserve or 

flight duty. 

* 

The reserve flight crewmember's reserve availability period may not )' ' 

hours except as permitted below. Actual flight duty time may be extended "x"""(19 a\h- .'' 

additional two hours for reasons beyond the control of the air carrier such as 

weather, ATC, or mechanical delays. With advance notice of less than ten hours, 

the reserve availability period may be extended as follows: 

\ Advance Notice Reserve Availability period 

.) 4 - 5:59 hours 20 hours scheduled + 2 in actual operation 

'\ 6 - 7:59 hours 22 hours scheduled + 2 in actual oþeration 

I I - 9:59 hours 24 hours scheduled + 2in actual operation 

RAP applies to the first duty period of a flight assignment. Subsequent duty 

periods of the flight assignment are subject to FAR 121 Subpart Q, R or S, flight 

duty time rules, as applicable. 

lnternational Flight Crews: 

The above RAP rules apply to internationalflights except where the reserve flight 

crewmember is assigned to an augmented crew under Subpart R or S in which 

case the flight and duty time rules of those Subparts apply for the entire flight duty 

assignment. 

12t02t98

NATIONAL AIR CARRIER ASSOCIATION 

RESERVE DUTY AND REST POSITION 

Reserve Duty and Rest Working Group Meeting 

September 2, 1998 

The following is proposed as an amendment to FAR Part 121 to establish a formal 

reserve duty and rest regime for domestic, flag and supplemental operations. 

121.xxx. Reserve Duty and Rest. Certificate holders may schedule flight 

crewmembers for reserve assignments us¡ng one of the following methods after 

providing the crewmember with a 12-hour notice of the particular reserve option that 

is being applied. Reserve options may not be changed without an intervening 12 hour 

rest. 

(a) The certificate holder shall provide the flight crewmember with a scheduled 

rest period of not less than I hours within each 24 hour period of reserve; or 

(b) The certificate holder may provide advance notice of an assignment to duty 

involving flight and provide an additional time of not less than one hour to report with 

the following limitations. The certificate holder must relieve the crewmember from all 

further responsibilities between advance notification and report time. 

(1) lf the flight crewmember receives at least I hours advance notice, the 

flight and duty limitations set forth in this Subpart apply. 

(3) Less than I hours but more than 6 hours advance not¡ce, the 

scheduled duty period is limited to 12 hours, but may be extended to 14 hours for 

operational delays. 

(4) Less than 6 hours but more than 4 hours notice, the scheduled duty 

period is limited to 10 hours, but may be extended to 12 hours for operational delays. 

( 9t t"""than 4 hours, the scheduled duty period is limited to I hours, but 

may be exteirded to 10 hours for operational delays; or 

(c ) Where the operator is unable to provide a flight crewmember with one of the 

rest or notification periods described in (a) or (b) above, the crewmember is limited to 

no more than 72 hours in reserve status without a planned rest period of at least 24 

consecutive hours. lf the crewmember is assigned duty involving flight, the subsequent 

minimum rest period of this Subpart shall be increased by at least one-half the length 

of the preceding flight duty period.

i 

I 

t-. 

:.-::l 

'!i¡9 

';:r 

Mr. Donald E. Hudson 

Avjation -Medical Advisory Gro up 

14707 East 2nd Avenue 

Suite 200 

Aurora, CO 80011 

20005 

Gentlemen: 


Mr. Clay Fourshee 


901 15th Street, NW 

Suite 310 

Washington, DC 

The undersigned (FPA, IACP, lPA, SWAPA, and IBT representing approximately 20,000 

crewmembers) concur with the basic document submitted by the entire labor group concerning 

the issue of Reserve and Reserve Rest. This submissíon is supplementary to that document 

and it addresses additional methodology applicable to the Part 135 and non-scheduled 

carriers (non-scheduled as used herein applies to carriers currently operating under pari 121, 

Subpart S (supplemental rules) excluding such carriers as FEDEX, UPS, etc. that may operate 

under supplemental rules, but do so with a known published operating schedule). 

It is recommended that the basic labor document, addressing a Protected Time period (pTp) 

and Reserve Availability Period (RAP) methodology, apply to all carriers, i.e., scheduled, 

non-scheduled (as herein defined), and Part 135. Additionally, it is recommended that 

non-scheduled and Part 135 carriers be provided an alternative method for reserve 

assignments where it can be validated that the PTP-RAP methodology cannot be applied. An 

example requiring this alternative means would be an aircraft with one crew at a station with a 

prospective duty to operatê the aírcraft at an undetermined time. 

The underlying ratÍonale of the Flíght and Duty Time ARAC workíng groups over the past 

seven years has been to ensure that crews are provided a reasonable sleep opportunity. The 

most effective means of rest is to provide a sleep opportunity at the same time each night. 

Recognizing that this is not always possible in the air transport industry, the PTP-MP 

methodology and a reduced duty time, based on predetermined notice periods, represent two 

means of satisfying the underlying rationale of ensuring a reasonable sleep opportunity. 

Thís alternative methodology greatly reduces the economic impact of regulatory reform on the 

non-scheduled industry. We belíeve that this submission should be helpful to the FAA in 

formulating a new rule that balances safety, economics, and the public interest. We are 

pleased that the FAA has addressed this issue and we are supportive of constructive change 

arising from the effort put forth by the respectiVe groups and the Agency. 

Dave Wells //s 

FPA, CAPA 

D.R. Treíchler 

IBT, CAP, 

Don Kingery lls 

IACP (non-CAPA) 

Lauri Esposito /is 

IPA, CAPA 

Bob Landa //s 

SWAPA, CAPA

PROPOSED REGU LATORY LANGUAGE 

l2l.xxxqlternative Means of Obtainíng Reserve Rest for Non-scheduled Operators (without a 

known schedule) and Part 135 Operators (separate subpart) 

ta) -Non-scheduled operators and Part 135 operators may schedule a flight crewmember 

and that flight crewmember may accept a reserye assignment as follows: 

(1) The operatorfirst must assign a PTP period, discussed elsewhere in this rule, 

provided the flight assignment has a known departure tíme (schedule), and the operator may 

then schedule and a crewmember may accept any assignment provided elsewhere in this rule 

excluding (2) and (3) below; 

(2) lf unable to comply with (1) above, and an advance notice before departure of 

not less than 14 hours is provided the crewmember, an operator may schedule and a 

crewmember may accept any assignment provided elsewhere in this rule excluding (3) below; 

or 

(3) lf unable to comply with (1) and (2) above, an operator may assign and a 

crewmember may accept a reduced duty period as set forth below: 

(a) W¡th 8 to 13:59 hours advance notice, the scheduled duty period is 

limited lo 12 hours, but may be extended to 14 hours for operational delays; or 

(b) Wìth 6 to 7:59 hours advance notice, the scheduled duty period is 

; limited to 10 hours, but may be extended to 12 hours for operational delays; or 

,.-:_..,: 

(c) Wth 4 to 5:59 hours advance notice, the scheduled duty period is 

limited to 8 hours, but may be extended to 10 hours for operational delays; or 

(d) \Mth less than 4 hours advance. notice, the scheduled duty period is 

limited to 7 hours, but may be extended t hour for operational delays. 

(e) For assÍgnments ín paragraph (2) and (3) (a) through (d) above, the 

,¡=-i..c operatormust relieve the crewmember from all further responsibilities between advance notice 

i+J,q¡ and report time.

ALPA's HANGAR Page 1 of2 

Volume 6, Number 2 June 25, 1999 

ALPA Declares Preliminary Victory in Flight-Time/Duty-Time 

Battle 

FAA Agrees to Enforce 7985 Rule on Pilot Rest 

ALPA recently declared victory in its almost 1S-year battle to compel FAA to "rigorously" 

enforce existing regulations on pilot flight-time/duty-time requirements. Improving pilot rest 

rules is one of ALPA's top safety priorities. 

FAA Administrator Jane Garvey told ALPA President Duane Woerth in a June 3 letter that her 

agency will finally begin to enforce 1985 rules requiring pilots to receive a prescheduled and 

protecteci rest period during the 24 hours before a flight, "The FAA has said on more than one 

occasion that, all else failing, we wouid rigorously enforce the current (pilot rest) rule," Garuey 

said in her letter. "To emphasize our commitment, I plan to publish our intent to enforce the 

current rules in lhe Federal Register." 

"ALPA has led the fîght to correct inadequate duty and 

rest rules for years and we are elated that 

Administrator Garvey is committed to moving forward 

finally on this critical aviatian safety issue." 

Duane E, Woerth, ALPA President 

Garvey also said FAA will issue a Supplemental Notice of Rulemaking altering its December 

1995 proposal regarding regulations governing the amount of time pilots can fly and remain on 

duty without a mandated rest period. 

The current regulations require that a reserve pilot be given at least nine hours of rest for 

every 24-hour work period. During this time, the pilot must be free of all official duties and 

cannot accept any assignments. The designated rest period can be reduced to eight hours if 

compensatory rest ís províded the -following day. 

FAA has set a 180-day deadline, giving all U.S. carriers until Dec. 72, 7999 to comply with the 

rules. At that time the agency will " ... begin a comprehensive review of certificate holders' 

flight scheduling practices and expects to deal stringently with any violations discovered." 

The FAA administrator's correspondence was in direct response to a May 13 letter fron-eapt. 

\4lqerth" asking Garvey to fulfill earlier promises to enforce the existing rules for pilot rest 

requirements. Woerth also urged FAA to forge ahead with other needed revisions that have 

hung ín bureaucratic limbo fcr the past four years. 

In addition, Woerth advocated that FAA perform a comparative risk assessment of pilot fatigue

ALPAs ITANGAR 

Page2 of2 

issues instead of a typical cost/benefit analysis. Such an assessment would be the first step in 

the development of any new and improved federal pilot fatigue rules. 

The National Transportation Safety Board concurs with ALPA's position on flight and rest rules' 

On June 1, its chairman, Jim Hall, urged FAA to take immediate action on pilot fatigue 

regulations. 

Back to ALPA Home Page

Letter: FAA Interpretation of FAR 121.471 - 4 Jun 1999 Page 1 of4 

U.S. Department 

of Transportation 

Federal Aviation 

Administrat¡on 

Captain Rich Rubin 

7700 N.E. 8th Court 

Boca Raton, Florida 33487 

Dear Captain Rubin: 

Rese¡ve Pilots Rest Press Kit 

JUN - 41999 

800 Independence Ave., S.W 

Washington, D.C. 20591 

This responds to y_our request 1'or an inle¡prqtatiol {¡l'the Fqderal AviattQn 

Regul¿tiqn$ 14 C.F.R. ç 121.471, Flight time limitations and rest requirements: 

All flight crewmembers. Section 121.471(b) states as follows: 

Except as provided inparagraph fc) of this section, no certificate holder 

conducting domestic operations may schedule a flight crewmember and no 

flight crewmember may accept an assignment for flight time during the24 

consecutive hours preceding the scheduled completion of any flight segment 

without a scheduled rest period during that 24 hours of at least the following: 

(1) 9 consecutive hours ofrest for less than 8 hours ofscheduled 

fligirt time; 

(2) l0 consecutive hours of rest for 8 or more but less than t hours 

of scheduled flight time; 

(3) 11 consecutive hours of rest for 9 or more hours of scheduled 

flight time. 

You present the following hypothetical: 

You begin reserve duty after cornpleting a scheduled 48 hour 2 day 

off period. You are then assigned a block of five days reserve duty 

commencing at 0001 on day one until 2359 on day 5. You do not 

receive any notice of a prospective rest period by the air carrier for 

any of the five served duty days. You are not called for flight duty 

during day one of your reserve duty. On day two, you are called at 

1900 for a flight duty period that will commence on day two a|2300 

and will end at 0745 on day three. 

Please note that you request an interpretation under 14 C.F.R. $ 121.471(b), but 

state that you are an international captain for an air carrier. Section I2l.47l(b) 

only applies to domestic operations. Flight time lirnitations for flag 

(international) carriers are specified in Subpart R Part l2l of the Federal 

Aviation Regulations. Since you have specifically asked about the interpretation

Letter: FAA Interpretation of FAR 121.471 - 4 J:url'1999 

of $ 1 21.471(b) in questions 1 -5, this interpretation is restricted to that section 

and the rest requirements for domestic operations. Additionally you use the term 

"flight duty" in your above hypothetical. The FAA uses the terrns "flight time" 

and "rest" in $ 121 .471(b). For purposes of this interpretation, we have assumed 

your use of the term "flight duty" to be synonymous with the term "flight time." 

Finally, you have not specified what you mean when you use the term "reserve 

duty." Therefore, for purposes of this interpretation, we assume that this means 

you have a present responsibility for work should the occasion arise. 

Question 1: Using the above example, would an air carrier be in compliance 

with the requirements of FAR 121.471(bX Please explain. 

No. We have consistently stated that reserve duty is not rest when the reserve 

flight crewmember must maintain accessibility (via telephone or pagerlbeeper) 

to the employer and there is a present responsibility to work. Therefore, the 

certificated carrier must provide an opportunity for the flight crewmember to 

obtain appropriate rest when scheduling the flight crewmember for flight time. 

In this instance, when you are called at 1900 for flight duty you receive 4 hours 

notice that you will be required to report for flight duty at 2300. Your flight duty 

will end at 0745 on day three; thus it will be 8 hours and 45 minutes long. In 

order to be in compliance with Section I2l.47I(b), the air carrier conducting 

domestic operations and the pilot rnust be able to look back over the 24 

consecutive hours preceding the scheduled completion of the flight segment and 

find the required scheduled rest period. In this instance, looking back24 hours 

from the end of the pilot's scheduled flight time (0745 on day three), the pilot 

only had 4 hours of rest - the time period between 1900- 2300L. The regulations 

(ç l2l.47l(bx2)), however, require a pilot scheduled for more than 8 hours but 

less than t hours of flight time to have 10 consecutive hours of rest. Since you 

received only 4 hours of rest in the 24-hour period, the flight schedule would be 

in violation of Section 121.471(b)(2). Furtherlnore, the reduced rest provisions 

of Section l2l.47l(c)(2) would not be met with only 4 hours of rest. 

I We assume that once you are notified at 1900 to report for a flight af 2300 that you no longer 

have a present responsibility for work between 1900 and 2300 

Question 2: Using the above example, would I [the pilot] be in violation of 

FAR 121.471(b) if I accepted the flight duty assignmentthat begins at2300 

on day two. 

Section I21.47I(b) applies to pilots and other flight crewmembers as well as the 

air carrier. Consequently, you would be in violation of this section if you 

accepted the flight assignrnent prior to completing the required rest period. 

Question 3: Does the FAA expect an air carrier to schedule pilots in 

compliance with FAR 121.471(bX If so, how is operator compliance 

measured and enforced? 

The law requires an air carrier to schedule its pilots in compliance with the 

regulations - in this instance ç 121.477. Section l2l.47l(b) applies to the air 

Page2 of 4

Letter: FAA Interpretation of FAR l2I.47l - 4 Jun 1999 

canier. Thus, the air carrier is expected to schedule pilots in compliance with $ 

l2l.47l(b) as well as all other pertinent Federal Aviation Regulations. 

Compliance is measured by analyzingthe facts and the applicable safety 

regulations published in the Code of Federal Regulations. The Flight Standards 

Service is responsible for investigating alleged violations of $ 121.471 and for 

initiating enforcement actions. 

Question 4: Does the F AA expect crewmembers to comply with the 

requirements of FAR l2l.47l(b)? If so, how is crewmember compliance 

measured and enforced? 

See the answer to Question No. 3. 

Question 5: What does the FAA advise a reserve crewmember to do if 

he/she is scheduled for flight duty and he/she has not received an 

appropriate prospective rest period as required by FAR l2l.47l(b)? 

You seek advice as to what a reserve crewmember should do if the rest specif,red 

in $ l2I.47l has not been provided. First, the reserve crewmember must 

determine whether all of the elements of $ 121 .471, including the reduced rest 

provisions in $ 121 .471(c), have been met. Second, if $ l2l.47l(c) cannot be 

used, you are hereby advised that $ l2l.47l(b) specifically prohibits a flight 

crewmember from accepting an assignment that violates this provision. In the 

event any flight crewmember finds himself/herself scheduled in violation of $ 

121.471, helshe should, at a minimum, advise the appropriate person at the air 

carrier. Depending on the air carrier's protocol, this may be the Chief Pilot, the 

Director of Operations or the Director of Safety. Additionally, a pilot always has 

a duty under $ 91.13(a) to notify the certificate holder when he/she is too 

fatigued to fly. 

Question 6: Can offduty time incurred during layovers fulfitt the24 hours 

off in 7-day rest requirement? 

Yes. We assume that "off duty time" -dh that the pilot does not have a present 

responsibility for work should the occasiõrf arise, 

Question 7. If the ans\üer to the above question is yes, what are the 

requirements for this rest period? Can pilots be reassigned during this 

period? fs it protected from interruption or contact? 

The FAA has consistently interpreted "rest" to mean a continuous period of time 

during which the flight crewmember is free from all restraint by a certificate 

holder. This includes freedom from work and freedom from responsibility for 

work should the occasion arise. See Letter of Interpretation to James Baxter. 

March 25. 1997 (copy enclosed). Thus, a crewmember who was required to be 

near a phone, carry a, beeper, or maintain contact by computer so that he would 

be available should the carrier need to notifu hirnlher of a reassignment would 

not be on rest. However. there would be no rest violation where an air carrier 

does not impose any requirements on the crewmember during the rest period, 

Page 3 of4

Subj: Horizon comPliance 

Date: 2t19t991:10:58 PM Eastem Standard Ïme 

From: 74113.U3@compusene.com (Don Treichler) 

Sender: 7 41 03.U3@compusene. com (Don Treichler) 

To: DJSTACEY@ao|.com (INTERNET DJSTACEY@ao|.com) 

cc:DJWMSW@aot.com (Dare Weils),76364.2764@compusene.com (Don Kingery), LLE5',16@aol.com (Lauri Esposito)' 

Smcphait@compusene.còm (Stere Mcphait - sweÃ¡, Gömith2617@aol.com (INTERNErGSmith26lT@aol.com) 

Dear Doug: 

On 2-18-99, I discussed Horizon Air compliance with the Calhoun letter of 

interpretation with Greg Simes, Horizon FAA POl. He stated that Horizon 

had not been required to comply with that letter except for the portion 

addressing pilots not receiving 24 consecutirc hours off in selen 

consecutire days during the crossowr fom one month to the next' 

Apparenfly Horizon initially indicated that they would comply with that 

portion and then decided not to do so. Greg is proceeding with enforcement 

action on the latest submission Volating that area. As for the portion of 

the enturcement letter, which states that in domestic operations you must 

be able to look at the prer,ious 24 hour period and find a minimum of 8 

hours of rest or you must termrnate your f ight, the Horizon POI stated 

that he has receiwd no guidance from the FAA at the national lercl as to 

whether enfcrcement action is desirable or permissable. Bottomline appears 

to be that the FAA national intends to IGNORE the existing regulation as 

well as their consistent interpretations of it orer the past 8 years and 

wait for rulemaking to resolle the issue. The FAA is likely to outsource 

an economic study of the resene issue that will take until late 1999. 

Following that, the FAA likely willwrite a Supplementary Notice of 

Proposed Rulemaking (SNPRM) and pror,ide 90 days for comment (and possibly 

another 90 days if someone so requests). All of this has occuned because 

the management side of the FAA rulemaking process has stated that 

enforcement would cost the airlines $100,000,000. This statement was made 

during ARAC meetings. I requested documentation of these figures and 

management agreed to supply the numbers. Later, in front of the FAA and 

labor, management refused to do so. Management refuses to do so to this 

lery day. The reason they refuse is (a) the figure is totally inaccurate 

and (b)they wish to wait until the comment penod forthe sNPRM and use 

the figure again when there is no opportunity to challenge it. As a 

result. misinturmation is allowed to stand unchallenged. Regretably, such 

action compromises safety 

Best regards, 

Donald R. Treichler 

lntemational Representatile 

Teamsters Ai rlíne Dir,ision 

7306 School House Lane 

Roseville, CA95747 

Tel.916-791ß747 

Fax 2757 

Prevously, the Northwest Region Administrator advised members of congress 

that Horizon Air had agreed to comply with the letter of interpretation. 

This is not the case. You may use this e-mail as an attachment to any 

conespondence you may hare with congressional members to ensure that they

Letter: FAA Interpretation of FAR 121.471 - 4 Jlun1999 

U.S, Department 

of Transportation 

Federal Arriation 

Administration 

t 

March 25.1997 

Mr. James Baxter 

P. 0. Box 250578 

San Francisco. CA 94125 

Dear Mr. Baxter: 

800 Independence Ave., S W 

Washingfotl D.C.20591 

Thank you for your inquiry requesting an interpretation of rest and duty 

regulations in conjunction with non-flight assignments by the air canier. Due to 

the loss ofpersonnel over the past year and the urgency ofother regulatory 

mattets, we have been delayed in anslvering your inquiry. We thank you for your 

patience. 

Your inquiry revolves around the definitions of "rest' and "duty" and the 

relationship between ground assignments and flight time duty. Interpretations of 

what constitutes "fest" or "duty" are the same under Part l2l or 135. The FAA 

has consistently interpreted "rest' as a continuous period of time during which 

the crewmember is free from all restraint by the certificate holder. This includes 

freedom from work and freedom from responsibility for work should the 

oecasion arise. The FAA has alsc consistently interpreteC "Cuty" to mean aotual 

work for an air carrier or the present responsibility for work should the occasion 

arise. (Letter from Donald P. Byrne, Assistant Chief Counsel, Regulations and 

Enforcement Division, to Assistant Chief Counsel. AGL-7, dated July 5, 7991, 

letterfrom DonalC P. Byrne to R.C. McComick, dated June25,1996.) 

You prolffi lhree situations in which you questioned whether the 

crewmember's assignment constituted "duty titne," I will respond to your 

tluestion regarding a reserve pilot's status first, as the rules here are plain. You 

inqrired whether acrewfiomber who had flown for 3 Cays in a row, lvas on 

reserve a fourth day but diúnot fly, and then was scheduled to fly another four 

Cays, is legal, Under the definitions stated above, this pilot would be in violation 

of Sætion 135.265(d). Reserve duty is not rest, as the type of reserve duty you 

described requires that the crer¡,rmember be available to fly, should the 

opportunity arise. In this specific scenario, the crewmember would have been 

without rest for 8 days, While the crewmember could have florvn for two days 

after the reserve day, on the 7th day the crewmember must be given the required 

rest before another flying assignment, Section 135.265(d) states that a 

crewmember must be relieved "from all further duty for a least 24 consecutive 

Page 1 of3

Letter:FAA Interpretation of FAR l2l.47l - 4 Jun7999 

hours during any 7 consecutive days." It is possible for a crewnember to be 

scheduled on reserve for 7 days and not be in violation ofthe regulation as long 

as the crewmember does not fly (Letter from Donald P. Byrne, Assistant Chief 

Counsel, Regulations and Enforcement Division, to B. Stephen Fortenberry, 

dated June24,1991.) However, once the crewmember takes a flight in Part 135 

operations, the rest requirements activate in order to ensure that the 

ciewmember has had iufficient rest prior to the flight. Thus, if the crewmember 

has not had a scheduled rest period during the previous 7 days, the air carrier 

and crewmember could be held in violation of Part 135 265(d) 

In your second and third situation you inquire whether ground school or a Crew 

Resource Management course lvould be considered duty. Again, duty must be 

thought of in relation to required rest. The FAA would not hold an ait canier or 

a crei',mernber in violation of Section 135265(d) if a crev"rnember was 

scheduled for 7 days or a month of ground school, CRM training or any other 

kind of gound assignrnent. As long as crewrnembefs afe on the glound, they are 

not in violation of a rest and duty regulation. However, once again, once that 

crewmember takes a flight, rest regulations activate. At that time, if the 

crewmember had been in ground school for the previous 7 days, that 

crewmember would be in violation of Section 135.265{d) as he had not received 

the required 24 hours of rest in a consecutive 7-day period. An air carrier can 

schedule a crewlnember to any kind of dull it desires for 6 consecutive days, but 

on the 7th day rest regulations will affect any flying assignment. 

Since "Iest" requires that a crewmember be free from all work obligations, 

ground school or CRM training would not qualiff as "rost" once a crewrnember 

initiates a flight. While it is not "düty," in the sense of flight duty, it is also not 

t'rgst. " 

Additionally, if a crewmember operates anaitctaft with insufficient rest, a 

certificate holder or crewmember could be charged with a careless or reckless 

violation under Section 91.13.In a prior interpretation the FAA has stated that 

the "lack of rest of the pilot is certainly a circumstance which could endanger 

others, and it is not necessary that the situ¿tion devolve into actual 

endangerment for there to be a violation of FAR 91.13." (Letter from Donald P. 

Byrne, Assistant Chief Counsel, Regulations and Enlorcement Division, to 

David Bodlak, dated October 28,lÐ1.) 

This interpretation \À/as prepared b¡'Terry Turner, reviewed by Joseph Conte, 

Manager of the Operations Law Branch and concurred with by the Air 

Transportation Division of Flight Standards Service. We hope this interpretation 

will be of assistance to you. 

Sincereiy, 

Donald P. Byrne 

Assistant Chief Counsel 

Page2 of 3

submission - Independent Pilots Association

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