800 Independence Ave., S.W.

Washington, DC 20591

July 24, 2013

Mr. Dan Elwell

Senior Vice President, Safety, Security and Operations 

Airlines for America

1301 Pennsylvania Ave., NW

Suite 1100

Washington, DC 20004

Dear Mr. Elwell:

In a June 28, 2012 letter, Airlines for America (A4A), petitioned the Federal Aviation 

Administration (FAA) to amend part 117 of Title 14, Code of Federal Regulations (14 

CFR). In its petition, A4A asked the FAA to add a 45-minute extension to the flight-time 

limits specified in 14 CFR § 117.11. For the reasons discussed below, the FAA has 

decided to deny A4A’s petition.

I. Background

A4A’s petition, which is dated June 28, 2012, deals with the final flight, duty, and rest 

rule that the FAA issued on January 4, 2012.1

 This rule, which does not go into effect 

until January 4, 2014,2 limits flightcrew-member fatigue in passenger aviation operations 

by regulating the length of flight time, flight duty periods (FDPs), and rest periods 

provided to flightcrew members conducting those operations. The pertinent requirements 

are codified in 14 CFR part 117. Under part 117, a pilot on an unaugmented operation 

may be scheduled up to 9 hours of daily flight time provided the pilot’s time of report 

falls between the hours of 0500 and 1959. Otherwise, the pilot is limited to 8 hours of 

daily flight time. These flight-time limits cannot be extended for unforeseen 

circumstances that are known before takeoff.3 

Part 117 also permits a certificate holder, subject to FAA approval, to implement a 

Fatigue Risk Management System (FRMS) that would allow the certificate holder to

deviate from the other requirements of part 117. In order to utilize this provision, the 

certificate holder would have to show, among other things, that the FRMS would provide 

“an equivalent level of safety against fatigue-related accidents or incidents as the other 

provisions of [part 117].”4

 1 77 FR 330.

2 See 77 FR 28763 (May 16, 2012). 3 77 FR at 363. 4 § 117.7(a).
2

2

II. Discussion

A. Scientific Evidence and Information Obtained During the Rulemaking

As stated above, A4A’s petition asks the FAA to initiate a rulemaking to add a 45-minute 

extension to the daily flight-time limits specified in part 117. If implemented, this 

extension would permit flightcrew members working on unaugmented operations to 

accumulate 9 hours and 45 minutes of flight time if their FDP begins during the peak 

circadian time period specified in part 117. However, the FAA has already considered 

imposing a similar daily flight-time limit, as part of the flight, duty, and rest rulemaking, 

and ultimately rejected that approach in the final rule.

As A4A’s petition points out, when the FAA issued the notice of proposed rulemaking 

(NPRM) for the flight, duty, and rest rule, the FAA proposed a flight-time limit of 10 

hours for unaugmented flights that have a report time during peak circadian times.5

 This 

proposed flight-time limit was only 15 minutes longer than the 9 hours and 45 minutes of 

flight time that would be permitted if A4A’s proposal is implemented. 

In response to its 10-hour flight-time proposal, the FAA received over 1,300 individual 

comments, many of them from pilots with firsthand fatigue experience, stating that flying 

for 10 hours would lead to unsafe levels of fatigue.6 In addition to the concerns raised by 

the commenters, the FAA also considered studies showing that fatigue risk increases after 

8 or 9 hours of work. Specifically, the FAA cited to a series of studies by Simon Folkard 

and Phillip Tucker, which examined the national accident rate and showed that 10 hours 

spent at work resulted in a significantly higher risk of an accident than 8 or 9 hours spent 

at work.7 The FAA also cited to two aviation-specific studies which showed that pilots 

who spent at least 10 hours on duty disproportionately contributed to the number of 

accidents.8 As a result of the data provided by these studies and the considerations raised 

by the comments, the FAA ultimately reduced, in the final rule, the proposed 10-hour 

flight-time limit to 9 hours for peak circadian times.9 This final peak-circadian-flighttime limit of 9 hours still constituted a 1-hour increase from the 8-hour daily flight-time 

limit that was imposed by the then-existing regulations.

A4A’s petition takes issue with the FAA’s reliance on the Folkard & Tucker study. First, 

A4A argues that the primary purpose of the Folkard & Tucker study was to examine 

industrial employee shift work and not the impact of accident risk over hours on duty. 

While this is true, this does not change the fact that the study did in fact examine accident 

risk over hours on duty. 

 5 75 FR 55852, 55863 (Sep. 14, 2010).

6 See 77 FR at 362 (summarizing comments). 7 Id. (citing Simon Folkard & Philip Tucker, Shift work,safety and productivity, Occupational Medicine,

Feb. 1, 2003, at 98).

8 Id. (citing Jeffrey H. Goode, Are pilots at risk of accidents due to fatigue?, Journal of Safety Research, 34, 

at 311 (2003); John A. Caldwell, Fatigue in aviation,Travel Medicine and Infectious Disease, 3, at 

90 (2005)).

9 Id.
3

3

Next A4A argues that the Folkard & Tucker study used national accident trends in 

professions that did not include aviation and that aviation is different because it is heavily 

regulated and has a number of redundant safety mechanisms. However, the FAA is 

unpersuaded by this argument. As an initial matter, the FAA is unaware of any data 

showing that flightcrew members become fatigued at a slower rate than the rest of the

general population. To the contrary, the two aviation-specific studies that the FAA cited 

in its flight-time discussion in the final rule both show that pilots who are at work for 10 

hours or more disproportionately contribute to the accident rate. Turning to the Folkard 

& Tucker study, that study and one referenced (Nachreiner, et. al) used different 

statistical techniques, such as meta-analysis and convergent validation analysis, to 

analyze published peer-reviewed studies of accident risk. Convergent analysis determines 

whether the reported trends are consistent and reliable and regarded as generalizable 

trends for the risk of an accident as a function of time into work, regardless of the work 

force or actual task performed. Because the Folkard & Tucker study applied metaanalysis to a number of peer-reviewed studies of accident risk, the Folkard & Tucker

study had a very large sample from which to draw its conclusion. The conclusion itself is 

persuasive because the results of all the studies that the Folkard & Tucker study analyzed 

were consistent and indicated the same trend, that is, as the work period increases, 

accident risk also increases and the function becomes exponential at around the timeframes that the A4A petition recommends exceeding.

In response to A4A’s specific concerns, the FAA has also examined the scientific 

literature to determine whether there are any peer-reviewed studies that contradict the 

conclusions set forth in the Folkard & Tucker study. The results of this examination

showed that the scientific literature actually corroborates the results reached by the 

Folkard & Tucker study. For example, a study by Kerstin Hanecke, et. al, examined 1.2 

million accidents of nearly all of the working population in Germany, high as well as low 

risk jobs, and concluded that:

The results show that there is clear support for the conclusion already 

drawn by [Folkard and other studies] that accident risk increases 

exponentially beyond the 8th or 9th hour at work. In addition, this seems 

to be a rather conservative estimate, as shown by the results of some 

sensitivity analyses (not presented).10

Another study, conducted by F. Nachreiner, et. al., analyzed data from a total of about 

2000 fatal accidents and concluded that “there is a reliable substantial increase in the risk 

of a fatal accident beyond the 9th hour at work.”11 The Nachreiner study added that“[t]he 

results would thus support the argument that there is a general trend for the accident risk 

 10 Kerstin Hanecke, et. al., Accident risk as a function of hour at work and time of day as determined from 

accident data and exposure models for the German working population, Scand J Work Environ Health, 

1998; 24 suppl 3:43-48, at 47 (1998). 11 F. Nachreiner, et. al., Fatal accident risk as a function of hours into work, Hornberger S, Knauth P, Costa 

G, Folkard S, eds. Shiftwork in the 21st Century. Frankfurt: Peter Lang, 2000, at 24.
4

4

to increase with time after 6 to 7 hours of work and that this increase is not simply a 

linear but an exponential one.”12

Because over 1,300 commenters with firsthand fatigue experience have informed the 

FAA that flying on an unaugmented flight for 10 hours leads to dangerous amounts of 

fatigue and because these commenters’ concerns are corroborated by the pertinent 

scientific studies, the FAA, at this time, believes that permitting a flight time that is close 

to 10 hours, such as the 9 hours and 45 minutes requested by A4A for certain periods of 

the day would be unsafe. Accordingly, the FAA cannot implement A4A’s suggestion to 

provide an extension for the 9-hour daily flight-time limit for unaugmented operations.

Turning to the other daily flight-time limit specified in part 117 for unaugmented 

operations, a flightcrew member who starts an FDP between the hours of 2000 and 0459 

is limited to 8 hours of flight time. This is because an FDP that starts during that time 

will be conducted during the flightcrew member’s window of circadian low. As 

discussed in the flight, duty, and rest rule, “flightcrew members who fly during their 

window of circadian low experience severe performance degradation.”13 For example, a 

NASA study cited by in that rule showed that “‘75% of night workers experience 

sleepiness on every shift, and 20% report falling asleep.’”14

If A4A’s suggestion is implemented, an unaugmented flightcrew member operating at 

night during his or her window of circadian low would be able to accumulate 8 hours and 

45 minutes of flight time. This flight time would only be 15 minutes less than the 9 hours 

of flight time that is permitted for operations that take place during the day. Because 

operating at night during the window of circadian low significantly degrades flightcrew 

member performance, the FAA cannot set an industry-wide standard that allows

flightcrew members operating at night to fly for the same amount of time as flightcrew 

members who fly during the day. Accordingly, the FAA cannot implement A4A’s 

suggestion to provide an extension for the nighttime 8-hour daily flight-time limit the 

applies to unaugmented operations.15

B. Remaining A4A Arguments

We are also unpersuaded by the remaining arguments presented in A4A’s petition. First, 

A4A argues that “decades of experience” show that a flight-time extension can be taken 

safely. However, as the commenters and the studies cited above point out, this is not 

accurate, as people who work for extended periods of time disproportionately contribute 

to accident risk. 

 12 Id. 13 77 FR at 355 (citing NASA, Crew Factors in Flight Operations X: Alertness Management in Flight 

Operations, at 19-34 (Apr. 1999), 

http://humanfactors.arc.nasa.gov/zteam/PDF_pubs/ETM.TM8_99rev.pdf). 14 77 FR at 356 (quoting NASA, supra note 13, at 28). 15 A4A’s petition does not make any arguments specific to the flight-time limits that apply to augmented 

operations. Accordingly, we do not address those flight-time limits here.
5

5

A4A next argues that the regulatory schemes of other countries do not have daily flight 

time limits. While A4A acknowledges that other provisions of this rule are less stringent 

than analogous provisions in the other regulatory schemes, A4A does not believe that 

these provisions are sufficiently less stringent to justify an inflexible daily flight-time 

limit. In response, we note that, as the FAA explained in the final flight, duty, and rest 

rule “the Administrative Procedure Act requires the FAA to consider the specific 

operating environment that it is regulating instead of simply following the foreign 

standards.”16 Thus, while the final flight, duty, and rest rule is arguably more stringent 

than foreign regulations on the issue of daily flight-time limits, it is more lenient than 

those standards in other areas. For example, A4A’s petition acknowledges that 50% of 

the time, the FAA’s rule permits FDPs that are longer than FDPs permitted by foreign 

regulations. The reason that the FAA was able to permit these longer FDPs is because, as 

the final rule explains, the flight-time limits in § 117.11 allowed the FAA to increase the 

pertinent FDP limits and provide certificate holders with additional flexibility without 

sacrificing safety.17 Because the FAA tailored the flight, duty, and rest rule to the 

specific environment that it regulates, parts of this rule may be different from its foreign 

counterparts. This means that in some places the rule is more stringent while in other 

places the rule is less stringent than foreign aviation regulations.

A4A also argues that other parts of the flight, duty, and rest rule mitigate fatigue 

sufficiently to allow flight-time extensions. A4A adds that, because the final rule permits 

FDP extensions, the FAA should also allow flight-time extensions. However, the FAA 

notes that part 117 was designed to work as a single cohesive part. Thus, as discussed 

above, it is the unextendable daily flight-time limits to which A4A objects that provide 

the level of safety necessary for the FAA to impose less stringent FDP limits (that A4A 

presumably favors). If the flight-time limits were to be made less stringent, than other 

parts of this rule would have to be made more stringent because the level of safety that 

factored into their calibration would now decrease. Thus, the other parts of this rule do 

not support the addition of flight-time-limit extensions.

Finally, A4A points to the fact that the Federal Motor Carrier Safety Administration 

(FMCSA) and the Federal Railroad Administration (FRA) imposed longer work-hour 

limits on their regulated entities than the FAA imposed on flightcrew members. With 

regard to FMCSA, the FAA explained, in the final rule, that it “has taken a different 

approach in addressing fatigue risk among pilots than FMCSA has with respect to 

commercial truck drivers.”18 The FAA specified that:

This is because the two industries operate differently both in terms of the 

likely number of days the affected individuals work per month and the 

respective operating environments. For example, pilots regularly cross 

multiple time zones in a very short period of time—something that is 

simply not possible in other modes of transportation. Additionally, pilots 

may work several days that are very long, but then be off for an extended 

 16 77 FR at 361-62. 17 Id. at 359-60. 18 Id. at 392.
6

6

period of time, a practice that naturally imposes a nonregulatory 

restorative rest opportunity. Finally, the nature of commercial flying is 

such that under typical conditions, the actual operation is likely to require 

intense concentration primarily during take-offs and landings, with a 

constant, but generally predictable level of concentration required for 

other phases of flight.19

The FAA also notes that a commercial truck driver who realizes, while driving, that he or 

she is tired can pull over and take a break. Conversely, a pilot on an unaugmented flight 

who realizes that he or she is tired while flying a plane does not have that ability and will 

eventually have to land the plane while fatigued. Accordingly, while FMCSA’s approach 

to hours of service is instructive, it is not dispositive in this case. FRA’s approach to 

work-hour limits is also not dispositive in this case because the railroad industry does not 

operate in a similar manner to the airline industry.

C. Ability to Obtain Flight-Time Extensions Under Existing Regulations

In addition to the above analysis, we also note that the ability to obtain an FRMS 

counsels against the FAA initiating a rulemaking to add extensions to daily flight-time 

limits. Under § 117.7, a certificate holder can submit a proposed FRMS that provides for 

flight-time extensions to the FAA for the FAA’s review and approval. As part of its 

submission, the certificate holder would have to provide the FAA with actual data 

showing that the flight-time extensions in the proposed FRMS would provide for a level 

of safety that is equivalent to the one provided by part 117. If the FAA approves the 

FRMS, that FRMS would allow the certificate holder to deviate from the requirements of 

part 117 and utilize flight-time extensions in its operations. Thus, if a certificate holder 

believes that it can safely utilize flight-time extensions in its operation(s), that certificate 

can simply apply for an FRMS under the existing regulatory scheme without the need for 

FAA rulemaking.

 19 Id.
7

7

III. Conclusion

Because, as discussed above, the lack of flight-time extensions in part 117 is justified by 

both comments received during the rulemaking process and the current state of fatigue 

science and because certificate holders have the ability to obtain flight-time extensions 

within the current regulatory structure of part 117, the FAA concludes that it is not 

necessary, at this time, to initiate a rulemaking to change part 117. Accordingly, A4A’s 

rulemaking petition is denied and Docket No. FAA-2012-0708 is being closed. 

Sincerely,

/s/

John S.Duncan

Deputy Director, Flight Standards

 Service