Date of Award


Document Type


Degree Name

Master of Science (MS)




The introduction of ultra-long range commercial aircraft and the evolution of the commercial airline industry has provided new opportunities for air carriers to fly longer range international route segments while deregulation, industry consolidation, and the constant drive to reduce costs wherever possible has pressured airline managements to seek more productivity from their pilots. At the same time, advancements in the understanding of human physiology have begun to make their way into flight and duty time regulations and airline scheduling practices. In this complex and ever changing operating environment, there remains an essential need to better understand how these developments, and other daily realities facing commercial airline pilots, are affecting their fatigue management strategies as they go about their rituals of getting to and from their homes to work and performing their flight assignments. Indeed, the need for commercial airline pilots to have access to better and more effective fatigue mitigation tools to combat fatigue and insure that they are well rested and at the top of their game when flying long-range international route segments has never been greater. This study examined to what extent the maximum fatigue states prior to napping, as self-accessed by commercial airline pilots flying international route segments, were affected by a number of other common flight assignment related factors. The study also examined to what extent the availability of scheduled en-route rest opportunities, in an onboard crew rest facility, affected the usage of en-route napping as a fatigue mitigation strategy, and to what extent the duration of such naps affected the perceived benefits of such naps as self-accessed by commercial airline pilots flying international route segments. The study utilized an online survey tool to collect data on crew position, prior flight segments flown in the same duty period, augmentation, commuting, pre-flight rest obtained in the previous 24 hour period, fatigue state at report time, circadian rhythm disruptions, assigned rest periods in an onboard crew rest facility, experiencing spontaneous sleep episodes, and napping metrics. The study also reports on some common en-route fatigue mitigation strategy themes, as reported by the study participants and how these relate to the survey question responses of survey participants. Study results suggest that there are significant relationships between fatigue states prior to napping and augmentation, fatigue states when reporting for duty, assignment to en-route rest in an onboard crew rest facility, and having experienced spontaneous sleep episodes. The study results also suggest that there is not a significant relationship between being assigned scheduled rest periods in an onboard crew rest facility and the usage of en-route napping as part of an individual pilot’s fatigue mitigation stategy. Finally, the study results suggest that short duration naps, averaging less than 30 minutes, are most commonly being employed by the subject population to beneficial effect.