Compound Fatigue Risk in Medium-Haul Pilots

Fatigue from multiple sources (e.g., circadian, workload, stress, etc.) can create a compound safety risk. Pilots operating medium haul (M-H) routes may be susceptible to compound fatigue, but sources of fatigue in M-H operations have not been robustly quantified.

In an anonymous survey, airline pilots working M-H rosters were asked to rank on a scale of 0-10 the level of fatigue they experience from 40 separate factors across four domains: 1) circadian; 2) environmental; 3) operational; and 4) psychosocial, with higher scores indicating more fatigue. Pilots also reported habitual sleep duration.

A total of 223 pilots (90 Captains; 133 First Officers) completed the survey. Pilots rated circadian factors as most fatiguing [mean (SD); 6 (1)], followed by factors in the psychosocial and environmental domains [both 5 (1)], and finally, the operational domain [4 (2)]. Pilots reported sleeping 7 h on average; sleep was not significantly related to fatigue ratings.

Operational fatigue factors related to higher work volume (e.g., working longer hours, shorter breaks, etc.) were rated as more fatiguing. Schedule features that impinge on the window of circadian low (e.g., early starts, late ends) were fatiguing even in M-H pilots with daytime schedules that allow for sufficient sleep duration. Devine JK, Hursh SR, Behrend J. Compound fatigue risk in medium-haul pilots. Aerosp Med Hum Perform. 2025; 96(12):1063-1068.