Summary of Fatigue Research for Civilian and Military Pilots

OCCUPATIONAL APPLICATIONS For both civilian and military pilots, sleep duration and time of day are consistently related to fatigue rating. Fatigue is greater when pilots have fewer hours of sleep or travel later at night or earlier in the morning. Fatigue is also greater as the number of flights flown and the length of flights increase. In addition two-person crews report significantly higher fatigue than three-person crews for long duration flights. Finally, errors increase with less sleep and accident risk becomes higher, especially for duty hours 13 hours or longer. These findings can be used to design fatigue management systems for airline and military aviation operations. TECHNICAL ABSTRACT Background: Fatigue has been on the National Transportation Safety Board's “most wanted list” since 1990 and remains a topic of investigation to this day. Of special interest is the effect of fatigue on aviation safety, especially since fatigue was a contributing factor to several hull loss and fatal aircraft accidents. In 2011, the U.S. Federal Aviation Administration issued the Flight Crew Member Duty and Rest Requirements, which mandated several aspects related to policy, education and awareness training, reporting and monitoring, and performance evaluation. Purpose: Available data on pilot fatigue are summarized to provide input for the development of the mandated fatigue risk management systems. Methods: A literature search was conducted using multiple terms directly and indirectly associated with fatigue. Additionally, outreach was conducted to identify current research that would not yet be in the literature. Results: Studies of aircrew fatigue have been performed on civilian and military aircrews across a wide range of missions and methods, including data collection in flights, simulators, laboratories, surveys of operational pilots, and accident data analysis. For civilian and military pilots, sleep duration and time of day are consistently related to fatigue rating. Fatigue is greater when pilots have fewer the hours of sleep or travel later at night or earlier in the morning. Furthermore, fatigue is greater when the number of flights flown and the length of the flights increase, and errors increase with less sleep. Conclusions: Fatigue is affected by operational factors and can cause degraded performance that can lead to fatal accidents. Some operational factors can be addressed through scheduling of aircrews and flights. This includes addressing aircrew hours of sleep; the number of successive, early wake-ups required for flights; the number of flights flown within a short period; duty length; and the number of pilots per long-haul flight.