Evidence based fatigue risk management during 24/7 operations: Objective assessment of pilots' sleep, performance, and fatigue during ultra long range and long range flights

Ultra long range (ULR) commercial flights are longer (greater than16 hours of flight time at least10% of the time) than long range (LR) flights (8 to16 hours of flight time), perhaps increasing the potential for fatigue-related performance deficits. Both ULR and LR flights are flown with augmented (3 or 4 pilot) crews to allow for in-flight rest. The purpose of this study was to measure the sleep, performance, and subjective sleepiness and fatigue in commercial airline pilots as they flew ULR and LR flight pairings. We compared the amount of sleep obtained, performance on a psychomotor vigilance test (PVT), and subjective rating of sleepiness and fatigue in the same pilots during ULR and LR flight pairings. N=74 Boeing 777 pilots were studied continuously during adjacent ULR and LR flight pairings. While controlling for flight duration, there was no significant difference in the amount of in-flight and sleep obtained between ULR and LR flight pairings. After controlling for layover duration, there was no difference in the amount of sleep obtained during layover between ULR and LR flight pairings. Pilots obtained more sleep while away from base during ULR relative to LR pairings, even after controlling for the time away from base. There was no significant difference in reported levels of sleepiness and fatigue during ULR and LR flight pairings. There was no significant difference in PVT speed throughout the flight during ULR and LR flight pairings. Results suggest that ULR flights are not inherently more fatiguing than LR flights despite the longer duty times associated with ULR operations. The methods used can be translated to a data-driven fatigue risk management system. These data inform both fatigue risk management system interventions and public policy.