Perceived fatigue for short- and long-haul flights: a survey of 739 airline pilots

Fatigue-related incidents in aviation may be self-reported by pilots in confidential systems. The aim of this study was to clarify what fatigue means to pilots on short- and long-haul flights (SHF and LHF, respectively).

Questionnaires were distributed to pilots through four airlines. Questions concerned the perceived causes of fatigue, its signs and symptoms in the reporting pilot and observed in others, as well as the strategies used to minimize its impact.

Of 3,436 questionnaires distributed, 739 (21.5%) were returned. For LHF, fatigue was seen as mainly due to night flights (59%) and jet lag (45%). For SHF, fatigue was caused by prolonged duty periods (multi-segment flights over a sequence of 4 to 5 d) (53%) and successive early wake-ups (41%). Self-reported manifestations of fatigue in 60% of LHF pilots and 49% of SHF pilots included reduction in alertness and attention, and a lack of concentration. Signs observed in other crewmembers included an increase in response times and small mistakes (calculation, interpretation). When pilots were tired, all the flying tasks seemed to be more difficult than usual. In both LHF and SHF, rest and sleep management were the primary strategies used to cope with fatigue. Analysis showed that duty time is a major predictor of fatigue, but that it cannot be considered independently from the other contributory factors.

For both LHF and SHF, pilots reported acute fatigue related to sleep deprivation, due mainly to work schedules: night flights, jet-lag, and successive early wake-ups. These causal factors could easily be assessed in investigation of accidents and incidents.