Flight crew fatigue VI: a synthesis

Sleep, circadian rhythms, subjective fatigue, mood, nutrition, and physical symptoms were monitored in flight crews before, during, and after scheduled commercial operations. Duty-related changes in these measures were examined in four different types of air transport: short-haul fixed-wing; short-haul helicopter; domestic overnight cargo; and long-haul. The extent of these changes, and the duty-related and physiological factors contributing to them, are compared among the different operations. During all operations, the level of sleep loss was such that the majority of crewmembers would be expected to have become increasingly sleepy across trip days, with some experiencing performance decrements. In addition, during overnight cargo and long-haul operations, crewmembers were sometimes flying aircraft during the circadian low point in alertness and performance. Specific recommendations for reducing flight crew fatigue are offered for each operating environment.