2-Crew Operations: Sleep, Sleepiness and Fatigue During Long-Haul Night Flights

Abstract

Introduction: As part of a research program concerning legal aspects of two-pilot operations on long-haul routes, the purpose of the studywas to investigate 2-crew extended range operations during a flight roster with two consecutive nicht flights and a short layover.Methods: The study was conducted in cooperation with a German airline on the route Frankfurt (FRA) - Mahe (SEZ). Eleven rotations (22 flights) have been investigated by pre-, in- and post-flight data collection from the two pilots. Recordings included sleep, taksload, fatigue and stress by measurement of EEG, ECG, motor activity and subjective ratings. The average actual flight times were 9:15 h (FRA-SEZ) and 10:05 h (SEZ-FRA). All flights took place at local nights. The layover in Mahe was during daytime and lasted 14 h. Results: During layover, sleep was shortened by 2 h on average compared with baseline sleep of 8 h. The two consecutive night duties resulted in a sleep loss of 9.3 h upon return to home base. Inflight ratings of taskload showed moderate grades, but for fatigue ratings an increasing level was observed. Fatigue was more pronounced during the return flight and several pilots scored their fatigue at a critical level. Motor activity, brainwave activity (occurrences of micro-events) and heart rate indicated drowsiness and a low state of vigilance and alertness during both night flights, but these effects were more pronounced during the second flight. Conclusion: From the findings it is concluded that a duty roster, as conducted in this study, is coming close to the limits of mental and physiological capacity.