2-CREW OPERATIONS - STRESS AND FATIGUE DURING LONG-HAUL NIGHT FLIGHTS

Background: As part of a research program concerning legal aspects of two-pilot operations on long-haul routes, the purpose of the study was to investigate two-crew extended range operations during a flight ros ter with two consecutive night flights and a short layover. Hypothesis : Present night time regulations may not be adequate for two-crew mini mum operations. Methods: The study was conducted in cooperation with a German airline company on the route Frankfurt (FRA)-Mahe (SEZ). There were 11 rotations (22 flights) that were investigated by pre-, in- an d post-flight data collection each time from the two pilots. Recording s included sleep, taskload, fatigue and stress by measurement of EEG, EGG, motor activity, and subjective ratings. The average actual flight times were 9:15 h (FRA-SEZ) and 9:53 h (SEZ-FRA). All flights took pl ace at night. The layover duration in Mahe was 13:30 h during daytime. Results: During layover, sleep was shortened by 2 h on average compar ed with 8-h baseline sleep. 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 increasin g level was observed. Fatigue was more pronounced during the return fl ight and several pilots scored their fatigue at a critical level. Moto r activity, brainwave activity (occurrences of micro-events) and heart rate indicated drowsiness and a low stale of vigilance and alertness during both night flights, but these effects were more pronounced duri ng the second flight. Conclusions: From the findings it is concluded t hat a duty roster, as conducted in this study, may impose excessive de mands on mental and physiological capacity.