The focus of this thesis is fatigue in aviation. It presents a detailed analysis of subjective fatigue and sleep patterns in short-haul operations. This operation was chosen because short-haul rosters encompass a range of scheduling factors that have been identified in the shiftwork literature as having a negative impact on alertness and performance. It is contended that studies examining these factors in the commercial aviation industry are scarce, and of those available, limited to investigations conducted outside of Australia. In addition, this thesis addresses a methodological limitation that has, to date, restricted the ability to measure fatigue during flight. It is contended that the scarcity of in-flight studies stems from the lack of a suitable performance test for measuring fatigue in time-constrained operating environments, such as aviation. The studies presented in this thesis are divided into two sections. The first section comprises three aviation studies conducted in Qantas airlines. The first two aviation studies examined the effects of scheduling factors on the subjective fatigue of flight crew employed by Qantas airlines. Two different populations were examined: B767 and B737 flight crew. Participants rated their fatigue and recorded information about their flying patterns for a minimum of 15 days. The results indicated that flight crew experienced mild to moderate fatigue in relation to their work. Importantly, different scheduling factors contributed to fatigue, including length of the flight duty period, number of flying hours, and duty start times. The third aviation study examined the sleep of B737 flight crew across a 3-day schedule. Sleep quantity and quality were determined from a sleep diary and wrist actigraphy data. The results indicated that sleep offset time, sleep duration, and sleep quality significantly varied across the schedule. In addition, early morning start times and late evening end times were key factors contributing to reduced sleep. The second section of this thesis comprises two laboratory studies that assessed the sensitivity of a brief (i.e. less than 10 minutes) psychomotor vigilance task (PVT) to the effects of sleep loss. A preliminary study compared performance during the 10-minute PVT with performance during the first half of the PVT during a night of wakefulness (23:00 ? 07:00 hours). A subsequent study compared performance during a 10-minute PVT with performance during a 90-second PVT and a 5-minute PVT during 28 hours of sustained wakefulness. The findings of the latter study indicated that performance during the 5-minute PVT and the 90-second PVT deteriorated in a manner similar to that observed during the standard 10-minute PVT. However, in line with the findings reported in the preliminary study, the shorter the task sampling time, the less sensitive the test to response slowing and performance variability. Based on these findings, it was surmised that a 5-minute PVT is likely to provide a more accurate measure of performance impairment than a test of shorter duration. Moreover, it was proposed that a 5-minute PVT may provide researchers with a reliable test for assessing changes in performance. In summary, the results of the aviation studies indicate that a number of scheduling factors contribute to fatigue and disturbed sleep in Australian domestic operations. The findings of this thesis are of particular concern, given that current aviation regulations do not fully consider the extent to which scheduling demands affect flight crew. It is apparent that flight crew would benefit from the incorporation of such findings into duty and rest limitations and scheduling procedures. Evidence demonstrating that (1) fatigue accumulates across the flight duty period, and (2) flight crew are at particular risk of higher fatigue when they are rostered to work an early morning duty suggests that the length of the flight duty period, the number of sectors worked and the timing of the duty period warrant particular attention. Finally, the results of the laboratory studies hold particular promise for future research, since they suggest that the 5-minute PVT may provide researchers with an alternative tool for investigating fatigue in the flying environment. / thesis (PhD)--University of South Australia, 2004.
| Identifer | oai:union.ndltd.org:ADTP/173372 |
| Date | January 2004 |
| Creators | Loh, Sylvia |
| Source Sets | Australiasian Digital Theses Program |
| Language | English |
| Detected Language | English |
| Rights | © 2004 Syliva Loh |
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