The Impacts of Australian Transcontinental 'Back of Clock' Operations on Sleep and Performance in Commercial Aviation Flight Crew


This aim of the study was to provide objective data to inform fatigue risk-management processes by determining the quantity and quality of sleep obtained by airline pilots during transcontinental back of clock operations, and any changes to subjective fatigue and neurobehavioural performance during these sectors. Typical transcontinental back of clock route pairings involve a departure close to midnight Perth local time, with a dawn arrival into an East-coast city such as Melbourne, Sydney or Brisbane. In many instances this first sector is followed by a second sector to another east-coast destination, with sign-off at approximately 0900 Eastern Standard Time. Data were collected by participants during a two-week period of a normal rostered flying for an airline. During each of the 14 days of data collection, participants were required to undertake the following: 1) Wear an activity monitor wristwatch 7 days prior to, and 6 days after, a transcontinental back of clock flight; 2) complete sleep and duty diaries, which record time of sleep, subjective alertness, and time of duty; and 3) complete a simple 5-minute Psychomotor Vigilance Task (reaction time task) during the cruise of each sector, and three times on non-flying days. The results of this study suggest that Australian transcontinental back of clock operations, as operated by the airline involved in this study, differed significantly from a baseline sample of daytime duty periods in a number of important areas with respect to prior sleep, neurobehavioural performance, and subjective fatigue. While there were some significant differences in sleep and subjective fatigue as a function of a single transcontinental sector of back of clock flying, these differences were, on average, of a magnitude that was unlikely to impact on flight crew performance and overall safety. However, when a primary transcontinental sector is followed by an additional east-coast sector, there is evidence of reduced prior sleep, impaired neurobehavioural performance, and high levels of subjective fatigue.

Type: Research and Analysis Report
Publication date: 27 March 2007
Publication number: 50171
Last update 07 April 2014
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