Charter pilots reported more hours of sleep in the previous 48 hours of duty than long- and short-haul airline pilots, according to a new study on commercial pilot fatigue by the Australian Transport Safety Bureau (ATSB). The study, based on responses from 625 commercial pilots, including 100 charter pilots, reported that “very few pilots from regional, charter, and aeromedical categories reported having less than five hours sleep in the preceding 24 hours.”

Less sleep on duty was more prevalent for international and domestic jet airline pilots than pilots of regional, charter, and aeromedical operations. Although around one-third of regional, charter, and aeromedical pilots reported being sufficiently alert, an equal amount in each these operation types reported “mild fatigue.”

More than half of pilots reported that, at the end of their last flight, they had had seven hours of sleep or more in the previous 24 hours, and more than 60 percent reported having more than 14 hours in the previous 48 hours. The survey also found a small but significant number of pilots, 10 percent and 17 percent, respectively, who reported obtaining less than five hours of sleep in the previous 24 hours or less than 12 hours in the previous 48 hours. “These sleep thresholds have been shown to be associated with impaired performance.”

More than 90 percent of pilots indicated their employer offered employees a formal process for removing themselves from duty due to fatigue. About one-third of respondents indicated they removed themselves from duty at least once in the past year, mostly between one and three days. But “the pilots who removed themselves from duty generally perceived their actions left a negative impression with management (with the exception of aeromedical pilots) and did not feel comfortable doing so.”