FLIGHT CREW FATIGUE V - LONG-HAUL AIR TRANSPORT OPERATIONS

We monitored 32 flight crewmembers before, during, and after 4-9 d com mercial long-haul trips crossing up to 8 time zones per 24 h. The aver age duty day lasted 9.8 h, and the average layover 24.8 h. Layover sle ep episodes averaged 105 min shorter than pretrip sleep episodes. Howe ver, in two-thirds oi layovers, crewmembers slept twice so that their total sleep per 24 h on trips averaged 49 min less than pretrip. Great er sleep loss was associated with nighttime flights than with daytime fights. The organization oi layover sleep depended on prior fight dire ction, local time, and the circadian cycle. The circadian temperature rhythm did not synchronize to the erratic environmental time cues. Con sequently, the circadian low point in alertness and performance someti mes occurred in flight. On trip days, by comparison with pretrip, crew members reported higher fatigue and lower activation; drank more caffe ine; ate more snacks and fewer meals; and there were marked increases in reports oi headaches, congested nose, and back pain. Scheduling str ategies and countermeasures to improve layover sleep, cockpit alertnes s, and performance, are discussed.