PILOTS flying long hours have five times as many accidents towards the end of the flight as they do at the beginning. A link between long hours and accidents has long been suspected, but a study by the US Federal Aviation Administration shows a sharp increase in accidents when pilots have been flying more than 10 hours.
The rules governing pilots鈥� hours vary from country to country. In the US pilots are not allowed to fly for more than 30 hours in 7 days. In the UK the limit is 55 hours 鈥� with a maximum flying time in any single session of 13 hours. Some countries, such as Austria, set no limits.
European proposals to harmonise flying hours, which would lay down a maximum of 14 hours on duty, have proved controversial. Pilots鈥� unions argue that long hours with short breaks are a recipe for more crashes (快猫短视频, 25 January, p 6).
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But although studies show that pilots deprived of sleep have more accidents, there has been no statistical evidence to show that long hours in the cockpit are linked with more accidents. So Jeffrey Goode of the FAA鈥檚 policy office looked at all the serious accidents to scheduled passenger flights in the US between 1978 and 1999. He excluded those caused by turbulence or where details of the pilots鈥� duties before the accident were not available, which left him with 55 accidents.
He compared how long the pilot had been flying when the accident occurred with the known frequency distribution of pilots鈥� flying hours. The accident rate rises slightly during the first nine hours that a pilot spends in the cockpit 鈥� but this increase was not statistically significant. But if the pilot had been flying for between 10 and 12 hours the number of accident increased by 65 per cent. Pilots flying 13 hours or more had 5.6 times as many accidents as the average. 鈥淭he analysis suggests that establishing limits on duty time for commercial pilots would reduce risk,鈥� says Goode.
The UK鈥檚 Civil Aviation Authority says the UK would be able to keep its 13-hour limit, even if Europe adopted 14 hours. However, the unions think that the UK will come under pressure to adopt the European limits 鈥� leading to more accidents. Jim McAuslan, general secretary of the British Airline Pilots Association, says, 鈥淭his is proof of our worst suspicions. I hope the CAA take these findings seriously. We shall be making the case for science to set the limits on pilots鈥� hours, not a political fudge.鈥�
