所谓“加程飞行”是指双发飞机在运营中,当一台发动机失灵需飞往备降机场时,能以其航班飞行中的一部分单发飞往60多分钟以外的备降机场。现在“加程飞行”已很普遍。当今各航空公司每月累积的“加程飞行”在1万多个航班以上,航线越过大西洋、加勒比海、印度洋、亚洲、塔斯曼海及西、南、中太平洋。 1953年颁布的“美国联邦航空条例”规定,双发飞机的运营航线离一个设施完备的机场,不得超过1小时的飞行距离。在当时,活塞发动机的过热一直是个大问题,所以这一规定曾是很有意义的。后来随着形势的变化,1小时的飞行改为2小时,现在有几种飞机/发动机的组合被允许作3小时的加程飞行。这样一来,远程直飞航线越来越多,大大提高了运营的可靠性和安全性。据统计,双发飞机运营成本要比3发或4发飞机的运营 The so-called “add-on flight” means that during the operation of a dual-engine aircraft, when an engine fails to fly to a standby airport, it can fly some of its flight to the alternate airport that is over 60 minutes away. Now “add flight” has been very common. Today’s airlines each month accumulated more than 10,000 flights with more than 10,000 flights over the Atlantic, the Caribbean, the Indian Ocean, Asia, the Tasman Sea and the west, south and central Pacific. The United States Federal Aviation Regulations, promulgated in 1953, stipulate that the operational route of a twin-engine aircraft should not exceed an hour’s flight distance from a well-equipped airport. At the time, the overheating of the piston engine was always a big problem, so this provision made a lot of sense. Later, as the situation changed, the 1-hour flight was changed to 2 hours. Now there are several aircraft / engine combinations that are allowed for a 3-hour flight. As a result, more and more long-range direct flights, greatly improving the operational reliability and security. According to statistics, the operating costs of dual-engine aircraft than 3 or 4 aircraft operation