49 years ago today, on January 21, 1976 (December 21, 1975 in the lunar calendar), two Concorde supersonic passenger aircraft made their first commercial flight. Concorde is a four-engine long-range supersonic passenger aircraft jointly developed by the former British Aircraft Company (now incorporated into British Aerospace) and Aerospace France. 1956-1961 In 2001, Britain and France separately conducted preliminary research on supersonic passenger aircraft. In 1961, the two countries each proposed their own design plans, but the aerodynamic layout and performance of the two plans were very similar. Due to the high development costs, the two countries decided to cooperate and share the development costs equally. In November 1962, after consultation, the two governments signed a contract to jointly develop two prototypes, officially naming the aircraft "Concorde". The former British Aircraft Company and French Aerospace Company were jointly responsible for developing the airframe, and the British Rolls-Royce Company and French Snecma Company jointly developed the engine. Prototype production began in 1965, test flights began in early 1969, and two pre-production aircraft were also delivered for test flights in late 1971 and early 1972 respectively. The pre-production model has made many modifications: the nose is lengthened by 0.6 meters, and the cross section of the nose is changed from circular to oblate to improve the cabin vision; The cabin has been lengthened from 33 meters to 38.7 meters, and the passenger capacity has increased to 128 people. At the end of 1975, it obtained type certificates for Britain and France, and on January 21, 1976, it was officially put into use on the route. However, due to Concorde's high fuel consumption and insufficient range, it could only barely fly across the Atlantic Ocean, its passenger capacity was also small, and the cost of use was much higher than that of subsonic passenger aircraft. As a result, British and French airlines lost $40 million to $50 million a year in the operation of Concorde, relying on government subsidies from the two countries to barely maintain their flights. Another serious flaw is that the noise level exceeds the U.S. FAR36 noise level standard for civil aircraft. The U.S. government does not allow Concorde to land on its soil, causing civil aviation companies in the United States and other countries to cancel orders. In the end, the US$3.2 billion supersonic passenger aircraft development plan failed. Concorde produced only 16 aircraft and was suspended in 1979. Air France and British Airways are now operating seven aircraft each.