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Hawker Siddley Trident

In the early 1960s, four new T-tail jet transports (the de Havilland Trident, the Boeing 727, the BAC 111, and the McDonnell Douglas DC-9) emerged within the highly competitive transport market. These aircraft shared many common configuration features in addition to the T-tail arrangement: aft-fuselage-mounted engines and all-moving (variable-incidence) horizontal tails, for instance. In Britain, the de Havilland Aircraft Company, Ltd. (who later merged with Hawker Siddeley Aviation, Ltd.), developed the Trident transport, which first flew on January 9, 1962. In the United States, Boeing brought forth its new model, the 727, which first flew on February 9, 1963. The BAC 111 first flew later that year on August 20, 1963. The Douglas DC-9 provided additional competition with a first flight that occurred a few years later, in February 1965.

Hawker Siddeley Trident [Siddeley not Siddley] was a medium range airliner that first entered service with the British European Airways company in 1964. The Hawker Siddeley Trident 2E was the first aircraft in the world to be fitted with Smiths Autoland Systems for landing in bad weather. De Havilland returned to the airline world in 1962 with a three-engine jetliner, the Trident. However, he designed it to fit the needs of one airline and one man: Lord Sholto Douglas, chairman of British European Airways. Other airlines found it unattractive and turned to a rival tri-jet: the Boeing 727.

The Trident Two-E was an effort to bring the Trident 1C closer to the Boeing 727-100 which was winning over most of Europe's airlines. It carried more passengers and had an extended range of 3600 miles. By this time BEA had decided that, like everyone else, it also needed a jet with a bigger cabin and with more powerful engines. Being the state airline it could not purchase the American-made Boeing 727 although it wanted the jet. The Trident 2E variant - built in Britain - was what it was forced to order. De Havilland built only 117 Tridents, while Boeing went on to sell over 1,800 727s.

Deep stall was found to be responsible for crashes experienced with the Hawker Siddeley Trident transport. On June 3, 1966, one of the first production Trident aircraft crashed during its first flight as a result of entering a deep-stall condition, with all four crew members killed. The aircraft was carrying out the first of a series of production test flights to qualify for a Series Certificate of Airworthiness. After completing a large part of the required tests, the stall tests were begun. Three approaches to stall were made to check the stall warning and stall recovery systems. The fourth stall test was made at an altitude of 11,600 ft in the landing configuration and with the stall warning and recovery systems inoperative. The Trident entered a deep stall with the nose going up to a 308-408 attitude. The aircraft turned to the left, the right wing dropped, and the plane went into a flat spin to the right. The investigation board concluded: "During a stalling test, decisive recovery action was delayed too long to prevent the aircraft from entering a superstall (deep stall) from which recovery was not possible." Later, on June 18, 1972, another Trident entered a deep stall immediately after takeoff from Heathrow airport in severe weather and crashed, with a loss of 118 lives.







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