The Trident, model DH121 or HS121, was a British short/medium-range three-engined airliner designed by de Havilland in the 1950s, and built by Hawker Siddeley Aviation in the 1960s, after the former became part of that group in 1960. Designed to a British European Airways (BEA) requirement, it had limited appeal to other airlines and sold in small numbers, with only 117 produced. It was an important airliner in Europe but high operational costs doomed it to a short lifespan. BEA's successor, British Airways chose to replace its fleet with the Boeing 737 and Boeing 757 in the early 1980s. In China the Trident remained active In Air China's service until the mid-1990s. The Trident is notable for being the first commercial airliner to make a fully automatic approach and landing in revenue paying service. Source: WIKIPEDIA
