Autoland was first developed in BLEU and RAF aircraft such as the English Electric Canberra, Vickers Varsity and Avro Vulcan, and later for BEA's Trident fleet, which entered service in the early 1960s. The Trident was a 3-engined jet built by de Havilland with a similar configuration to the Boeing 727, and was extremely sophisticated for its time. BEA had specified a "zero-visibility" capability for it to deal with the problems of its fog-prone network.