What was the Concorde?

A supersonic airliner, in service from 1976 to 2003, crossing the Atlantic in under three and a half hours at twice the speed of sound - fast enough that a westbound flight landed in New York at an earlier local time than it left London. Nothing has replaced it, and commercial flight has been slower ever since it stopped.

It was an engineering success and a commercial disaster. Friction heating stretched the airframe by about 25 centimetres in flight, so a gap opened on the flight deck that crews would wedge a cap into on the final flight. It was also enormously thirsty, seated only about a hundred, and could not fly supersonically over land because of the sonic boom - which removed most of the world's profitable routes at a stroke and was the real killer.

The crash at Gonesse in 2000 killed 113 and is usually given as the end, but the aircraft returned to service afterwards. What finished it was the collapse in demand after 2001 combined with maintenance costs on an ageing fleet nobody was going to build more of. It is a rare case of a technology being retired without a successor - the constraint was never really engineering, but economics and the sonic boom, and the latter is why supersonic flight over populated land remains banned.