Why did supersonic planes stop?

Concorde's last commercial flight landed at Heathrow on 24 October 2003, and Air France had stopped five months earlier. The aircraft was retired by its airlines because the numbers had stopped working, and several strands came together within three years.

The structural problem was the fuel bill. Concorde's four Olympus 593 turbojets burned more than 20 tonnes of fuel per hour to carry 100 passengers; a Boeing 747 of the same era carried four times as many people on roughly half that fuel. This was tolerable while the aircraft flew full at a fare well above subsonic first class, and British Airways did make a profit on its Concorde operation for much of the 1980s and 1990s. But only 14 production aircraft ever entered service, so every spare part, training course and maintenance procedure was spread across a fleet smaller than many airlines' regional fleets, and the aircraft required far more maintenance hours per flight hour than a conventional jet. The ban on supersonic flight over land confined the route network to London and Paris to New York, with a handful of other services that came and went, and the development cost, shared by the British and French governments, was never recovered.

On 25 July 2000 Air France flight 4590 struck a strip of metal on the runway at Paris–Charles de Gaulle, a tyre burst, debris ruptured a fuel tank and the aircraft crashed into a hotel at Gonesse, killing all 109 on board and four on the ground. The fleet was grounded for over a year while Kevlar tank liners, stronger tyres and other modifications were fitted. Service resumed in November 2001, two months after the attacks of 11 September had depressed exactly the transatlantic premium market Concorde lived on. Loads fell, maintenance costs rose with the aircraft's age, and in April 2003 Airbus, which had inherited the manufacturers' support obligations, informed both airlines that it would stop providing spares and engineering support. Without a type-certificate holder willing to support it, the aircraft could not keep flying, and both airlines announced retirement the same month.

The Tupolev Tu-144, which flew two months before Concorde in December 1968, had an even shorter career. After a crash at the 1973 Paris Air Show and another on a test flight in 1978, its passenger service between Moscow and Alma-Ata lasted only from November 1977 to June 1978, a total of 55 flights, and the type ended its days as a freighter and a research aircraft leased to NASA in the 1990s. In the United States the Boeing 2707 was cancelled in 1971 before a prototype was built. Supersonic travel stopped not because the technology failed, but because no operator could make it pay against widebody subsonic aircraft, and no manufacturer was prepared to build a successor.