Concorde flights cancelled as travellers begin to shun costly supersonic flight

British Airways has cancelled eight transatlantic Concorde flights in the next three weeks, restarting speculation that the world's only supersonic airliner may become a casualty of 11 September.

Yesterday, BA said four return trips between London Heathrow and New York JFK were involved, between 31 March and 13 April. The link is BA's most expensive and prestigious daily service, though passenger numbers are downas a result of the war in Iraq.

The airline said the cancellations are because of work needed to meet American security requirements. The Federal Aviation Administration says that from 9 April any aircraft flying to or from the US must have a reinforced cockpit door. BA said installation of these on its Concordes began later than expected. With only two available for service on some days, the airline said it would not have enough aircraft for "a robust operation", although the once-a-day schedule could in theory be flown by one. The only other scheduled BA Concorde destination is Barbados, with a Saturday-only service from Heathrow that will finish by May.

Since 1976, Concorde has offered high-spending travellers the chance to fly the Atlantic in under three-and-a-half hours, half the time taken by subsonic jets. After the crash of a New York-bound Concorde in Paris in July 2000 the aircraft was grounded by the Civil Aviation Authority. It flew again 17 months later, but to a reduced schedule of one London-New York flight a day in each direction. "To be frank, that's all the demand supports," BA's chief executive, Rod Eddington, has said.

Since the global slump in premium air travel began, exacerbated by 11 September, Concorde has looked increasingly exposed. The jet is the noisiest and thirstiest in the world, and has made a profit in operations only because the immense capital cost was written off by the Government.

Its client base is receding because of Americans' reluctance to fly, and, among those continuing to travel, an unwillingness to pay a fare of £8,293 – about 50 times the cheapest fare for the route.

There have also been fears that Concorde could be targeted by terrorists because of its high profile and its presence on the world's premier air route.

BA's seven Concordes are in the air for barely an hour each day on average, far below the utilisation demanded of subsonic aircraft. The airline consultant Jamie Bowden said: "Concorde's profitability has undoubtedly been affected by the economic downturn, and the aircraft can no longer exist as simply a flagship."