History of the supersonic airliner

LONDON, England (CNN) -- An Anglo-French project, Concorde entered service in the mid-1970s and is the world's only supersonic passenger aircraft.

Up to last year's crash, British Airways had seven Concordes, while six flew for Air France.

The supersonic jet is capable of crossing the Atlantic in three hours and 45 minutes at a cruising speed twice the speed of sound, or 1,370 miles per hour.

That makes the plane peerless -- military planes can match the speed but could not sustain Mach 2 for so long.

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Ironically before the disaster near Paris's Charles de Gaulle airport, the plane had been regarded as one of the world's safest passenger aircraft.

Before its inaugural flight in 1976 it had been subjected to 5,000 hours of testing, making it the most vetted aircraft in aviation history. A test pilot sent by the U.S. government said it "could be the safest airplane ever built."

The plane that came to be synonymous with the rich and famous was developed throughout the 1960s by British and French aerospace engineers. The future dominated the revolutionary design of the sleek dart-shaped plane.

The first Concorde, the 001, rolled onto the tarmac in 1967, but it took two more years of testing and fine-tuning the powerful engines before it made its maiden flight on March 2, 1969 over France.

Only 20 were ever built, though the original plan was for 300.

In 1972, the plane's future looked bright. More than a dozen airlines had placed orders for the aircraft, and even at a staggering $3.5 billion development cost, France and Britain expected to recoup their investment.

But a year later, the Arab oil embargo hit the fuel-guzzling Concorde hard, as the price of fuel spiralled and prospective buyers dropped out.

The world's desire to go supersonic was surpassed by the realism of subsonic flight in jets able to carry more people more cheaply, like the Boeing 747, or "jumbo jet," which first flew for PanAm in 1970.

Eventually, the British and French governments were forced to write off the cost of Concorde's production and virtually give the plane away to British Airways and Air France.

Before last year's crash, two flights departed each day from Heathrow, London, to JFK, New York, with one flight each day from JFK to Paris Charles de Gaulle.