British and French officials cleared the luxury Concorde for takeoff, laying out a series of safety modifications Wednesday that will enable the world's only commercial supersonic jet to return to service a year after a deadly crash killed 113 people.

The Civil Aviation Authority in London issued a "mandatory airworthiness directive," detailing the modifications that British Airways must take before returning any of its Concordes to service. French authorities issued a similar document to Air France, the British agency said.

"Once the changes are completed on each individual aircraft the regulatory authorities can return its Certificate of Airworthiness. Commercial operations can then resume at the discretion of the airlines," the Civil Aviation Authority said.

Air France grounded its Concorde fleet immediately after one of its jets crashed after takeoff from Paris on July 25, 2000. The dead included 100 passengers, mostly tourists from Germany, the crew of nine and four people on the ground.

British Airways doggedly kept flying its Concordes between New York and London until mid-August of last year, ending service just before the two governments withdrew the certificate permitting the fleet to fly.

Investigators believe a stray strip of metal on the runway punctured one of the doomed Air France plane's high-pressure tires, which blew a hole in a wing fuel tank and started a fire.

Key modifications to the aircraft include stronger tires, fuel tank linings made of bulletproof Kevlar, and extra protection for critical electrical and hydraulic systems on the underside of the wings.

"As an independent specialist regulator, the CAA has monitored all the work and the modifications very closely and is now satisfied that the changes will prevent any future catastrophic accident such as occurred at Paris." said Mike Bell, the Civil Aviation Authority's head of design and production standards.

British Airways, which last year announced a $20 million remodeling of cabin interiors and Concorde lounges in New York and London, planned a series of five test flights with employees filling the seats in the fabled aircraft.

Employees were invited to enter a drawing to get one of the 100 seats in the plane to help test all aspects of operations, including ticketing, boarding and in-flight services.

Four flights will turn around over the mid-Atlantic and one will go all the way to New York, British Airways said.

British and French authorities had been determined to return Concorde to service. The plane was a commercial failure, partly because no country would permit it to fly over land because of loud engines, and partly because the fuel-guzzling Concorde carries just 100 passengers, making it less economical than a jumbo jet. Only 20 were built, with 12 remaining in service.

But the delta-winged, needle-nosed plane conferred matchless prestige on British Airways and Air France, drawing celebrities and business people who thought their time was valuable enough to justify fares of more than $ 8,700 for a round trip across the Atlantic.

The Concorde flies faster than any other commercial aircraft, racing between Europe and New York in under four hours. Its fastest New York-London crossing was completed in just 2 hours, 52 minutes and 59 seconds.

The Concorde cruises at 1,350 mph, or twice the speed of sound, at an altitude of 60,000 feet.

Although Boeing Co. is developing a passenger jet -- the Sonic Cruiser -- that would travel at close to the speed of sound, industry analysts say it's too early to know whether the concept will be a success.

For the time being at least, the 31-year-old Concorde is in a class by itself.

"There will always be a certain number of passengers for whom getting from point A to point B in the shortest period of time is important, whether it be for diplomatic or business reasons or whatever," said Chris Yates, aviation safety and security editor for Jane's Transport.

"Concorde fulfills this niche market very well."