A doomed Air France jet did not break up in mid-air but plunged vertically into the Atlantic Ocean, investigators have revealed.
"The plane was not destroyed while in flight," said Alain Bouillard, who is leading the probe into the June 1 crash for the French accident investigation agency BEA.
"The plane appears to have hit the surface of the water in flying position with a strong vertical acceleration."
He explained that Flight 447 hit the water belly-first, but with a straighter descent than a more familiar diagonal landing.
All 228 people aboard the plane were killed when it plunged into the Atlantic en route from Rio de Janeiro to Paris.
Life vests found among the wreckage of the plane were not inflated, Mr Bouillard went on.
Speaking at a news conference in Le Bourget, outside Paris, he said the search for the jet's black boxes had been extended by 10 days and will continue through to July 10.
Mr Bouillard said the plane's defective airspeed sensors were a "factor but not the cause" of the Airbus A330's crash.
"It's one of the factors, but not the only one," he said, as the BEA released its first report on the disaster. "It's a factor, but not the cause."