WORLD: Air France jet dived vertically into the sea without warning

Air France flight 447 plunged nose-first straight into the Atlantic at high speed, accident investigators disclosed today.

The Airbus A330 was intact when it struck the water and accelerating as it fell, the French team leading the inquiry said.

Preliminary findings ruled out the possibility the plane broke up in mid-air, killing all 228 people on board.

But investigators are today no nearer to knowing what caused the flight, which set off from Rio de Janeiro for Paris on 1 June but crashed 930 miles off the Brazilian mainland.

"The plane was not destroyed while it was in flight. It seems to have hit the surface of the water in the direction of flight and with a strong vertical acceleration," said Alain Bouillard, who is leading the investigation on behalf of France's air accident board.

Mr Bouillard said life-vests found among the wreckage were not inflated, suggesting passengers were not prepared for a crash-landing in the water. The pilots apparently also did not send any mayday calls.

Control of the flight was supposed to have passed from air traffic controllers in Brazil to their counterparts in Senegal, but that never happened.

The lead investigator said the pilots had tried three times to connect to a data system in the Senegalese capital Dakar but had failed, apparently because Dakar had never received the flight plan.

"This is not normal," he said, adding that investigators were also trying to find out why it took six hours after the plane disappeared before an emergency was declared.

He said the search for the flight recorders, or black boxes, would continue until 10 July. The recorders emit a signal for a limited time.

The chances of finding the flight recorders are falling daily as their signals fade.

Without them, the full causes of the tragic accident may never be known.