The pilots of the Air France Airbus that crashed off Brazil may have struggled to the end to control their stricken aircraft because it remained intact until it hit the Atlantic, investigators indicated today.

In a first report on the disaster that killed all 228 aboard, the French accident bureau (BEA) reported that the Airbus A330 had not broken up at altitude and was not in a nose-down dive. The debris showed that it had shattered when it smashed belly-first into the sea early on June 1, the BEA said.

"The plane was not destroyed while it was in flight," Alain Bouillard, the chief of the investigation into Flight 447, said. "It seems to have hit the surface of the water in level attitude and with a strong vertical acceleration."

This could indicate that the crew had retained some control after the aircraft plummeted in four minutes from its cruising altitude of 35,000ft on its way from Rio de Janeiro to Paris, aviation experts said. An aircraft falling belly first is usually in a stall or recovering from one - not in a spin or a high-power dive.

No passengers were wearing life-jackets so it appeared that they had not been prepared for an emergency. There was no way of knowing if they had been conscious when the aircraft hit the water.

The investigators confirmed that the disaster began with faulty readings from speed sensors that caused electronic systems to disconnect and left the crew with the task of hand-flying a handicapped airliner.

Mr Bouillard said that it was too early to assign a cause to the crash but his outline of events confirmed a sequence that has been widely analysed by pilots and experts since they were leaked last month.

The airliner was flying at night in a storm zone. The "pitot" speed sensors fed faulty readings to data computers. This in turn caused the flight system to shut down and leave the pilots to hand fly the aircraft without the vital parameter of air speed.

"This does not mean that the aircraft was not flyable," Mr Bouillard said. "It means that it reverted to classical piloting."

Pilots expert in the A330 and A340 long-range Airbus family questioned Mr Bouillard's assumption. Managing an airliner in cruise in such conditions would be extremely difficult, a senior Air France captain told The Times.

The BEA refused to say that faulty pitot tubes were the cause of the crash. "We can say that the pitot is strongly suspected of causing the incoherent speed readings. It is one of the factors but not the only one. It is an element, not the cause," Mr Bouillard said.

Submarines and other vessels would continue to search for the airliner's two black box flight recorders on the ocean floor although their locator beacons may have run out of battery power.

The BEA voiced frustration with having to work only with information from a stream of automatic data messages that reported the cascade of failures in the last four minutes of flight. French aviation experts following the crash said that the BEA report had produced nothing new beyond the fact that the aircraft had not broken up before it hit the ocean.

http://www.timesonline.co.uk/tol/news/world/europe/article6624798.ece