The Air France jet that crashed into the Atlantic killing 228 may have stalled after pilots slowed down too much as they encountered turbulence, new information suggests.

Airbus is to send advice on flying in storms to operators of its A330 jets, Le Monde reported today. It would remind crews of the need to maintain adequate thrust from the engines and the correct attitude, or angle of flight, when entering heavy turbulence.

Pilots slow down aircraft when entering stormy zones of the type encountered by Air France Flight 447 early on Monday as it was flying from Rio to Paris.

The fact that the manufacturer of the aircraft is issuing new advice indicates that investigators have evidence that the aircraft slowed down too much, causing a high-altitude aerodynamic stall. This would explain why the aircraft apparently broke up at altitude over the Atlantic.

Airbus declined to comment on the report. A company official said: "Each time there is an accident, it is imperative for the manufacturer to inform all operators of the type of aircraft concerned of any specific procedures to put in place or any checks to carry out."

Jean Serrat, a retired airline pilot, told Agence-France Presse: "If the BEA [accident investigation bureau] is making a recommendation so early, it is because they know very well what happened. If they know what happened, they have a duty to make a recommendation, for safety reasons ... The first thing you do when you fly into turbulence is to reduce speed to counter its effects. If you reduce speed too much you stall."

Although the flight recorders lie about 12,000ft below the ocean surface, the BEA has data on the last four minutes of Flight 447, transmitted automatically by satellite to Air France's base at Paris Charles de Gaulle airport.

A stall, in which the wings lose lift and the aircraft becomes uncontrollable, would be consistent with the sequence of events that have leaked to the media from the Air France data. According to this, the first anomaly was the disconnection of the automatic pilot and computerised flight controls. This means that the pilots were hand-flying the aircraft.

It is not known whether Captain Marc Dubois, 58, was at the controls or just his two co-pilots, who were in their 30s.

A stall at 35,000ft – the altitude at which Flight 447 was cruising – is hard to recover from in still air. In the heart of a furious tropical storm at night, it could be near impossible. High-altitude stalls claimed several aircraft in the early days of jet aircraft.

Speculation over the fate of Flight 447 continued to rage as ships began trawling the crash area, spread over a 200-mile stretch. Debris, including airliner seats, has been identified from the air, about 800 miles off the Brazil coast. No bodies have been spotted

Nelson Jobim, Brazil's Defence Minister, said that a 12-mile-long slick of fuel had been found under the planned route of the Airbus. This meant it was improbable that there had been a fire or explosion, because the jet fuel would have ignited, he said.French experts dismissed this theory, noting that an explosion could fracture the fuselage and cause the break-up of an aircraft without igniting the fuel, which is mainly carried in the wings.

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