A conclusive report on the cause of the crash is expected this summer [Reuters/BEA]

An Air France jet that crashed into the Atlantic Ocean two years ago stalled three times before plunging into the sea, killing all 228 people on board, information from the plane's flight recorders shows.

French investigators said on Friday that data from the devices, known as black boxes, revealed the final minutes of the air disaster, with two co-pilots struggling to regain control of the Airbus jet.

The emergency began with a stall warning two and a half hours into flight 447 between Rio de Janeiro and Paris on June 1 2009.

The captain was on a routine break at the time and was summoned back to the cockpit by the second and third in command, but did not retake the controls.

The co-pilots wrestled with the plane's controls for three and a half minutes as it descended rapidly, falling 3,350 metres per minute, rolling from left to right and finally plunging into the Atlantic.

"There was an inconsistency between the speeds displayed on the left side and the integrated standby instrument system (ISIS), the French Bureau of Inquiry and Analysis (BEA), said.

"This lasted for less than one minute".

However the investigators said it is still too early to give the causes of the crash, and a full report is expected to be released this summer.

Airbus said the information released on Friday was consistent with the BEA's preliminary and interim reports and "constitutes a significant step towards the identification of the complete chain of events" that led to the crash.

According to the chronology provided by the BEA, the two co-pilots who were flying the plane decided at two hours and eight minutes into the flight to turn slightly to the left to avoid a zone of turbulence.

Two minutes later the autopilot disengaged, the instruments began showing "a sharp fall" in airspeed and the engine stall warning began to sound.

"So, we've lost the speeds," it quoted the second of the two co-pilots as saying.

After the captain returned, "all of the recorded speeds became invalid and the stall warning stopped," said the BAE report.

The last data on the recorder showed that the plane's nose was up at a sharp angle as it plunged into the ocean.

The BAE report said "the composition of the crew was in accordance with the operator's procedures."

The captain would normally take a rest during the flight and leave the two co-pilots at the controls.

Source: Agencies