A French airliner plunged out of control for four minutes before crashing into the Atlantic in 2009, investigators said, in a report raising questions about how crew handled a "stall alarm" blaring out in the cabin.
Information gleaned from black boxes, and recovered almost two years after the disaster killed 228 people, confirmed that speed readings in the Airbus cockpit had gone haywire, believed to be linked to the icing of speed sensors outside the jet.
As Air France pilots fought for control, the doomed A330 dropped 38,000 feet, rolling left to right, its engines flat out but its wings unable to grab enough air to keep flying.
The plane crashed on June 1, 2009, en route from Rio de Janeiro to Paris. Black boxes stopped recording at 0214 GMT.
France's BEA crash investigation agency said in a detailed chronology of the crash that commands from the controls of the 32-year-old junior pilot on board had pulled the nose up as the aircraft became unstable and generated an audible stall warning.
Aviation industry sources told Reuters that this action went against the normal procedures which call for the nose to be lowered in response to an alert that the plane was about to lose lift or, in technical parlance, 'stall'.
This type of aerodynamic stall is nothing to do with a stall in the engines, both of which kept working as crew requested.
"A stall is the moment at which a plane stops flying and starts falling," said David Learmount, operations and safety editor at the British aviation publication Flight International.
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