The Air France Airbus 330 that crashed into the Atlantic on its way from Rio de Janeiro to Paris in 2009 began its dive while the captain was resting and not at the controls, the French government said today. In its official report, France's BEA air-accident investigation agency said pilot Marc Dubois had left the cockpit for a rest about three and a half hours into the flight. Ten minutes later, the plane's autopilot disengaged and a copilot took the controls. The stall warning sounded twice as the plane rolled back and forth and pitched upward, climbing sharply before the co-pilot leveled it off. But the plane stalled a third time as it lost airspeed, apparently due to a faulty speed sensor. The captain rushed back to the cockpit, but by then the plane had started a dive from which it would not recover. "I don’t have any more indications" a co-pilot told the captain as the plane fell at 10,912 feet per minute. "We have no valid indications," the captain replied. In the last minute of its descent, the co-pilot handed off the controls, apparently to the captain, saying, "go ahead you have the controls." The plane crashed into the Atlantic with its controls set to point the nose up, killing all 228 people aboard.
Much of the speculation of what caused the crash among aviation experts in advance of the official findings has been a malfunction of the airspeed sensors called pitot tubes which can ice up in rough weather. The report does not mention pitot tubes by name, but it does say there was "an inconsistency between the speeds displayed on the left side and the integrated standby instrument system (ISIS)." Investigators have hypothesized that these malfunctioning speed sensors caused the initial stall. But according to the New York Times investigators "said it was far too early to say whether the crash was the result of errors made by the pilots or a technical malfunction." The engines operated normally throughout the flight and responded to controls, but the pilots couldn't correct the dive. The report shows the horizontal stabilizer never left the nose-up position once the plane began its fall.