A new report by BEA, the French aviation accident investigation agency, on the 2009 crash of Air France Flight 447 from Rio de Janeiro to Paris in the Atlantic Ocean has found that the crew lacked the appropriate skills to respond to an emergency warning after the plane stalled out due to faulty speed sensors. It said the captain was out of the cockpit on a break when the airspeed sensors iced over and shut down the plane's autopilot, reports Bloomberg.

The document chronicles the final hours of the Airbus A330 aircraft, revealing a plane that responded accurately to commands, and confusion on the part of the two co-pilots while the captain was off duty. Neither pilot appeared to realize the plane had stalled, even as an alarm sounded for 54 seconds before the jet hit the ocean in the middle of the night.

The comments in the cockpit display “total incomprehension of the situation, and they are heard saying several times that they don’t know what’s going on,” BEA Chief Investigator Alain Bouillard said in an interview after presenting the report.

Early reports had honed in on the airspeed sensors, called pitot tubes, while a preliminary BEA report on the flight recordings in late May detailed the plane's trajectory and the captain's absence at the time of the emergency, but stopped short of pinning the blame on the crew's actions.