Ice Formation On Speed Sensors May Have Led To Deep Stall

Unofficial, and we stress unofficial, reports about the analysis of the cockpit voice recorder recovered from Air France Flight 447 indicate that the captain of the Airbus A330 was not in the cockpit as the events leading to the accident began to occur.

The German magazine Der Spiegel reports that the recordings seem to indicate that Marc Dubois, the 58-year-old captain of the aircraft, was not in the cockpit when the trouble began. He reportedly rushed back into the cockpit "shouting instructions" to the the co-pilots in an attempt to save the aircraft. It is not clear why he was not in the cockpit, but he would not be required to be at the controls for the entire duration of the trans-Atlantic flight.

The magazine says that investigators close to the analysis say the recovered Flight Data Recorder shows that the crew took a course it thought would avoid the worst of the thunderstorms in the area, and that they had initially been successful, in that they did not encounter any additional severe turbulence.

The magazine reports that analysts believe the airplane may have entered a deep stall from which the crew was unable to recover. The A330 requires precise speed management at altitude to prevent such a stall, and if the speed sensors were iced over, such speed management would have been very difficult, they say.

The accident investigation is being led by the French Transport Ministry’s Bureau of Enquiry and Analysis (BEA).

FMI: www.bea.aero/en