Depend on it: pitot tubes WILL ice up flying through thunderstorms, and sometimes, like at the ITCZ, which AF 447 was flying through when it ran into trouble, pilots have no choice but to fly through thunderstorms.:
The investigation confirmed that the failure of speed sensors, called pitot tubes, which froze up and failed had set off a catastrophic chain of events. The report said the pilots lacked training to deal with this situation.
...Bonin was at the controls when the speed sensors failed. When the autopilot reacted to the confused readings by disconnecting itself and handing control of the plane to the pilot, he reportedly hauled the aircraft up to 37,500ft in an apparent attempt to slow it down. As a consequence the A330's stall warning sounded, meaning that the plane's aerodynamics were not generating enough lift even though its twin engines were working normally.
Robert, Bonin's co-pilot at the time, supposedly check-listing the emergency procedures, lost precious seconds calling the captain and failed to correct his colleague's error as the plane plunged towards the sea, said the report. Dubois had returned to the cockpit seconds before the crash but was unable to save the situation as it hit the Atlantic belly first.
A French pilot told Le Figaro newspaper: "This manoeuvre (the pulling up of the plane) is totally incomprehensible. My colleague must have panicked."
The BEA has produced safety recommendations including extra training on how to manually fly planes, including approaches to and recovering from a stall particularly at high altitudes. It also suggests planes be fitted with new video flight recorders and emergency data transmitters.
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