Aviation safety expert John Cox helped investigate the fatal crash of Air France flight 447 in 2009. More than 200 people were lost in that crash, considered one of the worst accident in French aviation history. Researchers now believe a stall was caused by iced-over instruments and two copilots with no training in manual aircraft handling at high altitude. They tipped the nose of the plane up, causing it to lose lift and speed as it climbed, instead of down, which would have increased the speed and prevented a stall.
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