Here's a scenario that may account in part for the recent loss of Air France 447: high altitude ice crystals inducing engine shutdown. The shutdown of both engines happened to a Qatar Airways A330 in 2006.
At high altitude near intense storms, moisture turns into tiny ice crystals that can be sucked inside an engine. At first, the crystals melt. But sometimes the water freezes again on metal surfaces. Eventually, accumulating ice can either break into chunks that damage turbine blades, or melt and douse the ignition system...
By examining the dual-engine flameouts in relation to storm patterns, Mr. Hookey and other investigators began unraveling the icing mystery. Powerful thunderstorms, particularly over the Pacific Ocean in the spring and summer, can spawn smaller-than-normal ice particles...
High altitude? 35,000 feet. Near intense storms? The aircraft flew right into a thunderstorm zone. Wrong ocean, but the right seasonality for high altitude ice particles.
