On June 1, 2009, Air France Flight 447, an Airbus A330 from Rio de Janeiro to Paris, crashed into the Atlantic Ocean. The crash came due to an aerodynamic stall caused by pilot inputs based on incorrect speed readings. These speed readings were incorrect due to ice crystals forming on what devices, which measure pressure based on the flow of air (or liquid) through a hollow cylinder?
Pitot Tube (Pitot-Static System)