ABSTRACT
During the first 22 months of the Second World War, there were over 400 accidents caused by confusion between the landing gear and flap controls of airplanes. As two similar switches on the dashboard it was easy to confuse them and inadvertently activate the wrong one. Such as, in the rush from engine start to takeoff, raising the flaps before take off (they were down for the preflight inspection) sometimes resulted in the landing gear retracting while taxiing out to the runway! Early human factors researchers determined that for different functions, one should have discriminably different control devices. Thus, the gear lever was made like a wheel on a stick (or like a lollipop), and the flap lever was formed to be like a piece of flat airfoil. That did reduce the accident rate somewhat, but did not totally eliminate it.
