Krüger flaps were invented by Werner Krüger in 1943 and evaluated in the wind tunnels in Göttingen, Germany.[4] One of the earliest civil applications was the Boeing 707, whereas the Swiss company FFA claimed the first use of the flap in its FFA P-16 fighter which flew in 1955.[5] The flap was added to prevent wing stall with an extreme attitude take-off with the tail dragging on the runway, a scenario that had caused two de Havilland Comet accidents. A preliminary flight test had been made on the Boeing 367-80 (simply known as the Dash 80) using a fixed flap and a skid on the after-body.[6] After the Boeing test flight on the B-707 prototype on 15 July 1954, Krueger flaps were first used in production for the Boeing 727 which made its maiden flight on 9 February 1963.[7]