There is a great deal of misunderstanding regarding the definition and use of the V1 speed. Years of inconsistent terminology in reference to V1 has probably contributed to this confusion. Before 1978, FAR Part 1A defined V1 as the critical engine failure speed. In 1978, the definition was changed to takeoff decision speed, and VEF was established as the critical engine failure speed. After a series of serious accidents involving high-speed RTOs, the aerospace industry formed a work ...


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