Abstract: An aircraft performance margin indicator including a display (21) that, during takeoff and landing, informs the pilot of the ability of the aircraft to either stop safely or achieve a safe flying speed before reaching the end of the runway is disclosed. A plurality of dedicated microprocessors (41, 43, 45, and 47), each of which receives pertinent data about the aircraft, the runway and the existing environmental conditions, produce one or more symbol control signals. The symbol control signals control the position of symbols that form part of the display (21). The display scale is a normalized runway and the display includes an airplane symbol (23) that shows the location of the aircraft as the aircraft moves down the runway. The microprocessor controlled symbols include GO and STOP bugs (25 and 31) and a ROTATE bar (27). The ROTATE bar indicates the last point at which the aircraft can be safely rotated under present FFA regulations.