The capability of V/STOL aircraft (including helicopters) to fly an assortment of approach and landing flight profiles dictated the need for a display that presents pilot situation information in the vertical plane. This paper describes the development of a display system known as the Flight Profile Indicator (FPI) designed to provide this information in a manner analogous to that of the USAF Horizontal Situation Indicator (HSI).
The FPI is a cathode ray tube (CRT) device that displays the geometrical relationship between the parameters necessary to determine the aircraft situation in the vertical plane.
The significant advantage of the FPI is that it minimizes the pilot's need to interpret various kinds of vertical situation information presently available on aircraft instrument panels and provides a more rapid, accurate, and easier assessment of the aircraft status and flight progress in the vertical plane. It is not intended, however, to replace existing guidance and control information such as flight director displays; but will complement current and projected navigational aids and displays.