Abstract: A millimeter wave radar is placed on an aircraft and several radar targets are placed near a runway. The targets are discrete objects, each having a relatively localized radar cross section, a unique signature or a unique range bin, and a position which is accurately known. Targets should be spread over the length of the runway. Radar corner reflectors and active or passive repeaters are preferred. The locations of the radar targets with respect to the runway can be transmitted to the aircraft, or they can be stored on board. On board memory requirements can be reduced by requiring all airports to select one of only a few standard target placement patterns, or even only one. Targets are inexpensive, as are radars whose only precision requirement is in range, and not in azimuth or elevation angles. Range to at least three targets in the radar's field of view is all that is required for an on-board computer to determine the aircraft's location.