Method and apparatus for conformal runway alignment on a head up display

Abstract

An aircraft display system positions a synthetic runway which is properly aligned with a target runway even during crosswind approaches. The relative position of the target runway is computed in a manner which reduces the accumulated error associated with previous systems. The lateral deviation rate of the aircraft relative to the extended centerline of the target runway is computed from data provided by various aircraft navigation and sensor systems. A track error angle representative of the difference between the extended centerline of the runway and the ground track of the aircraft is computed from the lateral deviation rate and ground speed. Runway bearing relative to ground track is computed from the track error angle and lateral deviation angle. Compensating runway bearing relative to ground track with drift angle yields a runway bearing relative to aircraft heading which is useful for positioning a synthetic runway on a display. The preferred application is for head up display systems during instrument flight conditions but can also be used on head down displays to provide proper correlation between the synthetic runway and the flight path vector symbol.