The Boeing Company
Methods and systems for determining airspeed of an aircraft

Abstract:

Aircraft and methods and systems for determining airspeed of an aircraft. The methods and systems allow for calculation of airspeed in near-ground and on-ground aircraft operation. A GPS altitude and a vertical acceleration of the aircraft are obtained for a current time frame. A geometric altitude for the previous time frame is determined, and the difference between the GPS altitude and geometric altitude are combined with the vertical acceleration to calculate a geometric altitude rate of change. The geometric altitude rate of change is used to calculate a pressure altitude rate of change, which is used to calculate a pressure altitude for the aircraft. A static pressure is calculated from the pressure altitude, and the airspeed is calculated using the static pressure.