Patent Document ID: 9031719
Application ID: 13855124
Patent Flag: 1

Claim One:
1. A method in a device for navigating an aircraft, the device including an accelerometer configured to measure an acceleration a B of the aircraft, the aircraft comprising a mass m, the method comprising: measuring a ground speed associated with the aircraft; estimating an airspeed of the aircraft based on the acceleration a B of the aircraft and controlled aerodynamic forces applied to the aircraft, estimating the airspeed of the aircraft including: multiplying the acceleration a B , with a mass m resulting in a required aircraft force for experienced motion ; calculating a controlled aerodynamics A by a model of the controlled aerodynamics A having at least a rotation rate and a control state of the aircraft as input in addition to a current estimate for the airspeed A ; subtracting the controlled aerodynamics A from the required aircraft force for experienced motion resulting in a calculated drag force D ; and calculating an unfiltered air speed A from the calculated drag force D by reverse calculation of a model of the drag force D being dependent on the unfiltered air speed A ; estimating a wind field experienced by the aircraft based on the ground speed and the airspeed; and navigating the aircraft based on the estimated wind field.