Patent ID: 7791529

Claim:
A method of determining at least two components of the estimated speed vector ({right arrow over ({circumflex over (v)}) of an aircraft relative to the ground ( 19 ), the method comprising the following steps: successively forming at least two images (z 1 (x,y), z 2 (x,y)) of a single region of the ground, the images including distance data relating to the distance between the aircraft and points in the single region of the ground, the distance data corresponding to measurements delivered by a range finder; determining offsets ({right arrow over (d)}) between the images; determining a first raw or observed speed as a function of the offsets ({right arrow over (d)}) between the images; making inertial measurements of the movement of the aircraft; and combining the first raw or observed speed with the inertial measurements of the movement of the aircraft in order to determine the estimated speed vector({right arrow over ({circumflex over (v)}).