The apparatus of the present invention uses radar altimeter measurements and stored terrain altitude profiles to provide pre-filtered observations to a Kalman filter for estimating barometric offset at the airport runway, and barometric scale factor for offsets above the runway. These offsets are used...http://www.google.es/patents/US6094607?utm_source=gb-gplus-sharePatente US6094607 - 3D AIME.TM. aircraft navigation
