In accordance with this invention, generally stated, a navigation system for {HEAD ~ a vehicle} is provided with terrain correlation embodied in a construction which is independent of {TAIL ~ vehicle altitude} and which permits curvilinear vehicle course paths 
In accordance with this invention , generally stated , a navigation system for { HEAD ~ a vehicle } is provided with terrain correlation embodied in a construction which is independent of { TAIL ~ vehicle altitude } and which permits curvilinear vehicle course paths
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH