Terminal Phase Navigation

Precise measures of position and velocity of an aircraft have important applications during the landing phase. Such measures can be obtained, in directions, normal to an instrument landing system (ILS) reference path, by suitably tying together an inertial navigation system and an instrument landing system. Operations performed on the difference between ILS position and inertially-measured position yield corrections to the inertially-measured position and velocity. An important facet of the fully automatic landing problem is the acquisition of the ILS localizer course. A considerable improvement in performance, compared with that of a conventional system, may be realized during this phase by applying optimal control theory with a minimal time-to-acquisition criterion. The second part of this paper presents a practicable realization of a minimal-time controller which utilizes information derived from the ILS receiver and an on-board inertial navigation system. Solution characteristics are presented for the Boeing 2707 SST.