automatic landing system


automatic landing system

[¦ȯd·ə¦mad·ik ′land·iŋ ‚sis·təm] (navigation) The means for automatically guiding and controlling aircraft from an initial approach altitude to a point where safe contact is made with the landing surface.

automatic landing system

A system that permits aircraft to be landed automatically without any input from the pilot. In a typical system, the aircraft approaches from the outer marker to the inner marker beacon. At the inner marker beacon, the aircraft flight path is aligned with the defined glide path at a height of 100 ft above ground level and also with the runway centerline. During this phase, the autopilot controls the aircraft flight path using guidance from the ILS (instrument landing system). At this moment, the guidance signals from the ILS are disconnected and the autopilot controls the aircraft to maintain the pitch attitude and heading at the values set up during the approach. This is until the height is reached when the flare-out is initiated. The aircraft pitch attitude is controlled by the feedback of the radio altimeter. The aircraft flares out at this stage by progressively reducing the vertical velocity. If required, the aircraft's nose is straightened (if it was crabbed as a result of any crosswind on the approach path) and the aircraft lands with its nose in line with the touchdown direction. See autoland approach.