The airfield is approached (A-B) with the automatic pilot using barometric height to maintain a constant aircraft altitude (1500 feet for example), and using the ILS localiser signal to capture and then maintain the extended runway centreline (TRACK phase). The automatic throttle accurately controls the approach speed to the value selected by the pilot. When the ILS glide path beam is intercepted (at B), descent is started (GLIDE phase) with the barometric height control being disconnected and the aircraft being controlled to follow the ILS glide path beam (normally defining a 3 degree descent path to the glide path aerial). The ILS localiser signal is still used for lateral guidance.
At a height of approximately 300 feet the aircraft enters the coverage of the Leader Cable signal (at C) and the lateral input to the autopilot is automatically switched from ILS localiser to Leader Cable (LEADER CABLE phase). In elevation the aircraft continues to be controlled to the ILS glide path.
At a height of about 100 feet (D), the ILS glide path signal is disconnected and the aircraft controlled to a mean pitch datum automatically computed while flying down the glide path (ATTITUDE phase). This continues for a few seconds down to a height of about 60 feet (E), when vertical control is transferred to the radio altimeter (FLARE phase), with the rate of descent being gradually reduced to give a smooth touchdown. The throttles are automatically closed at a constant rate down to the engine safe flight idling speed.