*4.2.1. Civil applications of radar altimeter*

 Radar altimeters frequently used by business aircraft for landing, particularly in low-visibility situations and in automatic landings by enabling the autopilot to sense when to begin the flare- maneuver. Radar altimeters transfer information to the autothrottle. Above ground level (AGL),- radar altimeters commonly give interpretations up to 2.5-Kfeet (760m). The automatic landing capability of today's airplanes enhanced by installing at least one or usually several radar altimeters. Concorde and the British Aircraft Corporation BAC, 1–11 were equipped with radar altimeters even though they are old aircraft. In the present day, some of the smaller airplanes in a sub-50 seater category like jet stream series and ATR 42 are using radar altimeter [2, 6, 7].
