Wikipedia [1] says something very different - that during takeoff and landing commercial aircraft generally rely on radar altimeters, which are extremely accura

Wikipedia [1] says something very different - that during takeoff and landing commercial aircraft generally rely on radar altimeters, which are extremely accurate and reliable, but generally don't work above about 750 meters. See: http://en.wikipedia.org/wiki/Radar_altimeter#Civil_aviation_applications http://en.wikipedia.org/wiki/Radar_altimeter#Civil_aviation_...