Method and apparatus of automatically monitoring aircraft altitude

An apparatus and method for automatically and independently determining aircraft altitude and alerting the pilot to deviations from a target altitude exceeding a specified tolerance. The alerter comprises an altitude sensing means for sensing the present altitude of the aircraft. The invention discloses three sources for altitude information namely, a self-contined sensor such as a pressure transducer, a Global Positioning System receive, or an altitude encoder. A target entry means is used for entering the target altitude. An indicating means signals an altitude alerting condition upon the detection of a condition wherein the absolute difference is larger than the tolerance value. The altitude alerting apparatus may also comprise a display means for display of the present aircraft altitude information.