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A new definition of a reliable and accurate aircraft height

This paper introduces a new concept for the aircraft height, defined with respect to a mean terrain level. This quantity is called Above Mean Ground Level altitude. Unlike the traditional height measured by a laser altimeter, this quantity does not contain the terrain irregularities, undesired in the feedback signal by the guidance and control modules, for example during the Approach & Landing operations. In addition, typical drawbacks of each laser altimeter are avoided, such as the laser beam scattering and the missed reflections due to aircraft pitch and roll maneuvers, for example. The proposed estimation algorithm exhibits strong fault tolerant characteristics, performing a sensor fusion involving both GPS and AHRS sensors, besides the laser altimeter itself. The presented solution has been in flight tested and further verified thanks to the availability of a huge amount of flight data for a general aircraft application.