In-flight detection of errors for enhanced aircraft flight safety using DTED with GPS and radar altimeter

This paper describes an integrated architecture using digital terrain elevation data (DTED) with kinematic GPS (KGPS) and a radar altimeter. Flight testing was performed to assess the feasibility of enhanced flight safety. Reasons for enhanced flight safety are twofold: (1) the ad hoc integration of terrain elevation data into the cockpit could conceivably create scenarios that would lead to accidents because the cockpit display is quite realistic, and (2) controlled flight into terrain (CFIT) is reduced. The radar altimeter is the principal sensor used to compare navigation outputs with publicly available DTED. Results show it is feasible to define an operationally useful detection threshold to determine the level of agreement among KGPS, DTED, and the radar altimeter by using a mean-square-difference test statistic. If the test statistic exceeds the detection threshold, the pilot can be warned that the terrain depiction does not agree with the navigation solution provided by KGPS, so that flight safety is enhanced.