Present novel and non-trivial system, device, and method for generating altitude data and/or height data are disclosed. A processor receives navigation data from an external source such as a global positioning system (“GPS”); receives navigation data from multiple internal sources; receives object data representative of terrain or surface feature elevation; determines an instant measurement of aircraft altitude as a function of these inputs; and generates aircraft altitude data responsive to such determination. In an additional embodiment, the processor receives reference point data representative of the elevation of the stationary reference point (e.g., a landing threshold point); determines an instant measurement of aircraft height as a function of this input and the instant measurement of aircraft altitude; and generates aircraft height data responsive to such determination.