Vertical flight path error altimeter

Claim 1

In a vertical flight path control system for an aircraft that includes actual flight data input means for providing a first signal representative of horizontal distance traveled by the aircraft and a second input signal representative of actual altitude of the aircraft, apparatus for programming a desired vertical flight path and for comparing actual altitude with programmed altitude corresponding to the horizontal position of the aircraft along the desired flight path, said apparatus comprising first means settable in accordance with the horizontal distance to be traveled by the aircraft along the desired flight path and responsive to said first input signal to provide a horizontal distance reference signal representative of the instantaneous proportion of the horizontal distance of the desired flight path traveled by the aircraft, second means settable in accordance with the altitude at which the aircraft is to fly at predetermined locations along the desired flight path and responsive to said horizontal reference signal to produce an altitude reference signal representative of programmed altitude corresponding to the instantaneous horizontal location of the aircraft along the desired flight path, and third means responsive to said second input signal and said altitude reference signal for producing an error signal representative of the deviation between actual altitude and programmed altitude.