Abstract: A collimated head up display of pitch related information for an aircraft operator. A generated pitch signal combines a gyroscope signal referenced to the airframe with an inertial signal referenced to the head up display or combiner screen. A pitch error signal representing the difference between the generated pitch signal and the inertial pitch signal is limited and integrated to develop a pitch correction signal which is added to the gyroscope signal. Reference of the inertial signal to the combiner screen of the display eliminates static alignment errors. The pitch correction signal may be selected for display during alignment of the combiner screen.

Abstract: In an aircraft terrain warning system utilizing a radar altimeter wherein the rate of closure to the terrain is compared with the aircraft's altitude above the terrain to generate a warning signal when the closure rate is excessive for a particular altitude, the closure rate signal is limited and biased depending upon the aircraft's closure rate and configuration in order to significantly increase the time response of the system while at the same time reducing nuisance warnings. The amplitude limit on the closure rate signal is varied, above a predefined altitude, as a function of the closure rate signal in order to provide increased warning times at greater closure rates. Circuitry, responsive to the aircraft's flap positions, is also provided to alter the characteristics of rate limiter so as to provide warning parameters that more accurately reflect operating conditions at lower aircraft speeds.

Abstract: In a warning system for aircraft that generates a warning signal when the aircraft is descending during a take-off or missed approach phase of operation, the warning is inhibited for a predetermined loss of altitude in order to allow the aircraft to descend a short distance without triggering a nuisance warning. Specifically, a circuit is provided to integrate a signal representing the aircraft's rate of descent until the integrated signal is equal to a predetermined drop in altitude whereupon the warning signal is triggered.

Abstract: The warning system includes a function generator for generating a signal representative of a minimum altitude over terrain as a function of the aircraft's speed. This signal is combined with a signal representing the aircraft's actual altitude over the terrain and if the aircraft is below this minimum altitude a warning signal is generated. A circuit is included to inhibit the warning signal, and thereby nuisance warnings, when the aircraft overflys another aircraft. In addition, electronic circuitry is disclosed for implementing the invention that is compatible with at least two separate types of air data computers.

Abstract: In a terrain warning system wherein the rate of the aircraft's closure to the terrain is compared to the aircraft's altitude above the terrain in order to generate a warning signal for excessive closure rates, a circuit is provided to inhibit the warning signal when the aircraft begins to climb in response to the warning signal and to measure the altitude gained by the aircraft resulting in the reactivation of the warning signal if the aircraft has leveled off before gaining a predetermined amount of altitude. The circuit includes: a memory element to indicate that a warning signal has been generated; a circuit to generate a climb signal in response to a barometric rate of change signal indicating the aircraft is climbing; and an integrating circuit responsive to the barometric rate signal to determine the amount of altitude the aircraft has gained while climbing.

Abstract: In an aircraft terrain warning system utilizing a radar altimeter wherein the rate of closure to the terrain is compared with the aircraft's altitude above the terrain to generate a warning signal when the closure rate is excessive for a particular altitude, the closure rate signal is limited and biased depending upon the aircraft's closure rate and configuration in order to significantly increase the time response of the system while at the same time reducing nuisance warnings. The amplitude limit on the closure rate signal, is varied, above a predefined altitude, as a function of the closure rate signal in oreder to provide increased warning times at greater closure rates. Circuitry, responsive to the aircraft's flap positions, is also provided to alter the characteristics of rate limiter so as to provide warning parameters that more accurately reflect operating conditions at lower aircraft speeds.