Abstract: Systems are provided to derive a value of barometric pressure at a defined location in the atmosphere at a computed geometric height. By using the geometric height in a look-up table of pressure/height values representing a standard atmospheric profile, atmospheric deviation data indicative of the difference between measured and reference pressures at that atmospheric location (C) is derived. Ground-based interrogators (10,20) located at spaced positions are used to initiate response signals from airborne transponders commonly installed in transient aircraft (C). Using resulting range data based on round-trip timing differences in signals sent to (12,16) and received from (16,14) the airborne transponder (C), geometric analysis and computation is used (18) to determine the geometric height of the transponder representing a specific atmospheric location.

Abstract: A system for correcting errors in static pressure, airspeed or airspeed rate caused by maneuvering that causes variations in static air pressure measurements compares a barometrically derived vertical velocity or altitude signal with an inertially-derived vertical velocity or altitude signal to provide a correction signal that is representative of changes in static air pressure and is used to correct the static pressure, airspeed or airspeed rate signal.

Abstract: An apparatus for converting aircraft altitude encoder measurements into higher resolution values, including a microprocessor connected to monitor the aircraft altitude encoder output signals, a pressure transducer and converter network for providing incremental pressure change readings, also connected to the microprocessor; the microprocessor being programmed to utilize the incremental pressure readings to calculate corresponding incremental altitude signals between transition points of the aircraft altitude encoder readings. The method of the invention includes the steps of monitoring aircraft altitude encoder transition points, reading incremental pressure variations between transition points, and calculating incremental altitude variations between altitude encoder transition points.

Abstract: A primary flight display having a vertically oriented linear scale format altimeter therein which includes a non-numbered coarse tape-like image area, for displaying markings relating to altitude and a fine scale tape-like image area juxtaposed with said coarse tape-like image area said fine scale image area for displaying numerals in vertical translational movement and a central current altimeter reading with at least part of the reading disposed about said coarse scale image area.

Abstract: An accumulating altimeter includes a programmable accumulator which selectively accumulates altitude changes from a reference altitude in accordance with accumulation thresholds. Altitude changes in the direction of interest, e.g. altitude gains, are accumulated once a non-opposing accumulation threshold has been reached. Opposing altitude changes which are less than an opposing accumulation threshold are used to offset non-opposing changes. Opposing altitude changes which are equal to or greater than the opposing accumulation threshold are used to re-establish the reference altitude, whereafter accumulation of non-opposing altitude changes resume after the non-opposing accumulation threshold has been reached.

Abstract: An altimeter instrument is provided with display means which is locked or unlocked as a function of the output of a sensor which indicates whether the instrument or the apparatus whose altitude the instrument is sensing is in motion or about to be placed in motion or is stationary for a more than a predetermined period of time.

Abstract: An integrated primary flight display apparatus for an aircraft provides coordinated information with minimum eye scan distances. Various cathode ray tube generated presentations are centered toward a common electronic attitude director indicator having indicia thereadjacent and pointers centrally directed. A moving altitude scale is utilized with a fixed vertical speed scale employed to select the correct vertical speed for leveling off at a given altitude. An arcuate shaped heading indication is expanded in angular extent to achieve enhanced sensitivity.