Abstract: A method and system for locating aircraft with respect to airport runways selecting as a function of aircraft state parameters one of a plurality of candidate runways that the aircraft on which it is installed is most likely to encounter, whether taxiing, preparing for take-off, or approaching to land.

Abstract: A method for locating aircraft with respect to airport runways and taxiways, generating and annunciating situational awareness advisories as a function of aircraft state parameters relative to a determination of the aircraft location.

Abstract: A method for locating aircraft with respect to airport runways and taxiways, generating and annunciating situational awareness advisories as a function of aircraft state parameters relative to a determination of the aircraft location.

Abstract: An apparatus and method for filtering data that include retrieving a plurality of data samples from memory; computing a locus of the samples; computing a distance between an input value and the locus; comparing the distance between the input value and the locus with a first threshold value; applying a distance-based filter to the samples; and comparing an output value of the median filter with a second threshold value.

Abstract: A terrain server provides access to a central database of terrain elevation and other geographical, political, and industrial feature data (terrain data). Systems requiring terrain data, called clients, send requests for such data to the terrain server when such data is needed. The terrain server retrieves, processes, and transmits the terrain data as specified by received requests. Processing necessary to access and format the data as required by the client is performed by the terrain server in accordance with parameters specified in the requests. Specialized formatting, merging of data from different databases, and the combining of dynamic data from other systems is alternatively performed by the terrain server.

Abstract: A warning system for aircraft equipped with an autopilot system having a radio altitude hold (R/A HOLD) function and/or a barometric altitude hold (ALTITUDE HOLD) function monitors the R/A HOLD and ALTITUDE HOLD function control switches, as well as the touch-controlled steering (TCS) control to determine when the functions have been engaged. When either of the R/A HOLD or ALTITUDE HOLD function control switches are selected while the autopilot system is engaged, the system samples the radio altitude or barometric altitude at the moment that the R/A HOLD or ALTITUDE HOLD functions are selected and stores the sample as a reference or datum. The system then compares the current radio altitude or barometric altitude with the datum. Should the actual radio altitude or barometric altitude exceed the datum by a predetermined amount, a warning is generated. In order to prevent spurious warnings, the system is disabled when the touch-control steering is active.

Abstract: A terrain clearance signal generator particularly usable with ground proximity warning systems provides a signal representative of terrain clearance when the radio altimeter signal is unreliable, such as in the case of excessive pitch or roll, out of track or other conditions resulting in invalid readings. The system monitors such conditions and takes a sample of the last valid radio altitude reading prior to sensing an invalid condition and, upon sensing an invalid condition, updates the sample utilizing barometric altitude signals or integrated barometric altitude rate or inertially-derived Z-velocity signals.