EGPWS LINE MAINTENANCE MANUAL
When an aircraft penetrates either the TCF or the RFCF alert envelope, the aural message “TOO LOW TERRAIN” will occur. This aural message will occur once when initial envelope penetration occurs, and one time thereafter for each 20% degradation in either Altitude (AGL) or Altitude (ASL) depending on which envelope was violated (TCF or RFCF respectively). EGPWS cockpit alert annunciations remain illuminated until the alert envelope is exited. The TCF and RFCF functions are not available in the MK XXII.
2.2.9.1 RUNWAY DATABASE
The EGPWS Runway Database consists of data records for all airport runways offered for the coverage provided by the Terrain Database. For the MK V and MK VII, all hard surface runways in the world 3500 feet or greater in length are supported. For the MK VI, all runways 2000 feet or greater in length within the database region installed are supported. The MK VIII has the ability to select >2000 foot or >3500 foot runway lengths. For the MK XXII, only runways 2000 feet or greater with a published approach procedure are included. The database provides the means of accessing the records of runways closest to the current aircraft position.
2.2.10 TERRAIN ALERTING AND DISPLAY (OPTIONAL)
The Terrain Alerting and Display (TAD) function monitors aircraft position with respect to local
Terrain Alerting outputs (lights and audio) behaves in the same manner as the standard GPWS mode alerts. Either caution or warning alerts will initiate a specific audio alert phrase. The caution aural is “CAUTION TERRAIN” or “CAUTION OBSTACLE” and the warning aural is “TERRAIN, TERRAIN, PULL UP” or “OBSTACLE, OBSTACLE, PULL UP” (minor variations exist).
Complementing the terrain threat alerts, the EGPWS also maintains a synthetic image of local terrain forward of the aircraft for display on EFIS Navigation Displays (ND’s),
The EGPWS provides up to two optional external displays outputs, each with independent
2.2.10.1 TERRAIN AND OBSTACLE DATABASE
The EGPWS Terrain Database is the earth’s surface divided into grid sets and cells referenced to the geographic (latitude/longitude) coordinate system of the World Geodetic System 1984
Digital Elevation Models (DEM’s) are available for most of the airports around the world today. In cases where data is not currently available, DEM’s are generated from available topographic maps, sectional charts, and airline approach plates. The process of acquiring, generating, assembling, and updating the database is governed by strict configuration controls to insure the highest level of data integrity for generation of the EGPWS Terrain Database.
The EGPWS Terrain Database is organized in a flexible and expandable manner. Using digital compression techniques, the complete database is stored in
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