48Detailed OperationTerrain (TER) FunctionThe Terrain Function shows a map of the terrainin the area relative to your airplane’s position andaltitude. The GMX 200 has a standard internally basedterrain function. The GMX 200 also supports an exter-nal TAWS sensor. When the external TAWS sensor isconnected, it replaces the GMX 200’s internal Terrainfunction.Terrain information can be supplied by one of twosources:• Internal GMX 200-Based Terrain• External TAWS-Based TerrainReview the Limitations section in the front of thisguide for the limitations that apply to the terrain data.Internal GMX 200-Based TerrainThe altitude information comes from an externalaltitude encoder or GPS altitude depending on yourinstallation. For pressure altitude, displayed altimetersetting has to be adjusted, or baro-corrected, just likethe one in your aircraft’s instrument panel.Terrain Page with GMX 200-Based DataThe terrain screen has a 360-degree and a 120-degree display. Both screens will show terrain relativeto your position. Colors used for terrain display areshown below.Terrain Elevation Color Coding Reference(Normal Terrain Model)NOTE: The Terrain function shows you the gen-eral terrain elevations relative to your altitudeand are advisory in nature. Individual obstructionsmay be shown if available in the database. Terrainis displayed from database information and maytherefore potentially contain some degree of er-ror. Do not use this information for navigation.ObstructionsObstructions, such as towers and other man-madeobjects, are part of the GMX 200 updateable database.Obstructions over 250 feet high are shown on the mapswith tower symbols. The symbol is color coded to sig-nify the relative altitude of the tower to your aircraft’saltitude and follows the same conventions as the colorcoding for terrain.Obstruction iconsObjects that are at your altitude are shown in red;objects that are near your altitude are shown in yellow;objects with towers that are significantly below youraltitude colored green. Obstructions are shown on theTerrain
