Hazard Awareness190-02207-02 Rev. 1 GPS 175/GNX 375 Pilot’s Guide 5-27Terrain AwarenessWARNINGDO NOT USE TERRAIN AND OBSTACLE DATA TO NAVIGATE ORMANEUVER AROUND TERRAIN. THEY ARE AN AID TO SITUATIONALAWARENESS ONLY.Terrain controls are accessible from the Terrain menu. Map overlay keys are accessiblefrom the associated map menu.5.13 Terrain Configurations5.13.1 GPS Altitude for TerrainFUNCTIONAL REQUIREMENTSGPS altitude is derived from satellite measurements. To acquire an accurate 3-D fix(latitude, longitude, altitude), a minimum of four operating satellites must be in viewof the GPS receiver antenna.The terrain system uses GPS altitude and position data to:• Create a 2-D image of surrounding terrain and obstacles relative to theaircraft’s position and altitude• Calculate the aircraft’s flight path in relation to surrounding terrain andobstacles• Predict hazardous terrain conditions and issue alertsAVAILABLE TERRAINCONFIGURATIONS• Terrain Proximity• Terrain AlertingAlerting functions are dependentupon the configured terrain alertingoptions.
