Garmin G300 Pilot’s Guide190-00921-00 Rev. E 155Hazard AvoidanceSystemOverviewFlightInstruments EISCOMInterfaceGPSNavigationFlightPlanningHazardAvoidanceAdditionalFeaturesIntegratedAutopilot Annun/Alerts Appendix IndexThe G300 GPS receiver provides the horizontal position and altitude of theaircraft. Aircraft GPS altitude is derived from satellite position. GPS altitude isthen converted to a mean sea level (MSL)-based altitude (GPS-MSL altitude) andis used to determine terrain and obstacle proximity. GPS-MSL altitude accuracyis affected by satellite geometry, but is not subject to variations in pressure andtemperature that normally affect pressure altitude sensors. GPS-MSL altitudedoes not require local altimeter settings to determine MSL altitude. It is a widely-used MSL altitude source.Terrain and obstacle databases are referenced to MSL. Using the GPS positionand altitude, the Terrain feature portrays a 2-D picture of the surrounding terrainand obstacles relative to the position and altitude of the aircraft. GPS positionand GPS-MSL altitude are used to calculate and predict the aircraft’s flight path inrelation to the surrounding terrain and obstacles. In this way, the pilot can viewpredicted dangerous terrain and obstacle conditions.Alert windows appear on all pages (except the Terrain (TER) Page) to inform thepilot of proximity to the terrain and obstacles, as well as an unsafe descent rate.These alerts depend on user-defined parameters in the Terrain Page setup.SYNTHETIC VISIONTerrain is integrated within Synthetic Vision (when active) to provide landcontours (colors are consistent with those of the topographical map display),large water features, towers, obstacles over 200’ AGL, as well as visual andauditory alerts to indicate the presence of terrain and obstacle threats relevant tothe projected flight path. Synthetic Vision terrain information is displayed in redand yellow shading on the PFD. Refer to section 8.1 (Synthetic Vision) for moreinformation.TERRAIN INFORMATIONThe areas of the terrain shaded red are predicted to be within 100 feet below orabove the aircraft. The yellow terrain areas are between the user-defined CautionElevation and 100 feet below the aircraft. By default, the Caution Elevation is1,000 feet; therefore, the areas in yellow are between 1,000 feet and 100 feetbelow the aircraft. The black areas are further than the Caution Elevation. Aprojected point of impact is marked with an “X” symbol.
