Garmin G1000 NXi Pilot's Manual

Also see for G1000 NXi: Cockpit reference guide Supplemental Maintenance Manual Cockpit reference guide Reference guide Pilot's guide

Contents

190-02177-00 Rev. A Garmin G1000 NXi Pilot’s Guide for the Cessna Nav IIISYSTEMOVERVIEW FLIGHTINSTRUMENTS EIS AUDIO PANEL& CNS FLIGHTMANAGEMENT HAZARDAVOIDANCE AFCS ADDITIONALFEATURES APPENDICES INDEX291HAZARD AVOIDANCEThe terrain system uses information provided from the GPS receiver to provide a horizontal position andaltitude. GPS altitude is derived from satellite measurements. GPS altitude is then converted to the height abovegeodetic sea level (GSL), which is the height above mean sea level (MSL) calculated geometrically. The systemuses GSL altitude to determine alerts for the Terrain-SVT and TAWS-B systems. GSL altitude accuracy is affectedby satellite geometry, but is not subject to variations in pressure and temperature that normally affect pressurealtitude sensors. GSL altitude does not require local altimeter settings to determine MSL altitude. It is a widely-used MSL altitude source. Therefore, GSL altitude provides a highly accurate and reliable MSL altitude source tocalculate terrain and obstacle alerts.The terrain and obstacle databases used by the terrain system are referenced to MSL. Using the GPS positionand GSL altitude, terrain system displays a 2-D picture of the surrounding terrain and obstacles relative to theposition and altitude of the aircraft. Furthermore, for the Terrain-SVT or TAWS-B systems, the system uses theGPS position and GSL altitude to calculate and “predict” the aircraft’s flight path in relation to the surroundingterrain and obstacles. In this manner, the Terrain-SVT or TAWS-B systems can provide advanced alerts of predicteddangerous terrain conditions.Baro-corrected altitude (or indicated altitude) is derived by adjusting the altimeter setting for local atmosphericconditions. The most accurate baro-corrected altitude can be achieved by frequently updating the altimetersetting to the nearest reporting station along the flight path. However, because actual atmospheric conditionsseldom match the standard conditions defined by the International Standard Atmosphere (ISA) model (wherepressure, temperature, and lapse rates have fixed values), it is common for the baro-corrected altitude (as readfrom the altimeter) to differ from the GSL altitude. This variation results in the aircraft’s GSL altitude differingfrom the baro-corrected altitude.RELATIVE TERRAIN SYMBOLOGYThe terrain system uses colors and symbols to represent terrain and obstacles (with heights greater than 200feet above ground level, AGL) present in the databases relative to aircraft altitude. The system dynamicallyadjusts these colors as the aircraft altitude changes, and after takeoff and landing.While the aircraft is on the ground, the system displays relative terrain 400 feet or more above the aircraftaltitude using red, and terrain at less than 400 feet above aircraft altitude using black, as shown on the On-Ground Legend. When the aircraft is in the air, the system displays relative terrain information using red,yellow, green, and black, as shown on the In-Air Legend. As the aircraft transitions from on-ground to in-air, orfrom in-air to on-ground, the display of relative terrain momentarily fades into the corresponding colors. ForTerrain-SVT or TAWS-B systems, if an alert occurs, the relative terrain colors transition to the In-Air Legend ifin the On-Ground Legend was shown in order to provide the flight crew with the most information possible.Figure 6-53 Relative Terrain LegendIn-Air LegendOn-Ground Legend