Garmin G1000 Mooney M20TN - Manual (Page 269)

190-00647-00 Rev. A Garmin G1000 Pilot’s Guide for the Mooney M20M/M20R/M20TN 6-33
HAZARD AVOIDANCE
6.3 TERRAIN PROXIMITY
CAUTION: Do not use Terrain Proximity information for primary terrain avoidance. Terrain Proximity is
intended only to enhance situational awareness.
NOTE: Terrain data is not displayed when the aircraft latitude is greater than 75° North or 60° South.
G1000 Terrain Proximity is a non-TSO-C151b-certified terrain awareness system. It increases situational
awareness and aids in reducing controlled flight into terrain (CFIT).
Do not confuse Terrain Proximity with Terrain Awareness and Warning System (TAWS). TAWS is more
sophisticated and robust, and it is TSO-C151b-certified. Terrain Proximity does not provide warning annunciations
or voice alerts. It only provides color indications on map displays when terrain and obstacles are within a certain
altitude threshold from the aircraft. Although the terrain and obstacle color map displays are the same, TAWS
uses more sophisticated algorithms to assess aircraft distance from terrain and obstacles.
REQUIREMENTS
Terrain Proximity requires the following components to operate properly:
• Valid 3D GPS position
• Valid terrain/obstacle database
GPS POSITION AND GPS-MSL ALTITUDE
The G1000 GPS receiver provides the horizontal position and altitude. GPS altitude is derived from satellite
position. GPS altitude is then converted to a mean sea level (MSL)-based altitude (GPS-MSL altitude) and is used
to determine terrain and obstacle proximity. GPS-MSL altitude accuracy is affected by satellite geometry, but is
not subject to variations in pressure and temperature that normally affect pressure altitude sensors. GPS-MSL
altitude does not require local altimeter settings to determine MSL altitude. It is a reliable MSL altitude source.
Terrain and obstacle databases are referenced to MSL. Using the GPS position and altitude, the Terrain Proximity
feature portrays a 2D picture of the surrounding terrain and obstacles relative to the position and altitude of the
aircraft. GPS position and GPS-MSL altitude are used to calculate and predict the aircraft’s flight path in relation
to the surrounding terrain and obstacles. In this way, the pilot can view predicted dangerous terrain and obstacle
conditions.