Terrain Awareness And Warning System; Requirements; Limitations; Taws Alerting Using The Gps Position/Gps-Msl Altitude - Garmin G1000 Pilot's Manual

6.3 TERRAIN AWARENESS AND WARNING SYSTEM (TAWS
Terrain Awareness and Warning System (TAWS) is an optional feature to increase situational awareness and aid
in reducing controlled flight into terrain (CFIT). TAWS satisfies TSO-C151b Class B requirements for certification.
Class B TAWS is required for all Part 91 aircraft operations with six or more passenger seats and for Part 135
turbine aircraft operations with six to nine passenger seats (FAR Parts 91.223, 135.154).
TAWS provides visual and aural annunciations when terrain and obstacles are within the given altitude threshold
from the aircraft.

REQUIREMENTS

TAWS requires the following to operate properly:
• The system must have a valid 3D GPS position solution.
• The system must have a valid terrain/obstacle/airport terrain database.

LIMITATIONS

The data contained in the TAWS databases comes from government agencies. Garmin accurately
NOTE:
processes and cross-validates the data, but cannot guarantee the accuracy and completeness of the data.
TAWS displays terrain and obstructions relative to the altitude of the aircraft. The displayed alerts and
warnings are advisory in nature only. Individual obstructions may be shown if available in the database.
However, all obstructions may not be available in the database and data may be inaccurate. Never use this
information for navigation or to maneuver to avoid obstacles.
Terrain information is based on terrain elevation data contained in a database that may contain inaccuracies.
Terrain information should be used as an aid to situational awareness. Never use it for navigation or to maneuver
to avoid terrain.
TAWS uses terrain and obstacle information supplied by government sources. The data undergoes verification
by Garmin to confirm accuracy of the content, per TSO-C151b. However, the displayed information should
never be understood as being all-inclusive.

TAWS ALERTING USING THE GPS POSITION/GPS-MSL ALTITUDE

TAWS uses information provided from the GPS receiver to provide a horizontal position and altitude. GPS
altitude is derived from satellite measurements. GPS altitude is converted to a mean sea level (MSL)-based
altitude (GPS-MSL altitude) and is used to determine TAWS alerts. GPS-MSL altitude accuracy is affected by
factors such as satellite geometry, but it is not subject to variations in pressure and temperature that normally
affect pressure altitude devices. GPS-MSL altitude does not require local altimeter settings to determine MSL
altitude. Therefore, GPS altitude provides a highly accurate and reliable MSL altitude source to calculate terrain
and obstacle alerts.
TAWS utilizes terrain and obstacle databases that are referenced to mean sea level (MSL). Using the GPS
position and GPS-MSL altitude, TAWS displays a 2D picture of the surrounding terrain and obstacles relative
to the position and altitude of the aircraft. Furthermore, the 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
manner, the TAWS system can provide advanced alerts of predicted dangerous terrain conditions. Detailed alert
modes are described later in this section.
190-00592-02 Rev. A Garmin G1000 Pilot's Guide for the Diamond DA40/40F
HAZARD AVOIDANCE
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