190-02692-00 Rev. A
Garmin G1000 Pilot’s Guide for the Piper PA-32 Saratoga 325
HAZARD AVOIDANCE
SYSTEM
OVERVIEW
FLIGHT
INSTRUMENTS
EIS
AUDIO PANEL
& CNS
FLIGHT
MANAGEMENT
HAZARD
AVOIDANCE
AFCS
ADDITIONAL
FEATURES
APPENDICES INDEX
6.6 TAWS-B
WARNING: Do not use TAWS information for primary terrain or obstacle avoidance. TAWS is intended only
to enhance situational awareness.
NOTE: Terrain and obstacle information is not displayed if the aircraft is outside of the installed terrain
database coverage area.
NOTE: The data contained in the TAWS databases comes from government agencies. Garmin accurately
processes and cross-validates the data but cannot guarantee the accuracy and completeness of the data.
TAWS-B (Terrain Awareness and Warning System - Class B) provides increased situational awareness and aids
in reducing controlled flight into terrain (CFIT). TAWS-B provides visual annunciations and voice alerts when
terrain and obstacles are within the given altitude threshold from the aircraft. The displayed alerts and warnings
are advisory in nature only.
TAWS-B satisfies TSO-C151b Class B requirements for certification.
TAWS-B requires the following to operate properly:
• A valid terrain/obstacle/airport terrain database
• A valid 3-D GPS position solution
TAWS-B uses terrain and obstacle information supplied by government sources. Terrain information is based
on terrain elevation information in a database that may contain inaccuracies. Individual obstructions may be
shown if available in the database. Garmin verifies the data to confirm accuracy of the content, per TSO-C151b.
However, the displayed information should never be understood as being all-inclusive and data may be inaccurate.
TAWS-B uses information provided from the GPS receiver to provide a horizontal position and altitude. GPS
altitude is derived from satellite measurements. GPS altitude is then converted to the height above geodetic
sea level (GSL), which is the height above mean sea level (MSL) calculated geometrically. The system uses GSL
altitude to determine TAWS-B alerts. GSL altitude accuracy is affected by satellite geometry, but is not subject
to variations in pressure and temperature that normally affect pressure altitude 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 to calculate terrain and obstacle alerts.
The terrain and obstacle databases used by TAWS-B are referenced to MSL. Using the GPS position and GSL
altitude, TAWS-B displays a 2-D picture of the surrounding terrain and obstacles relative to the position and
altitude of the aircraft. Furthermore, the system uses the GPS position and GSL altitude to calculate and “predict”
the aircraft’s flight path in relation to the surrounding terrain and obstacles. In this manner, TAWS-B can provide
advanced alerts of predicted dangerous terrain and obstacle conditions.
Baro-corrected altitude (or indicated altitude) is derived by adjusting the altimeter setting for local atmospheric
conditions. The most accurate baro-corrected altitude can be achieved by frequently updating the altimeter
setting to the nearest reporting station along the flight path. However, because actual atmospheric conditions
seldom match the standard conditions defined by the International Standard Atmosphere (ISA) model (where
pressure, temperature, and lapse rates have fixed values), it is common for the baro-corrected altitude (as read
from the altimeter) to differ from the GSL altitude shown on the MAP - TAWS-B Page.
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