Pilot's Guide

17190-00587-02 Rev. B
Garmin GTS Traffic Systems
Automatic Mode Switching
The system can automatically switch between Operate and Standby modes
based on whether the ownship is in the air or on the ground. The system will
automatically select Operate mode 8 seconds after becoming airborne. Standby
mode will automatically be selected 24 seconds after landing.
Calculated Height Above Ground
For aircraft that are not equipped with a radar altimeter, the system can
calculate the height above ground using information from various optional
interfaces. This calculation can enable additional functionality (such as ground
traffic filtering), without requiring a radar altimeter interface.
Height above ground can be calculated using an internal airport database
and optional 3-D GPS interface. The system’s internal airport database contains
locations and elevations for airports throughout the world. By comparing the
3-D GPS position and altitude to the airport database, the ownship’s height
above ground can be calculated. If GPS altitude is not available, 2-D GPS input
(position only) can be used along with baro-corrected altitude from an air data
computer to perform the calculation.
Additionally, if the system has detected that it is on the ground, the on-
ground position and pressure altitude will be used as a known ground reference
point. If GPS position is not available, the on-ground altitude will still be used
as a reference point as long as the ownship is on the ground and for up to 60
seconds after takeoff.
NOTE: The Calculated Height Above Ground feature is only available
in GTS 825 and GTS 855 systems with system software version 2.20 or
later.