Pilot's Guide

18
Garmin GTS Traffic Systems
190-00587-02 Rev. B
Ground Traffic Filtering
To reduce nuisance alerts and reduce traffic display clutter, traffic that is on
or near the ground may not be shown on the traffic display or generate traffic
alerts. There are several methods used for filtering out ground traffic.
Mode S Targets
Mode S transponders include in their replies an indication of whether the
aircraft is on the ground or in the air. Mode S traffic that indicates the traffic is
on the ground will not be displayed or generate an alert. This is the only method
used to determine whether Mode S traffic is on the ground.
NOTE: The system does not indicate to the crew which traffic targets are
Mode S equipped.
Radar Altimeter
Radar altitude, if available, may be used to determine which traffic targets are
on the ground. For example, if the current radar altitude is 1000 feet, then traffic
with a relative altitude of -1000 feet would be considered to be on the ground
and would not be displayed or alerted on. Ground traffic is only filtered when
the radar altitude is less than 1,700 feet.
Calculated Height Above Ground
If radar altitude is not available, calculated height above ground may be used
to filter out ground traffic. Calculated height above ground is used similarly to
how radar altitude is used. Ground traffic is only filtered when the calculated
height above ground is less than 1,700 feet.
ADS-B Receiver
A 1090 MHz Extended Squitter (1090ES) receiver is built in to the GTS System
Processor. ADS-B Out broadcasts from other traffic may include additional
information such as flight ID, position, altitude, velocity, and direction. These
broadcasts from other aircraft are correlated with active transponder replies.
The accuracy of the ADS-B broadcasts and additional information allows for
improved accuracy and other enhancements to the traffic display. Refer to the
traffic display documentation for information on display enhancements for
ADS-B traffic.