Gts 820 Traffic; Theory Of Operation - Garmin G1000 Manual

HAZARD AVOIDANCE

6.10 GTS 820 TRAFFIC

The GTS 820 Traffic Advisory System (TAS) is intended for advisory use only to aid the pilot in
WARNING:
visually acquiring traffic. No avoidance maneuvers should be based solely upon TAS traffic information. It
is the responsibility of the pilot in command to see and maneuver to avoid traffic.
Pilots should be aware of TAS system limitations. TAS systems require transponders of other aircraft
NOTE:
to respond to system interrogations. If the transponders do not respond to interrogations due phenomena
such as antenna shading or marginal transponder performance, traffic may be displayed intermittently, or
not at all. Aircraft without altitude reporting capability are shown without altitude separation data or climb
descent indication. Pilots should remain vigilant for traffic at all times.
TIS is disabled when TAS installed.
NOTE:
The optional Garmin GTS 820 is a Traffic Advisory System (TAS). The GTS 820 enhances flight crew situational
awareness by displaying traffic information for transponder-equipped aircraft. The GTS 820 also provides visual
annunciations and voice traffic alerts to assist the pilot in visually acquiring traffic.
The GTS 820 is capable of tracking up to 45 intruding aircraft equipped with Mode A or C transponders, and up
to 30 intruders equipped with Mode S transponders. A maximum of 30 aircraft with the highest threat potential
can be displayed simultaneously. No TAS surveillance is provided for aircraft without operating transponders.

THEORY OF OPERATION

When the GTS 820 is in Operating Mode, the unit interrogates the transponders of intruding aircraft while
monitoring transponder replies. The GTS 820 uses this information to derive the distance, relative bearing,
and if reported, the altitude and vertical trend for each aircraft within its surveillance range. The GTS 820
then calculates a closure rate to each intruder based on the projected Closest Point of Approach (CPA). If the
closure rate meets the threat criteria for a Traffic Advisory (TA), the system provides visual annunciations and
voice alerts.
TAS SURVEILLANCE VOLUME
The GTS 820 surveillance system monitors the airspace within ±10,000 feet of own altitude. Under ideal
conditions, the unit scans transponder traffic up to 40 nm in the forward direction. Range is somewhat
reduced to the sides and aft of own aircraft due to the directional interrogation signal patterns. In areas of
greater transponder traffic density or when TCAS II systems are detected, the GTS 820 automatically reduces
its own interrogation transmitter power (and therefore range) in order to limit potential interference from
other signals.
When paired with a 1090 MHz extended squitter transponder, the GTS 820 uses Automatic Dependent
Surveillance - Broadcast (ADS-B) data from participating airborne aircraft transponders to enhance the
positional accuracy and display of traffic within the TAS surveillance range. Traffic data supplied only by
ADS-B Ground Based Transceivers (GBTs) is not displayed.
476 Garmin G1000 Pilot's Guide for the Socata TBM 850/900 190-00709-05 Rev. D