Ownship Air/Ground Detection; Automatic Mode Switching - Garmin GTS 820 TAS Pilot's Manual

6.4.3.1.3 TAWS/Windshear Alerts
TA aural alerts may be temporarily muted by higher-priority aural alerts,
such as TAWS or windshear. The TA aural alert will resume when the higher-
priority aural alert is no longer active.
6.4.3.1.4 External Switch
A TA aural alert may be canceled with an optional momentary pushbutton
switch. Pressing this switch during a TA aural alert will cancel/mute that aural
alert. Subsequent TA aural alerts will be played, and the switch must be pressed
each time that it is desired to cancel/mute a TA aural alert.

6.5 Ownship Air/Ground Detection

Optional external interfaces can be used to determine whether the ownship
is on the ground or in the air. Interfaces that may be used for determining the
air/ground state include:
• An air/ground switch (e.g. squat or airspeed switch).
• GPS groundspeed. Greater than 35 knots indicates in air, and less than
30 knots indicates on ground.
• Air/ground message from a Garmin avionics system.
Ownship air/ground detection is used for the automatic mode switching and
calculated height above ground features.

6.6 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.
The system can automatically turn on the ADS-B In feature shortly after power
up if the unit is configured to have the ADS-B In function operate independent
of active surveillance. The ADS-B In feature is turned on 8 seconds after power
up. If the ADS-B In feature was turned off while on the ground, the ADS-B In
feature will be turned on 8 seconds after becoming airborne. The ADS-B In
feature will not be turned off automatically.
For GTS 800, GTS 820, and GTS 850 systems using SW v4.10 or later or
GTS 825 and GTS 855 systems using SW v3.10 or later, when a Pressure Altitude
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Garmin GTS Traffic Systems 190-00587-02 Rev. E