190-00734-11
GTX 33X and GTX 3X5 ADS-B Maintenance Manual
Rev. 6
Page 8-3
8.5 GTX Airborne Test Mode
Operation of the GTX 330/330D and GTX 3X5 is accomplished using the faceplate of the unit. Refer to
section 3.1 and section 3.2 for details. The GTX 33/33D and GTX 3X5R are controlled using the
GTN 6XX/7XX or GNS 480. Refer to section 3.3 for details. The GTX 3X5R may be controlled by a
G1000 system. Refer to section 3.4 for details. Refer to the operational documents listed in table 1-1 for
basic GTX operation.
NOTE
For dual transponder installations, the procedures contained in this section must be
completed for each installed transponder.
NOTE
A GTX or GTN in Ground Test mode or Airborne Test mode will automatically return to
normal operation of the Air/Ground logic when the unit is powered off and then turned on
in normal mode. When the unit is in Ground Test or Airborne Test mode, an alert message
will be annunciated on the GTX or GTN screen.
NOTE
The transponder should only be placed into Airborne Test mode for testing. Once testing is
complete, either return the squat switch to original settings or remove the GTX from
Ground Test mode.
8.5.1 GTX 33/330 Airborne Mode (v8.02 or higher)
The transponder must be placed in an airborne state to reply to any Mode A or Mode C interrogations. The
GTX uses advanced Air/Ground logic to determine the state of the transponder. This logic must be
temporarily defeated in order to place the transponder in an airborne state for testing. To place the
transponder into an airborne state, perform the following procedure for the GTX interface installed in the
aircraft.
Panel Mounted Transponder
1. Start the GTX in Ground Test mode (hold the
CRSR
key and press the
ON
key).
2. “TEST” will be annunciated on the GTX 330/330D main screen.
Remote Mounted Transponder (GTN Interface)
1. Start the GTN in configuration mode (hold the
HOME
key while cycling power).
2. Navigate to the XPDR 1 Installation Settings page and press the Force Airborne Test key.
3. Restart the GTN in normal mode.
Remote Mounted Transponder (GTX 33/33D, GNS 480 Interface)
1. Enter the configuration mode on the GNS 480.
2. Navigate to the GTX configuration pages and locate the SQUAT SWITCH setting.
3. Set the SQUAT SWITCH to “Yes,” and set the SENSE to “LOW.” If a squat switch is present in
the aircraft, configure the SENSE to override.
4. Restart the GNS 480 and transponder in normal mode. The transponder will now be in airborne
mode.
