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190-01007-04 Rev. K
GTN 725/750 Cockpit Reference Guide
Transponder
TCAS II Transponder Mode Controls
The GTN can also control the modes of a TCAS II system through a
GTX 3000. The TA Only and TA/RA modes are added to the transponder
control panel. Selecting TA Only or TA/RA will command the TCAS into the
selected mode, but depending on the aircraft configuration (e.g., on ground),
the TCAS may remain in a different mode.
Special Squawk Codes
As you change a squawk code, the original code will be sent until you are
finished selecting the new code.
The table below lists special squawk codes:
Squawk Code
Description
1200
Default VFR code in the USA
7500
Hijacking
7600
Loss of Communications
7700
Emergency
Special Squawk Codes
NOTE:
While 1200 is the default VFR squawk code, the installer can
configure any code to the VFR key. This is to support international
operations where 1200 may not be used.