Garmin GTX 320A - Manual (Page 5)

Code Selector
The code selector consists of four, eight-position switches that provide 4,096 active
identifi cation codes. The code selected should be either a VFR code or a code assigned
by ATC. Regulations require that aircraft equipped with a transponder must operate the
transponder, including Mode C equipment unless otherwise directed by ATC.
When making routine code changes, you should avoid inadvertent selection of codes
7500, 7600, or 7700 causing momentary false alarms at ground facilities. For example when
switching from code 2700 to code 7200, switch fi rst to 2200 then 7200, NOT to 7700 and
then 7200.
This procedure applies to nondiscrete code 7500 and all discrete codes in the 7600 and
7700 series (i.e., 7600 to 7677, 7700 to 7777) which trigger special indicators in automated
facilities. Only nondiscrete code 7500 will be decoded as the hijack code. An aircraft’s
transponder code is utilized for ATC tracking capability, therefore you should not turn the GTX
320A to SBY when making routine code changes.
Important Codes
1200-The United States VFR Code for any altitude.
7600-Loss of Communications.
7500-Hijacking (Never assigned by ATC without prior notifi cation of the pilot that the
aircraft is subject to unlawful interference).
7700-Emergency.
0000-Military use. Never squawk this Code.
See the Aeronautical Information Manual (AIM) for an explanation and uses of identifi ca-
tion codes.
IDENT Button
On occasion, a controller will request “SQUAWK IDENT” to identify your transponder
return from other aircraft. Respond by momentarily pressing the IDENT button, activating the
Special Position Identifi cation for approximately 20 seconds.
Reply Light
The reply light will blink each time the transponder replies to an interrogation. The reply
light remains illuminated during the IDENT time interval and during TST function.
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