Post Installation Configuration & Checkout Procedure; Operation - Garmin GTX327 Installation Manual

5 POST INSTALLATION CONFIGURATION & CHECKOUT PROCEDURE
5.1

Operation

The coverage you can expect from the GTX 327 is limited to line of sight. Low
altitude or aircraft antenna shielding by the aircraft itself may result in reduced
range. Range can be improved by climbing to a higher altitude. It may be possible
to minimize antenna shielding by locating the antenna where dead spots are only
noticed during abnormal flight attitudes.
The GTX 327 should be turned off before starting aircraft engine(s).
If the GTX 327 is configured with Automated Airborne Determination, flight
operation is automatic and not dependent on user mode selection. Whether STBY,
ON or ALT is selected on the ground, the transponder annunciation continues to
indicate STBY and does not respond to radar or TCAS interrogations. When liftoff
is sensed, the unit automatically selects the ALT mode.
5.1.1 Function Selection Switches
The function selection switches are:
• OFF 
Powers off the GTX 327. Pressing the STBY, ON or ALT key powers on the
transponder displaying the last active identification code.
• STBY  Selects the standby mode. When in standby mode the transponder will not reply to
any interrogations.
• ON 
Selects Mode A. In this mode, the transponder replies to Mode A and Mode C
interrogations, as indicated by the Reply Symbol ("®"), but the replies do not
include altitude information.
• ALT 
Selects Mode A and Mode C. In ALT mode, the transponder replies to
identification and altitude as indicated by the Reply Symbol ("®"). Replies to
altitude interrogations include the standard pressure altitude (29.92 inches Hg.)
received from an external altitude source, which is not adjusted for barometric
pressure. The ALT mode may be selected in aircraft not equipped with an optional
altitude encoder; however, the reply signal will not include altitude information.
GTX 327 Installation Manual
190-00187-02
Figure 5-1. GTX 327 Front Panel
NOTE
NOTES
Page 5-1
Revision K