AXP340/322 ADS-B Transponder

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SAFO1506

Printed From: Avidyne
Category: Avidyne General
Forum Name: AXP340/322 ADS-B Transponder
Forum Description: Topics on the Avidyne AXP340/322 ADS-B Transponder
URL: https://avidynelive.com/forum_posts.asp?TID=694
Printed Date: 26 Mar 2026 at 1:14pm
Software Version: Web Wiz Forums 12.07 - https://www.webwizforums.com

Topic: SAFO1506

Posted By: Dlesh123
Subject: SAFO1506
Date Posted: 06 Jun 2015 at 7:27pm

Now that the FAA has decided that they want the transponder ON for all ground operations at all airports, will there be a SB to disconnect the automatic switch from ground to air that switches the transponder from standby to ON?

Or can that be permanently overridden?

Doug

Replies:

Posted By: Gary T
Date Posted: 07 Jun 2015 at 3:56am

From the AXP340 owner manual: p.4 & 5

If the installation includes an automatic air/ground input, such as a gear squat switch, IFD540 speed-based air/ground discrete, or similar external input, the AXP340 will start in GND mode on the ground and will automatically transition to ALT mode during takeoff roll/liftoff.

GND Mode The transponder is on, but will not reply to any interrogations.The transponder will respond to Mode S ground interrogations from surface movement radar. This mode is only available in installations that send a ground/air discrete signal to transponder.

I believe we will be in compliance with the FAA.

-------------
Gary-T

Posted By: oskrypuch
Date Posted: 07 Jun 2015 at 4:55am

Gary is correct. A ModeS transponder (340 included) uses its GND mode for ASDE-X compliance, on the ground. That is preferable to an ALT mode on the ground.

* Orest

Posted By: Dlesh123
Date Posted: 07 Jun 2015 at 5:27am

Thanks for clearing that up