Transponder GND VS ALT mode

[tommyturner]

All the current FAA data now instructs you have the Transponder in the ALT mode when on the ground if you have ADSB out. It has been my believe that the GND mode on the Dynon transponder met the FAA requirements but I am having trouble finding any documentation to support that. If that is correct then point me to the documentation or give me an explanation of the difference in the two modes.

Thanks

Tommy

 

[dynonsupport]

SAFO 15006 is unfortunately poorly written, and doesn't cover Mode-S transponders well unless you somehow already knew how ground mode works. We answered here a while ago, which hopefully answers your question:

http://dynonavionics.com/cgi-bin/yabb2/YaBB.pl?num=1433394211

Bottom line, Dynon's ground mode is reporting altitude, so it counts. In fact, it is against the ADS-B rules to be in AIR mode when on the ground so you must go to ground mode either manually or automatically.