It's been a while, but I believe Trig uses GPS ground speed to determine
flight status.Â* The concern is about gliders flying in wave and clocking
extremely low ground speed resulting in the transponder reporting the
glider on the ground.

On 11/30/2019 5:37 PM, Mike N. wrote:
How is Trig determining ground / alt without a switch?

I'm planning on a manual switch. I'll just add setting it to alt in my pre-takeoff instrument set scan.

--
Dan, 5J