Silvaire wrote:
As a result, since almost all my flying is done squawking VFR in the US I cannot clearly remember the last time I touched any button or knob on the transponder. It gets turned on and off with the avionics master switch.
That is what I do as well. Most transponders power up to the last mode. I never set ALT mode, except after the unit comes out from maintenance where an avionics tech or mechanic has either powered off the transponder using the transponder button/switch rather than the avionics master or set it to STBY Then it either does not turn on with the avionics switch or ends up in STBY. That will mess me up as it won’t discover it until I am out at the runway as part of my pre-takeoff check list.
In Zurich, you have to have the transponder on even on the ground. Check the AIP for specific procedures. On the club’s Seneca, the GND mode has been removed by a firmware update a few months ago (it has a GTX 345 I think).
NCYankee’s comments explain what I have recently seen. My GTX330 always switched to GND on landing but since it has been
upgraded to ES with the latest software it stays in ALT mode after landing and during taxi. If I switch it to Standby it will switch automatically to ALT at take-off so from now on I will leave it in ALT all the time. Garmin confirm there is no GND mode for the ES version.