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STBY mode while manpulating XPDR code

I believe ‘GND’ is part of the Mode S extended squitter that prevents airborne interrogation and TCAS alerts, but allows interrogation by ground movement radar.

KHWD- Hayward California; EGTN Enstone Oxfordshire, United States

Ok, then it would make sense that Mode A/C transponders don’t have it.

ESME, ESMS

GTX330 has a GND mode, not just the ES, so I assume that it part of basic Mode S, not extended squitter?

EGKB Biggin Hill

GND is part of basic mode S.
I use it only at very big airports. Most regional airports don’t have a ground radar.

ESMK, Sweden

My GTX330 switches automatically AIR/GND using a differential air pressure switch – described here. So this is never touched. All I ever do is enter the txp code.

Administrator
Shoreham EGKA, United Kingdom

They are awesome (GTX330)

Arne wrote:

I use it only at very big airports. Most regional airports don’t have a ground radar.

I always use it. Why have different procedures depending on airport size when GND instead of SBY will work at any airport?

ESKC (Uppsala/Sundbro), Sweden

The 2020 ADS-B requirement in the US demands automatic air/ground switching. I suspect that requirement will eventually propagate to other regions.

All the new transponders allow that. It can be achieved by input from squat switch, airspeed switch or automatically based on GPS speed/height change.

Unfortunately, my Trig TT22 needs a software update to implement the GPS auto-switching, but at least I have until 2020 to comply.

My other installation is a Garmin GTX 335 with internal WAAS GPS and that works very well with a clean sheet PAPR report.

KHWD- Hayward California; EGTN Enstone Oxfordshire, United States

ATC here (Denmark) asks pilots to NOT go to STBY when changing squawk. The stated reason being that there is a risk that the radar software will loose your track’s continuity and will have to wait for successive replies after you switch back on ALT before it will give speed, direction and altitude trend. When I mentioned the risk of passing through the emergency codes while dialing, the answer was that it was not an observed problem.

I have seen a youtube with a U.S. controller stating essentially the same.

Of course, with modern transponders with numerical 0-7 pushbuttons, this is not an issue. As the 4th digit is entered, the new squawk kode is activated without dialing “through” any other combinations.

huv
EKRK, Denmark

Flying since 1970 all over the world (mostly airliner) I can reassure you that no procedure requires the transponder to be set to SBY while dialing in a new code.
No SOP at all – must be the private whim of a 300h+ flight instructor … out of misunderstood system knowledge or to impress students and nobody dares to say it’s nonsense

EDxx, Germany
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