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How do you operate/set up your transponder (on the ground)

I just phoned ATC at my airport and asked (EKRK – no ground radar). It is not a big issue, the controller said, but they clearly prefer that transponders are not ON/ALT while taxying, as the blips occasionally clutters their screen a bit. He also said that they never had reports of TCAS warnings from approaching traffic as a result of active transponders on the ground, and he believed that the TCAS is suppressed below a certain altitude.

So I will continue do what I have been taught; check SBY/GND mode on power-up, set ALT when cleared to line up or take-off, and switch back to SBY/GND after leaving the runway after landing.

Last Edited by huv at 17 Dec 11:58
huv
EKRK, Denmark

@chflyer it seems Garmin displays GND mode also when appropriate.
From the GTX 330 manual:
If the GTX 330 is configured for Automated Airborne Determination, normal operation
begins when take off is sensed. When the aircraft is on the ground the screen automatically
displays GND. The transponder does not respond to ATCRBS interrogations when GND
is annunciated. When a delay time is set (dependent upon installation configuration), the
GTX 330 waits a specified length of time after landing before changing to GND mode

From October 12th, transponder operation EU rules are now in Part-SERA. As I recall the rules are quite similar to what has been in Doc 8168 for a long time. The main difference is that they are now EU legislation.
SERA.13001 – Operation of an SSR transponder
(a) When an aircraft carries a serviceable SSR transponder, the pilot shall operate the transponder at all times during flight regardless of whether the aircraft is within or outside airspace where SSR is used for ATS purposes.
Nothing at all about operation on the ground, not even in SERA.13015 – SSR transponder Mode S aircraft identification setting

Last Edited by huv at 17 Dec 11:43
huv
EKRK, Denmark

@Silveraire
European controllers love discrete transponder codes. I rarely fly 7000. Quite a difference with the US

Tököl LHTL

BTW the Avidyne and King Mode S units are reportedly a rebadged Trig TT31 – see e.g. here.

Administrator
Shoreham EGKA, United Kingdom

I never need to change the mode on my txpdr, only the squawk code which is 7000 by default unless/until I am given a discreet squawk. No chance to set ALT on the ground.

I have an Avidyne AXP340 which is ADS-B certified (if so installed/configured, i,e. with ground/air discreet signal to the transponder…. squat switch or GPS-in).

The manual for it indicate 4 possible states:
ALT – txpdr will respond to all interrogations
ON – txpdr will respond to all interrogations, but altitude reporting is suppressed
SBY – txpdr is on but will not reply to any interrogations
GND – txpdr 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 the txpdr

For an ADS-B installation with ground/air state input (e.g. gear “squat” switch or discreet GPS signal from separate GPS/Nav/Com), GND is selected automatically on landing or while taxiing and ALT is selected automatically when airborne. Pilot-selectable states in air are ALT-ON-SBY and pilot-selectable states on ground are GND-SBY. Current state is displayed on the xpdr screen, as well as ADS-B status and position (i.e. GPS input).

Compared to the comments above re Garmin, it sounds like they behave essentially the same, but the Avidyne displays the current state (GND or ALT).

LSZK, Switzerland

Xtophe wrote:

CS.ACNS entered into force on 1st Jan 2014.

TT31 ETSO certificate are dated Feb 2011. Its installation manual refers to ETSO.C112 and C166. I haven’t checked the details about the ground mode and I don’t have access to EUROCAE specs anyway.

Original european approval of GTX330 appears to be through the LBA in Oct 2002

Ok, then bookworm’s comment that manual switching is not permitted would only apply to equipment certified 2014 or later. Then there will be lots of transponders out there that can and must be manually switched between GND and ALT modes.

ESKC (Uppsala/Sundbro), Sweden

It all depends when and against which spec they were certified.

CS.ACNS entered into force on 1st Jan 2014.

TT31 ETSO certificate are dated Feb 2011. Its installation manual refers to ETSO.C112 and C166. I haven’t checked the details about the ground mode and I don’t have access to EUROCAE specs anyway.

Original european approval of GTX330 appears to be through the LBA in Oct 2002

Nympsfield, United Kingdom

bookworm wrote:

Manual switching is not permitted by CS ACNS.D.ELS.020. If no automatic switching is available, it has to be treated like a Mode A/C (always airborne mode). In which case my comments on A/C transponders apply.

Then how come the Trig TT31 is approved, while having a manual “GND” setting?

It is also a consequence of CS ACNS.D.AC.020 (c) and CS ACNS.D.ELS.025 (c) that blind altitude encoders are not allowed. Yet lots of aircraft are flying with blind encoders.

There is something odd here.

ESKC (Uppsala/Sundbro), Sweden

I did a google on CS ACNS.D.ELS.020 and found this [ local copy ].

At the bottom of page 26 it has:

So a GTX330 is illegal for a new installation in Euro-land?

Administrator
Shoreham EGKA, United Kingdom

It used to be set on take-off, and, long ago, to sby while changing squawk. Now transponders don’t change until new code is fully entered, and should never be switched to sby in the air.
And the FAA said, some years ago, to squawk fully once moving on ground. I don’t recall anything from EASA. Or is my recollection wrong?

Maoraigh
EGPE, United Kingdom
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