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Transponder installation rules for UK LAA aircraft (and certified aircraft too)

10 Posts

Picking up @wigglyamp ’s old post:

You can’t perform a Mode A\C transponder installation any longer. In the U.K., the requirement is in Schedule 5 of the ANO. An existing Mode A\C installation can be maintained and repaired (using the same equipment) but any change of equipment constitutes a modification which then limits it to being Mode S only.

UK LAA TL_3_03 contains:

Is this only for LAA (Annex 1) types, or others too?

Administrator
Shoreham EGKA, United Kingdom

It would be interesting if the above is correct. Maybe it is correct only for Annex 1. But then finding EASA regs anyway is an art

Administrator
Shoreham EGKA, United Kingdom

No response on this one, curiously…

It sounds like the UK LAA rule indeed overrules the EASA one, which is useful because it means LAA aircraft can do a Mode C installation (either from nothing, or installing a different Mode C model to what they had before) whereas for certified aircraft only Mode S (or replacing a Mode C with an exact same model) can be done legally.

This is relevant because a lot of people don’t want to install Mode S, due to the much higher chance of getting busted under the new UK CAA infringements policy.

Administrator
Shoreham EGKA, United Kingdom

Schedule 5 of the ANO applies only to non-EASA aircraft and say this on transponders:

Transponder
17.—(1) Where required by the notified airspace being flown, aircraft must be equipped with a secondary surveillance radar transponder.

(2) In sub-paragraph (1), “secondary surveillance radar transponder” means such type of radio equipment as may be notified as being capable of—

(a)replying to an interrogation from secondary surveillance radar units on the surface; and
(b)being operated in accordance with such instructions as may be given to the aircraft by the appropriate air traffic control unit.

That is the entire text of the transponder requirement for non-EASA aircraft (which is more than LAA aircraft; there are non-EASA certified types too e.g. Piper Apache, Cessna 140).

Andreas IOM

Ah, but what about installing a Mode C, in a virgin aircraft?

If not prohibited, it is permitted, but what about the EASA regs referred to? I would think @wigglyamp will know especially as he has an RV.

Administrator
Shoreham EGKA, United Kingdom

Schedule 5 is the regulation that wigglyamp was referring to – and I don’t see anything in schedule 5 that requires a particular transponder mode. I pasted its entire text. Schedule 5 only applies to non-EASA aircraft (if there is a different Schedule 5, someone will have to post a link because that’s the only one I can find in the most recent ANO).

Andreas IOM

Yes; I have been digging around and the only reference I can find is a series of UK CAA related stuff going back to 2009, saying the CAA will not approve new txp installations unless they are Mode S. One pointer (again, back to ANO Sch 5) is here.

But I can’t find any EASA regulation saying that new installs must be Mode S.

So, is it correct that a non-EASA aircraft (basically, uncertified, though not quite the same thing) can have a new Mode C installation performed, and do so anywhere in Europe?

Administrator
Shoreham EGKA, United Kingdom

I’ve also been digging to see where my original statements came from.

The UK requirement for Mode S for IFR was promulgated via several UK AIC, with the final details in AIC 105/2005 that required IFR operating as GAT in designated TMA and enroute airspace by 31 March 2005. Subsequently AIC 27/2007 required Mode S compliance for IFR in all other airspace, and suggested that a further AIC would follow for VFR aircraft with implementation, both by 31 March 2008. I’m sure this was published and had the ‘No more Mode A/C installations’ bit included, but I can’t find it.

Looking at EASA CS-ACNS, it certainly allows certification of Mode A/C installations per CS ACNS.D.AC.001, so I guess there is no issue now in fitting an A/C transponder in an EASA aircraft, where the need to comply with AIP GEN 1.5 for IFR is not needed.

Avionics geek.
Fairoaks. EGTF

I found an old LAA document which quoted a CAA one from c. 2009 saying the CAA will not allow any new non-Mode-S installations, but the referenced CAA document (30+ pages) didn’t actually say that Well, I could not find the text in it…

The requirement for carrying Mode S for IFR, and for a lot of VFR too in some countries’ airspace, is not in dispute by anyone AFAIK, and hasn’t been for more than 10 years as a matter of practicality / airspace access. For LAA aircraft this is almost entirely moot from the IFR angle, due to the tiny numbers approved.

Very interesting that there isn’t an EASA Part M prohibition on Mode C installations on certified aircraft too.

So my Q becomes: if there is no EASA Part M ban, how can the UK CAA block it, or how will they even know about it? Does a UK Part M company have to notify the CAA of the details of each job?

Administrator
Shoreham EGKA, United Kingdom

Peter wrote:

Does a UK Part M company have to notify the CAA of the details of each job?

If the CAA aren’t directly approving the mod (only nowadays when they get a Minor change application delegated to them by EASA or directly for a CAA-controlled Annex 1 aircraft) they’re none-the-wiser about what has been done to an aircraft. However, the operator (sometimes via the Part M) is required to keep the radio station licence up to date and when it’s issued or renewed, it requires the on-board transmitting equipment to be listed including the relevant equipment approval or TSO, so this is the only place that would show a Mode A/C had been installed.

Actually the latest UK aeronautical radio licence application doesn’t even require the specific type of equipment or it’s approval to be listed anymore: https://www.ofcom.org.uk/__data/assets/pdf_file/0022/123646/OfW585-Aircraft-radio-licence-application-form.pdf

OFW585 local copy

Last Edited by wigglyamp at 04 Aug 16:19
Avionics geek.
Fairoaks. EGTF
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