Peter wrote:
after some PPL student kicked things off earlier by saying his FI told him to n
wigglyamp wrote:
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.
This seems to be the standard route. This was applicable in the Netherlands as well, and currently is for 8,33 kHz as well. No regulations to support mode C on the long run, so I wouldn’t invest in mode C, not even for replacement.
The replacement limitations might be laid down in EU 1207/2011 Haven’t got time to re-read the document now. The final deadline is in there for sure.
Airborne_Again wrote:
Sure you can, in the UK as in the rest of EASA-land. See CS-STAN.
You can not. Replacing by the same P/N is never an issue, replacing by another P/N under CS-STAN is only possible if it is a mode S transponder. CS-STAN covers mode S only.
Cool turn of events here 
I’m stilled puzzled by the reason why having the transponder on at all times though.
LeSving wrote:
I’m stilled puzzled by the reason why having the transponder on at all times though.
Pretty obvious, isn’t it? To make TCAS and other traffic information and collision avoidance systems useful for manned as well as unmanned aerial vehicles
It’s a commonly used and effective way of getting people to use equipment perceived as good for safety.
You get it with seat belts (which don’t have to be fitted in cars registered before some date early in the 20th century) which have to be worn if fitted.
With transponders, it’s obvious. The biggest thing is protection of large aircraft on which TCAS is mandatory – particularly given the widespread (and often gloating) reports of people avoiding Mode C to escape CAS bust enforcement which is an incredibly dangerous practice and it’s hard to believe that anybody would do it (but plenty do, evidently… anybody fancies a flight with me on a sunny weekend?).
The other day I was waiting to depart for an unusually long time (a busy circuit) and at one point 1/3 of the planes landing were Mode A only i.e. deliberate Mode C invisibility, or (given the low cost) intentional avoidance of getting the altitude encoder fixed → deliberate Mode C invisibility. Most were school owned. There is one “ATPL FTO” there and they are always showing Mode C however.
We are now decades into Mode C and still so many people are deliberately not using it, despite there being zero civil liberties issues. The reasons for not using Mode C are IMHO 100% dishonourable. Can anyone think of an honourable reason for turning off Mode C?
Arguably the Mode S mandate plays into the hands of the civil liberties people but that sort of thing was rarely a problem in Europe where a carrot is not essential to accompany the stick It was handled very badly in the PR department and they should have implemented TIS (traffic info) on the data channel, like was done in the USA as a carrot for Mode S adoption. And now same with ADS-B although I doubt it will ever be mandatory for all flight OCAS. This means that a large section of GA (probably the majority of aircraft) will be able to carry on non-TXP or with just Mode C, legally post-October, provided they avoid flying into Mode S airspace, which most of them can. It is the VFR flyers who sometimes need Mode S (and most of these will be in N Europe, excluding France) who will be the least happy because they will be legally required to turn on Mode S all the time – or remove the transponder altogether (or damage it).
I get where mh is coming from but in his examples there will be no problem getting permission to fly invisible.
Each of us has an opinion on this, which is fine. Mine is that I get pi*ssed off when I fly with my £12,000 TCAS system and – below say 2000ft – more than half the planes which whizz by, sometimes very close and mostly not seen until very late, are not showing on it, or are showing Mode A only, yet they are totally obviously transponder-capable types and probably 90% have one fitted. And somehow I don’t really believe they are doing this just well away from CAS… the whole point of doing it is to be invisible, which makes sense only in the context of CAS busting. A lot of it may be poor (stupid FI) PPL training, as evident from my earlier post. I see very few true vintage types. But if I was flying a vintage type I would get a TXP and have a battery for it. A lithium battery is light and small.
Peter wrote:
My instructor advises that the flying school rarely set transponders to ALT when flying, and advise that I shouldn’t either. Their view is twofold: that it carries little benefit – local ATC are too busy to be giving voluntary deconfliction guidance off the back of it – and that it carries a negative; without it, there’s little evidence against you if there is a level bust.
I didn’t realise things were that bad in UK instructing on the use of transponders. I would say that this instructor is actually being wilfully negligent if he/she is teaching students that.
Peter wrote:
A quick search here digs out this and I found this and there is plenty of other stuff saying that the UK CAA won’t approve any new installations of Mode A or C.
Well, ok, I didn’t realise you were talking about replacing it with a different mode C transponder.
Peter wrote:
Can anyone think of an honourable reason for turning off Mode C?RobertL18C’s comment about not wanting to upset TCAS systems when doing aerobatics below CAS could be one. Other than that I can’t think of any.
Peter wrote:
Arguably the Mode S mandate plays into the hands of the civil liberties people …
Why would a mode S transponder do so more than a mode C one?
I didn’t realise you were talking about replacing it with a different mode C transponder.
I wrote: “The problem, probably, AIUI, is that if you have one of these you are not allowed to replace it except with the exact same model. At least, that is the UK situation.”
RobertL18C’s comment about not wanting to upset TCAS systems when doing aerobatics below CAS could be one
That’s true, though that is perhaps 1% of GA movements. And the said TCAS-equipped traffic will get your relative altitude anyway, together with the warning, so they can assess whether you are a threat. That must be a part of life of flying just above the base of CAS, with many pilots (myself included) flying 100-200ft below the base. Traffic in CAS can be base+500ft though from what I see that is rare.
Why would a mode S transponder do so more than a mode C one?
Because Mode S is picked up by FR24 and other websites. It can also be picked up by any even slightly tech savvy person with a rod antenna and a UHF receiver (which can be a hacked freeview receiver) and then you can pick up traffic hundreds of nm away, depending on their altitude. Same with ADS-B.
I have seen a demo of ADS-B from airliners all over Europe being picked up with a single centrally located antenna and IMHO any good RF guy could do the same for low level GA, for Mode S or ADS-B.
The issue is that if you have a Mode S transponder, there is no way to have it running at all without your tail number being radiated. You can select Mode A only (no Mode C) but the Mode S will still come out.
So, people with a Mode S unit installed who don’t want to be seen turn it off completely, in the process buggering up TCAS warnings in other aircraft.
And, people with a Mode S unit who don’t want to be seen, but still want to be visible on TCAS systems and to radar controllers (who can then give others a better traffic service) can’t do anything because you cannot legally change Mode S → Mode C. Illegally, of course, you could pretend no transponder was installed previously and just swap the unit…
I am not defending this; I don’t give a flying **** about who can see where I am flying, but it seems to bother some people.
Peter wrote:
…there is no way to have it running at all without your tail number being radiated.
OK, I see, the tail number is there. If you don’t want to be recognised, you can easily change that to “N12345” or a fake registration (at least with most of the transponders I fly with) while still transmitting the assigned squawk, altitude and other relevant data. If you enter your fake tail number in your flight plan as REG/N12345 not even ATC will notice…
