TXP or not TXP?
 

I'm currently building a PFA permit aircraft (Pioneer 300) and am contemplating the avionics fit.

The question is, should I fit a transponder, and if so, which :confused: :confused:

Choices:
i) Dont bother fitting a transponder in the hope they'll never become mandatory (I am aware of the representations against compulsory Mode S)

ii) Fit a mode C at a cost of abt £1000, in the hope that Mode S will not become mandatory

iii) Bite the bullet, fit a mode S at a cost of abt £2000 - £3000 in the hope that mode S wont be superceded by future technology (IDSB?)

I would certainly prefer the safety of a squawk, but dont want to shell out thousands of £s on redundant technology or un-needed sophistication.

Any prooners in the know able to proffer some advice?

I can't answer the Mode S thing.....

But I would be inclined to fit some sort of txpdr, if for nothing else to help get zone transits and the like. I recently looked at a Permit aircraft, and although it is possible to get a class D zone transit without one at the moment, you could get refused one, and if the a/c is fairly slow, this could make a big difference. The pilot in my case got a D transit ok, but the radar controller couldn't see him all the way through, even with the gain turned way up (so he could "see seagulls") :D

The other time might be if you wanted to enter the Channel Islands Class A, which I would from where I live. I don't know their policy on allowing non-txpdr equipped a/c in, but if you've got one, it's going to be more difficult to refuse you entry......

Plus there is a definite safety aspect, its nice to know that controllers (and military controllers) know you're about, even if they aren't talking to you.

Just my view.

As a follow on to Al's post - When are you going to be in a position to fit this transponder?

Come April next year there's going to be a lot of used transponders on the market as people fit mode 'S'. If you want a stop gap measure that's cheap but will see you through the mode 'S' "will it / won't it happen" period do that. The market will be flooded to the extent that they'll cost peanuts (relatively speaking).

Txp should be required (or otherwise) by Xmas. Why do you say April Chilli, I thought proposed mandatory Mode S was still a few years off?

Not sure about fitting a 2nd-hand Txp without the instruction manual (and who keeps them!)- is there much to it? Does the altitude encoder need calibrating?

Certainly agree with EA that a Txp of some type is preferable, just dont want to make the wrong choice.

Err, is this something I need to get sorted out? I am TXPDR-less at the moment and am happy to remain that way. Do I really need to have one by Xmas?????

Mode S XP will be mandatory for IFR early next year.

Mode S XP is proposed to be mandatory for everything that flies in 2008, but nobody yet knows if there will be exemptions for some categories of planes e.g. those without an electrical system, non-CofA planes, or whatever...

Personally I would buy a used Mode C XP. It will trigger the TCAS of any nearby airliner (not that you, with your top-end GPS, will ever stray into controlled airspace :O ) and any radar unit will see your altitude readout which (even though "unverified" if you aren't talking to them) is of GREAT benefit to everybody else who is getting a radar information service.

Then, if you need Mode S in 4 years' time you can pull out the Mode C and put in a Mode S, little or no installation cost involved. And they will be cheaper by then.

Not wishing to ruin the panel of my 1947 pride and joy with any modern avionics, is there a tiny Mode C unit I can instal inside the little glove box that will run off the 12V battery that sits behind the seats?

It must be small and use a small amount of electricity.

(Sorry if I have hijacked this thread. Perhaps any answers could be PM'd instead?...)

Xmas is my anticipated build completion Mono, not introduction of compulsory txp's.

There is a small Mode C txp produced by Microair (same size/weight as their radio - costs £300 more!). Not sure how long it'll run from a battery tho, txp's have a pretty hefty tx power and must use a fair bit of juice. Have you thought about installing one of those mini turbo-alternators now available?

Thanks for the info abt txp's for IFR IO, should ensure there will be a suitable supply of mode C's coming up. Still looking for info ffrom anyone about how easy (or otherwise) they are to install. Another potential problem is that many IFR-type machines operate on 24V, I've only got a 12V system.

Dunno where you got the idea I've got a top-end gps BTW, mines a lowly Pilot III, and is of course never used as the sole source of my navigation. ;)

I am building an MCR01 and had the same problem. I am fitting a full size second hand transponder. It is all ready to go, but not turned it on yet! It is defiantly the most cost effective way, as the cost of new Mode S will drop by more than the cost of the second hand unit over the time.

One word of advice, if you fit the right transponder, it will use the same size hole and could even use the same tray as its Mode S stable mate. I go this slightly wrong as my tray is not compatible, the man from B-King was economical with the truth!

Rod1

There's loads of second hand txpdrs for sale in the US, from $400 and up for a mode C. I saw a KT76A pre-owned with fresh FAA Form 8130-3 and 90 day warranty for $490 with new antenna ($400 without the antenna). Runs on 14v, it was $70 for a 28v kit.

Got to be worth getting one over there for £225!

EA;)

Well if you will go to fast food restaurants for your Avionics Advice!:}

You'll find that's mainly twins. The vast majority of singles who will be changing to mode 'S' (and there will be quite a few) are 12-14V systems - mandatory mode 'S' for them is April 2005.

Socata TB aircraft are 24V.

Re Microair, I would check approvals - these used to be for "experimentals" only.

Re Honeywell/Bendix-King, most IFR pilots I know are not fitting their Mode S transponders - the Garmin one is much better because it has push buttons. For Mode S, Honeywell have reverted to the four rotary knobs which I would never go back to, after using a (Honeywell) push-button transponder.