Transponder: Mode S

[John R81]

As we have new rules in UK from 1 January 2010 regarding minimum transponder capability in certain airspace, I am considering swapping from Mode C to S transponder.

Currently I have a Bendix King KT76C mounted along with other Bendix King coms in a single panel (EC120). Is there a Mode S transponder which will simply slide into the existing KT76C tray to reduce time / labour?

Any suggestions / help gratefully received.

John

[Bertie Thruster]

Trig TT31






Google

[John R81]

Thanks for the link. The squawk code seems a little fiddley to operate - select each code element separately and press enter to move on. Anyone have experience with this Trig unit?

[RVDT]

KT 70 or 71 has the same form as the 76C for Mode S replacement.

[John R81]

KT70 looks to have easier operation than the TRIG unit - 4 knobs, each one changes one element of the squawk code. For a single pilot helicopter that is much easier, though the "push button" approach on my KT76C is even easier.

The downside of the KT7 is the $5.9k price tag, compared with the £1.4k price of the TT31. Difficult to see the justification for the price difference!

[HeliComparator]

Bear in mind that the requirment for Mode S for helicopters in Europe is for "Elementary Surveillance" which is Mode S + Flight ID. Pretty sure the Trig does Flight ID. If you buy an American product, make sure you get a version that does Flight ID - some don't.

HC

[homonculus]

We had one put in at the end of 2009 and I too was worried about the ease of inputting, but went along due to price. I am glad I did. Although it may look a little more basic than some others, I think a single button input is far easier with a high cockpit workload than four separate dials, and easily learned. Perhaps not as good as a digital input, but unless yo have money to burn......

The other features are simple and logical, the display excellent. Recommended

[John R81]

Definately not "money to burn". Looking into the CAA exemption to 2012 http://www.caa.co.uk/docs/33/ORS4_670.pdf . It may be that the range available (and the price!) may improve.

Thanks for inputs

John

[7AC]

homonculus, what type did you fit?

[wigglyamp]

Mode S

The Honeywell plug-in replacement for your current transponder is the KT73, not the 70/71. Only the KT73 meets European Mode S requirements with flight ID.
It'd still be cheaper to put in a Garmin GTX330 even though there is more labour invoplvd to change tray and connector. Thr Garmin has push-button entry and some other useful features - flight timetr and audible altitude alerter.

[RVDT]

Flight ID - what a bucket of worms that is.

[kevin_mayes]

Flight ID, Hmm, its so the CAA can directly invoice you for your filght....

[John R81]

Thanks. The KT73 at $4069 (ex VAT) is cheaper than the KT70 with better functionality than the TT31. However the price difference is still shocking!

The Garmin GTX 330 at £2595 is a little better, but it appears I am paying for functionality that is not going to work in europe - the TIS?

The Garmin GTX328 is even better priced, at £1,799. Garmin claim that it meets european regulation (see Garmin Announces GTX(TM) 328 Mode S Transponder ). However, no enhanced Mode S which is what UK CAA requires, I understand!

Will the Garmin 330 unit easily interface with the Bendix King coms system, I wonder? Can I get any additional display on my GPS?

[HeliComparator]

John

The CAA / Europe don't require enhanced mode S for helicopters, only elementary surveillance which as I said is mode S + flight ID.

Enhanced mode S requires loads of aircraft parameters to be input to the transponder such as bank angle, speed, altitude presets etc so you have to have a substantial mod to able to fit it - hence even the CAA realise its not practical for a small (or even large) helicopter.

Kevin, Flight ID makes no difference to the CAA's capability to invoice you, they already have your 24 bit unique address from the basic mode S which is registered with them (look in G-info).

HC

[John R81]

Clearly I do not understand what I am talking about.

so, does the GTX 328 meet UK requirements, then? If so then it seems to be the one to go for. Close to the price of the TT31 but with 0-9 squawk input buttons for ease of use (same as my current transponder!).

[Ready2Fly]

Garmin states on their website:

Similar to GTX 330, GTX 328 includes features such as displaying outside air temperature, altitude monitoring, count up and count down timers (using a built-in digitized voice annunciator to alert the pilot when preset altitude limits have been exceeded or timer expiration), density altitude functions and front-panel input for flight ID.

Since the GTX-330 Mode S Transponder provides TIS (Traffic Information Services), EHS (Enhanced Mode S) functionality and transmits power that exceeds the requirement for VFR aircraft in Europe, the European GTX 328 does not offer TIS, EHS or ADS-B functionality.

GTX 328: Meets European flight regulations without breaking the bank.

This is what has been mentioned here before. The only question therefore is: Does UK CAA have another 'special rule' here.

So, to be 100% sure, i would seek written confirmation from the UK CAA. Besides sending an email to mode.s (at) caa.co.uk you might want to check:

Mode S Home Page | Mode S | Airspace Policy
and
EUROCONTROL - United Kingdom

Edit:
I am pretty sure you will find an B206 owner here, who did recently upgrade his avionics and used a GTX-328 in it (i'll send you the reg. by PN)

[s1lverback]

Mode S

I wrote an article on TRIG and Filser offerings some years back in Pilot back in 2004 (when Mode S became a topic) as alternatives to Garmin and Bendix.

At the time they were good budget options in lieu of any other LAST (Light Aircraft SSR Transponder) unit, but in the mean time Garmin (more so) and Bendix have reduced their prices, so that you are only saving ££s (if that) rather than £££s.

Coupled with some of the other nice features you get when you add 430/530 etc; we ended up installing the Garmin GTX330 in 3 of the fixed wing fleet we use (because we use them for IFR and VFR; they already had 430s) and the price difference wasn't that great by the time you installed it - so even less of an issue if you fly choppers

Our avionics chap told us what and where to buy. We bought our units from Bournemouth for about £1800-2000 (2008 and 2009) and it cost another £5-700 for installation/paperwork.

Look, feel + usability of the Garmin is excellent. Touch button is excellent for one handed operation as its fast and means you don't have to watch the dial - just punch the 4 digit squawk and the 4th digit entered activates the squawk. VFR button returns you to 7000.

The Garmin 330 is also ADS-B ready (no upgrade path for 328 to ADS-B)...and that is the next thing that will come along (already in the pipeline - approx. 5 years away). The 328 was designed for the European market and is supposed to be a straightforward swap-out, but in practice (correct me if wrong) I seem to remember the rack and harness still need to be installed.

Bendix KT73 is other real option as it can use the same rack as the KT76C (which FEDA has), but is more expensive (as you know), has 'twisty knob action', is no cheaper to install and if you want it ADS-B ready needs the KT76 rack replaced with a KT73 one (which has a 2nd auxilliary connector for these features).

After that you'll want a new 'touch' comm panel like 340 or even PMA units so that passengers can enjoy music from the ipod...

John R81, I sent you a PM.

[homonculus]

We put a TT31 in a R44. I would have gone for the Garmin, but not only was there a significant price difference on the unit, there was also a significant extra price for the cradle and loom, whilst the TT31 was a direct replacement for the 10 year old transponder we previously had. It really was a no brainer - you still get a timer!

[s1lverback]

TT31 (with ADS-B, but twisty knobs) is £1850 from Harry M as full install kit and £1815 from Harry using old KT76A tray (as direct replacement)
Garmin GTX328 (no ADS-B) £1799 from Transair
Garmin GTX330 £2595 from ASG (this is old pricing - same as it was when we were looking)
US price = $3595 (Aircraft Spruce / Chief / others) @ £2250
Price via our avionics guy is £1700 for GTX328 and £2300 for GTX330 (currently)+ install and Mod (EASA) paperwork.

If VFR only (and not really bothered about ADS-B yet), then GTX328 is the one.

For the European position see:
EUROCONTROL - General Aviation - VFR Briefing Room

Anyhow, bored myself now