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SR22: Upgrade to WAAS

Maybe other SR22 pilots are interested in this upgrade.

This spring I decided I want to upgrade the two GNSA430 navigators of my 2006 SR22 to WAAS. The main reason is that I prefer to fly RNAV/GPS approaches.

There were various possibilities:

1. Send the 2 GNS430s to Garmin and have them upgraded to WAAS for $ 3.400 each plus freight
2. Sell the two 430s and buy 2 used 430Ws
3 Install GTN650s or IFD440s

I found two 430Ws with only about 400 hours on them for € 13.000 and a buyer for my 2 GNS430s for € 8.000, so I went that route.

Installation: Contrary to what many will tell you the installation is NOT “plug and play”. While you can leave your 430 trays in the airplane, because the W trays are are the same and all connections aswell – all older SR22s have their GPS antennas attached to the understand of the glareshield (a solution I never liked). While I never had any reception problems Cirrus prescribes to have the antennas on top of the fuselage for WAAS.

Some US installers put the GPS 1 antenna on top of the cabin and put # 2 under the glareshield again. Since I have heard that SR22 pilots with that solution have had problems receiving WAAS signals on NAV 2 especially when when the GPS satellites are very low over the horizon (signal can be blocked by the engine) I decided to have both antennas on the outside.

For WAAS you have to order two new antennas aswell, the type is Garmin GA-35, each $ 325 plus VAT (…). The old antennas do not work with the WAAS navigators.

But where do I put the 2nd antenna? In the front of the fuselage, in front of the Skywatch antenna they would be too close to each other, which is not recommended. But in the back, between the COM antenna and the rear window most older SR22s do not have the necessary EMM shielding integrated in the composite. The solution is described in an SB form Cirrus: sand of the paint, open the fuselage and install the MM shielding … repair the composite, paint … NO THANKS! First I did not want to pay for the 40 hours all this will take, second I hate the idea to ruin a perfect surface for that …. (Newer SR22s have the EMM shielding in the back too, you have to check the maintenance manual for the serial number).

The solution is to change the COM antennna for a “CI-200-2580” combined COM-GPS-WAAS antenna. It looks exactly iike the old COM antenna, even has the same footprint and attachments. Price: $ 1300 …. So now the GPS 1 antenna will be installed in the front and GPS 2 will use the new multifunctional antenna.

The price for the whole thing is around € 9000 now. A lot of money, but I think it was the cheapest way to get WAAS/EGNOS capabiity.

Last Edited by Flyer59 at 18 Oct 08:25

I don’t think you will regret it Alexis. Flying an LPV approach to 200ft is wonderful and the accuracy the GPS provides is far greater than a GPS into ILS approach. WAAS will be increasingly important for IFR over coming years. And the Cirrus is a pretty simple upgrade. Some of the prices I have heard for larger jets with proline and other avionics that need WAAS are astronomical. Take your number and multiply by 30.

Last Edited by JasonC at 18 Oct 08:30
EGTK Oxford

Yes, I know Jason! I regularly flew LNAV approaches, sometimes even when there are was ILS available and even those were very nice. Now I am really looking forward to the LPV and LNAV/VNAV approaches – and the coupled SIDs

Put the plane to EDMS yesterday, ready next Friday ;-)

The old antennas do not work with the WAAS navigators

I am sure they work perfectly but they do not comply with the STC

We had a thread on this recently. The difference in the noise margin is below trivial. The separation is a purely marketing (product differentiation) trick.

I will be looking at LPV when Shoreham gets it but my preferred solution (2×IFR540) is not looking good, due to the large quantity of these which one has to get to get two that completely work. Maybe Avidyne will fix their massive QA issues at some point…

Unfortunately “plug and play” is a bad phrase. There is no such thing in this context. It came in with win95 which scanned the attached hardware, and using huge tables, looked up the “correct” drivers for it. Nothing like that ever exists in avionics.

Shoreham EGKA, United Kingdom

That’s possible, but i don’t know. I thought the old antennas would not work.

You said that a couple of times, but why would you like to install 2 IFD540s? Wouldn’t one be enough plus a IFD440?

I went for the Garmin Upgrade of my existing GNS430. Done within a week, antenna swap was very easy to do as well. I love the faster performance of the WAAS unit, it is much easier to use than before the upgrade. Like changing from an old Celeron to a I7 or so in PC terms.

Alexis, did you get the LPV approval done? I think it is quite interesting to do that as more and more GA airports have them and the number will continue to build up.

By far the biggest cost and time consumption however was the certification process to get the LPV approval and all that, but it was worth it as quite a few training fields around here have LPV approaches such as Donaueschingen and some others.

Flying the LPV approach is something I have yet to experience but the test crew who did the flight test after installation were raving about the performance of the whole system. During the tests they took the airplane down to very low height above the runway (in VMC clearly) and stated that accuracy was perfect. Good to know. Now I need to get my IR sorted so I can finally get out of this murk here and get some flying done.

LSZH, Switzerland

The STC Avionik Straubing has includes the LPV certification (€ 750 for both units)

I recently bought an Avidyne equipped SR22, which was already installed with 430Ws (so I was spared the issues of upgrade path, antennae etc). However, the question for me was ‘what to expect from them’?

Already I really appreciate the GPS vertical guidance (which previously, on a GNS530, I’d had only on the ILS). But I had thought I would get curved paths, which I don’t. For example, no DME arc approaches available for selection. And no curves are displayed in the typical teardrop procedural approach, so heading mode has to be used for the turn.

Not had time yet to investigate properly why this is, but I’m sure the avionics gurus here will know! Three possibilities seem clear:-

1. I misunderstood what to expect from the W version of the 430
2. The set up of the 430W needs changing
3. The capabilities of the 430W are dependent on the autopilot it’s hooked up to. Mine is the STEC55X. (Although the DFC90 is under active consideration! Just got to get the prop and mags overhauled as a priority, since the previous owner hadn’t bothered.)

Cambridge EGSC

Since I will only get the W units next week I am no expert in this, Achim might want to answer!

AFAIK – not all procedures exist for WAAS, but many curved approsches should be in the database. Also holdings, if they are part of the approach procedure are in the database, so if you have to use one of those for course reversal it should be possible to fly those procedures coupled.

PS: I have the DFC90 and I would say without hesitation that it is really the best available upgrade for an Avidyne SR22, even more importnat than WAAS.

Last Edited by Flyer59 at 18 Oct 11:07

I am not sure if Jeppesen+Garmin ever coded any curves in the UK database.

Even my KLN94 has curves in the US data but none at all in the UK data.

This is nothing to do with WAAS/EGNOS – except peripherally in that the “W” boxes conform to a higher TSO spec which might stipulate/enable additional classes of database items to be coded. @NCYankee is the expert on this.

If the curved track is not in the database, no autopilot will fly it (possible exception: unpublished holding patterns). But if it is in the database, any autopilot that supports ARINC429 roll steering (KFC225 being one of the earliest), or any autopilot which is fed via a roll steering converter (which converts ARINC429 into a faked heading bug – a lot of old installations have this) can fly it. The (any) autopilot is not aware of the curved track; it just flies a series of progressively changing headings.

One way to verify this would be to install a GNS430W simulator on a PC, fly over to some UK airport, and see what you see….

Shoreham EGKA, United Kingdom
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