As I mentioned on this thread: http://cessna170.org/phpBB2/viewtopic.php?p=41003#41003 I've recently upgraded my 170 with a Garmin 430W, which replaced an old Trimble GPS, a King ADF, and an Apollo COM transceiver. A 430 was actually the least expensive upgrade that would give me IFR GPS capability with dual NAV/COMs, according to the avionics shops I talked to. The work was done by Modern Avionics at Minneapolis Flying Cloud airport (FCM), and it's first-rate. I've had some time to fly with the new stuff, so here's a pilot report.
The panel looks like this now:
For several reasons, I also indulged in a Garmin GPSmap 496, which I mount on the yoke using the mount that came with it. It works without a remote GPS antenna, and the XM Weather antenna sits on top of the glare shield. I bought a separate power/data cable for it, so I could wire it into the avionics power bus and the data output of the 430. Slicker than anything, when you tell the 430 to go somewhere, the flight plan and waypoints are automatically copied up to the 496, so you see them on its moving map as well. Avionics porn!
Several people have told me that the 430's display is too small, and what's really needed is a 530. I think the 496 solves this problem for a lot less money than buying a 530, and it does an awful lot more as well. Maybe because the 496 isn't constrained by TSO compliance issues, Garmin could load it up with nice features they couldn't possibly support on the 430. These two units complement each other beautifully.
I didn't dwell long on the decision to buy a 496 vs a 396 for $600 less, mostly because it didn't seem to be the time to cut corners. The 496 has WAAS, a five times faster CPU, and AOPA's airport taxi diagrams that overlay the moving map automatically to help you once you're on the surface of the larger airports. The 430W also has a 5x faster CPU, and these two units are the first I've ever seen that respond instantly to any command you give them. There is absolutely no lag on anything except for the weather screens if the XM receiver hasn't gotten the download yet.
I haven't flown on instruments in more than two years, but I did about 70 minutes dual under the hood yesterday evening without fatigue, in continuous light turbulence. I think the 170 is going to be a really nice instrument aircraft, given that it has no autopilot. My AI and DG are absolutely solid and stable with the 4" of vacuum the gauge says they're getting from the venturis. I'm wondering if the gauge is reading low.
Garmin is only shipping WAAS units now. If you order a new 430 or 530, you'll get the "W" version unless the shop has some old stock to sell you for the old price. If you're buying a used unit, I think it's worth the $1500 to get it upgraded to WAAS. Unless you've got a central radio stack, you'll also have to buy a little annunciator module that you can see below the AI and altimeter in my panel. This is a Good Thing, and I would actually recommend installing one even if it isn't required. I seldom consciously look at it, but when one of its indicators flashes yellow ("WPT" or "MSG" or "INTEG") I pick it up immediately. (I haven't actually seen "INTEG" any time after my preflight checks.)
If you've flown with a 430 before, you'll notice two differences right away with the WAAS unit: 1) It will say "SUSP" while you're vectoring to the final approach course. Normal sequencing is enabled automatically when you're set up to intercept final. 2) Unless the satellite solution is poor, your glide slope will come alive on any GPS approach, and you'll see "LNAV+V" or "LPV" on the GPS panel. You can use the vertical guidance instead of "chop and drop," and if the approach has lower LPV or LNAV+VNAV minimums, you can descend lower as well.
Less noticeable: the WAAS units will experience RAIM alerts less often, because the receivers use the WAAS satellite itself as if it were one more satellite in the GPS constellation. You'll get a CD-ROM with the 430 or 530 that contains a Windows PC based simulator for the unit. One feature of the simulator is RAIM prediction. You enter a flight plan into the simulated unit, tell the RAIM software your ETD and estimated groundspeed, and it tells you whether the stars will be aligned right for your flight, or if you should wait a while. You have to be online to use this feature, because it uses the internet to get current satellite ephemeris and outage information. I'd bet that negative results from this software would be quite rare, unless there's a rash of satellite outages at some point.
My aircraft lost 8 pounds with the avionics swap, but when I read the flight manual supplement I learned that for IFR use, there are three manuals that have to be in the aircraft, readily available to flight crew. Didn't weigh them, but they must take back at least 2 or 3 of the 8 pounds I lost. And if they think I'm going to go digging into one of their manuals at some critical point in an IFR flight, they must be crazy!!
I rehearse each planned flight the evening before on the PC, and do as many what-ifs as I can, to make sure I'm completely familiar with the 430's operation before I start the flight. Believe me, this thing will pull your eyes and brain away from your VFR and instrument scans quicker than anything, until operating it becomes second nature. Two hours prep on the PC for each hour of anticipated X/C flight is not unreasonable until you've really learned the unit. [/soapbox]
The flight manual supplement also contains a limitation. I can't quote it because it's in the airplane right now, but basically, the WAAS units haven't completed their TSO C146a certification yet, and because of that, any alternate you're required to file has to have a non-GPS approach that you're equipped to fly. If you're concerned about this, let me know, and I'll get you the exact quote. One web site I found said this would be fixed in the next software upgrade to the unit.
I'm enough of a nerd to think instrument flying is some of the most fun you can have with your clothes on, but I've always been frustrated by crappy equipment. I'm finally flying with the best stuff I've ever had, in some ways even better than the SR20 I spent some hours in a few years ago. If you've got $15-20K to spare and want an upgrade like this, I don't see how you could do better.
Best Regards,
John
on yur minimum equipment list now ?? Yeah, I'm envious too.
??