Garmin - good GPS?

[Balkanhawk]

Hi all,
I need some opinions. Looking to replace our KLN 90B GPS with a modern unit. It a small twin aircraft that does a lot IFR.

I have been looking at the garmin 400w. It has a small moving map and an approach database. Can anyone tell me if the garmin units are any good and if other manufacturers have similar units?

[madlandrover]

Any of the properly mounted Garmin units are good. Maybe look at upgrading to a GNS430 to give you a comm/nav box as well? GNS530 is about as good as non-glass cockpits get in my experience - GNS430 or 530 backed up by something like a King KX-165 is hard to beat as an all-round package.

[IO540]

KX165A does 8.33, FWIW.

[Balkanhawk]

Hi, its only a standalone GPS we need. The comms/nav boxes are all fine. Are there any other systems out there (Freeflight, Bendix king etc) of comparable capability?

[Genghis the Engineer]

I don't know the specific model, but would comment that sooner or later I've always regretted any GPS unit I've owned, which wasn't built by Garmin. So in general, their units and product support I find excellent.

G

[IRpilot2006]

The KLN90B does do all that is practically needed for IFR this side of the pond.

Which functions do you want which it doesn't have?

[Balkanhawk]

The KLN90B doesn't do non-precision (VOR,NDB) approach overlays, fly the approach with the GPS but the pilot monitors the needles and DME.

The moving map will also be an improvement.

[IO540]

The KLN90B doesn't do non-precision (VOR,NDB) approach overlays, fly the approach with the GPS but the pilot monitors the needles and DME.

Do you realise what this involves?

GPSS, LPV, EGNOS. The last two are "vapourware" in Europe.

You can fly NP approaches using the OBS mode, perfectly well. In Europe, a lot of the GPS overlays are incomplete anyway.

For GPSS, you will want to install an EHSI, or a "glass" implementation of that e.g. G500, EFD-1000, etc.

The moving map will also be an improvement.

That's true :)

[englishal]

We have a combination of 430W and aircraft powered (and hull mounted antenna) Garmin Aera 550 as backup GPS. In the event of a power failure in the aeroplane we still have vacuum instruments and Aera available which will run on it's internal battery for 4 or so hours. We also have a Zaon plugged into the Aera for traffic info which is also wired into the GMA430 audio panel for announcements like alt / terrain / traffic.

[IO540]

I would absolutely have a battery backed up GPS.

Unfortunately (short of a 2nd panel mount GPS, backup battery powered via a nontrivial paperwork exercise ;) ) the only way is a handheld unit mounted "temporarily" ;) in the yoke or similar.

I have a Garmin 496 thus mounted, with its audio output wired to the aircraft intercom. I got the yoke wiring signed off but obviously the 496 has to be "officially removable".

It works brilliantly as a substitute for the £25,000 Honeywell GPWS system and - apart from maybe cases of loss of obstacle clearance while flying an approach (I think the G496 basically disables its 2-minute trajectory extrapolation when flying anywhere near a known approach) - I am sure it is every bit as good, and it provides a "five hundred" warning at 500ft AGL anywhere at all; great for doing the gear-down check. After flying with this for 4 years now, and having seen the warnings during certain visual approaches, I am at least 99% sure of never flying into terrain enroute. A fantastic feature for £1000... especially when you consider how many people get killed in CFITs.

It took a while to work out the audio connections, because Garmin's docs are useless and they rather arrogantly would not offer any additional info. I have the details if anybody wants to do this.

There is a simple upgrade from a KLN90B to a KLN94, I believe, which is not a bad option.

And a Garmin 430's screen is only marginally bigger than the 90/94 screen, by the time a chunk is lost to the radio frequencies etc. If I was spending any serious money, for IFR, I would never have a 430-sized unit as my sole moving map. The main feature of the 430 is that it is common as muck, replaces an old clapped out radio (a common enough requirement ;) ), gives you an FM Immune radio (likewise), and incidentally also gives you 8.33k spacing. Today I would install a 530W, or perhaps a 430W with a big MFD which is capable of displaying stuff like Jepp approach plates, or just a decent map.

The other thing is that if you fly any significant VFR, you need a GPS which can display VRPs. These tend to be mainly portable units, though the now-obsolete KMD150/KMD550 products have European VRPs in them which was brilliant for my pre-IR long trips abroad. I would think the modern MFD products (GMX20 kind of stuff?) will display VRPs but it needs to be checked.

Often, outside the UK, one cannot file an I flight plan to a destination which does not have an IAP and then (filing Y to achieve Eurocontrol acceptance) you are flying 100% "officially VFR" at the end and are thus vulnerable to ATC throwing a few VRPs at you. A lot of foreign international-airfield ATC can barely speak English and a pilot not finding a VRP gets them really excited ;)

Personally I fly with a KLN94 and a KMD550 MFD which is damn hard to beat for a mixture of VFR and IFR. I never bothered to install GPSS (even though it is just 4 extra wires in my case; about a day's labour) because even on a long trip, say 800nm, one has to adjust the course pointer maybe 20 times which is no great hardship :) The only thing I can't do is fly one of the complicated PRNAV STARs/transitions (e.g. see LOWW) if ATC tell you the name of it with not enough time to load the individual waypoints by name from the database... and of course I can never have PRNAV which would be a ~£20,000 refit exercise.

Anybody doing a serious IFR refit today must go for PRNAV compliance and get all the flight manual supplement paperwork. Most UK avionics shops are not capable of delivering this 100%, and some of those who are don't always deliver it, judging from pilots I know personally who got ever so slightly short-changed despite having paid 5 digits.