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Upgrading Avionics
Hello Everyone:
I have recently renewed my private pilot certification after a lengthy hiatus. Now to preface this conversation, when last I flew, GPS for aviation was non-existent.  So, it has been a while. My previous experience was with UNICOM and VOR.  Fast forward to 2021 and I find myself buying into a Cessna 172N.  The plane currently contains the original Cessna transceivers.  I would like to be able to use the plane to travel the country side to find the best $100 hamburgers.  One radio is currently not working and needs to be serviced.  With this we are looking to upgrade the radio to something a little more current.  As I understand it, one possibility is replacing it with something like a Garmin GNC.  During my recent recertification, the plane I flew had a similar Garmin unit dash mounted.  I felt it to be rather easy to use and convenient.  I would like to have some sort of GPS component, but I don't know what the other possibilities are.  Would it be best to just replace the radio with a similar model, such as a King Transceiver and use an I-Pad with ForeFlight rather than use Garmin in dash device?  The idea is to keep the cost down but not cheap out.  My concern about purchasing a dash mounted Garmin is forced obsolescence and having to buy a new one every so many years.  Using the I-Pad means that it would have to be powered and mounted or held somehow.  Again not understanding or knowing all of the possibilities, what would you do?

Thank you
2 Replies

It is becoming rather difficult to fly IFR without an IFR GPS system. It can be done, but is getting recently more and more limited as the VOR network is dismantled.
Therefore you probably should install a Nav/Com.
With that said, get some quotes. There are three major choices:
GNS 430W/530W
GTN 650/750
IFD 430/530.

The GNS Series is over thirty years old since design started, and has been supported over twenty years. Garmin announced almost a decade ago they have purchased the last critical parts and will store and use them for repairs. The point being, when Garmin runs out of these parts, there will be no more support for the devices. How long you have until that happens is a guess. I recall when Garmin made the announcement, they estimated they had supplies for roughly 15 years. It is anyone's guess how good that estimate was.

I would therefore suggest, go play with all of them, see what you and your partners like. Then get quotes.

Lastly, installation is a very significant portion of the cost. And you need to determine if you are going to go the cheapest possible, or the shop which is more complete and removes all the old wires and gives a clean install.

1188 Posts
A lot depends on what sort of flying you and your co-owners are doing.

If it includes any IFR training or flying, the FAA has made it well-nigh impossible to operate easily in the IFR system without an IFR GPS, most preferably with WAAS.  Installing something like a used Garmin 430W nav/comm/GPS would be about the minimum to do that comfortably.  As for obsolescence, it's been 20 years since the GNC400/500 series was introduced, and they're still the most common unit in light singles.  If you wanted to look farther, a GTN650 would have all the functionality of the 430W plus a lot more features, but the installed price would be well over $10K.  That said, the installed cost of the 650 might not be that much more than a 430W, and you'd be getting current production and longer expected operating life.

In addition, those Cessna/ARC radios are ancient, mechanical, 1960's technology.  They're unreliable and hard to fix, not to mention lacking any features modern radios have.  One reasonably priced option is to replace one or both of them with the TKM MX-300 unit, which is a slide-in replacement (no installation work, about two minutes to remove the old and insert the new plus three minutes for the airframe logbook entry which you can sign yourself under Preventive Maintenance) for the ARC 300-series nav/comms.

MX300 NAV/COMM - TKM Avionics

The Garmin GNC radios are really nice, but the price plus cost to install is significant, and it's only a nav/comm -- no GPS like the 430W which includes nav/comm plus IFR GPS.

That said, if neither you nor your partners have any IFR plans, the lowest cost option would probably be to replace those old ARC radios with MX-300's, and go with iPad/Foreflight tied to a portable Sentry or Stratus device to provide GPS VFR navigation, flight planning, moving map, aeronautical charts, and ADS-B-in traffic and weather.