Legacy (non-WAAS) GPS vs 2nd NAV (or DME)

[MarkH]

Starting from the presumption of a single nav/com with a portable GPS.

Would it be more worthwhile to install a second Nav or a Legacy GPS? Even a Garmin 175 is $5K + installation. If one is looking to expand an airplane's IFR capability but spend closer to $3K (including installation), what would be POA's suggestions to consider.

Also, any thoughts on what legacy GPSs are most maintainable without manufacturer support? The advantages I see of a second Nav are: repairability without the manufacturer support and no risk of being unable to databases because they are not available.

 

[WDD]

Seems like you want to expand the airplane's IFR capability, and you currently don't have an installed GPS.

Given the decline of the number of VOR's and even ILS approaches, and the increases in RVAV approaches, I would hold off until I could install at least the Garmin 175. Spending money to install a non WAAS GPS or 2nd NAV would do very little vs installing a WAAS GPS.

 

[Darryl Snover]

Having been down this route already - I have a KLN-94 GPS, which was already installed, but not 'certified for IFR', so I was starting from a point of needing the required annunciators and CDI. Doing the work myself (supervised by an A&P IA), I still spent about 1 AMU, and I already had the 'expensive' parts. If I didn't already have the KLN-94, there's no way I would have taken the time and effort to get it IFR approved. However, I had the unit, my labor was 'free', with a willing A&P IA, and a willing FAA ASI.

Since you don't have a panel-mounted GPS, you're looking at a full install anyway, which is going to be the same whether you are installing an 'old' GPS or a 'new' one. Plus, non WAAS GPS's will require more paperwork (field approval with all that that entails - which yes, I had to go through). New GPS units don't require field approval, as they have STC's that cover most airframes.

Unless someone practically GIVES you the GPS, and you install yourself (again, with a willing A&P IA and FAA ASI), you're much better off buying a new GPS. Otherwise, you're looking at 3-4k for a used GNS, or maybe a bit cheaper for a KLN-89b/94 (or similar), plus all the install costs. Your savings will be a mere 1 or 2 AMU, at best, plus you will need to find a shop willing to install it.

 

[WDD]

For some reason, I've been puzzling over this a little today. Yes, I know - I need to get a life LOL.

I think the GPS avionics development is similar to what PC's were doing in the 90's. You could buy a legacy 286 PC when 386's were the norm, but because things improved so much it wouldn't be worth it. (Showing my age, I guess). The same with legacy GPS's, which would be non WAAS. Also, you're smart to think about support, as even Garmin hasn't supported non WASS GNS in a long while. I read another post where the person couldn't even get a screen replaced - no parts.

Keep coming back to the suggestion that you could spend a few thousand dollars on installing an old non WAAS GPS unit and you'd not have anything for your trouble. You really wouldn't be saving money at the end of the day.

 

[TCABM]

… what would be POA's suggestions to consider...

Defer the upgrade until you can afford to install a supported, IFR-approved GPS, preferable WAAS.

If you’re thinking of a cheap upgrade to sell the plane for a higher price, you probably won’t recoup the costs anyways, so discount accordingly and go on your merry way.

 

[MarkH]

Defer the upgrade until you can afford to install a supported, IFR-approved GPS, preferable WAAS.

If you’re thinking of a cheap upgrade to sell the plane for a higher price, you probably won’t recoup the costs anyways, so discount accordingly and go on your merry way.

I'm thinking of a cheap upgrade to do to give me a little more usability immediately after buying the plane. But the more I read the more I see that holding out for a WAAS GPS is the way to go.

 

[TCABM]

I'm thinking of a cheap upgrade to do to give me a little more usability immediately after buying the plane. But the more I read the more I see that holding out for a WAAS GPS is the way to go.

There is no ‘cheap’ way to get GPS into a plane that doesn’t already have it. Unless by cheap you mean in the $15k+ installed range.

 

[Jim Carpenter]

You could perhaps find a used DME unit (KN64 or such), but with install and antenna, still maybe $1500. That would at least increase the capability of your single NAV ship.
You mentioned single NAV/Comm, I'd personally really want a 2nd Comm for IFR flying.....I know it never ends.....
That said, I'd vote with the "save up for WAAS GPS" consensus.

 

[MarkH]

You could perhaps find a used DME unit (KN64 or such), but with install and antenna, still maybe $1500. That would at least increase the capability of your single NAV ship.
You mentioned single NAV/Comm, I'd personally really want a 2nd Comm for IFR flying.....I know it never ends.....
That said, I'd vote with the "save up for WAAS GPS" consensus.

The second comm is planned regardless of the IFR upgrades. My Yankee had a single comm and I wished for a second comm every time I requested flight following.

Edit: Its also part of the reason I am asking this question, the WAAS GPS is out of budget, but if avionics work is being done, the "While you are in there..." questions arise.

 

[Ed Haywood]

There is no ‘cheap’ way to get GPS into a plane that doesn’t already have it. Unless by cheap you mean in the $15k+ installed range.

There is also no better example of FAA processes driving up the cost of flying, while impeding safety.

A Garmin Aera 760 WAAS GPS costs $1400. Take the same functionality, put it in a radio box and TSO/STC it, and you get the GNS 175 for $5K. And $10K install cost is absurd. A bare minimum install could be as simple as putting in a rack bay and connecting power, ground, CDI, and antenna cable. 5 wires. Sure you can run up a lot more labor with interfaces such as MFD, autopilot, audio, etc. But let's be honest: the real cost driver here is Garmin's ability to limit install to licensed shops, which is a function of their virtual monopoly, which is partially a function of barriers to market entry erected by the FAA.

This is all justified in the name of safety. But how safe is it to have thousands of aircraft owners trying to milk life out of decrepit avionics or flying on 2 Navs because they can't afford to upgrade?

/rant