Single GI-275 and G5 stack

[GRG55]

You're dealing with some of the same decisions/thought processes I encountered on my current upgrade path. The GI275 and G5 are in different worlds; they don't talk to each other in any way. What they can do on their own, and what they're certified to do, is different as well.

With two GI275s (which back each other up) it is possible to do away with your legacy instruments, i.e. airspeed, altitude, and heading indicator. Whether this is advisable from a UI standpoint is another matter. In my view they're far too miniscule to rely upon for that purpose; the airspeed and altitude indications are not substantially larger than a 14-point typeface on a piece of paper held out at arm's length. Legible, but hardly ideal flying single pilot IFR bouncing around in light to moderate turbulence. Frankly I'm a little surprised this was considered suitable from a certification perspective, but they got it, so that's that. If I were to install a pair of GI275s I'd leave my legacy steam gauges even though it would not be legally required.

As a result, that sent me back to the G5s while leaving the altitude and airspeed indicators in their normal locations. Much easier to scan/interpret in the same scenario as mentioned previously.

Just to further reinforce the "size" issue, I still have my legacy VSI although the G5 features a very accurate version. It's the same problem -- just too small. I can pick up the tiny G5 VSI in my scan if I concentrate but it's not natural and it fades into the clutter of the background all too easily. My little piston bird is old and I still use FPM for all kinds of things. It'd be great to ditch the VSI as I could really use the panel space for other things but it just doesn't work for me. If I won't ditch optional equipment such as a VSI I'm sure not going to ditch the primaries.

Autopilot is the big consideration for a lot of us. Unfortunately the G5s won't communicate with my old Altimatic III, but the GI275 would. I'm leaving open the possibility of installing a GI275 in the place of my mechanical standby attitude indicator at some point in the future, if it's possible... it's not yet clear if this mix-and-match will be permissible. My avionics tech believes it is possible but not yet legal. I haven't dived into the depth of the legalities surrounding this. For now the shop, mine anyway, won't mix and match the two units in any way.

I agree with Bill re: the G3X. That unit was out of reach in terms of making a responsible financial choice about the panel of my 54 year old airplane. Would be nice, though.

I'm in almost an identical situation. Want to replace both gyros, but need a way to drive the Alimatic IIIC as I can't possibly justify (or even fake a good rationalization) replacing the autopilot. I also see no reason to remove the redundant airspeed, altimeter, vertical speed indicators.

I'm not quite understanding your choice of the G5s over the GI275s? Both displays appear too small for the ancillary information on the sidetapes to be easily readable. Because of the autopilots we both have it seems the GI275 is the logical option. What am I missing here with your selection of the G5s?

 

[Jdm]

I regularly fly both. The G5’s FMA’s are obviously laid out well. Reversionary fields are great. I do like them, especially when coupled with the GFC500 AP. Never flown a coupled 275 though. Guessing it would do well also. I’d probably go with the 275z regardless. Display is just so dang nice!
Been playing around with these slaved to the 650xi vs 750. We have great choices these days!

 

[asicer]

I would expect that combo to run high 20s/low 30s installed.

Only a 30% upcharge? Forget the GI275's, then.

You trust the autopilot so much you had the yoke removed?

 

[Ryan F.]

I'm in almost an identical situation. Want to replace both gyros, but need a way to drive the Alimatic IIIC as I can't possibly justify (or even fake a good rationalization) replacing the autopilot. I also see no reason to remove the redundant airspeed, altimeter, vertical speed indicators.

I'm not quite understanding your choice of the G5s over the GI275s? Both displays appear too small for the ancillary information on the sidetapes to be easily readable. Because of the autopilots we both have it seems the GI275 is the logical option. What am I missing here with your selection of the G5s?

Price, for starters. A couple of GI275s push the price a lot closer to the tipping point for a full-size PFD like the G3X Touch, which I can't justify... but also the GI275's display size for the purpose of their primary function (ADI, HSI). They're just too small and cluttered. It might seem like a small thing, but the G5's use of the "corner space" is a selling point for me. It's a UI which looks and functions a bit more like a professional avionics suite.

I will consider a GI275 down the road a bit to drive the Altimatic in place of the mechanical vacuum powered ADI I have which now serves as my backup in the former turn coordinator hole.

 

[Ryan F.]

So many configurations. Here’s a few pics of what I have..

Good pictures... thanks! I think the MFD/CDI combo is a good use of the GI275's screen real estate. It's especially nice for panels which are crimped for space since it can "be" a CDI when you need it, which let's face it... isn't all that often... and a "MFD" at others. I would probably leave it up as a traffic display most of the time and possibly terrain mode on instrument approaches in which obstacles or terrain are an issue (common for me where I am in the northeast.)

Maybe down the road when I move out of my KX-155 and replace it with the GNC-255 I'll pair it up with one of those and mimic that configuration. I'll have to recover from this upcoming round of avionics upgrades first though.

 

[GRG55]

Price, for starters. A couple of GI275s push the price a lot closer to the tipping point for a full-size PFD like the G3X Touch, which I can't justify... but also the GI275's display size for the purpose of their primary function (ADI, HSI). They're just too small and cluttered. It might seem like a small thing, but the G5's use of the "corner space" is a selling point for me. It's a UI which looks and functions a bit more like a professional avionics suite.

I will consider a GI275 down the road a bit to drive the Altimatic in place of the mechanical vacuum powered ADI I have which now serves as my backup in the former turn coordinator hole.

Thank you for the clear response. That is very helpful!

We've been installing G5s in our Club's training 172s for a few years now (I think we have about half of our fleet of 13 Skyhawks completed). The majority don't have (or need) autopilots of course.

And I would probably be leaning that way for my own airplane, except for the lack of ability of the G5s to provide attitude information to the Century/Altimatic autopilot.

A G500 or G3X is out of the question. I was considering doing what you did and move the AI to the TC slot to run the autopilot. In my case maintaining the vacuum system isn't an issue as I have redundant pumps and I need it for the boots.

I haven't seen a GI 275 yet, but should do a side-by-side comparison with the G5 ADI at a Garmin dealer to see for myself how the use of the "real estate" compares.

 

[Ryan F.]

And I would probably be leaning that way for my own airplane, except for the lack of ability of the G5s to provide attitude information to the Century/Altimatic autopilot.

A G500 or G3X is out of the question. I was considering doing what you did and move the AI to the TC slot to run the autopilot. In my case maintaining the vacuum system isn't an issue as I have redundant pumps and I need it for the boots.

Given that scenario I wouldn't hesitate to run dual G5s and keep your mechanical ADI to run the autopilot. In my case the vacuum system only powers the two mechanical ADIs I have remaining in the panel and I'd just as soon get rid of those, except for the cost. There's maybe a small "backup" justification in that my autopilot runs off a completely separate attitude source powered by vacuum instead of electricity but it's probably too weak a "card in the deck" to really play meaningfully.

I haven't seen a GI 275 yet, but should do a side-by-side comparison with the G5 ADI at a Garmin dealer to see for myself how the use of the "real estate" compares.

The reviews are pretty much spot on -- the clarity/resolution and brightness is definitely a notch above the G5s, and you get edge-to-edge display which is nice. You'll need to decide if there's enough there to run them in the center of your six pack as an ADI and HSI. You can declutter them, but even so there's a lot going on in a very small space.

 

[Mtns2Skies]

The reviews are pretty much spot on -- the clarity/resolution and brightness is definitely a notch above the G5s, and you get edge-to-edge display which is nice. You'll need to decide if there's enough there to run them in the center of your six pack as an ADI and HSI. You can declutter them, but even so there's a lot going on in a very small space.

I went with the decluttered option, and I'm happy that I did. But I'm also a luddite. See picture on previous page for what that looks like.

 

[David Megginson]

Thank you for the clear response. That is very helpful!

We've been installing G5s in our Club's training 172s for a few years now (I think we have about half of our fleet of 13 Skyhawks completed). The majority don't have (or need) autopilots of course.

And I would probably be leaning that way for my own airplane, except for the lack of ability of the G5s to provide attitude information to the Century/Altimatic autopilot.

A G500 or G3X is out of the question. I was considering doing what you did and move the AI to the TC slot to run the autopilot. In my case maintaining the vacuum system isn't an issue as I have redundant pumps and I need it for the boots.

I haven't seen a GI 275 yet, but should do a side-by-side comparison with the G5 ADI at a Garmin dealer to see for myself how the use of the "real estate" compares.

Personally, I wouldn't dump my mechanical ASI and ALT regardless, but it would be a no-brainer to choose the GI-275 over the G5 if I were replacing my DG. In terms of display, the GI-275 display has almost three times as many pixels as the G5 (207,840 vs 76,800), even though it occupies a smaller space. The GI-275 does more, and does not require the extra GAD 29B ($700) for autopilot support, which covers most of the price difference in HSI mode. The built-in connectivity also makes an FS 510 ($1,500) unnecessary for a GTN navigator.

 

[WDD]

When I look at the used planes in the market, the only conclusion I can come to is just accept the fact that you have to factor in another $50k to rip everything out and put in a GTX 345, GTN 650, G3X 10', and a new second nav/com to boot. Toss in a GI 275 for back up and rip out the vacuum system as well. Pre wire and have a cut out for a later Garmin autopilot and a second G3X screen (7 inch) if you want.

In my fantasy world where I can own a plane, I don't want to worry about a 40 year old radio loosing the display, or an auto pilot stop working, or whatever.

Who would have thought that 1/2 the value of a plane is avionics, which will all be considered in 10 years as old and out of date as what how today we see a non WASS 430.

 

[David Megginson]

When I look at the used planes in the market, the only conclusion I can come to is just accept the fact that you have to factor in another $50k to rip everything out and put in a GTX 345, GTN 650, G3X 10', and a new second nav/com to boot. Toss in a GI 275 for back up and rip out the vacuum system as well. Pre wire and have a cut out for a later Garmin autopilot and a second G3X screen (7 inch) if you want.

In my fantasy world where I can own a plane, I don't want to worry about a 40 year old radio loosing the display, or an auto pilot stop working, or whatever.

Who would have thought that 1/2 the value of a plane is avionics, which will all be considered in 10 years as old and out of date as what how today we see a non WASS 430.

On the other hand, we have lots of portable backups now, so you can stick with the 40 year old panel-mounted stuff knowing you have navigational guidance, attitude information, comms, etc still if something goes on you.

If I were refitting a plane with 1970s avionics, I'd pull the transponder and replace it with a GNX 375 (WAAS GPS/ADS-B transponder combo) for $7.5K + installation, and stop there.

 

[flyingcheesehead]

Not sue about the version, but installation was complete around March if that helps. It’s set up as an MFD with page 1 default to CDI as my preference.

I guess I meant whether you had ADAHRS+AP, ADAHRS, or Base version of the hardware, and configured as AI/HSI/MFD/EIS etc. Looks like you have the MFD, probably Base version of the hardware... But I like your install, and it seems like you probably wouldn't even need to bother setting altimeters/bugs the way you're using it?

A couple of GI275s push the price a lot closer to the tipping point for a full-size PFD like the G3X Touch, which I can't justify...

You can't even put a G3X Touch in a twin anyway, can you? I thought it was for singles only. Full glass in the twin is quite a bit more expensive.

 

[WDD]

Is the GNX 375 identical in size and function to the GTN650 except no nav/ com and but has a transponder? Does the GNX 375 transponder have the same functionality / wi fi connectivity with ABSD traffic / weather in as the GTX 345?

If all the same - seems a GTX 375 and a new nav com radio would be the same as a GTN 650 and GTX 345.

 

[David Megginson]

Is the GNX 375 identical in size and function to the GTN650 except no nav/ com and but has a transponder? Does the GNX 375 transponder have the same functionality / wi fi connectivity with ABSD traffic / weather in as the GTX 345?

If all the same - seems a GTX 375 and a new nav com radio would be the same as a GTN 650 and GTX 345.

The GNX 375 is smaller than the GTN 650, and costs about half as much (pre-install) as a GTX 345 and GTN 650 combo (less, if you consider not having to purchase a FS 510, because the GNX 375 can do flightplan transfer as well as weather/traffic). I wouldn't replace the existing navcoms in this hypothetical 1970s panel if they were still working OK.

 

[WDD]

I’ve got to missing something. Why do people then do the GTN 650 / GTX 345 combo?

 

[David Megginson]

I’ve got to missing something. Why do people then do the GTN 650 / GTX 345 combo?

I bought my GTN 650 + GTX 345 combo in 2017 because I wanted to upgrade to an IFR GPS and ADS-B transponder, and that was the best deal available at the time (going with Avidyne would have cost about $1,500 more with the pricing available then, though it came down shortly after). They're great units, but I didn't really need to replace a navcom—it was just the default for both the GTN and IFD—and if I were doing it now I'd save about half the cost by sliding the GNX 375 into the transponder slot and keeping my old navcoms.

Some people do want to replace a navcom at the same time, so they still want a GTN 650 or IFD 440 (or their bigger siblings).

Also note that, depending on how old your existing CDIs are, you might have to install a new mechanical CDI for your IFR GPS as well.

 

[Ryan F.]

I’ve got to missing something. Why do people then do the GTN 650 / GTX 345 combo?

Because it includes a nav-com.

I think it's easy to overlook the cost of a standalone full-featured, modern and high-quality nav-com. A King KX-165 is $4600-$4900; a Garmin GNC-255 is $4000-$4500. Integrate it into a GTN 650 and you get some very nice additional features -- look up airport info and tap a frequency to load it; the localizer or VOR frequency automatically moves to the standby field when loading the approach; etc. And certainly not low on the list of advantages is the space saved by including the nav and com radios into the Navigator. (You can even remote the transponder by going with the GTX 345R, which I wish I'd done in retrospect. You can control the transponder from the GTN650.)

I will be the first to say that the GNX 375 is a heck of a value proposition. Garmin really tipped the scales by including functionality previously requiring the FS 510, which rolls in for an additional $1500 when going the GTN650/GTX345 route. I probably would have been heavily tempted to go this route had the option existed back in 2016, but it didn't, and I've been enjoying all of those features for the four years the GNX 375 wasn't yet on the market.

 

[asicer]

I will be the first to say that the GNX 375 is a heck of a value proposition. Garmin really tipped the scales by including functionality previously requiring the FS 510, which rolls in for an additional $1500 when going the GTN650/GTX345 route.

The FS510 has Wi-Fi and Bluetooth. GNX375 only has Bluetooth. Wi-Fi is needed for Database Concierge.

There's a couple other differences between a GNX375 and a GTN650+GTX345+FS510 combo, such as VNAV and a D-> button.

 

[Ryan F.]

The FS510 has Wi-Fi and Bluetooth. GNX375 only has Bluetooth. Wi-Fi is needed for Database Concierge.

There's a couple other differences between a GNX375 and a GTN650+GTX345+FS510 combo, such as VNAV and a D-> button.

I agree, those distinctions are worthy of note.

And I absolutely love Database Concierge.

Edit: and don't forget the GTN650's larger screen...

 

[asicer]

Edit: and don't forget the GTN650's larger screen...

I'm reminded every time I need to enter an identifier.

 

[WDD]

Got to admit at my age a larger screen is nice. Is the only difference between the 750 and 650 the screen size? Seems like a lot of up charge for a larger screen.

 

[David Megginson]

The FS510 has Wi-Fi and Bluetooth. GNX375 only has Bluetooth. Wi-Fi is needed for Database Concierge.

There's a couple other differences between a GNX375 and a GTN650+GTX345+FS510 combo, such as VNAV and a D-> button.

It's hard to imagine paying extra for the database concierge. With my GTN 650, it takes about 5 minutes to update the data card on my laptop every cycle. I keep one card in the unit, and the other in my flight bag, and update and swap every time my calendar notification pops up. I might use the concierge if I had it, but it's the flight plan sync that's the big deal missing from the GTX 345.

 

[WDD]

Why would you sync a flight plan to a transponder?

 

[Ryan F.]

It's hard to imagine paying extra for the database concierge. With my GTN 650, it takes about 5 minutes to update the data card on my laptop every cycle. I keep one card in the unit, and the other in my flight bag, and update and swap every time my calendar notification pops up. I might use the concierge if I had it, but it's the flight plan sync that's the big deal missing from the GTX 345.

I'd have thought the same before using it. It's pretty great. Imagine forgetting about database updates... literally. Just let your iPad do the work and download the updates automatically. Next time you go fly, the iPad will automatically connect and you'll get a chance to update the databases in a few seconds. No more swapping cards, no more laptops, no more being concerned with effectivity cycles. The unit's always updated, every time you fly.

If a few bucks per year are more valuable, I understand and don't blame you, but you have to enjoy the effortless nature of it all before dismissing it. Just my opinion.

 

[CA182R]

Got to admit at my age a larger screen is nice. Is the only difference between the 750 and 650 the screen size? Seems like a lot of up charge for a larger screen.

GTN 750 has the ability to display the Garmin Flitecharts and it has an optional remote audio pannel. To my knowledge, these are the only differences over the GTN 650. And I think the up charge is pretty high indeed...

It would be nice if the GTN series had a synthetic vision page, kind of like the Avidyne.

 

[CA182R]

Regarding the 2" navigators series like GNX 375, I don't know if these units can be interfaced at all with a GTN or even another 2" navigator. This could be yet another difference with the more expensive GTN route.

 

[Jdm]

Got to admit at my age a larger screen is nice. Is the only difference between the 750 and 650 the screen size?

As mentioned, Flitecharts & remote audio options are available with the 750.
Remember also that screen size allows more on screen options, which reduces button pressing to get to the correct page. CDI/OBS buttons and nav freq controls are a little easier to get to on the 750 because of it’s screen size. The 650 requires an extra button push to get to these functions because there’s no room for them on the home page. At least that’s the case with my 650’s configuration. I’ve got equal time using the new 650xi and the 750 legacy. Both are great but the 750 would be my preference if money and panel space were not an option. Not so much because of flitecharts or remote tuning, it’s the display layout that I prefer.

 

[asicer]

Regarding the 2" navigators series like GNX 375, I don't know if these units can be interfaced at all with a GTN or even another 2" navigator. This could be yet another difference with the more expensive GTN route.

Another key difference is if you plan to have a G5 and a non-Garmin autopilot combination at some point in time. As I recall, the G5 can only talk to the 175/355/375 or a NAV radio but not both if it is connected to a 3rd party autopilot.

 

[PPC1052]

Why would you sync a flight plan to a transponder?

Because the GNX 375 is, in addition to being an ADSB out transponder, also an IFR certified GPS navigator.

 

[WDD]

Syncing to the GNX 375 navigator I understand. I was responding to the statement of syncing to a GTX 345 transponder. Do you mean linking to get traffic and weather?

 

[GRG55]

...It would be nice if the GTN series had a synthetic vision page, kind of like the Avidyne.

I wonder how useful syn viz is on a display that is in the radio stack, where most people install their IFR GPS navigators.
Seems if one is in hard IFR and wants to use syn viz you'd want it on your PDF in direct line of sight.

 

[CA182R]

I wonder how useful syn viz is on a display that is in the radio stack, where most people install their IFR GPS navigators.
Seems if one is in hard IFR and wants to use syn viz you'd want it on your PDF in direct line of sight.

I was thinking if one has a GTN 650 and a GTN 750 in the radio stack, the 650 (especially Xi) could display synthetic vision. But yeah other things can do that job.

 

[Fracpilot]

I was thinking if one has a GTN 650 and a GTN 750 in the radio stack, the 650 (especially Xi) could display synthetic vision. But yeah other things can do that job.

The 650 screen is too cluttered already. I just keep mine in flight plan mode. The map is kinda useless since it’s so small. I use ForeFlight on the iPad and my Aera 660 for the displays vs the 650.

I wish I would’ve went with the 750 instead of the 650.


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[WDD]

I wish I would’ve went with the 750 instead of the 650.

For the screen size? For the cost difference - would it be that much more to just get a 7 inch G3X and a 650 vs a 750?

 

[David Megginson]

Syncing to the GNX 375 navigator I understand. I was responding to the statement of syncing to a GTX 345 transponder. Do you mean linking to get traffic and weather?

The GTX 345 (the transponder, not the GNX 375) will relay the position etc. from a WAAS GPS to a mobile device over Bluetooth, along with its own ADS-B traffic and weather and AHRS attitude data (for synthetic vision, a virtual attitude indicator, etc). It does not relay flight plan information in either direction. When I bought in 2017, it was the most-efficient way to get mobile connectivity (sans flight plan syncing) without paying US $1.5K more to add a FS 510 to my GTN 650 (or a similar amount extra to enable the feature in the IFD 440, where it was a $$$ add-on at the time, not yet part of the base price).

 

[David Megginson]

The 650 screen is too cluttered already. I just keep mine in flight plan mode. The map is kinda useless since it’s so small. I use ForeFlight on the iPad and my Aera 660 for the displays vs the 650.

I wish I would’ve went with the 750 instead of the 650.

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Have you considered keeping the 650 in default nav mode instead of flight plan mode? That makes it really easy to switch quickly to flight plan (tap on the active waypoint) or to the map (tap on the map icon) and back again with the back button.

Personally, I'm happy not to have the huge 750 screen on my panel, because I don't want to feel like I'm flying the screens instead of the airplane, but we all have different preferences.

 

[Bill]

One reason we are happy with two GI275s we are getting vs doing a G3x Touch like screen is having a big fat ipad running foreflight. Most information that a G3 would display is on the iPad, so we're good with NOT having a big expensive chunk of glass on the panel. Looks snazzy, but not nearly as cost effective.

 

[WannFly]

For the screen size? For the cost difference - would it be that much more to just get a 7 inch G3X and a 650 vs a 750?

huge.

750 is about 5k more for the hardware, install is same for both units. for that 5k you cant get G3X installed.

 

[Fracpilot]

For the screen size? For the cost difference - would it be that much more to just get a 7 inch G3X and a 650 vs a 750?

I have a 310 so the G3x isn’t an option. Not sure why Garmin won’t just get it certified for all aircraft under 6000 lbs like the G5’s.

Same thing with their AP. If the GFC500 was certified for a 310 I would’ve bought it a long time ago. They don’t even have the GFC 600 Certified for the 310 giving up market for the STEC 3100.


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[Fracpilot]

Have you considered keeping the 650 in default nav mode instead of flight plan mode? That makes it really easy to switch quickly to flight plan (tap on the active waypoint) or to the map (tap on the map icon) and back again with the back button.

Personally, I'm happy not to have the huge 750 screen on my panel, because I don't want to feel like I'm flying the screens instead of the airplane, but we all have different preferences.

No I haven’t. I’ll give it a try in default Nav mode. Thanks for the tip.

Ps. If you’re unhappy with your 750, I’ll trade you my 650 for it...hehe.


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