What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

1 vs 2 EFIS screens

N546RV

Well Known Member
Alright, fun conversation time. I keep working on firming up my panel plans, and this is the one spot where I've flip-flopped multiple times.

Aircraft mission will be primarily VFR, though I want IFR capability for those days when there's an overcast layer to punch through. With this in mind, I'm not after extreme redundancy, but I will still be planning for some kind of backup/failover ability. Rough panel plan is for a Skyview system and a 650 or IFD440 for the TSO'd GPS.

When I originally was drawing up panels, I wanted two screens, and was generally planning on a pair of 7" Skyviews. Later, after looking at price lists and comparing to my bank account, said plans tended more towards a single 10" display.

Question 1 is kinda the easy one: Does anyone out there running a single EFIS screen find themselves wishing they had the extra screen real estate? Part of me thinks it'd be nice not to cram PFD/map/engine all onto one screen, the other part points out that it's not exactly a small screen...

Question 2 is more fun and kinda expands on 1: Keeping in mind my redundancy thoughts above, let's suppose that option 1 is a single Skyview EFIS and a separate backup instrument (G5/GRT Mini/etc), and option 2 is a dual Skyview with no separate backup. Assume that in either case, the backup instrument is supplied with an equivalent backup battery system or some such.

What are people's thoughts on the pros and cons here? Option 1, to me, does provide some extra redundancy, but at the expense of having an instrument that's chopped liver 99.9% of the time. Option 2 sacrifices a bit of redundancy in favor of an instrument that's more useful day-to-day.

At the moment I feel #2 fits a little better with my mission, but I'm here to find out all the reasons I'm wrong. Fire away!
 
Me

I have a single screen and wish I had a second.

I have a GRT Mini backup to the AFS main screen but I wish I had a second AFS screen dedicated to map or approach plate. If I had it to do over I would put a second screen. But like you I wanted to save the cash

even a mounted IPAD would be better than my single screen.

I upgraded the primary to touch screen and that is great but still flip back and forth between split screen and full screen efis. with a second screen I could leave it alone.
 
My single 10" Skyview is just fine for VFR. I left room for another screen on the co-pilot side, but I don't find myself ever really needing it. There is a lot on the screen, but it doesn't feel like I'm missing anything that a second screen would provide. There is plenty of real estate on the 10" screen for EMS, PFD and MAP sections.

If I was going to do any IFR, I would definitely add a second EFIS screen, EFIS battery, and redundant ADAHRS.
 
I see you are building an RV8. I have 2, 10 inch Dynon screens in my RV8 panel. I use the left one as a PFD exclusively and the right is split between map and engine monitor. My 53 year old eyes really like the setup. It does take up a lot of panel space but I still had room for 2 Dynon radios, intercom and autopilot control panel on the bottom of the panel. If I was upgrading to IFR, I would definetaly replace one with a 7 inch screen.
 
I have a single 8.5" (non Dynon) screen for a VFR aircraft. If I could've fit a 10" Skyview in the panel I would have, but it just wasn't possible.

The 8.5" screen is just enough to get a good combo of information for what I need. I looked at 7" screens at Sun N Fun and felt I would struggle with the display real estate priorities on it. A 7" screen ended up being my least desirable option, unless it was a secondary screen to a larger display.

If I were to do a VFR aircraft with occasional IFR capability, I would install the largest EFIS screen which could fit, and only if there was no room for a second EFIS screen, I'd back it up with something like a G5 or similar instrument. Backup batteries for both, in the IFR case.
 
Two screens

Our 7 came with a D-180 and an EKP IV. We really liked the D-180 which was used for PFD and EMS functions. We really didn't like the EKP IV which was, for my son and I, outdated, difficult to use and update. We made the decision to ditch the EKP and add, in it's place, a seven inch Skyview which we use almost exclusively for navigation. This has worked out beautifully as we now have plenty of informational "real estate" but also have absolute redundancy as each has it's own ADHRS, magnetic compass sensor and backup battery. At any moment, I can switch the Skyview to PFD mode and, in the case of electrical failure, I could effectively double my backup time by selecting one off then on when needed.
 
Currently my -6A has a single 8.4" GRT EFIS that spends most of it's time as a PFD with Engine data on a bar on the bottom. Additinally, I have a TT Vizion PFD / Autopilot, Garmin GPS400, and iPad running WingX fed with a standalone GPS/AHRS. Everything has a battery backup for a minimum 30 minutes. For cross country cruising on autopilot, I toy with going to MAP / Engine on the EFIS, but the required switch back to the PFD screen just to change the altimeter setting sucks, actually makes me wish for another GRT screen for just that single issue (maybe that's their marketing plan?).

For IFR, I switch the EFIS to split PFD / HSI with engine bar on the bottom during arrival.

My setup is more than adequate for your stated mission, with a few nuisance items that could be solved with a second screen. A current generation GPS would only make things better. I would make the primary screen as large as possible.
 
.... but the required switch back to the PFD screen just to change the altimeter setting sucks, actually makes me wish for another GRT screen for just that single issue (maybe that's their marketing plan?)
Yeah that's a bit of a deficiency. Dynon fix that issue with their SV-knob-panel giving you a permanent baro set control, and MGL have the baro knob function on all their iEFIS screens. I'm a little surprised GRT hasn't caught up!
 
For me personally I find that information density impacts situational awareness. I.E. The more information there is on a screen, the less I see. I have an RV-8 with 3 screens, each with a dedicated function.
  • D100 - EFIS
  • D120 - EMS
  • IFLY - 740 Moving Map, Traffic, Weather
My flying profile is predominately 2-3 hour VFR flights. If I were to upgrade to a Skyview system I would definitely go with a multi-screen system.
 
It's a little bit of apples and oranges, since I have four EFIS in my RV-10.

If you are going to being flying any significant time in IMC, I would recommend two screens (for redundancy as you mentioned) and for ease of use.

The Skyview's (and AFS) are great from a redundancy perspective. Anything attached to the Skyview network is available to both screens. This doesn't solve every issue with redundancy, but it does resolve a fair amount of them.

The other thing to think about is what resources do you want available when you're in IMC. For example, the default Dynon map, a sectional, an IFR Lo chart, or an approach plate. The rub comes with most EFIS can only display one map product at time on a screen.

I use my MFD primarily as a navigation tool. 99% of the time, I leave the default map up. Sometimes I will display the IFR LO chart. I almost never use the sectional. (It's a bitmap with north up orientation only, which I don't like. I'm a track up guy, but I digress). When I'm on an approach, I want a map up AND the approach plate. Unfortunately, I can't display both on the same screen. I end up splitting my PFD and displaying the map and the HSI/Engine panels. I put the plate up on the MFD. I find that this helps with situational awareness as I transition from enroute to approach modes.

Once I pass the IAF, it doesn't matter. My focus is solely on the approach plate. It's nice having geo-referenced plates that also overlay ADSB traffic. Although traffic shouldn't be an issue in IMC.

The other option is to display the plate on an iPad. I personally don't like that option, since the iPad really isn't in my standard can view. I find looking down at it distracting. Also, since I've got the glass panels, I see no reason not to have everything I need viewed on them.

I know that I didn't answer your question, but I hope I've given you some things to think about. There is no correct answer, just what will work well for you.
 
There is a lot more to this than you think. Having installed many of the mainstream systems, there are benefits and drawbacks to ALL of them.

For IFR Flight, having an independent backup is a valuable thing. I am aware of a G3X system with a G5 backup that lose everything, including the G5, for a period of time in Flight. I am aware of a Skyview stem that did the same. I have never heard of a Skyview system with a G5 that lost everything, or a G3X with a GRT Mini that lost everything.

With that out of the way, the multiple screen really depends on the system. Of course, everybody who has a single screen would love to have a second screen. The Skyview Classic is not a great system for a single screen if you use it for all 3 systems (PFD, MAP and Engine). The option for only vertical separation between these systems is less than ideal for a single screen, alththough having a widescreen format helps a great deal. The HDX greatly helps because it has the resolution to put the engine along the bottom, which gives you more real estate (at least apparently and for aspect ratio) for the PFD and map. The HDX also has a great and easy way to make the map big and hide the less critical engine data, while still keeping PFD and more critical engine data. The G3X Touch landscape screens I really have about the same comment about as the Skyview Classic, although the sidebar doesn’t display all engine data, so you have to pull up the big engine display and even change tabs within it to see all engine data. The AFS and GRT have always allowed the engine at the bottom, splitting the remainder of he screen between PFD and map. For a single screen system, I would pick Dynon HDX or AFS 5000 series hands down.

Multiple screens can pose other problems in and of themselves. Namely, what happens if you lose one of the screens. With Skyview, you have 5 serial ports that go to both screens, and everything else is tied to both screens through the network. THis way, if you lose a screen, the other screen still talks to everything. The AFS has 5 serial ports per screen, and a lot of the remote modules are Skyview network, so they talk to both screens. The serial items are tied to one screen only, so losing a screen loses the serial devices that that screen controls. This requires some more planning and “what if” scenarios. The GRT is similar to the AFS in this way. The G3X has Canbus and serial, so some things talk through the Canbus and other things through serial. Somebody a little more versed in planning G3X systems can explain what items are serial only and what things can be lost if you lose a screen, but it is similar to the AFS and GRT in this way. I believe GRT is the only system that uses serial strictly without having a system network/bus system that ties many of the remote modules together. The GRT does have more serials ports per screen, however.

I can go into a whole lot more detail on this, but that would get even more long winded than I have already been here.
 
If plannng an IFR aircraft 2 screens was my choice.
This is where the portrait display really shines IMO as I have 2 directly in front of me. A failure of either screen is merely inconvenient, but an absolute non-event.

As far as architecture, the CAN bus ties all the remote boxes to the screens, however serial data is routed from both ADAHRS to both screens individually so if the main CAN bus goes down you will still have primary instruments on both screens (mfd can be switched to PFD easily or if one screen fails the other automatically displays all the lost data).
Most of the G3X components have dual power inputs as well, in my case the back up battery powers both screens, both ADAHRS and Com 1.

The G5 has it own battery and ADAHRS but is also on the CAN bus, not sure how all the G3X components could be affected by a single failure but I'm sure the G3Xpert folks would like to know more about the system failure Jesse mentions if this actually happened and was not an installation induced error.

The 660 on the LH side is totally independant but also get flight plans from a serial connection. This has since be replaced by an Ipad Pro 10.5 which is better for these old eyes and mainly used for plates. The huge map on the Ipad is also pretty sweet, and of course the Ipad communicates seemlessly with foreflight to the G3X and the GTN.

If anyone has more questions on the G3X system feel free to call.

IMG_7793-650.jpg
 
Last edited:
I am aware of a G3X system with a G5 backup that lose everything, including the G5, for a period of time in Flight. I am aware of a Skyview stem that did the same. I have never heard of a Skyview system with a G5 that lost everything, or a G3X with a GRT Mini that lost everything.

This kind of data is really hard to come by. Mind describing for us the nature of failures for those single-vendor systems? A software bug shared by the primary and backup systems? Power issues? Something over the common network that brought all systems down?

I'll give you an example that I know of. We had a 767 loose all displays on approach once. There was a bug in the software that allowed an unsupported character be sent to the PFD for display. It crashed. Then the PFD auto-reverted to the MFD (backup) and brought it down too. BOOM. Nobody hurt if memory serves, I got that story second hand.
 
For IFR I would definitely want more than one screen. For VFR I am going with one EFIS and an IPAD. You would be amazed at how much SA a tablet provides. I think Google maps will by my primary navigation tool for back country flying, but I use Jepp-Pro at work and it is a phenomenal SA builder, both on the ground and in the air.

Plus I can put it in front of the right seat if that person wants to fly. I put a second in. I will have a couple of RAM mounts to mount it in the middle, or in front of the right seat.
 
Everybody has an opinion on this one, and they are all valid, based on everybody's individual assessments of risk/reward.

In our case I installed a GRT HX and GRT Mini-X for an IFR ship. Approach plates and other IFR-related charting is handled by an 8" Android tablet running FltPlanGO, and the GNS480 moving map / IFR database fills out the situational awareness picture. The Mini-X stays in PFD mode pretty much all the time, allowing the bigger HX screen to be used for mapping, HSI etc. The engine data is displayed on a separate, stand-alone engine monitor (old school AF2500).

While this aircraft hasn't yet flown hard IFR, it has done a few approaches and some enroute navigation. To date I'm happy with this mix of equipment. Over on the co-pilot's side I've got real estate for another screen which likely will be from another manufacturer (AFS is currently the favored vendor for this device) so as to ensure a software bug in one manufacturer's product won't wipe out the entire cockpit.

All of the avionics are powered by a simple essential electric bus design with its own backup battery, plus the Mini-X has its own internal battery. Tests to date indicate that most electrical system failure modes will result in the avionics being powered for a considerable length of time, several times greater than the legal minimum endurance.

The combination as described above meets my requirements for redundancy, simplicity and cost of acquisition.
 
Back
Top