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Mike D 02-18-2013 07:52 AM

To remote or to not remote?
With all the new EFIS systems, it seems the control of remote transponders, radios, and audio panels is the rage these days. To clarify, I am talking about avionics with no other way to control, or see, them other than through the EFIS.

I have to question if this is a good thing. VFR, I don't really have an issue other than the potential resale value. But because I am not yet IFR rated, I don't know what I don't know. But my gut says this might not be good in IMC.

Will remote audio panels work with all the brands of Efis's? Or are they proprietary? Same question with transponders, radios, and all the other gizmos.

So what say you? To remote or not to remote?

Kahuna 02-18-2013 08:03 AM


Originally Posted by Mike D (Post 745286)
With all the new EFIS systems, it seems the control of remote transponders, radios, and audio panels is the rage these days. To clarify, I am talking about avionics with no other way to control, or see, them other than through the EFIS.

I have to question if this is a good thing. VFR, I don't really have an issue other than the potential resale value. But because I am not yet IFR rated, I don't know what I don't know. But my gut says this might not be good in IMC.

Will remote audio panels work with all the brands of Efis's? Or are they proprietary? Same question with transponders, radios, and all the other gizmos.

So what say you? To remote or not to remote?

Mike, I am remote controlling and Im not sure what you mean by VFR or IFR? Whether or not you push buttons on an EFIS or an end unit, I find absolutely no functional difference.
The end units all have their own serial sentences. Means that NO, not all EFIS will control all end units. Just a matter of time before they do though. Once the EFIS manufacturers have the UI done and a basic code around the serial in and out, its not a big deal for them to code to them all in pretty short order.
What I find with my GRT is that the interface of the GRT is MUCH better to enter information into. BIG, right in front, nice digital display. Simple, elegant. Turn a dial, bam, frequencies sent. Or better yet, turn no dials.. waypoints are already in the EFIS, just select the freq you want. Pretty cool!

There is no functionality improvement. There is space savings and ease of use.

Each EFIS manufacturer has a list of what they control now, and those lists are updated weekly so check back often.

ColoRv 02-18-2013 08:06 AM

With secondary screens, automatic switching, backup batteries that keep the system up for longer than the fuel in your tanks will last....I see no downside to remote mounted. My transponder is under my back seater's leg, and the PAR100 radio is mounted on a shelf behind the PFD...which means the radio was short enough to mount it where a standard would never fit. I'm all for remote the end a bundle of wires from a control head to a remote box is no more failure prone than internal wiring.

Kahuna 02-18-2013 08:21 AM

Some thoughts on IFR. Lets talk integration. Integration by definition means that your life should be simpler. Stop dealing with 10 things on the panel and deal with one. If your in a huge cockpit, maybe you done care if your messing with 10 different units. Here is a sample of whats possible off the top of my head.

Your IFR, you going into your destination. Typically you must stop looking at attitude and begin the mundane, distracting, task of looking up the atis and weather for decisioning.
Your EFIS knows alot about what you want already. It knows where you are going. It knows your gonna need the weather. It knows what the weather is. It knows what you likely gonna want to know and when. One button can now give you weather in text. Or text to speech audio in your headset. It can set your baro, tell you the best runway for the winds. It has notams current. It knows what runways are closed, what ILS is out of service, etc. It can help you make lots of decisions at the push of a button. Whether VFR or IFR, it can stop you from being distracted off your flying attitude job and keep you focused on the screen while doing other simple tasks. The possibilities are endless. We are not there quite yet, but we are getting there.
Course when the screen goes TU, we have to have a plan for that as well. But the EFIS gives us so much integration, reduced workload, simplicity of use etc, we should not be scared of it. We should learn it, use it for what its good for, plan for the failures, and enjoy the fun of integration. Its really cool stuff.

Mike D 02-18-2013 10:47 AM

Kahuna, you make it sound great?
My concern for IFR, comes from my fear of the display going black. I am still a nube, when it comes to wiring things for redundancy.

Is there a transition type of avionics? ColoRV mentioned the PAR100. Can this be both remote and independent? Meaning, if I buy the PAR100 and my current system does not have the ability to control it remotely. Then I upgrade to the HXr (when I win the lottery). Will this radio/audio panel do the upgrade? Will it be a compromise?

I think there are many others like me that need to upgrade or replace one thing but don't have the money to do the whole panel. But i also don't want to spend money for avionics that won't work with my eventual plans of an HXr

I would like to keep the conversation high level so we can learn independent of the system chosen, but here is my specific situation:
I have a GRT sport, PS engineering 1000 II, GNS 480, icom A200, digiflight II, and a Garmin 320a. I would like to upgrade the intercom to an audio panel. So what panel do I choose. I will eventually move to an HXr (but not this year) and the transponder will need to move toward ADS-B compliment eventually. Or maybe this is a question for Stein. :)

dynonsupport 02-18-2013 11:05 AM

As the guy at Dynon that is tasked with thinking about these exact issues, let me offer my thoughts:

As we were all taught when we got our PPL:
1) Aviatie
2) Navigate
3) Communicate

The PFD part of your EFIS basically covers #1, and the MFD covers #2. So if your EFIS fails, the fact that you might lose your transponder or radio only affects #3. Your day only gets a little worse ;)

At Dynon, we design all of our systems so if you have two screens, everything works normally on the failure of one. So if you were really IFR, you had a backup, right? If your backup was another SkyView screen, then you now use that screen to control the transponder. Nothing in the plane has changed except you have 1/2 the screen real estate and 1/2 the buttons. The workload goes up some, but not through the roof, and most of that workload is not due to the transponder, which you are not touching because you have your squawk already.

If you use a dissimilar backup like the Dynon EFIS-D6, then you do lose your transponder if you lose your only SkyView screen. However, this is not a flight critical loss. You might be limited to what airspaces you can enter, but that's about it.

Another issue is that almost everyone is already relying on their EFIS for the transponder even if they don't realize it. Probably 95% of experimental builders today use the EFIS as the altitude encoder for their transponder. This means that when the EFIS stops, so does the Mode-C altitude encoding. This is what you need to fly IFR or in controlled airspaces anyway, so unless you also put a standalone encoder in, you were already relying on the EFIS. On top of that, no matter how you control your transponder, you probably only have one of those. If it were a standalone transponder, it could have failed on it's own unless you are putting two transponders in.

So, the transponder is a case that when well engineered, you really may have increased reliability by having it integrated since you have more than one controller running it.

You can make all the same arguments for a integrated radio or audio control panel as well.

Where the radio and audio panel break down is in the User Interface. I actually think the UI for the transponder is great. You get 8 buttons and can just type in your Mode-A code really quick. No spinning knobs, and the 4 digits are pretty easy to remember when they are assigned in case you need to move across a menu or two to enter it.

I'm not as convinced with a radio or audio panel. I personally don't think that having to dig into a menu every time you want to enter a frequency, swap frequencies, or change the volume is a good user interface. When the controller says "change frequency to 128.975," I don't think you should need to hit BACK->BACK->RADIO->MHz->turn knob->KHz->Turn knob->Flip flop. If all you fly is VFR at uncontrolled airports, maybe the EFIS can always have a good suggestion ready for your next frequency and you can swap when you aren't busy, but if you are in any Class C or B airspaces, you're going to get given frequencies that nobody knew was coming.

I think the same is true of adjusting squelch, volume, and sources with an audio panel. When you want the volume changed, you want it NOW. You don't want to have to go into a menu.

Because of this, the radio that Dynon is working on will have a control panel, and will require it to operate. The reason for this is not because of redundancy, it's because the UI is right. It will use SkyView to give the control panel all sorts of amazing features, but the control panel will also give you exactly the knob or button you want all the time.

It does also give you redundancy as well, which does have moments where it's nice. If you do lose all your EFIS units, at least you can still communicate, and I think the radio is something more likely to save someone when their EFIS fails in IMC than their transponder is.

I think the real question builders should ask is what happens to their workload if a device in the plane fails. Accident and human factors studies will tell you over and over that workload is a big deal for safety in a plane. So, the real issue with the "eggs in one basket" design is if the loss of the basket causes your workload to be come unacceptably high.

So ask yourself: If I lose my EFIS in my kind of flying (VFR, IFR, IMC), how big of a deal is that? For some people, the loss of attitude, altitude and airspeed may hardly bother them since it's bright and sunny out. In this case, the loss of the transponder along with it is probably a non-issue. The radio might actually be the most annoying thing to lose in this case, and losing your intercom so you can't talk to the non-pilot next to you and explain the situation will be annoying as well. But neither of those is a saftey of flight issue until the co-pilot starts punching you in the shoulder trying to get your attention.

If you're in IMC, then losing your EFIS is a big deal. No PFD, no EMS. That will make any IMC pilot nervous. But, you likely still have your navigation (Certified GPS), and you have some sort of backup airspeed, altitude, and attitude. Here, the loss of the transponder is annoying, but unlikely to lead to any real workload increase. Again though, the radio is a larger loss and is doubled if you lost your transponder and can't squawk the no radio code. If you were tied to an integrated audio panel, this could actually be a big issue, because all you will have access to is your primary COM radio, so you may lose other sources you were used to having.

I'm sure some EFIS vendors can integrate a radio better or worse than others depending on what kind of knobs, and buttons their hardware has. There is no single answer, you have to evaluate how you fly, where you fly, and exactly what your system configuration gives you in various failures. For Dynon, for our average customer, we believe the transponder can be remote, but a radio or audio panel needs to be it's own module. That's right for a large group of customers, but will inevitably be wrong for some. There are good arguments each way, and thankfully the market is giving builders options to chose what is right for them.

--Ian Jordan
Chief Systems Architect
Dynon Avionics

krw5927 02-18-2013 02:11 PM

Ian, thank you for a well-written, informative, and non-biased reply. I learned something from you today.

Mike D 02-18-2013 04:30 PM

Ian, great post. This is exactly what I was looking for. Very informative and a good look into the thought behind the UI and features.

In VFR, I could lose everything and be okay. But in IMC, losing the attitude/altitude/airspeed would be well beyond my comfort zone. And if this was combined with the loss of radios, I would need new underwire if I lived through it.:eek: (Not IFR rated yet, so this is not a serous concern yet)

So, this is the concern behind my questions. Looks like I will go with the full radio stack.

Now the question is; how to upgrade piece meal and work with the great features of the new EFIS's? It would be great if the radios could be controlled by both the EFIS and radio control head.

Seems the Trig TT22 and TT31 mode S transponders can be controlled by the EFIS and the Trig control head. So this may solve the upcoming ADS-B issue and not require a whole panel upgrade.

But the radios and audio panel are still in question. Will the PAR100 or PMA5000EX work with Dynon, GRT or any of the other EFIS's? How about the ICOM 210 or garmin radios? Can it be controlled by the EFIS? Will a Dynon radio play nice with a GRT EFIS?

Also, any thoughts on autopilots solely controlled by the EFIS for IFR in an RV? Although I have a TT Digiflight now, the AP's for the EFIS have some great features at a relatively low cost. Very enticing.

dynonsupport 02-18-2013 08:52 PM


The Trig transponders cannot be controlled by an EFIS and a control head at the same time. I believe only the very expensive Garmin GTX-330's can, and only if someone reverse engineers the non-published protocol, and they take up more panel space to boot.

The Dynon radio will never work with any product but our own. It is an integral part of SkyView, not just a radio that happens to work with SkyView.

The radio in the PAR100EX can't be controlled by anything except the PAR100EX audio panel. The PAR5000EX is just an audio panel, and the volume can't be digitally controlled, so there's nothing to interface with there. Even if you could, would you really grab a knob on your EFIS to change the intercom volume when the real knob is right there on the panel already?

I think the real question here is what are you trying to get out of integration? You seem to be concerned if things will "work" with an arbitrary EFIS, but why do you want to connect them at all?

The main thing you can really get with a standalone radio is the ability to tune the standby frequency of the radio from the EFIS. Many EFIS systems support this to the Garmin SL40, SL30, Icom A210, and some other radios which use the Garmin SL30/40 protocol. This does not let you do things like change volume however.

On another topic, the Autopilot is the same as the transponder. I tried to point out in IMC that you don't actually lose your PFD, since you have a backup. So the worst you lose is your transponder or radio if you have any sort of well thought out backup strategy. So the real question is not "what if I lose my PFD and my radio and my transponder and my autopilot" it's "what if I lose my transponder and radio and autopilot?"

One thing I think might help people to understand the redundancy story is to turn your thinking upside down. Start with your backup, but think of this as your primary flight instruments, whether this is analog steam gauges or another EFIS. That's because these are instruments you'll have no matter what single failure you have.

Ok, so now you have airspeed, altitude, airspeed, and maybe more covered in your plane. They never go away because they are backed up.

Now you put in another EFIS as "backup." This single screen has a transponder, autopilot, radio, map, and maybe even more in it. But it is not your primary flight instruments, it's your backup. So what you lose when you lose this is your transponder and autopilot.

Now you can see that having the AP in an EFIS isn't putting your eggs all in one basket. In fact, it can be better than a standalone AP. If all you put in the plane is an EFIS and an AP, then if you lose the EFIS, all you have is the AP. But if you have an EFIS+AP, and a backup to your primary, then depending on the failure, you either still have EFIS+AP or just a PFD. A better situation than just AP in my mind.

One interesting example in certified land is the Garmin GTN750. This is a COM, NAV, GPS, Transponder, and audio panel all in one box. It's a big, beautiful screen, and it's a lot of eggs in one basket. It literally means that if it fails, you probably can't navigate or communicate. But you see it in certified planes because you can still aviate, and that's the #1 thing.

At some point, the most awesome backup instrument in the world sounds like a PFD, MAP, radio, transponder, audio panel, autopilot all in one. Because now you have a backup everything. But wait! Now those eggs are all in one basket, and I'm nervous because if I lose my backup transponder I loose my backup autopilot and my airplane is really wounded! But wait, they were all supposed to be backups....

One thing I urge people to remember is that you can add too much redundancy to the plane. Eventually, it weighs too much to get off the ground. We don't put second engines on the planes, we don't generally have two transponders, we don't have redundant cables and pushrods to control surfaces. You can only do so much. And in that vein, try this thought exercise:
  1. Write down what you feel you must have to fly and get back to the ground. Buy two of each of those.
  2. Now write down everything else. Next to each of those, make a column and write down what you MUST still have working in the plane if that fails. For instance, "Transponder and Radio" if you think you will be very unsafe if you lose the transponder and radio at the same time.
  3. Don't put those two items in the same box. Everything else, put it one box if it's cheaper, lighter, better, or just cooler. You can handle it if they all go at the same time
And remember, just because your radio and transponder aren't in the same box doesn't mean they don't share the same wire from the alternator and battery, and it doesn't mean they don't share the same airframe that can get hit by lightning or some other trauma. It never ends if you think about it too much.


BHunt 02-18-2013 11:15 PM

Awesome thread guys! Thanks

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