F

flydoc

Active Member
Two quick questions...

1. It looks like the Garmin G3X has Altitude Pre-Select from the docs, but I don't see any info that the Advanced EFIS has it. Not sure how important this really is :), but I had a C-182 a while back and that was a major selling point when I bought the plane. It looks like you can set the vertical speed, etc, but not the final alt.

2. I remember reading somewhere that if you lose the EFIS, the integrated AP from TruTrak can still function as a backup to the EFIS, or as a tie-breaker if you are getting conflicting info from 2 different EFIS's. Is this true that the AP will still function w/o the EFIS?

Thanks! Just trying to get a head start on Oshkosh!

Mark Hanley
Finishing the RV-10
 
Mark:

I've been flying the G3X/GX Pilot combo for several hours now and can answer your basic questions.

As far as I know, the G3X and AFS/AFS Pilot have similar functions. Both can do altitude preselect and vertical-speed commands to fly until reaching the "bugged" altitudes. I'm not sure if AFS has this feature, but the G3X allows you to set either VS or a pitch altitude to hold until reaching the bugged altitude. This plus basic altitude hold, pitch hold without a bugged altitude, and vertical guidance from outside nav sources. The G3X does not allow you to set a desired airspeed, as the Grand Rapids allows you to do, for example.

I know the G3X only syncs to a WAAS GPS approach or will follow internal VNAV guidance when there isn't an external WAAS receiver (such as the 430W) in the system. (My one gripe is that you can't have the system follow VFR VNAV guidance if there is a 4XX/5XXW in the loop; the system is permanently "tethered" to the external GPS.) So for the G3X, the vertical nav modes are only for GPS LPV or LNAV+V approaches; no vertical commands are provided by an ILS approach.

The GX Pilot will function fine all by itself. It'll climb or descend by commanded VS or hold altitude. It will follow GPS-based track or a simple flight plan through the RS-232 data feed. I don't honestly know if it can still decode the ARINC 429 lateral and vertical steering commands from a source other than the G3X.

I don't think the GX Pilot (or the AFS equivalent) works as a tie breaker. You have to choose which source is right, but I also believe that the AP performs all the basic attitude computations internally, and that the link with the G3X is only to receive steering commands. Now, if the G3X goes crazy and sends crazy steering commands, the GX Pilot will follow them, but you can easily revert to totally internal (to the autopilot) modes.

Does that help?
 
Question for you Marc, based on your last paragraph - can you engage the GX Pilot in Heading/Alt Hold mode without going in to GPSS/GPSV, like you can with a straight VSGV and the GRT? That allows the Autopilot to be a good standalone "backup" to the G3X suite.

Paul
 
Ironflight said:
Question for you Marc, based on your last paragraph - can you engage the GX Pilot in Heading/Alt Hold mode without going in to GPSS/GPSV, like you can with a straight VSGV and the GRT? That allows the Autopilot to be a good standalone "backup" to the G3X suite.
Click to expand...

I'm not Marc but I have flown with the G3X and GX Pilot a bit. :) Yes, the GX Pilot can still be operated using its own built-in altitude hold, vertical speed, and track-hold or wing-leveler modes. I'm a big fan of this kind of dissimilar redundancy, as I know you are!

cheers,
mcb
 
Thanks Matt - yup, that's just the way I like it! There are lots of time I just want the A/P to hold on to the airplane for a second while I do something else, and I don't have to go through setting up the EFIS to do that. Nice.
 
So for the G3X, the vertical nav modes are only for GPS LPV or LNAV+V approaches; no vertical commands are provided by an ILS approach.
Click to expand...

So it will not follow a guide slope on an SL 30 or a 430 when flying an ILS?
 
mburch said:
The G3X autopilot interface does not currently support VOR, LOC, or ILS modes.

mcb
Click to expand...

Hmmm. I wonder what the next beta package will include, eh? <grin>

I have to say this is the one feature offered by the GRT (and the AFS) that I do miss in the G3X, though living in California it's more that I fly the ILS for convenience and practice than pure necessity. And given that it's for practice, I really should be hand flying, eh?
 
Ironflight said:
Thanks Matt - yup, that's just the way I like it! There are lots of time I just want the A/P to hold on to the airplane for a second while I do something else, and I don't have to go through setting up the EFIS to do that. Nice.
Click to expand...

Actually, the G3X/GX Pilot does this very nicely now. Let's assume you have the AP head powered and ready to go, but you're hand flying. Press and hold the CWS switch, then release. The G3X/GX comes up in roll and pitch hold, so the airplane will continue to do what it was doing when you brought the AP on line. You can then select HDG or GPS NAV for lateral, and decide what you want it to do vertically. But it's just as happy to hold wings level and whatever pitch attitude you gave it.
 
flydoc said:
Two quick questions...

1. It looks like the Garmin G3X has Altitude Pre-Select from the docs, but I don't see any info that the Advanced EFIS has it. Not sure how important this really is :), but I had a C-182 a while back and that was a major selling point when I bought the plane. It looks like you can set the vertical speed, etc, but not the final alt.

2. I remember reading somewhere that if you lose the EFIS, the integrated AP from TruTrak can still function as a backup to the EFIS, or as a tie-breaker if you are getting conflicting info from 2 different EFIS's. Is this true that the AP will still function w/o the EFIS?

Thanks! Just trying to get a head start on Oshkosh!

Mark Hanley
Finishing the RV-10
Click to expand...

Hi Mark

The AFS system has altitude preselect, as well as vertical speed setpoint. The system will fly a coupled ILS and GPS LNAV/VNAV approach extremely well. It flies the ILS (and GPS) like it's on rails, MUCH better than the Bonanza A36 with King AP that I used to own. With the Bonanza, close in on an ILS the system would cause the airplane to hunt badly, so bad that you needed to be uncoupled below 500' agl.

If the AFS EFIS goes TU, the AP will keep the wings level while holding altitude and heading. It is a great system. I have not flown behind the Garmin system to be able to compare, but I suspect once the Garmin product matures both systems will be similar in performance.
 
Integrated AP

Thanks everyone for the replies. This answers my questions. One thing, it seems that Garmin has made a company wide decision not to do geo-synchronized approach plates like the ones available from several vendors. I haven't seen this in any of their products. I would think this would be extremely useful in hard IFR. Does anyone know if this is a planned upgrade for Garmin?

Thanks again,
Mark Hanley
Finishing the RV-10
 
flydoc said:
........geo-synchronized approach plates......does anyone know if this is a planned upgrade for Garmin?
Click to expand...

Seems I remember reading this is a planned upgrade for the G696, if it's going to happen my guess would be around OSH.

I can tell you that the geo-referenced plate on the AFS system are outstanding....highly readable even on the smaller screen of the 3400, and with great scrolling so you can quickly view the profile and mins. There is no zoom feature, but that is not needed, even for my aging eyeballs. They even have a cool RV type icon for the moving airplane. Another thing I like about them is they are rendered from NACO plates, so you're not dependent on Jepp and their expensive pricing....
 
Obstacles and Synthetic Approaches

flickroll said:
Seems I remember reading this is a planned upgrade for the G696, if it's going to happen my guess would be around OSH.
Click to expand...

Thanks, Jim. If I could ask you a couple of questions about the AFS 4500, does the AFS show obstacles and shaded terrain on the PFD? Can't tell from the website. And lastly, does the Advanced EFIS have a synthetic approach to runways that don't have approaches (like the GRT units). Sorry about all the questions. Beginning to feel like a pest :p.

Thanks again,
Mark Hanley
"Finishing" the RV-10
 
flydoc said:
Thanks everyone for the replies. This answers my questions. One thing, it seems that Garmin has made a company wide decision not to do geo-synchronized approach plates like the ones available from several vendors. I haven't seen this in any of their products. I would think this would be extremely useful in hard IFR. Does anyone know if this is a planned upgrade for Garmin?

Thanks again,
Mark Hanley
Finishing the RV-10
Click to expand...


This is comeing soon, if not already updated
 
I've flown behind the G3X/GX combo for about 25 hours now. In general it's a good system. I do like the AFS/Digiflight method of tracking to altitude better. With AFS you set the vertical speed once (i.e. +/- 500 fps) and the autopilot immediately tracks to wherever you set the altitude bug. It's easy with few buttons and intuitive.

To track to an altitude with the GX/G3X combo you press the "ALT/PTCH" softkey, then set the altitude bug by turning the joystick, then press "AP VS" and select a vertical speed by moving the joystick up or down. Lots of buttons and not super-intuitive.

I do really like the G3X/GX system as a whole but there are issues to be worked out. They really do need to get the VOR/LOC tracking added ASAP as well. If they can do it with GPS, it has to be pretty easy. If they're are going to be playing in the experimental market, they need to keep up.
 
The G3X/GX operating logic is based off the certified G1000 GFC 700 autopilot. As a safety measure, changes in altitude require the pilot to select the method of climb or descent, which can be either VS (vertical speed) or PIT (pitch hold). This helps ensure the autopilot does not do anything the pilot is not expecting. While this does require one additional press of the associated autopilot mode softkey or CWS button, we believe in the operating logic that has been utilized in numerous hours of G1000 flying. A lot of time is spent working out interfaces to certified equipment and we like to leverage successful and proven designs when it makes sense for G3X.

Full coupling to VOR/ILS is expected to be available by the end of the year.

Geo-synchronized FlightCharts (NACO) are currently available for the G3X with software level 4.0 AND FlightCharts database cycle 1011. Geo-synchronized Jeppesen charts will be available soon as well.
 
Just as a point of comparison, the GRT/TT works in a similar fashion for altitude changes in that you select the new altitude and then have to select a climb rate. Granted, if the climb rate doesn't change since your last climb, you just "click through it" very quickly. But you don't get an instant altitude change by selecting a new altitude. I like this in that you can't do something suddenly without being deliberate about it.

Paul
 
tonyjohnson said:
Paul,

Do you know how the new GRT autopilot integrated with the EFIS will handle this issue?
Click to expand...

I haven't flown it yet Tony - but as I understand it, their autopilot is their EFIS software, so I woudl expect it to have the same functionality.

Paul
 
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