Thoughts on the G3X

Well now that we have the RV-3 out of Phase 1, I guess that means we have about 40 hours flying behind the dual-screen G3x! (That is, of course, split between Louise and I – and Louise had more G3X flight time than I did before we started, since she did the lion’s share of the trip when we ferried “Flash” back from Oshkosh 2010). While we have been mostly concentrating on the airframe Phase 1 so far, the fact that the G3X has been pretty transparent to our efforts says volumes – it is pretty natural to use.

One of the best things we have found so far (aside from the fact that it has been a reliable set of flight instruments) is the recording capability. The GRT system I have been flying for years in the RV-8 proved to me just how valuable it is to be able to test fly without hand-recording data, and their system works fine – although you need a user-developed program to read the data files post-flight. The G3X data files are in an Excel-readable format, with column headers already attached, so you just put the flash drive in your computer and double-click…voila – the data is easy to read and plot, right there! (Of course, one cool feature of the GRT recorder is that you can play the files back on the screen and make videos of the flight while sitting stable on the ground later one….).

So far, I had only one instance of the AHRS losing it's reference – I was able to confuse the AHRS bad enough that it decided it needed some quiet, straight and level time to re-align after a serious aerobatic sequence of maneuvers.( I must admit, my own physiological AHRS was happy for the quiet time as well…) The folks at Garmin looked at the files I generated and tweaked some parameters – and the problem hasn’t repeated. The sequence was multiple rolls followed by significant pitching (think Immelmans and loops with rolls at the end....)

Screen readability has been outstanding – I have not yet seen a lighting situation where we couldn’t clearly read the screens. I was curious how I’d like having the PFD offset from the centerline, and it has been a complete non-issue. Autopilot control is done mostly with the PFD buttons and knob, and Map/flight planning is done with the MFD controls – a nice split that works logically. Having had a 696 for a couple of years, the human interface is fairly logical, but it does take a little bit of learning if you are new to the system. We wired out system up with the ability to put it in to “demo mode”, so we could fly it on the ground during construction – this made a big difference as well.

The integration between the TruTrak GXPilot (autopilot) and G3X is impressive, and we have just begun to tap it’s capabilities. I have not used it enough to confidently know what is going to happen with every combination of button pushes, so I’m not going to file IFR with it yet – but I am pretty sure that once I devote a little time to it, there will suddenly come a day when it “clicks”. One of the unique problems with a single-seat airplane is that you can’t have a safety pilot along while you’re learning to fly all the modes – it would be nice to have a ground PC simulator for the system, but I suspect that would cost a fair amount of development time for Garmin – and they might not feel that there was a big enough return. But the aforementioned Demo Mode is a good start.

Engine monitoring is very stable, and the filtering on most of the parameters is right on. Aside from a flaky left fuel sender and elevator trim indicator (both are problems outside of the G3X), everything indicates fine. We have a start-up procedure that illustrates the thought put into the menu system – once the system boots, we acknowledge the warning message on the MFD, then just twist the knob all the way right – and the right-most page is engine stuff – what we want to look at for start. If you suddenly had the need to look at a parameter – turn the knob all the way right – it’s what you need. Good design.

Integration with the GNS430W is very clean. The ability to run on either the internal (G3X) or external (430W) flight plans is something that was added in the past year, and works remarkably well – I really like being able to build multiple plans and switch between them. The approach features from the 430W work seamlessly through the G3X to the autopilot, and I watched it fly a fully coupled, full-GPS approach yesterday without touching a thing – it anticipated turns, began the decent, and told me “500 feet” as we got there - very nice.

I have very little time with traffic systems, but the GTX 330 gives us TIS information which is displayed on the G3X, and I have adapted to it very quickly – the point of almost missing it on the GRT when I fly the RV-8. The only issue I have seen is systemic (not related to the Garmin) – when flying a series of Acro maneuvers, the ATC system gets confused and displays me as traffic to myself – which can be un-nerving when you get a traffic call in the middle of a loop. False alarms can make you complacent, and I might have to start turning it off before having fun. In the same vein, I get repeating terrain alerts on every landing, and it would be nice to be able to acknowledge the first one, then not hear anymore. The idea of inhibiting critical alarms is, of course, a slippery slope. I’ve been talking to the Garmin guys about how I think this should be implemented, and I’ll be the first to admit that I don’t have a good answer.

All in all, I am extremely happy with the G3X so far. It is reliable, capable, and for the most part, well thought out. Improvements come with each software drop (free updates), and I can only see the feature set getting better and better. I look forward to moving into some IFR flight with the system (after additional evaluation and practice of course). We’ll stretch it’s legs a bit now that we are free to move around the country – and I really look forward to seeing what the Synthetic Vision will show in the mountains. Hmmm…sounds like a LONG cross-country might be needed….

Paul

G3X Pirep

So far have only a couple hours behind a dual screen G3X system.

In one word "great!"

The calibration process went better than expected. Followed the prompts on the screen. The Synthetic Vision and Pathways in the sky are great for increased situational awareness. I really like the display of traffic on the PFD in its relative position in "3D". For example, when a traffic target gets within a certain distance the traffic target icon blossums into a yellow circle. Sure gets your attention.

Tech support from Garmin was great whenever a question came up.

Highly recommend the G3X

Hold after missed approach

Has anyone had a chance to see how a G3x/430w/GXPilot setup behaves on a hold following a missed ILS approach? Specifically, I'd like to know if the autopilot continues following the 430w GPS roll steering commands through the published missed approach sequence (including the hold).

I'm considering an upgrade to the G3X, and I want to make sure I know what I'm getting into.

Thanks,

M

You have to command an approach certified GPS to continue beyond the MAP. Once you command the missed approach, should follow the missed to the hold just like normal.

The 430W will output GPS roll steering commands after the MAP if you tell it to like he says above. THe G3X/GXPilot should follow this just fine but I don't have one so I can't say for sure. This is basic AP stuff so I would be shocked if it did not.

foka4 said:

Has anyone had a chance to see how a G3x/430w/GXPilot setup behaves on a hold following a missed ILS approach? Specifically, I'd like to know if the autopilot continues following the 430w GPS roll steering commands through the published missed approach sequence (including the hold).

I'm considering an upgrade to the G3X, and I want to make sure I know what I'm getting into.

Thanks,

M

Click to expand...

foka4 said:

Has anyone had a chance to see how a G3x/430w/GXPilot setup behaves on a hold following a missed ILS approach? Specifically, I'd like to know if the autopilot continues following the 430w GPS roll steering commands through the published missed approach sequence (including the hold).

Click to expand...

Hi M,

The short answer is: Yes, it works great!

By way of a longer answer, I'll walk you through what I do when I'm flying a G3X/430W/GX Pilot equipped aircraft on an instrument approach. The same basic series of steps applies to both ILS and GPS WAAS approaches:

1. Well outside the final approach fix, I brief the approach from my printed plate or electronic chart. At this point I enter the initial missed approach altitude ("climb to ___ft") in the G3X PFD's altitude preselect field, and I also use the Baro Minimums feature on the G3X PFD to dial in the DH/DA for the approach.
2. When cleared for the approach, I press the autopilot APPR softkey on the G3X PFD to arm the autopilot to capture the localizer and glideslope (for an ILS) or the GPS course and glidepath (for a WAAS LPV or LNAV+V approach). The airplane then captures the lateral and vertical guidance and flies itself down the chute.
3. Upon reaching the decision height or missed approach point, when the G3X approach minimums voice alert sounds in my headset - "minimums, minimums!" - I use the autopilot disconnect button on the stick to disengage the autopilot and take control manually. At the same time, I'm adding power and pitching the nose for climb attitude. The important thing at this stage, of course, is to get the airplane climbing away from the ground, not be pressing buttons. That's true no matter if you're using an autopilot or hand-flying.
4. Once the aircraft is established in a climb and I'm at an altitude where it's safe to mess with the avionics, I press the SUSP button on the 430W to activate the missed approach procedure, then press the autopilot NAV softkey on the G3X PFD. That engages the autopilot again with GPS nav mode active, and it also defaults to holding the climb pitch attitude (PIT mode) that I established when I was hand-flying.
5. Most of the time, that's all I need to do to fly a fully coupled missed approach! In the roll axis, the airplane steers itself through the full missed approach procedure and enters the hold all on its own, where it's happy to stay all day until I tell it to do something else. Vertically speaking, if I take no further action the airplane will climb at a constant pitch attitude (and thus a fairly constant airspeed) until it reaches my pre-selected altitude, at which point it will capture that altitude and level off.
6. If I decide I want to climb faster or slower, I can use the joystick on the G3X PFD to adjust the pitch attitude, or I can do the same thing using the CWS button on the stick. Or, I can use the autopilot VS mode softkey on the G3X PFD if I decide I want to climb using a vertical speed instead of a pitch attitude. And if the missed approach procedure involves something more complicated like a crossing altitude restriction or a series of step climbs, that's no sweat to accomplish either.

As with everything else in instrument flying, it's easiest when you get things set up ahead of time. It actually takes longer to read through the procedure than it does to make it happen - get to the missed approach point, start your climb, tap a couple of buttons, and then let the equipment do the driving while you talk on the radio.

By the way, for anyone reading this who has experience flying behind the certified G1000 system with the GFC700 autopilot, you should find the sequence of steps described above very familiar. In fact these are the exact same things you'd do if you were flying an instrument procedure in any GFC700 equipped airplane up through a Citation Ten, since the G3X autopilot interface inherits its design from the same lineage.

Hope that helps you get a picture of the process. If you're planning to be at Sun-N-Fun or Oshkosh, stop by and I'll walk you through a demo of how it works using the real equipment!

- Matt

Magnetometer Calibration

Our airport does not have a compass rose but the calibration worked just fine using the G430 heading (about page 5 in the NAV function).

dfechter said:

Our airport does not have a compass rose but the calibration worked just fine using the G430 heading (about page 5 in the NAV function).

Click to expand...

We were in the same boat - no compass rose at our private field. But because it's just a small paved airpark, there was no re-bar in the pavement either, so we just used a surveying compass to lay out a nice North-South line, and used that as a baseline. The calibration process was very easy to follow, and we haven't seen any problems in flight.

Paul