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Can't seem to load approach

Postby gdtrfb58 » Mon Nov 23, 2015 5:35 pm

I have an HXr with GRT autopilot. I am connected via ARINC and Serial to a GNS 480.
First of all, I was able to load approaches last year. Plane was out of commission from April - November. Now back flying and can't seem to load approaches.

When I power up the 480- all the needles move appropriately (therefore, I believe the ARINC is connected and working). I am able to copy a flight plan from the 480 to the GRT (therefore, I believe the serial port is connected correctly).
1 thing I noticed, if I load the approach and then look at the flight plan on the 480, all the intermediate waypoints of the approach will be in the flight plan. If I view on the GRt, they are not. They also dont appear on the GRT if I copy again.

OBS on GRT is set to the 480

I first load the approach on the 480 (no problem). I then go to the GRT. The sections under "ARM" are all grayed out. This was true yesterday for both an ILS & a GPSV.

On the ILS, the 480 was tuned to the localizer and the OBS set to "loc"
I was able to hand fly the ILS. The crosshairs never appeared, but the CDI showed both the vertical and lateral guidance. Another anomaly, the ILS included a procedure turn, but I was vectored in to capture on the leg after the PT. I selected that leg on the 480 and "fly leg", yet the CDI showed opposite deflection (as if it was "reverse sensing"). I was actually descending through clouds so I didnt check the CDI built into the 480 for comparison.

I believe that each time I was trying to do this with the flight plan set to "external", but I might have tried "internal" as well. Does flight plan have to be on "Internal" with the last WP being the airport? If so, does it matter that the approach waypoints aren't in the internal FP?

I am pretty sure this is an operational problem (mine) not an equipment malfunction.

I did go back and view all the videos and re-read all the user guides.
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Re: Can't seem to load approach

Postby Bobturner » Tue Nov 24, 2015 11:27 pm

I may be all wrong here, as I do not have a 480. I have a 420W. I have to do more than "load" the approach on the 420W; I have to "activate" it too. After calling up the approach from memory, selecting the IAF or vectors, I push "enter" TWICE. The first push loads the approach into memory; the second push activates it into the flight plan. If the approach is activated the GRT ARM selections should not be grayed out.
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Re: Can't seem to load approach

Postby Bobturner » Tue Nov 24, 2015 11:29 pm

PS I would recommend not flying any actual imc until you get this sorted out.
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Re: Can't seem to load approach

Postby gdtrfb58 » Wed Nov 25, 2015 12:07 am

On the 480 you have to "execute" the approach, which I did each time, but the choices remained gray. I fly with a 480 in every aircraft I have flown ~12 years, so I am pretty proficient with it.

It initially took me ~15-20 hours to get comfortable flying IFR with the GRT, but then I didn't fly with it for 7 months. It's amazing how fast you lose proficiency.

I agree about staying VFR. Happily, the weather here is supposed to be good for the next week. I plan to fly with another pilot (until I get this down) so I can push buttons.

Luckily, I can still hand fly the ILS the old fashion way using the CDI (on the GRT). The situational awareness is still lightyears ahead of where I would be in most of the other aircraft I fly. Geo-referenced plate, weather and Synthetic Vision with the runway on the screen!
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Re: Can't seem to load approach

Postby GRT_Jeff » Wed Nov 25, 2015 2:53 am

The 480 might not send us all the approach waypoints, and even if it does, it won't tell us what to do with them. This means the EFIS can't directly fly an approach procedure in ENAV mode. You would need GNAV mode or a direct connection to an autopilot that can read 480 data, assuming the 480 will generate autopilot commands for that procedure.

The ARM functions will only work if valid data is detected and you're displaying it on the PFD.
GPSV - The GPS data must be valid and displaying on the PFD localizer/glideslope indicators
LOC/LOC-REV/ILS - an ILS frequency must be tuned (active)

The ARM functions can only be used for the final part of the approach. They are designed to fly straight down to the runway and will not fly any turns or holds in the procedure. You must not EXECUTE the ARM mode until those turns have been completed and you are ready to intercept the localizer or runway.
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Re: Can't seem to load approach

Postby Sportsman » Wed Nov 25, 2015 5:14 am

Jeff - I'm not sure I understand your response to this question, so please bear with me...

Customer indicates GNS480/HXr combination previously was able to load an approach, but now cannot.
Have there been any changes to this area of the HX/HXr code in recent versions?

If no changes in HX/HXr code, and assuming the code in the GNS480 hasn't been updated, what's changed?

Your response seems to indicate GRT has a lack of knowledge of GNS480 interface capabilities, even though the 480 has been around since the early days of the WS/HS screens and compatibility with the 480 has been a part of the GRT installation manuals since those early days. I suspect we're asking you to go back into the archives on this topic. The HX installation manual clearly indicates compatibility with GNS480, including wiring diagrams to install this pairing using either analog or A429/RS232 serial connections. In light of this background I think those of us using GNS480's are left scratching our heads. Would you be able to provide a little more clarity, please?

As an aside, even the barebones autopilot featured in the legacy Dynon devices will faithfully follow the lateral guidance portion of approaches loaded from a GNS480. Having witnessed this in action recently I have to believe the GRT product offers at least this level of performance, and I would suspect the GRT product indeed offers significantly enhanced performance. Any additional details you can share would be truly appreciated.
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Re: Can't seem to load approach

Postby Sportsman » Wed Nov 25, 2015 5:16 am

As a follow-up to my post above, is there a chance the inability to load an approach has something to do with the relative ages of the nav databases in the HXr and GNS480? Is this a situation where having old data in one box and new data in another could produce a mis-compare between the waypoints and thus a failure to load an approach?

Just trying to noodle my way through this...
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Re: Can't seem to load approach

Postby gdtrfb58 » Wed Nov 25, 2015 11:29 am

All the databases are current.

The I use the 480 with a Century 2000 and a STEC-50 regularly and I can fly the entire approach once I select "execute" on the 480 and "Direct to" the first leg. Depending on the AP, you can select "Heading" and "Capture" together and the AP will intercept the approach. I have GPSS in 1 aircraft and it will fly the holds as well.

I think my problem is with the sequence.
I have to be on GNAV initially.
Do I have to be on an Internal Flight plan, external or doesn't it matter?
It';s not a problem of selecting "Execute" on the GRT too early, I cannot even "Arm" on the GRT.
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Re: Can't seem to load approach

Postby Bobturner » Wed Nov 25, 2015 5:03 pm

I always use external flight plan (flight plan in 420W).
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Re: Can't seem to load approach

Postby gdtrfb58 » Wed Nov 25, 2015 10:59 pm

IMG_1059.jpg
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Ok. Tried again today.
Went out to airport. On the ground, Loaded a flight plan to MGJ into 480. Copied to GRT. Selected an approach on the 480, loaded (GPS 21) and "execute" (on 480). Went to GRT (still on ground) and all the menu choices were accessible (Arm, etc). I armed the approach and the "Execute" softkey appeared as it should. I shut down the master and took care of some other things. Went back to aircraft, got my clearance and departed. Once in the air, I actually changed approaches on the 480. Went to the GRT AP menus and everything is grayed out again.(Photo attached). I noticed that ENAV is available, but not GNAV. I was able to fly the approach on the AP, but not "armed" as an approach. It followed the imported FP (including the approach fixes) and I manually entered the altitudes, but it was never in "Approach Mode". Later, I was able to enter a synthetic approach to runway 11 @ HPN and I was able to Arm it and execute, but it never captured the gluideslope. I am stumped.
If you notice on the photo of the 480, I tried this enroute, before I was at the IAF (TRASE). I tried again after TRASE, but still no joy.
BTW the 480 is GPS 2. The First Photo is the screen when I was flying to TRASE. Note the AP indicators. No approach.
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IMG_1061.jpg (106.78 KiB) Viewed 13341 times
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