GPSV mode with Trio ProPilot and GNS 430W

I've got a Trio ProPilot autopilot and a Garmin GNS 430W. The GPSS lateral steering from the 430W has always worked well with the ProPilot. Yesterday was the first time I've been to an airport with an LPV approach since I installed the autopilot, so it was the first opportunity I've had to try out the GPSV vertical steering. It didn't work

I loaded the KMTW RNAV RWY 17 approach in the 430W, and it went active. LPV was showing in green reverse video on the 430W when I was on the final approach segment. The GPSS lateral steering was working. The vertical path was there on the CDI, but the GPSV LED on the ProPilot never blinked, lit or did anything at all.

As I understand it, the GPSV signal comes over the same ARINC 429 bus as the GPSS signal, so if GPSS works that should mean my wiring is OK. I can't find any mention of any special configuration or tricks in the Trio manuals, so I think everything is setup OK on the autopilot end. But, the 430W Installation Manual lists many different options for the ARINC 429 DATA OUT. I'm pretty sure I've got "ARINC 429" selected as the format. I don't recall whether I've got High speed or Low speed selected.

If anyone has their ProPilot's GPSV working with a GNS 430W, I'd love to know what your setup is for the ARINC 429 Config. Which 429 format have you selected? High speed or low speed? I'm only going to be in Manitowoc for another couple of days, and then I'll be heading back to Ottawa. There are no LPV approaches in the Ottawa area, so I'd like to take advantage of my time here to debug this.

Thanks for any info or advice.

Kevin,

Two things to check on the Main ARINC 429 Config Page in the 430W, which I believe is the first thing you see in config mode:

1. Make sure the output data format is "GAMA 429" (not "ARINC 429").

2. Make sure the selection next to "VNAV" says "Enable Labels".

mcb

Thanks Matt. I hope to get a local flight off first thing tomorrow morning, and I'll adjust those config settings and try again.

Once I confirm these config settings do the job I'll suggest to Trio that they add the info to their manuals, as GNS 430Ws are so prolific.

For Garmin, the GNS 400W series installation manual does a great job of explaining the format of the RS-232 outputs, but there is next to nothing about which labels are sent in each of the various ARINC 429 options. It would be nice to have an appendix that went showed exact which labels are sent, and how each data item is formated.

Kevin Horton said:

It would be nice to have an appendix that went showed exact which labels are sent, and how each data item is formated.

Click to expand...

Have you checked out section 4.6.1.2 in the install manual? That shows which formats transmit which labels. As for formatting, unfortunately ARINC charges for their documents (more's the pity). But your autopilot manufacturer ought to be able to tell you which labels they need... at a guess, I'd say 121 and 117G at a minimum.

mcb

mburch said:

Have you checked out section 4.6.1.2 in the install manual? That shows which formats transmit which labels. As for formatting, unfortunately ARINC charges for their documents (more's the pity). But your autopilot manufacturer ought to be able to tell you which labels they need... at a guess, I'd say 121 and 117G at a minimum.

mcb

Click to expand...

Matt - I missed that section. Thanks for the pointer. I was expecting to find the info in an appendix, like they did with the RS-232 stuff.

I hadn't noted the VNAV "Enable Labels"/"Disable Labels" setting. I bet mine is disabled.

GNSS LPV Approach

Hi Kevin
''There are no LPV approaches in the Ottawa area, so I'd like to take advantage of my time here to debug this.''
-----------------------------------------------------
Don't you think this is weird that Ottawa being the Nation's Capital is the only airport in Canada where there is still a Loc Back Course as the only approach on the most often used runway??

With your connection at Transport Kevin, could you pull some strings so we can get an approach with minimums we can used all the times..

I'll buy the beer if you can pull this thru..;-)

Cheers

Bruno

RV-4 said:

Hi Kevin
''There are no LPV approaches in the Ottawa area, so I'd like to take advantage of my time here to debug this.''
-----------------------------------------------------
Don't you think this is weird that Ottawa being the Nation's Capital is the only airport in Canada where there is still a Loc Back Course as the only approach on the most often used runway??

With your connection at Transport Kevin, could you pull some strings so we can get an approach with minimums we can used all the times..

I'll buy the beer if you can pull this thru..;-)

Cheers

Bruno

Click to expand...

You'll have to find another excuse to buy me a beer Bruno, as this problem is way beyond my pay grade. I think any new ILS system would have to be funded by the airport, and I doubt they are prepared to foot that bill, as it is exceedingly rare to have weather approaching LOC-BC minimums and winds that don't allow use of the ILS on either Rwy 32 or 07. I'd like to see an LPV approach on 25, and the development of that procedure would be paid for by Nav Canada. But, I suspect they are prioritizing LPV approach design for runways that don't have any decent approach now.

It is clear that the FAA has put a lot more resources in developing LPV approaches than Nav Canada has. Many of the airports in upper Michigan and Wisconsin have LPV approaches at each end of their main runway. In Canada, I'd have to fly a long ways from my home base to find an LPV approach. Down here there I count 87 LPV approaches in the state of Wisconsin alone.

I did get a local flight off this morning, but my passenger was looking very green around the gills by the time I came back to the airport. I really, really wanted to get her on the ground before she exploded, so I didn't dare take the time to try a coupled LPV approach. I made it, but not by much.

I've got two more in-laws lined up for flights tomorrow morning - hopefully I can fit an LPV approach test in on one of those flights.

Kevin. I've got the ProPilot to work with the 430W. I just recently sent it back to Trio to add the GPSS and GPSV features. I'm not sure if they've made any updates recently. So far I've only tried a few approaches and it seems to work fine. Even though I didn't really know what I was doing because I got my IFR ticket before GPS's. I have a selector to switch between the 430W and AFS EFIS. So far I have yet to figure how to make it work with the EFIS. It tracks like a drunken sailor when using the ARINC output from EFIS. The EFIS does display the output from the 430W fine. I'll have to spend more time on that issue. The guys at Trio are very helpful and even return emails on weekends. I'm sure they can help you out with it.

I did four short flights this morning, taking various in-laws up for flights. KMTW to KSUE, two flights out of KSUE, and then back to KMTW. I tried the LPV approach on the way into KSUE, and it worked as advertised. The little GPSV LED blinked and lit as described in the manual, and the autopilot did a pretty good job on the LPV lateral and vertical tracking.

The GNS 430W 429 config for the failed test a few days ago was Data Out "ARINC 429", and the VNAV labels were disabled, which I assume is the default configuration. For today's successful test, I set the Data Out to "GAMA 429", and I enabled the VNAV labels.

Thanks Matt for the help.

GPS APPROACH

Hello Kevin

''You'll have to find another excuse to buy me a beer Bruno, as this problem is way beyond my pay grade. ''
--------------------------------------------
Ah well..I thought it was worth a try... We have being told at work that a GPS approach is in the works for RWY 25...not sure if it will have the lower minimums but at least we will be able to fly it fully managed in the Airbus vs selected for the B/C..

I saw your RV-8 in Gatineau...really nice machine...

Cheers

Bruno
p.s: It will still be my pleasure to buy you one Kevin..

A follow up: I discovered today that with the above GNS430W settings my Trio Pro Pilot not only couples up to LPV approaches, it works with the advisory vertical guidance (Garmin calls it LNAV+V) on RNAV approaches. I had tried this soon after first installing the autopilot, and it hadn't worked, so I had assumed that Trio didn't support that. But, up until today, I hadn't tried again since I changed the GNS430W settings as advised by Matt Burch. I'm very happy that it couples up to the LNAV+V vertical info, as it will reduce the workload if I ever have to fly an RNAV approach in poor weather.