GNS RNAV Problem

[Squawk2810 1]

Hello,

my VNAV is not working in RNAV approaches. It works with the default X-Plane GNS and also with the RXP GTN but not with the RXP GNS. (same settings for both)

For example, airport LHPR the RNAV (GNSS) Rwy 12.

At the point PR020 in 2.100 ft the aircraft should start the descent. The RXP GNS show only LNAV and wont start the descent. The RXP GTN shows LNAV+V at is working.

It tried with different airplanes and autopilots, always the same problem.

There also no problems with RNP approaches, only with the RNAV.

Does anyone have an idea?

 

Greetings

[RXP 2,338]

Hi,

I'm not sure about this one but first, there are differences between the GNS and the GTN for that matter:

https://www.garmin.com/en-US/blog/aviation/victors-vectors-lnavv-annunciations-on-your-garmin-navigator/

Then, it could be a known service advisory for the DB, like this one:

https://www.garmin.com/en-US/aviationalerts/service-advisory-1047-rev-a-lnavvnav-and-lnavv-full-scale-deflection/

It seems it is not easy IRL either:

https://www.pilotsofamerica.com/community/threads/rnav-approach-lnav-category-getting-glide-slope-lnav-v.91355/

I'm hoping more knowledgeable people will join in the conversation and shed more light.

Edited February 11, 2020 by RXP

[Squawk2810 1]

Hi Jean-Luc,

thanks for your fast answer and the infos!

Can you reproduce my problem?

I will testing this on other airports and RNAV approaches.

For your information, i use the current version of RXP and my GNS database is from year 2018.

 

[RXP 2,338]

5 minutes ago, Squawk2810 said:

Can you reproduce my problem?

I'm certain I'd get the same outcome. What would help is testing with a more recent DB eventually.

[Bert Pieke 7,591]

4 hours ago, Squawk2810 said:

At the point PR020 in 2.100 ft the aircraft should start the descent. The RXP GNS show only LNAV and wont start the descent. The RXP GTN shows LNAV+V at is working.

 

The GTN is a newer architecture which now includes things like VNAV support.

The GNS never had this and is no longer being developed by Garmin, so I would think that this is the real world situation also..

[fppilot 4,391]

51 minutes ago, Bert Pieke said:

The GTN is a newer architecture which now includes things like VNAV support.

I believe terms are getting crossed.  I read he is looking for AP coupled vertical guidance but the GNS database does not contain it for that airport where the GTN database may.  The GNS can fly LPV, LNAV+V, etc. approaches just fine where they exist in the database if the GNS is correctly coupled to the AP.

[Bert Pieke 7,591]

1 hour ago, fppilot said:

I believe terms are getting crossed.  I read he is looking for AP coupled vertical guidance but the GNS database does not contain it for that airport where the GTN database may.  The GNS can fly LPV, LNAV+V, etc. approaches just fine where they exist in the database if the GNS is correctly coupled to the AP.

I agree... VNAV and LPV, LNAV+V are different terms entirely.. and easily confused..

https://flightlevelsonline.com/2018/garmin-tips-and-tricks-27-vnav-comes-to-the-gtn-650-750/

https://www.garmin.com/en-US/blog/aviation/victors-vectors-lnavv-annunciations-on-your-garmin-navigator/

Edited February 11, 2020 by Bert Pieke

[Bert Pieke 7,591]

9 hours ago, Squawk2810 said:

For example, airport LHPR the RNAV (GNSS) Rwy 12.

At the point PR020 in 2.100 ft the aircraft should start the descent. The RXP GNS show only LNAV and wont start the descent. The RXP GTN shows LNAV+V at is working.

 

I checked a more recent European GNS database, and indeed that RNAV approach is LNAV only for the GNS530.

[Squawk2810 1]

13 hours ago, fppilot said:

I believe terms are getting crossed.  I read he is looking for AP coupled vertical guidance but the GNS database does not contain it for that airport where the GTN database may.  The GNS can fly LPV, LNAV+V, etc. approaches just fine where they exist in the database if the GNS is correctly coupled to the AP.

Exactly!

9 hours ago, Bert Pieke said:

I checked a more recent European GNS database, and indeed that RNAV approach is LNAV only for the GNS530.

Thanks for the info, good to know!

 

I don´t know if this is a RXP GNS or a database problem. Maybe it is in the real GNS the same behavior.

But i will have my real life checkflight soon at this airport, i can test in a PA28R with a GNS430.

Edited February 12, 2020 by Squawk2810

[RXP 2,338]

4 hours ago, Squawk2810 said:

But i will have my real life checkflight soon at this airport, i can test in a PA28R with a GNS430.

We're looking forward to this!

[fppilot 4,391]

Squawk (for lack of a name),
Are you able to get vertical guidance on a published LNAV+V or LPV approach?  What are your settings in the RXP GNS Configuration panel (see image)?  The panel is longer than shown and scrolls to provide settings in addition to what the image shows.  Settings needed may vary from aircraft to aircraft as unfortunately not all aircraft developers write to a single standard.  (Hope that changes with the advent of the new Microsoft Flight Simulator)

Edited February 12, 2020 by fppilot

[Squawk2810 1]

18 hours ago, RXP said:

We're looking forward to this!

sure, i will report

17 hours ago, fppilot said:

Squawk (for lack of a name),
Are you able to get vertical guidance on a published LNAV+V or LPV approach?  What are your settings in the RXP GNS Configuration panel (see image)?  The panel is longer than shown and scrolls to provide settings in addition to what the image shows.  Settings needed may vary from aircraft to aircraft as unfortunately not all aircraft developers write to a single standard.  (Hope that changes with the advent of the new Microsoft Flight Simulator)

yes i know and i am familiar with the settings panel, i tried different settings with several airplanes, always the same problem.

 

I think it its a database problem, because i tested it in LHSM its a airport 62NM southwest of LHPR.

LHSM has a similar RNAV GNSS approach at the descent (+VNAV) works with a problem.

[drnicolas 1]

May I try to show my expereiences.

For comparison, i have a bare metal GNS430W in a Mooney.

I tried several Approaches in real world:

LPV - If a LPV is indicated in the EASA-Chart, then my GNS430W will show me a glidepath. 

LNVA/VNAV - GNS shows a glidepath and in Display LNAV+V. An example is EDQG

LNAV + V - GNS shows a glidepath, but this is only advisory! The EASA chart shows LNAV only. I am not sure, but AFAIK this courtesy of Jeppesen database. An example is EDFM. Nevertheless a perfect add-on. Thanks to Jeppesen

 

On the X-Plane / RXP GNS I see only glidepath on offcially LPV approaches. Neither EDQG nor EDFM gives me a glidepath. The database cannot be responsoble for this - it might be the firmware of the simulator.

Happy Easter

 

[RXP 2,338]

Hi,

Please note the GNS Trainer ships with v3.3 of the Garmin software, while the latest GNS software IRL is 5.x+ . This might also explain some of the differences in the capabilities. Overall it is nearly 95% identical functionality between 3.x and 5.x Garmin GNS software but there are some of these functions related to the these new approaches which are slowly but surely differing over time between simulated and real devices as airports are increasingly adopting them.

[Bruce gazoo Smith 0]

Issue with RXP…X-plane 11 shows glide path functionality when useing gnss 530, but x-plane 12 won’t. Defult Baron shows Glide path flaged. Is this a data base issue or a settings problem? Not sure if my settings are set up correctly for x12.