Just wondering as I don’t have the ATR, but does it have LPV approach capability? Or is it like the CRJ with LNAV only?

I can confirm that the humble G1000 172 flies the approach correctly. Launching now in the ATR.

48 minutes ago, snglecoil said:

Just wondering as I don’t have the ATR, but does it have LPV approach capability? Or is it like the CRJ with LNAV only?

It can fly LPV, even RNP approaches. Good point to clarify though!

1 hour ago, mryan75 said:

I can confirm that the humble G1000 172 flies the approach correctly. Launching now in the ATR.

So I just flew the RNAV10 at TTPP in the ATR, it didn't quite touch down at the ARP, but maybe 50-100 yards short. So now I am going to fly the RNAV09 at TBPB and try that one. The ARP there is again about halfway down the runway.

This thread should be retitled "ATR  major Rnav  bug. "

1 hour ago, mryan75 said:

So I just flew the RNAV10 at TTPP in the ATR, it didn't quite touch down at the ARP, but maybe 50-100 yards short. So now I am going to fly the RNAV09 at TBPB and try that one. The ARP there is again about halfway down the runway.

You need more variety than TTPP. Please try somewhere completely different and see if the behavior for you is the same.

8 hours ago, sd_flyer said:

How do you do this? Is there a way to edit  navdata PMDG? I honestly wasn't aware!

Yup... In your PMDG folder in the community folder, search for a folder called SIDSTARS.  In it, you'll find a text file for every airport in the database, worldwide.  All the procedures are defined in there; you can modify them and write your own etc.  There's an old tutorial - I think hosted on Avsim - about creating your own custom procedures.  I've used this to build some of our custom RNPs and it's pretty cool to see the PMDG fly them correctly.  Mostly 😂.

There are other locations in the folder containing the SIDSTARS folder where you can modify airport data - that's where runway elevations can be tweaked.

PMDG stuff is easier to modify ironically because it's older, and uses this plain-text format in text files.  You can modify other navdata types used in newer aircraft like the Fenix as well, but this involves installing a database editor to modify the SQLite database.  This stuff is fun to tinker with... If you break something, just do a Navigraph update and everything will be back to default.

Just did the RNAV07 at TAPA and would have flown me straight into the ground about a mile short of the runway, although it is an LNAV approach with the phantom VNAV guidance. Next up will be TKPK.

1 hour ago, Stearmandriver said:

Yup... In your PMDG folder in the community folder, search for a folder called SIDSTARS.  In it, you'll find a text file for every airport in the database, worldwide.  All the procedures are defined in there; you can modify them and write your own etc.  There's an old tutorial - I think hosted on Avsim - about creating your own custom procedures.  I've used this to build some of our custom RNPs and it's pretty cool to see the PMDG fly them correctly.  Mostly 😂.

There are other locations in the folder containing the SIDSTARS folder where you can modify airport data - that's where runway elevations can be tweaked.

PMDG stuff is easier to modify ironically because it's older, and uses this plain-text format in text files.  You can modify other navdata types used in newer aircraft like the Fenix as well, but this involves installing a database editor to modify the SQLite database.  This stuff is fun to tinker with... If you break something, just do a Navigraph update and everything will be back to default.

That's really interesting! I never knew that.

1 hour ago, mryan75 said:

phantom VNAV

The VDP for this approach is at 630 MSL and 1.6 nm from the approach end of the runway. What is the relevance of where the 3 degree flight path angle intercepts the ground?

3 hours ago, jrw4 said:

The VDP for this approach is at 630 MSL and 1.6 nm from the approach end of the runway. What is the relevance of where the 3 degree flight path angle intercepts the ground?

The glidepath VNAV draws should extend from the touchdown zone of the runway, up through the VDP, in a straight line at whatever angle the glidepath uses.  So if it's 3.0 degrees, then the significance of where the 3.0 degree flight path angle intercepts the ground is that, if it's not in the touchdown zone, then the FMC isn't calculating VNAV path correctly.  Evidence of a bug, in other words.

If you can please contact the ATR dev Hans Hartmann to get this issue fixed that would be great. We had 2 major updates for the ATR since its release and should be expecting a 3rd update. People have noted RNAV issues with this specific aircraft on the MSFS forums so I hope it does eventually get fixed.

9 hours ago, Stearmandriver said:

Evidence of a bug, in other words.

Agreed, but that's been well established by now. But this is an LNAV only approach, so while the GP might be too steep, all that does is get me to the MDA a bit sooner. What seems odd here is that at this airport, the FMS doesn't seem to be using the ARP as the aiming point. Just something that needs to be fixed by the ATR dev......

So I just tried to fly the RNAV 08L to Miami which is an LPV with a nice low minimum. Should be the most precise RNAV on offer. Flew it in Clear Weather preset, so no atmospheric issues, used the stock airport. Flew the approach 3 times.

First: didn't capture when it should have, high the entire time with steep descent, then flattened out at about 500 feet and flew me all the way down to the midpoint of the runway.

Second: Captured glideslope 1.5 miles before it should have, was way low and would have resulted in CFIT.

Third time, I flew way out so I would have a 15-mile straight in final. Crossed VICUV at 3000... nothing.... nothing... nothing... about 1.5 miles from KACDE where glideslope intercept was 1,500 feet, it started diving to catch it. Crossed KACDE at 1,500. Was correct at 4 miles, correct at 3 miles, correct (roughly) at two miles, then got way low, I thought it was going to hit the ground, then at about 200 feet with 4 reds on the PAPIs it leveled off and flew at a very shallow descent rate... and landed halfway down the runway.

I'm kind of out of theories. The one thing that has been consistent is that there is about 0.6 miles added to the glideslope intercept waypoint, in this case KACDE. It should have been 4.5, and it was 5.1.

Does anyone know how to contact Hans?

The other thing I noticed is that the Navdata in the plane was from 2022, even though MSFS has updated the AIRAC several times since then, including in the last week or two.

I don't have any knowledge on this topic, but there is (or better: was) a topic on CRJ updates going at the Aerosoft forum

https://forum.aerosoft.com/index.php?/topic/176550-crj-update-status-with-new-staff/

This also mentions "fixes to the LNAV and VNAV issues" by Hans.

I didn't find a contact in Hans' profile but would suggest opening a ticket with Aerosoft who may - or may not - transfer your issue report to him.

Kind regards, Michael