VNAV transitions on RNAV/RNP approaches...

[robnewman76 0]

Hi all...

 

I'll start by saying that I'm very familiar with the Vnav function on the Q400... not just in the Majestic version, but in real life too... It's my day job

 

With that said, I'm having an issue with VNAV during approaches. Doesn't matter if I use a RNAV LPV approach, or a RNP approach... I set up both FMS to the apporach, enter it through the IAF, I have the field elevation set in the alerter with no ALT SEL, flying in NAV mode with FMS set as nav source... All as it should be. I even see the correct sequence of altitudes in the flight plan, all correct as per the IAP.

 

Now for the issue... As soon as I hit the IAF, my vertical guidance becomes "PITCH HOLD" (the active "VNAV PATH" is cancelled) and the continuous vertical path between the IAF and the next fix is screwed up... it tells me I am below the path. If I fly level, it will eventually come back, and I have to hit the VNAV button again to arm it.

 

This repeats at every fix, including those on the final course... Quite distracting when you're trying to follow a glidescope but it keeps changing at every fix.

 

 

I suspect the root of my issue lies with the changing glidepath... I believe it's normal behaviour of the vertical guidance system to "fail to Pitch Hold" if the VNAV path is out of limits...

 

Here's a picture showing what I mean (this happens on all FMS based approaches, to all airports)...

 

Anyone else having such issues? I could have sworn in previous builds I was able to fly seamless arrival/approaches with full VNAV... Is this perhaps a bug that has crept in in recent builds? Am I doing something embarrassingly wrong?

 

Thanks in advance...

[praga 0]

Version 1013, Airport LKPR works as expected.

[robnewman76 0]

Very curious...

 

I tried LKPR and has the same problems...

 

So I tried installing a newer nav data database (The latest update from Navigraph). The newer nav data seemdd to fix it

 

I guess there's a few gremlins in the default nav data...

[praga 0]

Tried today version 1014, I confirm I can reproduce WRONG behaviour. It is bug introduced in 1014. Please report. Add me as cc in the report.

 

Thank you!

Edit: Updating database to 1502 does not fixes the issue for me.

[crosswind 825]

@robnewman76,

 

Thank you for the detailed breakdown regarding the VNAV issue that you have been experiencing.  We will have another look at this and try to replicate it.  Apologies for the delayed response, as it is easier to get a quicker response by posting on the Majestic Software forums.  I don't frequent the AVSIM forums as much as  I would like to, and AVSIM's site seem to be extremely slow loading lately.