Hi,

Did not respect to level off and busted altitude at AFIVA wpt, speed was OK but instead of leveling off at 8000 FT it did climb to 10K

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Hi,

I see a few problems related to A/P in VNAV busting altitudes examples as to

Late level offs and busting altitude by 180 FT to 200 FT (in our case at 10K) see the picture

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Hi,

And a big problem with course to intercept to WIKIR, while I was on HDG 060 to intercept 006 and selected LNAV the airplane turned directly to the wpt instead to maintain the heading to intercept the Magenta line. Usually, it will maintain heading and intercept course to the wpt within 2 1/2 NM before the magenta line or earlier based on the ground speed. See the pics.

Thank you.

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Hi,

Or in descend, at WIKIR it did not cross it at 2500B

Thank you.

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AIIR#6 https://www.captainsim.org/forum/csf.pl?num=1588001095

Traian_Vuia wrote on Jul 27^th, 2020 at 5:43am:

Hi, Did not respect to level off and busted altitude at AFIVA wpt, speed was OK but instead of leveling off at 8000 FT it did climb to 10K

If you look at your first picture, there's an altitude missing on one of your waypoints, which usually means either there's a cost index/speed that makes the profile impossible to fly, or your PERF INIT isn't fully filled out/ improperly filled out.

LNAV: Yes LNAV it's broken, and it shouldn't fly directly to a waypoint if it's not on an intercept.

Your last report about 2500B... that's perfectly fine / normal / legal. At least your VNAV path vector shows you're a little off like it's supposed to. Jets in real life often cross +/- 100 that's totally expected while doing a descent and a complicated turn.

Alex,

What you need to know is the following:
You cannot have VNAV engaged at all if your performance data is incomplete and if you pay attention to the FMAs you will see clearly that the VNAV is (in green) ARMED.
That altitude missing that you correctly noticed is code related that is not computing correct to a wpt manually created as a PBD.
That 8K FT that I'm talking about is a "hard altitude" for a wpt that was busted, again a coding problem to be easily fixed.
We both agree that LNAV needs pampering.
As a real pilot, I assure you that with the latest versions of the FMC that issue not being able to comply with 2500B in our case is not "perfectly fine/normal and if you look at the ATP/L standards it's not. On top of that if the FMS is not capable to make a crossing restriction you will get UNABLE NEXT ALT.
As a real pilot, jets in real-life comply indeed with crossing restrictions. I have to admit that very small deviations are encountered under turbulent wx conditions.
As a real pilot, I would like to call to your attention that there is no "VNAV path-vector", we call it vnav deviation scale with a vnav pointer.
The bottom line here is that we're looking to have some items fixed for a better sim experience.

I have some issues with VNAV in 0.991 as well. I took off from UUEE, armed LNAV and VNAV and everything went well until it started descending for landing at LTAI.

As you can see in the image below, i was supposed to be above 17000 ft at the next waypoint (AI730) but the altimeter already indicates 14600 before reaching the waypoint.

VNAV was in control all the time, i didn't disconnect it or modify anything in the FMC. The deviation scale was disappearing from time to time, so that's why you can't see it in the screenshot.

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Alex Voicu wrote on Jul 28^th, 2020 at 9:48am:

I have some issues with VNAV in 0.991 as well.

If you want your report considered by developers pls follow the rules https://www.captainsim.org/forum/csf.pl?num=1588001095

Pls try HF0993