VNAV Path Descent

[Greaser]

Folks the crashes to desktop seem to have stopped since disabling xEnviro.  Now I am doing some actual flights but noticing some serious issues with VNAV descent.  During descent it pauses for a minute or two. There are no restrictions or anything but the descent just pauses. Eventually it resume descent often diving in altitude.  Approaches come in too high and fast.  Hopefully there will be fix soon because this is a real issue right now. 

[Litjan]

Hi John,

happy you got rid of the crashes.

The VNAV descent not working correctly in many cases is a known issue and there are plenty of threads here regarding the problem. In a nutshell: The VNAV descent works only for very straightforward descents without any restrictions. In most cases I recommend to fly the desired approach path with other basic autopilot modes and do a manual descent calculation, there are examples on how to do that in the enclosed instruction. We are working on improving VNAV, and while this should not be an excuse for VNAV not working, I like to mention that only a small fraction of descents in the real airplane are flown in VNAV.

Cheers, Jan

 

[Greaser]

Thank you for the reply. Good to know it's being improved. With those updates, will VNAV function below 3000 feet?  Will a RNAV/VNAV approach be possible?

Second, when setting FMC restrictions on descent I got "UNABLE CRZ ALTITUDE" (I figure though this is related to VNAV and will be fixed too) ...........

[wain]

glad I came across this, I had a few issues with VNAV but just resulted to manual hand flying the final bit of the approach/landing....it seems to come down initially for me then on capture of the ILS it's not descending anymore. I appreiate this may be a different issue and in all honesty may just be me, I have always been Airbus but since we have this now in XP11 I just can't leave it alone, it's my got to Airliner.....just love it......

[Litjan]

Glad you like it, wain!

For capturing the ILS you need to keep in mind that you need to both arm the APP mode (GS and LOC in white), set the correct ILS frequency and also dial in the correct localizer heading on the CRS selector that is related to the side that you tuned the ILS on (L or R). Also be aware that you must capture the LOC (green) first before the GS can be captured.

You can theoretically descend in VNAV on a "virtual glideslope", for this to work you MUST "dial away" (select something else) on the ALT window, otherwise VNAV won´t leave that altitude.

Jan

 

[wain]

thank you Jan...

[Greaser]

With those updates, will VNAV function below 3000 feet?  Will a RNAV/VNAV approach be possible?

[Litjan]

1 hour ago, johnc said:

With those updates, will VNAV function below 3000 feet?  Will a RNAV/VNAV approach be possible?

It should!

Cheers, Jan

 

[Greaser]

On 9/8/2017 at 2:55 AM, Litjan said:

It should!

Cheers, Jan

 

Nice!

[Greaser]

Hello, I was wondering if there is any news about how the VNAV work is going and if that can be used for RNAV landings with the 1.3 release ? Thanks.

[Litjan]

Hi johnc,

there is nothing new to report, unfortunately. Work on 1.3 has not begun, we are working on 1.21 (bug fixes and 11.10 compatibility).

Jan

 

[Greaser]

Ok no problem, thanks anyway.

[Litjan]

If flying RNAV approaches is what you are after, then that is possible with the current implementation already. As a matter of fact, the real 737-300 I flew was not certified to use VNAV during the approach - we flew them in LNAV and V/S. I think the problem was the single FMS/GPS receiver combo.

So you can already fly the GNSS or RNP approaches to the LNAV minimum, but not to the Baro VNAV minimum.

Cheers, Jan