VNAV Advisory Descend

freeze1058
Posts: 57
Joined: Sun Dec 22, 2019 1:27 pm
VNAV Advisory Descend

Post by freeze1058 » Fri Jan 24, 2020 11:46 pm

Hi,

is it possible to have the direct descend angle/FPM indication while descending manually using VS?

img.jpg
img.jpg (9.79 KiB) Viewed 2347 times

As soon as I press VNAV and switch to VS mode the indication "DIRECT 3.0° 1100v" disappears. In the FMS I see option VNAV ADVISORY, however enabling/disabling doesn't change anything.

Cheers,

Stefan

freeze1058
Posts: 57
Joined: Sun Dec 22, 2019 1:27 pm
Re: VNAV Advisory Descend

Post by freeze1058 » Mon May 18, 2020 8:05 pm

Hi,

in version 1.1.27 it appears that the magenta direct descend angle/FPM indication in VPATH has completely disappeared.

What happened to it?

Regards,

Stefan

Taguilo
Posts: 658
Joined: Sun May 11, 2014 11:49 am
Re: VNAV Advisory Descend

Post by Taguilo » Thu May 21, 2020 12:27 am

Hi,
Which version? .27 or .28?

In .27 it works fine. Can you reproduce and post an image? Or give more details?

Thanks!

Tomas

freeze1058
Posts: 57
Joined: Sun Dec 22, 2019 1:27 pm
Re: VNAV Advisory Descend

Post by freeze1058 » Thu May 21, 2020 8:32 pm

Hi Tomas,

the issue is reproducible upon two flights in 1.1.27 and one flight in 1.1.28. Since I re-started flying (stopped in December) I did not observe any additional VNAV information in magenta color anymore. The following screenshot shows a regular descend in VPATH:

ka350i_vnav_01.jpg
ka350i_vnav_01.jpg (199.21 KiB) Viewed 2209 times

Any ideas?

Cheers,

Stefan

clorix1
Posts: 30
Joined: Fri Apr 03, 2020 6:33 am
Re: VNAV Advisory Descend

Post by clorix1 » Fri May 22, 2020 12:16 am

Sorry to jump in, but did you make sure to enable the VNAV window in the FMS's MFD MENU page? It has three options: OFF, ON, and VNAV. This is separate from the ADVISORY VNAV option you mentioned.

Taguilo
Posts: 658
Joined: Sun May 11, 2014 11:49 am
Re: VNAV Advisory Descend

Post by Taguilo » Fri May 22, 2020 12:23 am

Hi Stefan,

Yes, I have an idea :-)

Go to CDU, MFD Menu key, and select VNAV in Window LSK option.


Tomas

C525B
Posts: 10
Joined: Wed Aug 31, 2016 7:15 pm
Re: VNAV Advisory Descend

Post by C525B » Fri May 22, 2020 9:47 am

I've also seen some funny stuff happen with the MFD VNAV window. I find that if there's not a target altitude on the next waypoint (e.g. direct to the dest. airport, or to a visual approach RX__ fix) then it will not display most of the time. In this case, if the VNAV window is turned on from the CDU, the screen real estate will be allocated but it will appear blank. Also, one time I bumped the barber pole in descent and that made the VNAV info hide itself.

The magenta text appeared to flicker as I exceeded Vno intermittently, and then decided to bury its head, lest the chief pilot catch wind.

My PL21 experience is in Citations (it shouldn't be too different) but FWIW I recall the advisory VNAV function should enable the "circle cue" suggestion on the VSI regardless of autopilot modes, whether you're on a STAR or not. If you have valid vertical waypoints set up on LEGS, it should coincide with the required V/S shown on the VNAV window. So for example, I make a visual approach to RWY16 with a 5-mi final, then go direct "RX16" and enter an altitude of 1500' over RX16, I should see a circle cue showing me required VS (as long as Advisory VNAV is enabled) and be able to fly to that fix/altitude with VNAV.

Taguilo
Posts: 658
Joined: Sun May 11, 2014 11:49 am
Re: VNAV Advisory Descend

Post by Taguilo » Fri May 22, 2020 1:35 pm

C525B wrote:
Fri May 22, 2020 9:47 am
I've also seen some funny stuff happen with the MFD VNAV window. I find that if there's not a target altitude on the next waypoint (e.g. direct to the dest. airport, or to a visual approach RX__ fix) then it will not display most of the time. In this case, if the VNAV window is turned on from the CDU, the screen real estate will be allocated but it will appear blank. Also, one time I bumped the barber pole in descent and that made the VNAV info hide itself.
Hi,

VNAV info in MFD will display:

- For CLIMB altitudes, as long as there is a valid CLIMB alt restriction in any wpt of the FP, that is not part of a missed approach when not flying the MAP procedure.
- For DESCENT altitudes, as long as cruise altitude is entered in PERF page and the aircraft has reached that altitude (and remains on it); OR distance to TOD is less than 50 nmiles or 2/3 of FP extension.
My PL21 experience is in Citations (it shouldn't be too different) but FWIW I recall the advisory VNAV function should enable the "circle cue" suggestion on the VSI regardless of autopilot modes, whether you're on a STAR or not. If you have valid vertical waypoints set up on LEGS, it should coincide with the required V/S shown on the VNAV window. So for example, I make a visual approach to RWY16 with a 5-mi final, then go direct "RX16" and enter an altitude of 1500' over RX16, I should see a circle cue showing me required VS (as long as Advisory VNAV is enabled) and be able to fly to that fix/altitude with VNAV.
Both Vertical Deviation Scale and Pointer will show when:
- PATH vertical mode is armed (Preselector altitude is below current aircraft altitude); OR 60 seconds before the aircraft arrives at TOD if the Preselector altitude is not lowered. Providing VNAV or Advisory VNAV is enabled.

There are other restrictions for the pointer only, (ie descent rate > 100 fpm, etc). All working as expected.

Tomas

C525B
Posts: 10
Joined: Wed Aug 31, 2016 7:15 pm
Re: VNAV Advisory Descend

Post by C525B » Fri May 22, 2020 7:41 pm

Okay, that's different than how it worked In the CJ (and the Beechjet with older Proline 4 for that matter), we didn't have to arm VPATH or reset the altitude. I thought that was the whole point of advisory VNAV. If there was a valid V-path of any sort, the VS cue and deviation scale would appear shortly before TOD without having to arm any additional modes.

Regarding the MFD VNAV window, did you see what I wrote about the text flickering and disappearing for the rest of the flight?

Taguilo
Posts: 658
Joined: Sun May 11, 2014 11:49 am
Re: VNAV Advisory Descend

Post by Taguilo » Fri May 22, 2020 8:04 pm

C525B wrote:
Fri May 22, 2020 7:41 pm
the VS cue and deviation scale would appear shortly before TOD without having to arm any additional modes.
And it's the same in the KA, 60 seconds before TOD both scale and pointer will show regardless of current vertical mode (in VNAV/Adv-VNAV)

Regarding the MFD VNAV window, did you see what I wrote about the text flickering and disappearing for the rest of the flight?
If you dove the aircraft hence departing from cruise flight, VNAV info on MFD was gone until you get a valid TOD again.
Therefore, if you come back to level flight but below cruise, you can restore VNAV info by going to PERF INIT page and select a new cruise altitude with your current one.


Tomas

C525B
Posts: 10
Joined: Wed Aug 31, 2016 7:15 pm
Re: VNAV Advisory Descend

Post by C525B » Fri May 22, 2020 10:08 pm

So why am I not seeing Adv. VNAV cues in this situation then?

Crz. alt. 9000 was entered. Vertical direct to the RX13L altitude executed, the only thing that appeared was the magenta target altitude. Still no cues after passing TOD, then I recalled your statement:
There are other restrictions for the pointer only, (ie descent rate > 100 fpm, etc)
So I initiated a descent with VS, then took this screen
2020-5-22_13-58-56-670.jpg
2020-5-22_13-58-56-670.jpg (414.36 KiB) Viewed 2142 times

C525B
Posts: 10
Joined: Wed Aug 31, 2016 7:15 pm
Re: VNAV Advisory Descend

Post by C525B » Fri May 22, 2020 10:20 pm

If you dove the aircraft hence departing from cruise flight, VNAV info on MFD was gone until you get a valid TOD again.
Therefore, if you come back to level flight but below cruise, you can restore VNAV info by going to PERF INIT page and select a new cruise altitude with your current one.
That's not exactly what happened...I was already established in a descent along the path.

Taguilo
Posts: 658
Joined: Sun May 11, 2014 11:49 am
Re: VNAV Advisory Descend

Post by Taguilo » Fri May 22, 2020 10:56 pm

C525B wrote:
Fri May 22, 2020 10:08 pm
So I initiated a descent with VS, then took this screen
This is another restriction:
When advisory VNAV is selected, the vertical deviation scale and pointer
show when the vertical deviation is within 1000 feet of the descent path.


However, I will check if this one is effectively working as expected.

Thanks!

Tomas

C525B
Posts: 10
Joined: Wed Aug 31, 2016 7:15 pm
Re: VNAV Advisory Descend

Post by C525B » Sat May 23, 2020 12:09 am

Right, I executed a V-direct (because the cruise segment of my test flight ended up being very short) so that is irrelevant. I made a second test flight with a longer cruise segment so that I could watch it approach a pre-calculated TOD, but that didn't make a difference.

Taguilo
Posts: 658
Joined: Sun May 11, 2014 11:49 am
Re: VNAV Advisory Descend

Post by Taguilo » Sat May 23, 2020 12:19 am

Well, the 1000 ft range for vertical path was not working fine, so I fixed it.

Thanks for the observation.

Tomas


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