News:

Precision Simulator update 10.173 (24 February 2024) is now available.
Navburo update 13 (23 November 2022) is now available.
NG FMC and More is released.

Main Menu

Resetting VNAV phases

Started by Toga, Wed, 28 Oct 2020 18:51

Toga

Is there a way to reset the VNAV phase? For example if you were to 'accidentally' press '"DES NOW", is there a way to reset it to go back to VNAV CRZ?

Cheers.

Hardy Heinlin

Sure.

When you are in ACT DES, enter a CRZ ALT on the CLB or CRZ page.

When you are in ACT CRZ and you want to get into ACT CLB, enter a CRZ ALT on the CLB page.


|-|

Toga

Thanks. I presume it only works if you enter a higher FL/ALT than you are already at.

Hardy Heinlin

Not when you want to get out of the DES.

Toga

I tested out pressing DES NOW when level in the cruise at FL370. VNAV then transitioned to the descent page as expected. With ALT mode engaged level at FL370 i then re-entered FL370 on the CRZ page and executed it. It just jumped back to the descent page. I tried also with the CLB page. It worked when I entered a higher FL than 370, FL380 for example. I was then able to enter FL370 on the CRZ page and continued on my way.

T

Hardy Heinlin

When your CRZ ALT is high enough and your distance to the destination is short enough, the FMC will activate the DES. You may get back into CRZ by re-entering the same CRZ ALT. But after a few seconds the FMC will re-activate the DES. This happens in the real FMC and therefore in PSX too.

In other words: When your new vertical geometry is such that the T/D is behind you, the FMC will activate the DES.


Toga


Toga

Hardy,

On some occasions - not all - i'm finding the FMC gets stuck in VNAV descent mode when executing a diversion to an alternate after a missed approach. I'm 51nm away from the diversion and only climbing to 8000ft. I go into the CLB or CRZ page and enter 8000 but it resets to the descent page again. I have found i'm able to put in a higher alt, say 9000, and it then resets to CLB phase. I can then re-enter 8000 and it's fine.
This doesn't happen that often but it has on some occasions. 

Hardy Heinlin

I can't comment as I don't know your exact situation and what exactly you're doing.

It's not only about distance to destination but also about waypoint constraints etc. pp.