I’m pretty sure I miss something but I can not get the vnav to work.
Ofp loaded from simbrief
I filled all the informations in the mcdu wind etc…
The yellow dot for vnav appears before takeoff but when I reach the set altitude it diseapears and I can not engage vnav anymore, when I click vnav on autopilot nothing happens…
I have the tc and td indicators on mcdu and route display…I’m puzzled.
Is there any tutorial available for vnav?
Did you set the FCU, at this time, to reach the next required altitude, either lower or upper ?
Thanks for your response.
I tried to push upwards the altitude knob to engage managed altitude mode, but it does nothing.
In the mcdu, all the waypoints don’t have their altitude and speed set, maybe it’s required in order to make vnav work ?
Indeed 
Managed Mode means it’s the MCDU data which are forwarded to the autopilot !
Ok but In my opinion the waypoints altitude and speed are set in the mcdu only if they are constraints on particular waypoints, otherwise they can be left unset, but I might be wrong.
Also, the route display properly shows indicators related to vnav, like little arrows for tod, toc, etc…
So in my opinion vnav should work with waypoints data available in the mcdu, even if it’s not set for some waypoints.
Again I might be wrong.
Simply, the altitude which is set and displayed on the FCU could be understood as “to be allowed to reach this altitude”
However in Managed Mode, the MCDU data stay responsible of forwarding the VNAV path
In non Managed mode, we can force the aircraft to reach a designated altitude, though this is is another question
That is also my understanding and the whole point of vnav.
But either it simply doesn’t work, or my understanding of pre-requisites to make it work is wrong.
I’ll try to figure this out, thanks for your inputs 
Do you use the A32NX from the Marketplace, or the one downloaded from the site ?
I use experimental version b88663f , installed with flybywire installer application.
https://docs.flybywiresim.com/pilots-corner/beginner-guide/takeoff-climb-cruise/#4-climb
https://docs.flybywiresim.com/pilots-corner/beginner-guide/descent/#2-starting-the-descent
I still don’t get it.
All my altitudes are set in my ofp, with altitudes set for each waypoint, but the managed altitude rotary knob on autopilot panel won’t engage if I click on it.
No way to get the yellow dot to engage vnav.
Does anyone got the vnav work in experimental a20neo flybywire ?
Have you tried to right click on it, to get the managed mode engaged ?
I left-click on the upper part of the knob, the way it’s supposed to do to engage managed altitude and vnav , but the yellow dot does not show and I stay in ´alt’ mode.
Could you please, put here your own flight plan including Departure and Arrival airports and runways, SID and STAR and at which precise waypoints the issue is coming ? So we can have a try and provide more detailed comment and workaround if any ?
Thanks but I doubt it’s related to a particular flight plan, I couldn’t make it work in any of my flight.
My questions is more does anyone could make this feature work, and if yes what are the prerequisites and procedure?
Well, as it’s a long time I didn’t started the A320 again, it looks like I have to go through the basic again, as I’m not able to perform simple actions like changing altitude using Selected Altitude, totally outside any Flight Plan or FMC management. The Aircraft still doesn’t want to go to lower altitude, nor to stop at altitude set on FCU, all it’s performing is going higher. V/S doesn’t work either in Selected mode. I’m with FBW 0.8.2 Stable. Is there any bug with simple Selected Altitude management in the mod ?
At last I figured it out !
When you climb, before toc/tod , set the toc altitude on the autopilot altitude knob, then engage managed altitude: yellow dot appears and the plane will climb according to the ofp altitude waypoints.
Reaching desired altitude, vnav disengages.
After tod, set requested « down » target altitude for descent with knob, usually the altitude to fix ils, engage managed altitude mode on autopilot and, voila !, yellow point is back , plane descends respecting altitudes of ofp waypoints.
Yes, it’s by design how it works for Managed mode.
Though, still have issue for the Selected mode (not any data filled in the MCDU), I have to figure out this situation, could be that this is not allowed.
Yes, fill your mcdu first.
Use simbrief and import it directly, very easy.
Then fill departure (Sid) and arrival (star and transition).
Fill perf pages also.
Use the mcdu on your smartphone with mcdu server.
