Blackbird Sims / Milviz Forum Archive

Descending towards LEPA in VNAV mode. ATC assigns me a rate of descent. Thus I try to change into V/S mode and fly the assigned rate.
VNAV just keep engaging again. Check this video:
https://youtu.be/nj9UnnK4Vc4

There was no way to get out of VNAV mode. What's wrong here?

Hi,

To disengage VNAV just press VNAV button on the FGS.


Tomas

What's the correct sequence to get out of VNAV then? First deselect VNAV, then select another mode? Or the other way round?

Are you absolutely sure this is how it works in the real aircraft? Seems counter intuitive to me... but who knows what the Italians might have come up with

The system is American .

But it definitely shouldn’t be like that. Selecting another vertical mode should bring you out of VNAV.

matpietsch wrote: ↑

Wed Mar 24, 2021 10:08 pm

The system is American .

But it definitely shouldn’t be like that. Selecting another vertical mode should bring you out of VNAV.

No. VNAV supports all pitch modes: FLC, VS, PTCH plus PATH (which is only available in VNAV). And actually the way to know whether or not a pitch mode is VNVA active is by spotting the V char before the mode name: VFLC, VVS, VPTCH and VPATH.
The master pitch mode for VNAV is PATH (VPATH when active), so the aircraft will switch to (and remain in) VPATH mode any time the aircraft is descending within the vertical profile.

Tomas

Emi wrote: ↑

Wed Mar 24, 2021 9:01 pm

What's the correct sequence to get out of VNAV then? First deselect VNAV, then select another mode? Or the other way round?

Are you absolutely sure this is how it works in the real aircraft? Seems counter intuitive to me... but who knows what the Italians might have come up with

Yes, that is how it works in the real aircraft. When you disengage VNAV, FGS reverts to PTCH, maintaining the current descent profile. You can then press VS and select a new vs profile.

Tomas