Vertical mode stays in TO/GA

[Tord Hoppe]

Hey, quick question. I´m brushing off my cobwebs and have setup a flight between FACT-ESSA using PFPX/TOPCAT for planning. When taking off the vertical mode stayed in TO/GA with VNAV in white. Also, no acceleration or change of thrust limit. I had to manually set FLCH and change the speed. This went on all the way to cruise alt. The MCP buttons LNAV, VNAV and FLCH where lit up, along with SPD since I manually had to set the speed.

I´ve also tried one default situ where this behaviour did not occur, so I´m trying to figure out what I did wrong. The FMC programming looked OK to me.
What are the most likely thing(s) I missed or did wrong, perhaps a tough question without detailed info?

[Hardy Heinlin]

Certain conditions inhibit VNAV engagement.

Do you have a situ for us to analyse your scenario?


Cheers,

|-|ardy

[Tord Hoppe]

Browsing through the manual I suspect that my error was not confirming values for GR WT and ZFW in PERF INIT during FMC setup. Should they always be selected by the LSK to make the font bold, even with WBS installed? Thinking back I seem to remember that the V-speeds were blank, I set them manually, does that match my suspicion?

[Hardy Heinlin]

Yes, make the GR WT indication big by pushing 1L.

GR WT must be confirmed by the pilot.

[pilotwannabe1]

If the weights are not confirmed, will VNAV still arm as in this case?

Thanks,
Rushad

[Hardy Heinlin]

LNAV and VNAV can be armed even when nothing in the FMC is initialized.

They just won't engage.


Cheers,

|-|ardy

[pilotwannabe1]

Got it.  Thanks!

R

[Tord Hoppe]

Just to confirm that that was indeed my error. I just did another completely successful flight, confirming the GR WT.