Unable to turn on vnav on prestart

[ljfitzy 0]

Hey all,After a few weeks off I'm back doing toms tute again, I'm up to page 102 where it asks me to select vnav on the ground? However when I push vnav it doesn't arm?Have I missed a step!?

[Brent 2]

Hey all,After a few weeks off I'm back doing toms tute again, I'm up to page 102 where it asks me to select vnav on the ground? However when I push vnav it doesn't arm?Have I missed a step!?

I always arm VNAV during taxi...I'm not sure if it's possible before engine start.

[SMaus 1]

So do I, although arming LNAV/VNAV is actually part of the before start checklist in the EGLL-KLAX tutorial.

[G-CIVA 62]

In the 744 VNAV can be armed prior to push at the gate & the checking of this in the 'armed' state {where applicable} is included in some B744 Operators Normal Checklists as a Before Push/Start Checklist Item.It should 'ARM' providing...The IRS's have been aligned correctly (or are in the process of alignment)All data has been entered correctly into the PERF INIT Page (i.e. no empty boxes)There is at least a rudimentary RTE in the RTE/LEGs Page(s)& finally at least one of the Flight Directors is in the ON position