VNAV won't engage

[Wendall 50]

Hi,This is the first time I've had a problem system-wise with the NGX. I've switched VC configs, clicked the SPD INTV button, flipped AT on and off, as well as both FD switches, and still can't get a ligh to show under the VNAV button. I thought maybe I didn't have VNAV installed in the aircraft I was flying, the PMDG Southwest paint for the 700WL, but that wasn't it.Any Help? or just reinstall?

[Leffe 4]

What does the Flight Annunciator read?/ Leffe

[Wendall 50]

THR HLD, then LNAV in a green box, then the third box is blank

[Leffe 4]

Ok, have you configurated the ac before take off. Set right trim? No pressure on yoke/stick?/ Leffe

[Wendall 50]

Yep, Trim is good, no stick pressure, flaps set to 5, and fully configurated.

[Leffe 4]

Ok, try to use Lvl ch for pitch mode some min and then try to change back to Vnav/ Leffe

[Spin737 102]

On the ground, will arm before you start your T/O?Check your FMC and make sure everything is filled and executed.

[Wendall 50]

On the ground, will arm before you start your T/O?Check your FMC and make sure everything is filled and executed.

No, it won't arm on the ground, and I double checked to make sure that everyting was filled out, and it was

Ok, try to use Lvl ch for pitch mode some min and then try to change back to Vnav

I tried this, and this also didn't work.

[Leffe 4]

Hmm, peculiar, cause I never have any probs engaging Vnav.Maybe there are some others with ideas?/ Leffe

Edited February 4, 2012 by Leffe

[Guest]

No, it won't arm on the ground

Maybe the first waypoint isn't within 5 degrees of the runway heading? In that case you won't be able to arm on the ground. Don't know why it won't go on after getting in the air... The only time I couldn't get VNAV on was after loading a saved flight.... Did you load a saved flight by any chance?

[Wendall 50]

Maybe the first waypoint isn't within 5 degrees of the runway heading? In that case you won't be able to arm on the ground. Don't know why it won't go on after getting in the air... The only time I couldn't get VNAV on was after loading a saved flight.... Did you load a saved flight by any chance?

I thought the 5-degree thing was LNAV, that can arm on ground

[Nixon 30]

I thought the 5-degree thing was LNAV, that can arm on ground

Your right Jackson.For VNAV to work you have to fill in the PERF page so that the FMS knows the weight of the plane etc and can therefore calculate the climb profile etc.

[Wendall 50]

Your right Jackson.For VNAV to work you have to fill in the PERF page so that the FMS knows the weight of the plane etc and can therefore calculate the climb profile etc.

Here's the funny thing, all speed/altitude targets are shown and visible on the LEGS page, its just the button that won't turn on.Just a thought, Service based failures are turned OFF

[Guest]

I thought the 5-degree thing was LNAV, that can arm on ground

Oops. LOL, of course. My bad... :( Edited February 4, 2012 by Guest

[Nixon 30]

Here's the funny thing, all speed/altitude targets are shown and visible on the LEGS page, its just the button that won't turn on.Just a thought, Service based failures are turned OFF

I guess a ticket to PMDG would be the best option.