Vnav not engaging

[Isaac Wong]

Hi all, when I press on vnav, v/s mode is engaged instead of vnav and the button isn't on green light as well. Do I have to activate anything to get vnav working? Also, the ELEC 1 and 2 under hydraulic pumps have a huge high pitch noise when I turn both on. I already have the headphone simulation and active spatial sound off but still the same.

[Touchdown7]

You have all your data set in the box, ie Perf Init etc.? That will be required before VNAV

[Isaac Wong]

Yes all are set. Speed and altitude for vnav is set in legs page as well. But the vnav just won’t turn on

[andhog]

Have turned on the flight directors?

[Isaac Wong]

Yes but only vertical line appear on FD as LNAV is engaged without VNAV

[andhog]

Have you armed auto throttle?

[Isaac Wong]

Yes they are armed

[Predy23]

You need to press EXEC after fill in all the data in the perf init page.

[Isaac Wong]

This is what it look likes, armed LNAV and activated perf init page

[Isaac Wong]

So the vnav activated after airborne somehow. But another issue is that the takeoff config warning keeps ringing after I hit toga button on the throttle

[Raygen15]

Hi Isaac, takeoff config warning can be triggered by a number of things.

Copied from another user, who got it straight from the 737 FCOM, takeoff config warning will be given if

• trailing edge flaps are not in the flaps 1 through 25 takeoff range, or
• trailing edge flaps are in a skew or asymmetry condition, or have uncommanded motion, or
• leading edge devices are not configured for takeoff or have uncommanded motion, or
• speed brake lever is not in the DOWN position, or
• spoiler control valve is open providing pressurized hydraulic fluid to the ground spoiler interlock valve, or
• parking brake is set, or
• stabilizer trim not set in the takeoff range.

Hope this helps!

[Isaac Wong]

Thanks, will check those later, btw I have some sharp noise when I turn on elec and the sound settings are normal

[Raygen15]

Hi Isaac, without a video of what you're seeing, it would be pretty hard to tell. But switching power sources will result in a small interruption / surge of power which does do things like lights flickering / different noises, like in the real airplane!