Vnav Trouble

Hello everyone, this is my first post and I hope to be an active part of this community!

Anyways, I arm Vnav and it says that it is set to the next waypoint altitude. Even the AP altitude and VS turn purple, but it never actually changes the altitude. I feel like I’ve tried everything.

Thank you for your suggestions!

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@LCRpilot welcome to the community!!!

At what part/stage of flight is this occuring?
If it’s during decent… It may be because your at lower altitude then what the next waypoint is set for.

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If it’s during the climb, VNAV will not engage.

You might’ve armed it to early how many nms does it say under vnav

You most likely armed it too early, on your status bar ( or autopilot menu ) it shows the distance and time remaining to your TOD thats when the plane will begin its descent. I arm it 1 minute before my TOD usually 8nm

Alright, I’ll do that and see if it works, thank you!

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I usually click it when it is 1nm away and it does turn on

TOD like it says :(

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In this picture, you are still 10 nm from the top of your descent so you’ll stay at the same altitude

Wouldn’t the TOD be 10,000 though?

So it won’t start descending immediately?

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So there is a TOD for each altitude and the VNAV won’t start descending right away? Is that how it works or am I just more confused?

Yes. The VNAV only descends when it is at the TOD. Otherwise, the aircraft will stay at cruise.

Yes, it wont.

Thank you all!

I believe there is a minimum descent rate. This is probably to prevent aircraft from descending at like -20 FPM if you activate VNAV too early. It will hold until the descent angle because greater than the minimum.


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