777 Bobbing up and down

Hello IFC,

Whenever I fly a 777, the aircraft always bobs up and down whenever I start descend.

For example: ATC instructs me to descend and maintain 8000ft. The descending to 8000ft is no problem, but once it’s hits 8000ft it will start to “bob” up and down. I see that it is trying to hit 8000ft by correcting the VS, but it’s too aggressive so it “overcorrects” so it’s bobbing up and down trying to correct it.

This has made me sacred of flying the 777 so any way to solve this?

Thanks!
Jing

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Hi @anon92417564!

If you’re using the 77W, this is a known issue, and one that I have to deal with too! Here’s how you can fix it temporarily:

When you reach your desired altitude:

  1. Turn off ALT
  2. Set V/S to 0

This will stabilize your flight.

Yes, but once I’ve stabilized the bobbing starts again so… the only way I can stop it is to hand fly but that’s a pain for me.

And you’ve made sure that ALT is always turned off while adjusting the V/S to try to stabilize?

So, I hit 8000ft, and I turn off ALT and only VS on?

Yes- here’s what I would do, for example, when I am trying to cruise at FL340.

At 33500 feet I’d turn off ALT, and start slowly lowering V/S by 100 ft/m increments so as to not pitch down too harshly.

By the time I’m at 33900 feet, I’d be at a maximum of 200 ft/m climb, and with 40 feet to go till my desired cruise altitude I’ll reduce the climb to 100 ft/m. Then, as soon as I hit my desired altitude, I’ll reduce the V/S to 0, and leave it be until I want to step climb or descend.

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Okay great! This may be closed now.

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Nice solution this has always been a problem especially during slow flight approaching the airport in most aircraft.

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