B777-300ER altitude issue

Does anyone notice that when 777300ER is curising in auto poilot the altitude bouncing around what you set more than any other aircraft? If you set at 30000ft, it will move up to 30070ft and then down to 29950ft. Is that a bug? Other aircraft always move around 30010 to 29990.

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This is an existing Topic. Please search before posting.

Your settings aren’t right to engage auto pilot. Either trim isn’t right your climbing or defending to fast or your speed is incorrect all these will contribute to the plane doing that.Correct me if I am wrong

in addition to what @IF_Aviation1 said, strong winds and turbulence may cause this. Check if you’re too heavy and if so descend to a lower cruise altitude. 77W should cruise no faster than M0.84.

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I have decend to 29000ft and 0.82m. It still happens.

I climb at 1700ft/min

I have notice this for a lone time. It only happens when I flew with 777300er. And it didnot happen 2 months ago.

It’s a known issue with the 77W. It tends to bob up and down like this. You could try and trim it out some so it’s a bit more stable, but most likely it will still do what you’re describing.

This also happens on the A321.

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I climb at 3000ft/min. It allows for a swift climb; I usually cruise at 37000/36000 feet for ultra long hauls (such as KMIA-FAOR), and 31000/32000 feet for regular long-hauls (such as YSSY-KLAX).

OK. Thanks a lot. I was hoping it can be fix soon, but it is happening for months.

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I can offer you a couple of suggestions when flying the 77W in order for you to avoid the issue. Firstly, if your aircraft is bobbing, try to disengage the autopilot and manually line the aircraft up for your desired altitude. The bobbing should not be a problem after that. Also, I would reduce the climb rate after FL280 to 800 fpm, especially if the aircraft is heavy, keeping N1 below 90% if able.

That being said, it is unlikely that the issue is going to be fixed because we have a 777 rework coming. If the above does not solve your issue, I would avoid flying the plane until we get a rework. I know it’s not ideal, but it will have to do for now.

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I am flying ZSPD-KJFK. Gonna fly higher a couple of hours later.

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OK Thanks a lot Maxim. Those were exactly what I did with my last 777300er flight. I have not been using it for a long time till today.

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I’ve seen this a lot, but it also occasionally happens with the A321.

There is already a thread explaining this please search before you post.

In the past I have heard something to fix this issue

Try turning off the ALT setting (once reached desired altitude) in auto pilot and put the VS at zero…

at least it doesn’t bob up and down to the point, you stall. And yes the a321 issue still occurs sometimes when I am not even going max speed like m.78, but it rarely happens

This should be fixed when the 777 rework comes out.

If nothing works then disengage your ALT autopilot but then engage the V/S one and put it to 0. It should be better.

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