777-300ER floating up and down during cruise

I am currently half way over the Pacific Ocean in a 777-300ER from Hong Kong to Vancouver with 275 Pax, 9100 kg of cargo and (initially) 92.5 tons of fuel. I climbed up to FL310 at 500 feet per minute after FL270. After I climbed up to FL330, the plane has been bobbing up and down all the time. I am 6 and a half hours into my flight (load 44%) and climbing up to FL350 and the plane is still bobbing up and down. Are there any ways to solve this or is this a bug?

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What’s the VS set to?

Also this is a known issue but we may be able to assist in the short term

What mach number were you at?

The step climb VS was 300 feet per minute

I have and am sitting M0.83

Hmm. The only time I’ve experienced this happening, is when I have my speed super high when cruising. So, you’re speed wasn’t a problem, since you were at M.83. I do not know the solution, though.

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Hmmm yeah that sounds unusual then. Does your AoA seem normal or high? Typically you see this oscillatory behavior when the aircraft is too high, too slow or too heavy. Did it eventually stabilize or is it still going?

Hello- this is a known issue that has not been fixed. It is not your fault. I experience this bug too. For a temporary fix, disable the ALT autpilot and set the VS to 0 when you reach your desired altitude. Here is the main bug thread:


It was constantly going.

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