Boeing 787-9 Pitching up and down VIOLENTLY at cruising altitude

I was flying a Scoot 787-9 from Singapore to Melbourne. Everything was going well, but just 2 hours from Melbourne, the plane started pitching up and down violently. Sometimes the plane went from -15 degrees pitch to positive 15 degrees pitch for no reason. The Autopilot was on at the time, and there was only 10 knots of headwind. I was at 36000ft and had 65% weight onboard. I have no idea how any of this could have happened. Eventually, the rocking got so bad that the Auto throttle had to change the thrust at times from 20% to 100%, and it was quite frequent. I ended the flight before it was about to crash. Could somebody please help me out?

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I think your plane was overweight

I would suggest going a bit lower, say, 32000 feet.

How fast were you going?

I’ve gone up to 42000 with that weight and had no issues

I don’t think my plane was overweight because I had burned half of the fuel tank, cargo was only 75% full and the cabin was like 90% full, so I don’t think I was overweight

I was going Mach 0.85, standard 787-9 cruising speed

Really? Well, this is the first time it’s happened to me. I’ve been flying 787s at even higher altitudes than that (I fly around FL 380 most of the time), and I’ve never encountered that issue. Is there some bug whilst flying in the middle of Australia?

Possibly wind-shear. What was your trim like?

I had no trim.

That may have been the problem

But normally on 787 flights I don’t put trim on anyways, and everything is normal

Hmmm, I’m not sure what the issue is.

Btw, if you want people who know more about the game to see this post, change its category to Support

Ok. Thanks for the help though

I highly doubt trim has any impact on this. All trim does is make it so you don’t have to constantly pull back on the controls, but the computer doesn’t care about doing that all of the time.

How do I change the category?

Even if you’re not too heavy for your cruise altitude 95% of the time, the aircraft is more vulnerable to external shocks when relatively heavy and high. There is just less safety margin.

Do you have a video you could upload?

I was able to get some pitching up and down at your weight and altitude by changing some combination of wind gusts, turbulence, and/or temperature.

But I couldn’t get exactly as you described. The level flight AoA was about 4 degrees at that weight and altitude which kind hints at flying more to the edge than not (though I wouldn’t say it’s excessive).

The most violent pitching I could produce was momentarily shutting off AP while out of trim/not at the calibration point, and then turning it back on again: the out of trim new VS gets locked into the new AP setting, and it makes the pitch up and down go crazy (to the point of stalling).

Well, unfortunately I deleted the replay. I could maybe replicate the flight with the same conditions and possibly send it to you later?

The location where it happened was near Wingellina, Australia. Cruising at 36000FT

It is extremely hot now over Australia, so It could lead planes to fly lower than usual.
I checked FL340 and FL 390.