A350 extremely unsteady while cruising

I was cruising in the A350 for a short flight, when the plane started to become very unsteady (pitch and roll), and at times seemed to be oscillating. It was at 27,000 ft and .85 for the speed. I don’t have the weight, but it was below MLW prior to departing. Autopilot was engaged, and there were no control inputs from me. I tried cycling the autopilot off and on with the hopes it might reset the issue, but it started again once autopilot was turned back on. Winds were not excessive, and I’ve encountered higher wind speeds without issue in the past.

Sounds like heavy turbulence to me. If you were under MLW and cruising at .85, even up to the A350’s service ceiling you should be fine.

If it wasn’t turbulence I’m already out of answers.

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Did you notice these issues while turning on AP? The A350 is known to have physics issues, especially with the aggressive turns it makes.

That’s happening for
A350
A320 family
B747 family
And when that happens Gump from aircraft .
😂

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No, it seemed fine. I used AP on the climb, and it seemed steady throughout turns. I only noticed an issue once I got to what I’d set as my cruising altitude. I know FL27 is a bit lower than normal, but I didn’t think it was excessive. I figured it was comparable enough to the lower end of a step climb, so it wouldn’t be an issue.

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AP issue. I have the same here with all planes.
Once I reach cruise, I disengage AP ALT ans give AP VS to 0. Only thing that works.
I’ve always wondered if this related to the fact that I use a joystick. Would need to fly without it to verify.

I don’t think so, because I was not using a joystick.

Any idea on the Trim setting and outside winds?

I totally don’t trim because i usually cruise at M.87 to burn off excess weight (Simbrief doens’t have an idea on the efficiency of IF’s A350 so usually it is gives me about 5 to 6 tons extra)

You can customize the plane parameters in SumBrief to make them match those of IF (various weights, pax / cargo / fuel capacity, and you can adjust the fuel index if you feel it doesn’t correspond to what IF has)

Easiest way for the trim is to trim up or down until the little purple indicator in the trim zone disappears.
There are a couple useful topics on the trim in IFC

Agree so, but getting exact parameters can be tricky, and the last thing I want is to run out of fuel before arriving and having to divert. I am not saying that I mind it, I am just saying I fly a little faster - helps when I have a busy day :)

Trimming has never been my cup of tea, I don’t trim because it can shift the center of gravity and mass.

I refer to this post if you have questions. Aircraft type can be different, but the idea is the same

Haha! The famous fuel stress 😂

In all humility, along my 4,300FH and hundreds of VA group flights organized, I can say with confidence that for all planes EXCEPT THE A340, you will never dry your tanks out before landing if:
• you use the simbrief standard
• choose 30 minutes extra fuel (in the top right part of the simbrief form)
• enter the accurate parameters (departure time, pax, cargo)
• load up the recommended fuel by SimBrief
• follow speed and altitudes recommended by SimBrief.

Yes, your ETE May remain in the red even until the last 20% of your flight. But that’s because it calculates per the current ground speed and fuel consumption (while the former may decrease or increase along the flight, the latter will decrease).

You can trust me with that, I’m a professional long haul oversleeper 😂

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Trim will never shift the mass of a plane.
It may momentarily impact the aerodynamic forces which MAY themselves in turn have an influence on the center of gravity but it really doesn’t have a direct influence on the center or gravity and certainly not on the mass.

What it will do, is increase in positive or negative the center point of a flight control to lower the pressure on that specific flight control - in this case the elevator

I didn’t note the wind speed, I wish I had. Although it was one of the first things I checked, and didn’t take note because it was not excessive. I’ve even tried the same flight parameters and tried to seek out high winds to see if I could duplicate it, but the aircraft stayed stable. Trim was at 0, as it was shortly after reaching my desired altitude. I just couldn’t figure it our because it was unstable on each axis. I tried to figure out how to post a video, but it would only allow screenshots. Maybe it was just a fluke since it hasn’t replicated the issue since then.

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