A350 Autopilot Error

Hello, fellows!

I was recently doing a long haul flight from El Dorado International (airport of the capital of my country) And as I ascended with my heavy load to FL42, the autopilot started going all crazy, violently moving (while trying to align with my course). This got to such a crazy extent that my aircraft spun out of control and crashed.

I tried doing this flight again, thinking that it was pilot error, and the same thing happened, again at FL42. I was, however, able to descend to FL38 and there the problem got solved. I went to FL42 various times, and the same thing happened.

I just think it is an autopilot error because I had very relaxed 3 knots frontal wind. Also, I sadly do not have any footage of the incident.

How can I solve this? Is it because of the weight? Have you had the same problems?


This is due to the weight of the aircraft. You need to step climb.

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Climbing to FL420 as a heavy aircraft. No bueno my friend. Try step climbing.


Si. Step climb is the solution or lower the VS rate 👍


He said he climbed to 4200ft.

Did you check if your speed was increasing and not decreasing?

He clearly means FL420.

Can we all stop replying and repeating each other now until the OP sheds some light?

Taking a heavy A350 to 42,000ft isn’t possible due to lack of lift to carry lots of weight. I’m currently flying long haul using the A350 in IF and I’m step climbing from FL330 to FL350 to FL370 to FL390 to FL410 every few hours.

Thank you so much for your helpful responses!
I would still have one question: which weight should I use for certain altitudes?
And (this is a question coming from a noob): How does the weigh translate to an autopìlot that’s so shaky it will deactivate autopilot? Why does that happen?

Again, thank you for being so kind and helpful in your responses!

Ideally you want to be at a lower altitude for the more weight you have. The reason aircraft step climb is because as they fly, they burn off fuel, reducing weight. The less weight, the higher you can go.

The AP shouldn’t shake unless you are heavily overweight, or are going to fast/slow.

Hmm, that’s good question, let’s see if I can explain this in an easy way to understand.

Basically, think about it like this. The plane you’re flying is heavy, you have let’s say a total of 95% payload, you can’t make it past 35000ft at your initial climb. If you go past it, and cruise at 37000ft, you autopilot will sway left and right because it can’t hold the weight balanced up in the air.

Winds and temperature also play a factor in this, although only wind matter in IF, while temperature, as far as I know, has no effect on your flight in Infinite Flight.

This difficulty in holding a steady balance of the flight can be roughly compared to if you were to hold heavyweights in both of your hands while tip-toeing on a thin rope 50ft up in the air, you’d have an extremely difficult time holding the balance, due to the excessive amount of weight, for you own physical strength. You’d much like the plane sway from left to right, before eventually losing balance and fall.

I hope that does explains/answers you question. If you have anything else are wondering about or find the information provided difficult to understand then do not hesitate to ask, we are all happy to assist :)


Thank you for such a clarifiying response!

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👍 hope your good with that

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One of the best ways to know which altitude to cruise at it to use simbrief to create a flight plan. You can use the following link to simplify the process: https://fpltoif.com/simbrief

When you get the flight plan it will show you the initial cruise altitude and the altitude for each waypoint as shown in the photos below.

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