A320 autopilot disconnect and unstable pitch behavior near FL330 during climb

Bug Reporting Hub Aircraft & Systems
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1

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ISSUE DESCRIPTION

Description of the issue: When climbing above FL320 at roughly 1500–2000 fpm, the autopilot consistently disconnects near FL330 and the aircraft begins to drift off course. Attempting to re-engage the autopilot results in aggressive pitch changes, causing the aircraft to climb or descend sharply. This issue has occurred repeatedly and appears to happen specifically around FL330 when climbing toward FL360. Climbing to altitudes below FL330 does not cause any problems.

FREQUENCY OF ISSUE

How often does this occur for you (Example: Just once, every time on sim load, intermittently)?

Everytime

REPRODUCTION STEPS

Please list clear steps you took in order to help our test team reproduce the same issue:

  1. Climb to FL360

  2. Wait for aircraft to disconnect autopilot

  3. Reconnect AP

YOUR SETTINGS

If the issue still occurs with no mods and add-ons, please continue to report your issue. If not, please move this post to the User Support Hub.

What peripherals are you using, if relevant:

[PC Only] Are you using Developer Mode or have you made any changes to it?

[PC, MSFS 2020 Only] Are you using DX11 or DX12?

[PC Only] What GPU (Graphics Card) do you use?

5070

[PC Only] What other relevant PC specs can you share?

MEDIA

Please add a screenshot or video of the issue occurring.

2

What climb mode are you using on your AP?
Regards

3

Not managed (Selected - around 1500fpm) seems to top out around 330. Am I just climbing too fast?

4

Having a specified climb rate as you get higher and higher leads to airspeed dropping while it’s trying to maintain your set climb rate.
So you can either reduce your climb rate as you go higher (don’t look away too long as it can get away from you pretty quickly at those altitudes!), or use a form of climb based on a specific airspeed. Something like FLC (flight level command) or managed airspeed vs vertical speed depending on the plane. That’s where you set the desired speed you want to maintain, and the plane will adjust the rate of climb it can manage at that airspeed as you go higher.
Currently you’re basically entering a high altitude aerodynamic stall, with the resultant actions you’re seeing when the AP just can’t do what you’ve told it to do, and disconnects and leaves you on your own! Some aircraft have a default setup to “fix” the problem you’ve set up by climbing too fast. Not sure if that’s modelled in the planes you’re using.
Hope that’s not too convoluted a response!
Regards

5

Understood. Thanks for the help!

6

@LinearHarbor929 : please let us know if @Habu2u2 advice resolved your issue.