Danger Fog, you Crash!

[DementedCorn327]

Interesting, there was a similar issue reported but it has been fixed in SU6:

Decreased aircraft airspeed in cloud

There is at least one topic on this, but it is not getting much traction despite being very easy to replicate. I’m talking about actual aircraft performance, not system (FPS), and it doesn’t make a difference if there are icing conditions or not. I’ve filed a zendesk ticket, excerpt below: When flying through clouds, airspeed reduces by at least 10 knots compared to the airspeed when not in the clouds. Occurs in both icing and NON icing conditions. In real life, in non icing conditions, ther…

Continuing the discussion from [RELEASE] Release Notes (1.20.6.0) Sim Update 6:

@OlieTsubasa443

Reduced the effect of clouds water density on air density (source of drag when flying through clouds) by a factor of 10

And later same issue reported again. This one is open so you can participate there:

Cloud density causing aircraft performance issues

Thank you using the Bug section, using templates provided will greatly help the team reproducing the issue and ease the process of fixing it. Are you using Developer Mode or made changes in it? no Brief description of the issue: performance decrease passing through the clouds compared to Sim Update 8 Provide Screenshot(s)/video(s) of the issue encountered: Detailed steps to reproduce the issue encountered: PC specs and/or peripheral set up if relevant: 12900K/RTX3090/32Go …

Were you using Live or custom weather ?. If custom, what were your settings to try to reproduce.
Did you try with other planes ?