[FIXED] World Update 3 has broken flight dynamics, exhibit A

There is a temporary fix for this by editing the cfg file within the aircraft: Flight Dynamics Bug Details - Community / News and Announcements - Microsoft Flight Simulator Forums

Confirmed that the Baron has the same issue as the PA-44 on the ground: parking brake required to keep the aircraft in position.

I will say that the observation about floating seems less of an issue. The planes do float more, but heavens to Betsy you can absolutely grease your landings! :slight_smile:

However, climb out is way out of the “normal” performance envelope for a naturally aspirated piston aircraft. The Baron does climb like a beast, but 150+ kts, 1000 fpm @ 20" MP? That’s amazing performance! :wink:

And it has nothing to do with flaps!

Agreed (min limit)

Agreed here as well

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I disagree. I copied flight_model.cfg from one airplane to the other. Having the same flight_model.cfg both airplanes should fly the same, have the same (L/D)max. But the two airplanes had different (L/D)max and other characteristics.

Disagree again. Use DevMod Aircraft Editor, Debug, Sim Forces to see some 10 force vectors. Fly stall, spin, snap roll and other aerobatics flight maneuvers and try to do this with FSX. You don’t have to believe me. You can test yourself.

That is correct. But try this: keep the wing_area the same but change the wing_span, say double it or half it. What do you expect? Try it!

The MSFS SDK file MSFS SDK/Documentation/03-Content_Configuration/SimObjects/00-Aircraft/Flight_Model.html explains:

The introduction of 3D geometrical information in the flight model through surface elements, as described in the previous paragraph, was clearly a first mandatory step toward improving the physics, as it has enabled the modelization of local phenomena. To better account for stall and all its variants (spin stall, deep stall, simple stall), each surface element has been enriched with a float parameter describing its level of stall. When reaching a certain level of stall, the behavior of the surface is changed using additional parameters so as to follow, broadly speaking, the behavior of a falling plate. Reading the litterature about airfoils behavior in stall configurations, it can indeed be shown that local boundary layer detachment leads to a very sudden change in the aerodynamical behavior of the airfoil, that can be assimilated to a falling plate. The interested reader is refered to this NASA experimentally based study.

This plate model is used in the new flight model to locally change the behavior of surface elements depending on local stall state. This local stall model enables to accurately simulate classical stall but also spin stall, which is intrinsically impossible with FSX non-geometrical flight model.

For my taste Asobo writes too much about “3D geometrical information in the flight model” and about “which is intrinsically impossible with FSX non-geometrical flight model” to keep the idea “the 3D model has no impact on the flight behavior”.

“We appreciate the passion we are seeing for this particular bug and your feedback on the situation is duly noted and will be passed on to the rest of the team for further consideration.” Hotfix the flaps bug now, not in sim update 3 - #99 by CapsLockDH

That’s the most tone-deaf response I’ve ever heard from a developer about a game breaking bug (I consider degrading the flight model on landing game breaking enough to call it game breaking).
It’s not passion either, it’s disgust at their inability to hotfix it immediately like any sensible product manager would.

“As this is not always easy to notice, and because this update was not supposed to be about the flight model, the issue was not caught by our quality teams despite all their efforts to avoid this type of situation.” via original post

This means their QA team doesn’t do full coverage test cases per release as a matter of course. That’s not encouraging on a lot of levels. It either means their QA isn’t big enough, or their processes ■■■■ donkey balls, or both. I can accept a complex sim having bugs, I can’t accept them not doing all they can QA wise to pick up issues - especially core functionality of the product - before a release. The release can either be delayed or problems documented in “Known Issues” (as they do already).

But to just not test things because the release “wasn’t about that” is incredibly bad from a software engineering testing perspective. You test standard functionality as a matter of course, every.single.time - even it’s slimmed down. Landing in all flaps configurations seems a bit of an obvious test case not to skip, at least on a subset of planes that exhibit very dynamic response. If it’s not possible to automate this (I think it should be doable tbh) and compare graphs of responses to detect issues, then at the very least farm it out to a group of pilots to run through a set of standard flight profile tests before you hit the big green release button.

I’ve been supportive of the rollout process and twitchy nature of MSFS up to now, given the complex nature of it, but seeing something like this slip through that points to a failure of basic QA practices makes me do a double take.


so i never buy from MS again if these Files show up in Steamversion!!!
can you please post a Pic that show this Files in the 172 classic Folder
that´s all i see


Sure would. Cheers

I would say that you are in the right place

and you see all these cfg. or more?
i miss the cfg.´s to fix this bug

In case you want to do it manually by yourself, these are the flaps values to fix:

Or use a 3-part mod
I think both methods are effective
As always

  • Keep track of what you do / change
  • Try it
  • Report your results


A technical note
If your path is something like:
C: \ Users [YOURUSERNAME] \ AppData \ Local \ Packages \ Microsoft.FlightSimulator_ \ LocalCache \ Packages

The AppData folder is hidden by Windows default

after the modifications on the simulator leave it as it is better :blush:

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You can’t fix C172 classic. It’s “de luxe” plane, config files encrypted against piracy.


I really would like to have a straight answer from Asobo:

You stated that the problem is too much lift on the flaps, and suggest we adjust the cfg files to compensate. My experience is that, even with this change, aircraft do not behave as they used to. I just (apparently) stalled at 85 knots in the C172 (G1000) at full flaps as I was coming in to land, and crashed nose down into the runway even though I was flaring and only a few feet off landing.

So please admit that there is more of a problem than just adjusting the flaps, and that this “fix” is not a full solution.

This is by no means the first time it has happened since the update. I am at 200 hours flight time in FS2020, and previously with an awful lot of successful landings in the C172. This sim no longer gives me pleasure. It was actually a step up flying in X-Plane yesterday, with the aircraft behaving as I expected - obviously the scenery not as good, but at least I was not in fear of my (virtual) life.

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One last thing
in the latest official patch they wrote:

Here the last change:
Look for the flight_model.cfg file - section [AERODINAMICS]

Look for the line:
now is:
lift_coef_ground_effect_mach_table = 0.0565: 1.25
change to:
lift_coef_ground_effect_mach_table = 0.0: 1.20, 1.0: 1.20

I checked before editing
This value was constant across all aircraft, regardless of Type and Size

I think we all agree on this :wink:

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The debate would seem to be about whether the new flight model is better. And it gives me cause for concern that a professional developer would release a product half done - not updating the config files. Expecting third parties to do it isn’t acceptable.

I suppose the problem with the latter is that it would make piracy of those planes much easier ?

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So there’s no difference, except your reason for using such a mod. Someone has already created a mod to “fix” the flaps issue on all Standard aircraft. There’s no need to tinker with files yourself. Why not give it a bash?

Sure, everyone does it according to his preferences / knowledge, as always

I am happy with mods that make aircraft better, but not with mods to fix a simulator programing error and if the workarround is change settings on config files Asobo must do it.