Originally Posted by
LEOCh
We are very unlikely to get the actual MAX stability data from Boeing but the Cm versus alpha data is more likely to be something on the left (similar to that suggested in Bjorn's corner at Leeham news). But many reasonably technical writers are describing something more like on the right. This seems unlikely because certification requires the aircraft to be safely flyable without stability augmentation.
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The behavior shown in your left plot would be compliant with 14 CFR 25.203(a), which I believe was the requirement that necessitated MCAS. The slope going flat or positive at any point prior to the stall would be non-compliant.