Earlier quoted context omitted.
>The MCAS is an optional component that reduces certification and training costs No. The MCAS was a "necessary" component for pitch stability - without it, a 737 MAX in a pitch-up attitude would, in the absence of correcting inputs, pitch up further and further until it stalled. Without it, the airframe is uncertifiable, full stop.
Cite? I'm certain that's not correct, everything I've read on it has said MCAS was specifically a software modifier put in place to allow the plane to respond substantially the same as a regular 737 without the larger engines, in order to avoid having to have additional training for all 737 pilots worldwide. Most aircraft, in a "pitch up attitude" will increase their angle of attack as thrust is applied. The issue wa…
Although to be fair my summary wasn't entirely accurate - it wasn't that a MAX was outright dynamically unstable with no control input, as I described, but rather not sufficiently stable as to cause a monotonic increase in stick force as AOA increases, which can cause the combined system of pilot + flight dynamics to be unstable since the pilot relies on stick force as an indicator.
> Most aircraft, in a "pitch up attitude" will increase their angle of attack as thrust is applied
This is both incorrect and irrelevant. Most aircraft will climb when power is applied, but will not change their AOA unless the thrust axis is off-center. To a first approximation, power controls climb rate, and stick input changes AOA. Change in behavior under different power settings has little to do with the problem with the MAX. The problem with the MAX is that at high angles of attack - i.e., when the stick is held back, causing the air to meet the wing (and the engines) at a steeper angle - the engines, which are flung forward, start producing lift of their own and produce a pitch-up moment. This means that the further the pilot pulls the stick back, the less hard they have to pull. This is a dangerous inversion that increases the control order of the system, as it breaks the usual assumption that a given stick force will result in a given AOA, more or less.