Why don't they just install a long enclosed ceramic channel down the length of the plane, fill it with mineral oil and make the plane a really long bubble level? As a backup?
Surely you know that gravitational force is indistinguishable from acceleration and the idea of 'down' sensed by any mass inside the plane is the vector sum of both.
I surely do. And stop calling me Shirley.
AOA is relative to prevailing wind currents NOT ground level! It has to be a sensor!