VicMel, an interesting analysis #3958. Together with that of Smythe … now confused.
(If) Vane-sensed AoA requires correction; is this correction in the vane unit or elsewhere. Peter Lemme argues that errors originate from the vane unit as AoA output is ‘sent’ and used by many separate boxes.
Alternatively a separate (remote) calculation would be more logical with the need of other factors, e.g. embedded in ADC for Mach; which box (function) is not so important if the corrected AoA is available on a digital bus to all other computational boxes. This would also negate the view of a vane-origin error.
Airspeed pressure-error corrections depend on the corrected AoA; differences between ADC computations are alerted (Speed, Alt, Disagree). This should not change the AoA.
AoA is use to position the low speed awareness symbol on the airspeed scale, but this too uses output AoA, it should not correct - change either AoA or airspeed.
Thus what correction is being discussed; where is the computation done, and how is the output accessed by many other functions requiring AoA - MCAS one amongst many.
Re vane damping; an earlier suggestion was that the vane slipped position on the shaft; fortuitously catching at different times and values in each accident. A slipping vane/shaft, when snagged would then act as a single unit involving aerodynamic and mass damping - but incorrect AoA.
Although unlikely, Occam might like the simple mechanical approach.
Alternatively, the digital views might follow Moore-Murphy, where with increasing complexity and add-ons, there is even greater risk of error, the need crosschecking and multiple sources would be paramount. Somewhat lacking in this system.