Originally Posted by HN39
If at any time in the descent he had pushed the SS fully forward 30 seconds and the THS had not moved, then it would have been an issue in AF447.
Looking at the BEA plots or better at mm43’s re-arranged plots (#1770) pitch response to the few consistent nose-down sidestick inputs appears very weak. Except the last one, pitch curve minima seem more related to high roll angle than stick down input. During these nose-down sick periods the elevator angle never increases above -15 deg. Why would the THS start moving up?
A possible reason could be that in the stall domain decreasing AoA increases a little Nz in an almost unchanged trajectory. Remembering that the pitch control is still C* it is easy to see that an Nz increase will decrement the actuating signal in the control loop. Moreover, the default gains used when CAS is invalid likely play against a fast response.