SLF here- looking at various articles/posts/analysis here and in aviation week, etc, and having spent many decades in aerospace- missile device testing - manufacturing /tooling of military and commercial aircraft, etc as a injun-ear - MY view of the MCAS ( Hal ) system fiasco boils down to the following simplified items
1) AOA mismatch notice/display an optional item- no doubt at a ridiculous cost- so pilots had no notice of that discrepancy
2) AOA single input with no matching- voting allowed to directly affect/move a critical flight control item ( stabilizer )
3) Pilots of 737 prior to Max ‘knew” that push pull of control column in opposition to autopilot would disengage autopilot and allow manual- direct control until autopilot manually reset/engaged
4) description of runaway stabilizer infers continuous movement despite column disconnect or no trim switch.- thus a positive action tripping circuit breaker is needed to stop
5) But MCAS- HAL on 737 MAX ignores both column and trim switch use- and moves stabilizer and then STOPS briefly- ALL dependent on ONE AOA value- with NO notice, NO display, and NO warning
6) Neither instruction manual or training mentions the absolute authority of MCAS- HAL- so pilots believing and trained that pull or push on control column, and/or disconnecting Autopilot gives them ABSOLUTE manual control at ALL times and that trim switch still works( briefly)
7) Pilots are now faced with a WTF conundrum. They are going too fast to lower flaps which stops MCAS-HAL and at a low altitude per training - “runaway” stabilizer seems to stop for a while- and autopilot is off so ????
8) Meanwhile stick shaker rattles, trim wheel starts and stops and ????
And only a few minutes to solve . . . " I'm sorry dave . . "
Last edited by CONSO; 13th Dec 2018 at 20:50.