Originally Posted by
GordonR_Cape
The recent comments about MCAS reinforce the point that it is very difficult to design a complex system that is safe, effective and reliable, and operates within the limitations of the human-machine interface.
From an entirely different perspective, this
reminds me of the (apocryphal) story of the monkey trap. Once the hand has gripped the food reward, the size of the fist is too large to withdraw from the trap.
MCAS software seems like a clever fix, but may actually be a trap. All kinds of contortions and wriggling, do not solve the underlying physical problem,.
Letting go of the 'easy' software fix may seem painful, but it might be worse to be trapped in a never-ending tug-of-war between physics, regulations and safety.
The basic problem is not physical it is lack of usage of the system science. The control loops are made to compete against etch other. The actuator of the pilot is elevator and the actuator of MACS is horizontal stabilizer. It is basically disaster waiting to happen. It is so fundamental design error that it is hard to believe that they were solving just feeling related issues.
Yes, a complicated diagnostics can be made to detect the disaster preconditions, but... . Far more straight forward would be to add actuator somewhere between stick and elevator to generate the right stick force (system that could be deactivated in a moment) if the problem were really the stick forces. Of course, the situation might be more complicated that announced publicly.