Originally Posted by
bill fly
Been said many times on these threads Peter. The logic of a separate dedicated feel trim compensator is indisputable.
But the software specialists are keeping their claws in deep.
Way back, British Airways helped certify the first European Cat 111 system. It took many actual approaches and a lot of flight hours until the reliability was proved (and incidentally held many folk up behind their min speed approaches) and the whole thing ran on relays.
Surprising what can/could be achieved without software - even in this day and age...
Bottomline? MCAS could have been designed with satisfactory architecture, integrity and reliability. It was not. A CAT I Approach system cannot be made CAT III capable, certainly not by a few software changes or even the addition of CPU or sensor. It has to be designed for the task from the ground up, with qualified subsystems, redundancies, and appropriate design assurance levels of software and complex hardware. Not implying that MCAS is equivalent to a CAT III autoland system, either, but neither will MCAS become what it must be by a few tweaks.