From the Canadian engineer's email:
...Not knowing the exact reasons for telling us that 12.1 as a fix is not effective (ref. F2.3 recent change to CAT), the fact is that it is
another point that was just discovered...
I read this as, the main mitigation measures supposed to defuse MCAS missfire (12.1) seem to be invalidated by a recent finding, that 12.1.B) leaves a misfire still as catastrophic event:
12.1
A) Activation by AOA
B) Limit MCAS authority
C) Inline Validity monitor, i.e. follow AOA values and accept only reasonable changes
D) Delta disagree, i.e. compare both AOA values and detect a defective sensor
Invoking Santa for help:
Now (! meaning none?) of this helps get us to a level of confidence that having MCAS onboard was ever a good thing. The only way I see
moving forward at this point ( and I say at this point because it's almost Christmas and we can always believe in
miracles), is that MCAS has to go....