From the ACARS and some great data via PJ2, and others, the a/p drops involuntarily when Law reverts 'out' of Normal to ALT. The Attitudes from the a/c computer that would cause the a/p to drop on its own when exceeded are here also. I recall that this a/c will not re-enter NORMAL out of ALT1/2 or DIRECT unless and until the ship has landed, and can be indexed (I think). So if from ACARS the a/p dropped by command from (Computer) ADIRU disagree, then I can't imagine why auto would be allowed to re enter the room even if invited.
Likewise, if DIRECT was attained, and RTLU and other minimum protections were operating, I can't easily imagine this accident happening unless something additional occurred (Svarin's nifty catch). The first and most likely candidate would be a/p trying to horn in after teasing the front with reacquired Bars and a less than sixty second a/s agree 2x2. But the pilots would know that NORMAL LAW is u/a, so why try to latch a/p only to see it booted (rejected) by the computer again??
Less likely, but possible, attitude excursions were attained that exceeded the a/p working limits and this caused the drop?
Less likely still, accompanying attitude extremes were disparate airstreams transiting the static and pitot ports which may have caused the TCAS and Windshear bunk that got sensed, as well as (actual) corrupt airdata??
These attitude extremes would be Wx and causative of UAS? Then, as the pilots recovered from UAS, abrupt and mechanically incoherent Pitch commands caused upset??
Too fanciful.... UAS, recovery, then the activity addressed by the (too late AD).
The more I try to understand this a/c's LAW, the more senile I believe I may be.
Last edited by bearfoil; 24th Apr 2011 at 23:54.