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Hi Chris - I'm struggling a little to understand what you mean. I'm not referencing anything too complicated, just the statement regarding the Abnormal Law, below. Now I know the BEA has stated that the airplane never reverted to "Abnormal Law" as a result of the high AoA but they dont' explain why and that is really confusing.
Struggling? That makes two of us! Sorry it didn't make sense. By the way, I had not considered the possibility of Abnormal Attitude Law. Perhaps I should.
If the initial drop of IAS on ASI 1 and ASI 3 was sufficient to trigger Abnormal Attitude Law, what would have happened when the ASI 1 recovered to 215kt at FL375? The IAS/Mach, AoA, Pitch, and Roll no longer justified it. In these circumstances, you note:
After aircraft recovery, and until the aircraft is on the ground, the available laws are:
- in roll: - yaw alternate law, (in this case Alternate Law 2)
- in pitch: - Nz law, (with recovered autotrim).
So autotrim would have been recovered? In which case, it would have resumed trimming: partly, perhaps, to neutralise the increasing up-elevator that had been selected by the system
– to maintain the G demanded by the sidestick as the airspeed fell
– while the THS had been frozen. It would certainly have needed to trim nose-up for the continuing decay of actual CAS as the aircraft approached FL380.
It is unclear precisely when the AoA reached +30, but at that point the THS would presumably be disabled again. My assumption is that the 1 minute taken for the THS to move from 3NU to 13NU would have been completed before that point.
In the post you are discussing, I proposed that the PF's "nose-up inputs" may have overridden any stall protection in Pitch-Alternate Law. If Abnormal Attitude Law had been triggered, it seems from Andy Tracey's paper that stall protection is not provided.
Reading the above, it all sounds exceedingly speculative in the absence of data. I only post it to show that, after some thought, I share your present confusion.
PS
Thanks,
A33Zab, I had no knowledge of the BEA's "Leak". Whoops...
