Hi
Originally Posted by
JD-EE
I have an idle question that does not bear on this crash. Why might Alt 2 latch in and not be able to be escaped back to normal once the aircraft is flying normally again? Permanently latching out the aircraft safety systems for half of a long (10 hours?) flight seems counter productive.
My guess: having encountered once a HARD failure (i.e. not intermittent), the system cannot be sure its sensors are back to normal.
OK, we (human) may analyse that a priori the speed (pitots) are back to normal.
But a computer cannot be sure of that (unless implementing complicated/prone to failure cross checks). So, as long as a real check of the once faulty part(s) (here: the pitots/ADR) has been done (on the ground, that is), the computers considers their functionnality (here: airspeed values) as unreliable ; or, at last, not enough reliable to revert back to NORMAL LAW and its associated protections.
Just an (educated?) guess, though. If anyone knowledgable can/may confirm or infirm, I'll be glad.
