This has all been covered in the mega-threads, so I'll go over this once only for the sake of my sanity...
Originally Posted by
PerAsperaAdAstra
What I meant here was as I recall when the airspeed data corrupted, the aircraft went into alternate law mode, which seems to have added to the crew confusion...
Going by the report, the only reference made on the flight deck was the PNF making the callout from the ECAM. The PF never acknowledged the callout.
Alternate Law should be neither confusing nor a big deal - in a pinch all you need to remember is that the "hard" protections are no longer there - i.e. it's possible to stall or spiral dive the aircraft if you overcontrol (just like a conventional aircraft), and that depending on the mode you're in, the aircraft will be slightly more sensitive in roll. In short, all it means is fly normally but be careful with the controls.
you are right about the stab trimming nose up due to the sidestick input, but I understood this trimming happened automatically under the "alternate law", recovering from a stall with full up stab trim would vastly confuse things.
Autotrim is active in Normal Law as well. I was lucky enough to be able to perform some experiments with a friend in an A320 sim, and what we discovered was that it was possible to roll the trim forward again with sidestick on its own as long as it was caught early enough (link to summary below).
http://www.pprune.org/tech-log/46062...ml#post6793521
This is what I meant by "so much importance to IAS", to me it seems there should be more parameters measured, before he system reverts to alternate law?
The drop to Alternate Law had nothing to do with the buffet or any other stall-related phenomena. As I said above, Alternate Law takes away the hard protections (i.e. limits) because the design rightly assumes that the pilots should have the final say if the data being fed to the computers stops the system from working effectively. The control laws are really just the equivalent of what the Flight Engineer used to do in the event of a technical problem - i.e. reconfigure the aircraft's systems in a way that provides the greatest degree of controllability and safety.
it touches on the clash between classic stick and rudder skills, and modern aircraft AP systems.
AP wasn't really involved here, as it disconnected right at the start of the sequence. FBW is *not* automation in that sense.
(By the way, how do you do a quote on a forum post?)
Check your PMs.