Will Fraser;
Re ACARS messages, indeed it is merely a messaging system and not a flight data analysis tool. We cannot imbue it with more even if it is all we have.
Much of this thread is taken up with "interpreting" ACARS and the tiny traces available; this is very unstable ground upon which to base any thinking whatsoever.
Most have accepted that the trace of the messages "IS" what happened. We do not know this.
Many, including myself, cautioned against such interpretation at the very start of this thread but those who don't know seem to have the least fear in treading in these deep and extremely complex waters. Your post expresses this quite well.
The reason for such caution is, among other reasons, the fact that the ACARS is a maintenance reporting and messaging system, not a flight data analysis tool. The granularity of the data is very high, (stating the obvious).
Also, the ACARS messages that many of spent hundreds of hours pouring over, is only a map of the incoming messages from the fault-reporting sections of the individual systems.
Each AF system component may possibly have it's own BIT (built in test) capability and, when such system is not functioning as designed, the BIT processes analyze, possibly attempt a fix and finally report the fault or failure through the AIMS, (Aircraft Information Management System). I say 'possibly have it's own BIT because the FIDS - Fault Isolation and Detection System also does this job and is installed on FMGC#1, but the AOM does not specify which internal and external failures it monitors/records).
All ACARS functions are heavily tailored to an individual airline's specifications, not Airbus's. We do not have a lot of information on AF's ACARS system design...
The inevitable conclusion and the reason why the sequence of ACARS messages may mislead in the kind of activities taking place here and elsewhere is, the ACARS sequence is a map of the incoming messages and NOT a map of the fault-failure sequence of individual systems, which, due to their internal designs and BIT processes, may not report faults/failures immediately.
The reasons for skepticism are significant. The foundation upon which any theories are posited, is at best, unstable. Hindsight bias is very active especially in the area of pitot and TAT discussions. I posted information a while back not to confirm theories but to make the complexity and uncertainty of the task ahead abundantly clear especially to those who have no experience or training in these areas. This is an extremely (and I mean extremely) complex aircraft which cannot be known deeply by any one individual, and we have mere traces instead of data and tiny slices of the much larger picture in the now-found wreckage of the vertical stabilizer.
One bare thread doesn't make the finished suit. We have small bits of bare threads dancing about and no possibility of summarizing - there is essentially nothing to summarize yet.
We simply do not know the reasons for system faults and structural failures. Further, we cannot even posit theories - such territory is "where angels fear."
We do not know, for example, if the reconfiguration to Alternate Law (1 or 2?) was because of a bank angle exceeding 45deg or because of the loss of ADIRU information, or....?
It is not the positing of theories which in and of itself is unproductive and possibly even harmful. It is the "independant life" such theories swiftly gain in a pressurized pyschological environment predisposed to "finding out" which can distract and blind otherwise knowledgable and intelligent perceptions or cues.