lomapaseo;
The discussions need to always reflect back to the initation, else we are using up an awful lot of bandwidth to no avail.
Precisely.
Unless the aircraft was under control or recovering
until a mid-air breakup occurred, what happened after the loss of control is not essential to understanding the causal pathway(s) to this accident.
bearfoil;
Re 'bias', having spent considerable time presenting flight data to those with the authority and responsibility to make changes and observing denial, explaining-away and normalization behaviours which set aside data in favour of opinion at work first-hand, I am familiar with the power of latent bias and the difficulty in breaking through a strongly-held world view which is not in accord with facts derived from non-empirical sources, (actual flight data as opposed to impressions of what the flight data 'says').
In this case it isn't just "human nature", it is more specifically labelled, "cognitive dissonance". Accepting a state of affairs which is strongly in conflict with one's "understanding of affairs", especially when "perceived stakes" are high as is always the case in this business, is a significant challenge especially where "groupthink" may be latently at work. Official reports may be no more than the very best efforts of particular world views, although it's never that simple. If we switch the words "see" and "believe" around from the phrase we're all familiar with, the phrase, "
I'll see it when I believe it" perhaps captures a sense of this.
With an activation speed of 250 knots, is the limit/blow back system dependent on indicated air speed? likewise, is the 2g threshold reliant on equipment that may have been reporting falsely, as other sensors were?
I left this notion out partly because I knew you'd know this as a possibility but also because I don't know what such possibility's effects would, specifically, be.
I believe the system would be predicated on Indicated/Calibrated Airspeed as that is what the airframe is exposed to; I know the A320's 'g' sensing is very reliable (unlike the B777 'g' parameter, which sensor is located under the cockpit and can be, in flight data work, suspect) so I would tend to dismiss the possibility of any errant 'g' data.
Before permitting too much credence to any notion involving, "automatic deployment of spoilers in response to errant data", it should be understood that the system has limited authority and is designed to only momentarily reduce wing-bending moment. The Lockheed L1011 - decades ahead of its time, (not sure if it was just the -500, ...411A?) had the same system.
MLA authority is limited to the ailerons and to spoilers 4,5, & 6 and always symmetrically. MLA adds a maximum of 11deg up-aileron onto any roll demand and a maximum of 9deg deployment symmetrically on any roll demand. Eight degrees of aft sidestick movement, (a HUGE amount at cruise speeds and altitudes) activates the system, (for obvious reasons - it is load-relieving the wings). Deflection is proportional to the 'g'-loading in excess of 2g. The system functions in Normal and Alternate laws. My tendency would be to place this low on any layering of possibilities.
Some thoughts...
My own impression of the cockpit environment during is that it would be a very challenging set of circumstances in heavy turbulence. Maintaining a stead pitch attitude in manual flight is not difficult nor is maintaining engine thrust with manual thrust - one just brings the thrust levers back, out of the CLB (Climb) detent and sets the power that was being used before disconnection of the autothrust, (Leaving the thrust levers in the CLB position with the autothrust disengaged would request max climb power which is more, (but not much more) than would have been commanded for cruise power).
But doing so while in heavy turbulence and while handling ECAM messages, which would be a series of Master Cautions and a few Master Warnings (with associated auditory warnings) all being re-prioritized themselves on the Lower ECAM as the affected systems degraded as a result of the original loss of ADR data, would in-toto, be a
very challenging environment for any crew no matter how disciplined, no matter how constituted, (captain absent, Relief Pilot in the Left Seat, etc). Cancelling warnings and assessing the next ECAM messages in a continuously re-prioritizing series of ECAM messages and drills would present a very busy and perhaps overwhelming number of "#1" tasks.
From the satellite imagery available in another thread and on the web and given 447's assumed path, (no deviation for weather), one may reasonably assume that turbulence would be increasing and the difficulty of handling the penetration of the line of TS may have been exacerbated by the unfolding degradation of some aircraft systems with associated warnings and demands for crew attention, as well as the difficulty in actually reading the PFD and ND displays (the ND has the radar presentation superimposed upon the navigation data) in turbulence.
Except for possible mid-air break-up, (which I had initially posited but through discussion with others, dismissed), these are the factors which I think are more critical to an understanding of this accident. Evidence for this view comes from the fact that other incidents of loss-of-ADR with similar patterns of ECAM/ACARS messages and which were discussed at great length in the original (replacement) AF447 thread now in Tech Log, have not resulted in loss of the aircraft.
infrequentflyer789;
So determining whether or not it was attached at impact becomes rather important... and therein lies the debate.
I don't think so. A VS separation would result in a high forward speed impact with the sea rather than a low forward speed, high vertical velocity impact. The evidence just isn't there for any high forward speed impact. Fragmentation of interior cabin parts was not high in this accident. Large, relatively fragile structures survived, intact.
Neither do I think that there is much to learn that we don't know already from the Japan Air B747 which lost the VS through loss of the aft pressure bulkhead and AA 587, in terms of pilot handling.
I like Occam too.
PJ2