Issue with BEA investigators is they had expert help at hand, they correctly understand how Airbus FBW works and are fully aware what "acceptable by certification authorities" means.
PPRuNers have no such resources readily available, therefore I find it unsurprising that some only slightly wrong theories about how Airbus FBW works resulted in quite flawed assumptions being passed as facts, leading to another oozlumistic round of suspicious glances being cast towards BEA, DGAC and Airbus.
Let's get to basics of aircraft stability: conventional certification rules state that no passenger transport aircraft will get certified unless she displays adequate static and dynamic stability in pitch. Static stability means aeroplane, when disturbed from trimmed speed, will return to it stick-free. Dynamic stability means it will do so in acceptable number of convergent oscillations. Stability is not just a matter of aerodynamics; control forces, controls architecture and power all affect it so it can be (and mostly is) significantly modified by FBW. FBW Airbi can not demonstrate hands-off stability in normal and alternate laws as due specific settings of their FBW they will not make an attempt to return to trimmed speed after the stick is released.
As for how Airbus FBW works, lets first start with how it doesn't. It was said it maintains 1g. It was said it maintains pitch. It was said it maintains alpha. In normal operation, none of this is true. It might maintain all three of it but not because it pursues them actively but only as a consequence of trying to
maintain constant flightpath when stick is pitch neutral.
So how it works for the pilot? First we'll assume steady, level manual flight with ATHR in SPEED mode (to digress a bit: most of the world flies this way while my company was pretty adamant: manual flight - manual thrust, no matter if it is Boeing or Airbus or whatever). If there's moderate pull or push and then release to neutral, FBW will maintain new flightpath, autothrust will compensate with thrust change, aeroplane will feel pitch neutral. So far so good.
Now let's assume ATHR is off, aeroplane is flying straight&level and a couple of degrees of pitch up are introduced while thrust remains constant. Aeroplane tries to maintain the flightpath but as some power now has to be used to climb, drag causes the aeroplane to decelerate. As it decelerates, it needs more AoA to keep the fligtpath so FCS introduces a little more pitchup on its own. Aeroplane feels slightly unstable but if power and pitch are reasonable, equilibrium point where the new flightpath can be maintained without further increase in alpha is met. Still good.
If we take extreme case, where aeroplane is flying straight & level and TLs are moved to idle, aeroplane indeed starts to pitch up on her own as the speed is bled off. How long does it pitch-up? Until alpha prot activates in normal law, low speed stability kicks in in alternate1 and introduces pitch-down or it stalls in alternate2.
So why is it all so seemingly complicated? Simples. To make life easier for mister pilot and provide him with perfectly conventional control response within the envelope. There is absolutely no need to think about flightpath or trim. Stick forward moves nose down. Stick backward moves nose up. Stick left rolls the aeroplane left. No points for guessing what does stick right. Many a claim was made on this rumour network that oh-so-complicated-Airbus-took-the-controls-away-from-me-when-it-shouldn't-have. None of them were substantiated except St.Johns and Bilbao - that's fixed now.
While the nomenclature between SA and TA Airbi is different, principles of protections are pretty similar. We didn't call it ALT1 and ALT2 when I was on 319. Their rough equivalents are "alternate with reduced protections" and "alternate without protections" (nitpickers, welcome).
How do I know AF447 wasn't deep-stalled? Well, I started by paying attention in high school science classes, which helped me to understand aerodynamics lessons during my flight training. One of them involved deep stall and I learnt it has specific meaning: it is stall which cannot be recovered by conventional means such as actions on elevator, stabilizer or power. While AF447 never fully recovered, mere reduction of power or just moving the elevators towards the neutral (while never reaching it) abruptly decreased its AoA - which is incompatible with deep stall as we know it. Now if your goal is to be taken seriously in discussion, you won't go a long way if you take well established terms and start assigning them just your own definitions.
Originally Posted by Lyman
Alternate Law in upset is absurd. And deadly.
If it were true, then dr. Evil Genius who invented should be stripped off of his PhD! He has less than three percent success in catching the crews in his trap!
Seriously, these unsubstantiated claims are so repetitive I can't even find them humorous anymore.
Originally Posted by Lyman
This means the pilot is constantly responsible for Pitch
Is it news for anyone else?
Originally Posted by Lyman
At four thousand feet, descending at 120 knots, I might consider a last will and testament, though a short one, an aural one, with a keyed mic.
Hollywood's bravo sierra. In their minds, crew was fighting for their lives until the end, there was no time for pathetic farewells. That they completely misunderstood their enemy and eventually committed the suicide by incompetence is tragic, not stupid.
Originally Posted by Lyman
I suspected the pilots were betrayed by the aircraft.
Harsh words, but if we assume they're true then so were others. Difference is they choose more appropriate response, even if it meant doing nothing at all while been confused about what is happening.
Originally Posted by Lyman
I don't think the A330 was tested at STALL with full nose up trim? Who would have the balls to do that?
Using brain instead of balls tends to produce better outcomes. Like not even trying what was computed to be fairly suicidal.
Originally Posted by Retired F4
Does that mean, that there was no chance of recovery or that they didnīt look into that matter?
Looking into that matter could turn out to be very expensive... not just in Euros but also in lives.
Originally Posted by Lyman
A sister ship to the 330 had an electrical short circuit in flight, and the crew lost half of their ECAM, lost Navigation, had cockpit cabin communication failure, and lost effective control of the stick, along with autopilot.
Any of this sound familiar?
No. Reference, please.
Originally Posted by rudderrudderrat
Normally all training is pre-briefed, so when the event happens in the simulator, there is no "surprise".
Glad I work for abnormal outfit.
Originally Posted by mm43
The real question is why a relatively simple loss of air data lead to such a monumental "cock up".
Panic.
Originally Posted by Zeroninesevenone
I am sure they are quite familiar to AB pilots. Still I think that the briefness of the messages can add to the congnitive stress situations more than ease it.
When ECAM works as designed and is faced with simple faults, it covers everything you need to know and do. No more, no less. No point putting "pretty please with sugar on top" on ECAM lines.
Originally Posted by OK465
I think the report alludes to the less than optimum task load for the PNF
Yup. Proper flightpath control was never achieved and that always takes precedence over ECAM actions.
Originally Posted by rgbrock1
Perhaps this correlation is not appropriate and I'm sure I'll be called out if it is. But, me thinks it is indeed appropriate.
I suppose it is even more appropriate than you assume it is.
Perhaps it is leftover in our DNA from the times our ancestors were preyed upon by cave hyenas and short-faced bears but there are two main types of panicky reaction: getting frozen (maybe the hunter won't spot you if you don't move) or running away in whatever direction (this might help confuse the predator or make it catch someone slower). Seems to me that it was very unfortunate set of events that both pilots simultaneously fell victim to panic. CM2 was trying to run away from the danger he sensed was coming from below and had no understanding for the aeroplane's energy state while CM1 got too scared to intervene. IMHO another important aspect of your story is that your comrades, while doubtlessly well trained, were simultaneously faced with realization that they are not in training anymore, that (unlike drill sergeants who just play-pretend) folks out are there are really bent on killing them and that not everything is going according to the plan. Sudden realization of one's own mortality can easily set the atavistic instincts in motion.