You clearly didn't read what I wrote, because I said they were comparing it to a *conventionally-controlled* aircraft. Alpha Max is irrelevant in that situation because full back-stick/yoke does not command Alpha Max in a conventional aircraft, it just moves the elevators to the stop - if the aircraft is moving fast enough, it will pitch up and climb, but if it is not, it will pitch up and stall.

As HN39 said, phugoid damping is not used when in pitch command (i.e. the mode Bechet was in), only in HAP mode (which Asseline was in).

As I said before, the fact that the investigation went as far as confirming the behaviour as normal, but no further, could be argued as a point that they missed an opportunity to further explore the mode switches (and consequences of those changes) involved. However, the events of the last three seconds in the context of an accident investigation could equally be considered a minor point when compared to the major systemic failures that led to the aircraft being put in that position. Namely:

• The airline provided woefully inadequate briefing materials
• The airline failed to perform even a cursory review and risk assessment of the flightplan
• The airline failed to check the flightplan against DGAC regs regarding minimum altitude for display flights
• The airline did not require the crew to submit an effective "Plan B" for each stage of the flight plan
• The airline did not require the flight crew to familiarise themselves with the airfield, other than how it appeared on the chart (i.e. no prior recce flight was required)
• Neither the airline nor the flight crew attempted to confirm which runway was in use for the airshow on that day

The result of these failures was that the flight crew were effectively entirely reliant on their ability to improvise at short notice - which, given the inherent riskiness of the manoeuvre, should have been completely unacceptable on the face of it. Even more so when you take into account that there were pax on board.

To the best of my knowledge, "Priority One" of accident investigation is working to ensure that the incident is never repeated.

Now, I'm no accident investigator, but if I were I'd be inclined to consider getting to the bottom of how the aircraft was permitted to get into that position in the first place as a much higher priority than getting too far into why the Alpha Max command was complied with more slowly than it otherwise might have been (especially given the fact that the flight had been woefully mismanaged long before Asseline pulled that stick back).

Put another way, if the mistakes and loopholes in the list above can be prevented and closed, then with all other things considered there should never be another aircraft put in that position again, making the assessment of precisely why the aircraft was slow to achieve Alpha Max somewhat of a moot point.

Again, I said before that Asseline's best hope of being able to get the investigation to look further into the matter of what the EFCS was doing in those last few seconds would have been to take his lumps and remain positively engaged with the investigation throughout. By disengaging from the investigation and subsequently actively briefing against it, he did his own cause more harm than good.

Now look at the thrust and IAS, and what the pitch is actually doing. :)

metalanguage
 

Metalanguage = object formal language in semantic brackets.

Example of semantic brackets in character strings is using a special character which is never used in the object language.
As the number of characters is very limited, the special character is often an unused string of characters, like : = , http://www , Ctrl Z, [/quote] and [quote], etc.

Building an object language vs metalanguage may use different gramatic too but it is not mandatory.

Children playing to be master or parents or king mostly build metalanguage to be considered as master, parents or king! Sometimes they forget to use the metalanguage and suddenly they are no more king, and everybody is laughing.

In the simulator a hidden mistake (forget the space between ":" and "=" and you discover a smiley no-no instead of the string ": =" ) in the metalanguage semantic brackets may modify the behaviour of the simulated system (plane, inertial system, aso) without you know it, and you have a bad surprise when you do the same action on the plane, despite your aerodynamic algorithm is OK.

It is always difficult to test the semantic brackets, you would mostly need a meta-meta-language!

All that applies well on well structured simple systems using formal language. Graceful degradation brings a greater complexity .... KISS!

@roulis - I've said before, the computer code is not manually keyed in in that manner. Code blocks are tested in situ against the formalised function, then assigned to an element in a graphical development environment, which then generates the logic path from those individually-tested blocks of code. Each subsystem is then itself tested against the required behaviour pattern, and as the subsystems are linked together to form an overall program "module", that module and its functions are tested individually and in conjunction with others.

These tests are run *every single time* a change is made, and the results of the tests plotted against a regression graph. Any change in that graph is immediately apparent, and will point to exactly where the program deviates from the specified behaviour.

Typical Dozy disinformation again - where is the quote ?

Speculation only from HN39 that would demonstrate how the system is inefficient but you're happy to take it for cash ... Where is the official reference ?

Here's a novel idea, why don't you find it and prove me wrong?

EDIT : Certainly whenever I've heard that factoid referred to in the past, I got the impression that they were talking about an unprotected (i.e. conventional) aircraft - not least because I can't see how it makes sense any other way!

It's not inefficient, it's a necessary consequence of an aircraft being commanded to achieve or hold a specific AoA - namely a tendency to begin a phugoid motion.

On a different subject, I strongly recommend you have a look at OG's post #734, then look at the graphic on Annex 10 p.13. Bear in mind that what you're looking at (I think) is a simulation of how the aircraft and systems would have responded to the commands as they were prior to impact had there been no collision (114 kt being very close to the airspeed achieved just prior to impact).

Assume the disinformation you're spreading around or retract it.

Knowing both are starting from identical parameters, why Asseline should be subject to it but Bechet not ... ?

Why?

(Or more to the point, how is it fair that you get to make unsubstantiated claims of a "restriction" in the EFCS (and insinuate that it may have been surreptitiously removed) unchallenged, whereas I must retract any statement with which you disagree out of hand?)

They're not starting from identical parameters. As stated:

Check the graphs on Annexe X, page 9. Look at the bottom of the page (when rotated lengthwise), and you'll see a graph indicated "Manche Longitudinal". Asseline's inputs are the broken, dotted plot and Bechet's are the unbroken plot. Note that on this particular run, Bechet snaps the stick back almost immediately approximately 3 seconds prior to when Asseline did the same. Bechet's action is just prior to when the mode switched from pitch command to HAP mode. Asseline's motion is also more gradual.

That's what responsible adults would do.

Yes they are, according to the graph at the remise des gaz, except that Bechet is 10ft lower ...

Then if I had to guess the one who could be more prone to phugoid motion I would go for Bechet not Asseline.

Not quite 10ft, and Bechet pulls back roughly at the same point as "remise des gaz", whereas Asseline waits for around 3s before doing the same.

How? Asseline was in HAP mode when he pulled full-aft, Bechet was in pitch command.

How much then ?

It does not change anything - they still have to deal with the same level of energy.
Still waiting for the reference stating phugoid damping under high AoA protection but none under pitch command ...

Firstly, both the Bilbao report and the Hudson river report mention phugoid dammping explicitly for the high angle of attack protection mode. If you have a reference stating that it is a feature of the pitch command mode then please provide that reference.

Secondly, I explained in post #707 why phugoid damping is necessary in alpha-prot and unnecessary in pitch command mode. I showed a phugoid motion that results from maintaining AoA after a disturbance of a steady flight condition. On the AF447 thread I showed similar simulations of airplane motion at constant pitch attitude after a pitch change, for example:
http://i.imgur.com/mYVPqZz.gif?1

Not my point - What makes phugoid damping a feature of high AoA protection but irrelevant when high AoA protection is activated from pitch command initially ?
In other words, by which subterfuge Bechet is not subject to phugoid damping as he is obviously hitting high AoA protection too ?

The point has been brought here but you did not comment.

OK465

That's the way I read it. A quick sum suggests that at 118kt (the end of the simulator run) 2 CFM56s at full chat would give a nose up pitch equivalent to about 10 deg up elevator.

For the reason given above, the net pitching moment (thrust plus elevator) at the end of the run was equivalent to about 7 deg nose up. There is an indication that the elevator is starting to move back up at the end of the run, but even at that point the pitch is barely sufficient to be consistent with the commanded alphamax of 17.5 deg plus a bit of climb. [The pitch scale appears to be incorrectly labelled which doesn't help!] It looks to me as if for most of the time the thrust is supplying more than enough pitch to satisfy the demand but towards the end the thrust contribution is levelling off and it is from that point onwards that one would see elevator movement alone doing the controlling/stabilising job. Unfortunately (for this discussion at least) there isn't enough time in that state to form a judgement.

For the A330 in clean configuration alphamax (normal law) is greater than alpha_SW (alternate law) at all Mach numbers less than 0.86. I do not know the value of alphaCLmax, except that it is greater than alphamax as explained in numerous Airbus documents. At high Mach number alphamax is actually buffet onset, as explained in the FCOM.

P.S.
I forgot to mention that we know one point of the alphaCLmax vs Mach curve: AF447 stalled at 10° AoA / M.67.

"Not my point"? IIRC you made it a point.

Bechet pulls the sidestick abruptly fully back at an AoA where the FCS is in pitch command mode and there is no phugoid damping. Therefore the airplane starts to pitch up achieving a rate of 2.5°/second one second later. About again one second later the AoA exceeds 14.5° and the FCS goes into alpha-protection mode. The elevator then moves to more nose-down positions in a way that is quite similar to the accident sequence and the rate of rotation starts to decrease. However, the inertia of the airplane pitching up at 2.5°/second and the nose-up pitching moment of the thrust increase allow the airplane to continue pitching up to about 16.5° while it begins to climb. That is what I see in that plot, although the resolution of the plot is not sufficient to show the AoA that is achieved.

My point was more precise and needed to be detailed :
No stall - Alpha max - How great is it really !
You just confirm here that everything was in the aerodynamics but only the FCS restricted Asseline at 2.5 deg short of alpha max and deprived him the opportunity to survive the poor situation he initially put himself in.

Why do you keep calling it a "restriction"? It isn't - it's a deliberately engineered damping feature to ensure stability when in HAP mode which is, after all, concerned with protection from stall and stabilising trajectory.

Asseline wasn't restricted by the EFCS, he was restricted by his own actions in the previous 30 seconds or so - chopping back too much thrust, and then seeming indecisive about whether to actually go for Alpha Max (while constantly bleeding off airspeed). The EFCS doesn't know there's an obstacle three seconds away, it just tries to comply with the commands as best it can, and in this case both the TOGA thrust and full back-stick came too late.

The A320 and its systems were designed for ferrying passengers between airports, and the protections were designed to fit that function - it was not designed for "playing chicken" with forests at low altitude and low speed!

OK465

Excuse my jumping back a couple of posts, but what I was actually describing as interesting was, starting from 114 kt, the sequential increases in thrust, airspeed, pitch and height. Each lags its predecessor as it must, but the end point is that the simulator run showed that the aircraft would have got to alphamax by about TGEN 336 and (with a reasonable extrapolation) 40 ft about two seconds later. This would be an elapsed time of around 7 or 8 seconds from the application of maximum back sidestick. The two other simulator exercises, Bechet's and an un-named pilot's show very similar times.

If we accept (as I think you do) that this simulator was a 'high fidelity' representation of the aircraft then these figures must mean something in terms of the actual aircraft behaviour on the day of accident. One might conclude that the EFCS was carrying out the pilot's command, but that the physics of the flight conditions were such that it would have needed around 7 or 8 seconds to complete the task.

That is a strange twist - many posts ago I first suggested that phugoid damping was a possible explanation for the 'attenuated' response of the airplane to full back sidestick.

... and I did not oppose it, but what you confirm here is that the phugoid damping (if it is actually the guy behind the restriction ...) was useless and detrimental performance wise.

Bechet did much better without it than Asseline with it.

Looking at the totality of the evidence from the four graphics presented in the BEA report it seems to me that the situation is as follows:

The HAP mode of the EFCS has no knowledge of what the engines are doing. Indeed, with thrust control switched to manual no part of the EFCS uses thrust information. Consequently any aircraft motions produced by thrust changes are treated in exactly the same way as perturbations coming from any other “outside” source such as atmospheric disturbances.

The HAP mode contains logic that in effect says: “Do not allow pitch to increase if the speed is falling”. Introduced to ensure trajectory stability in the phugoid mode, it has its own logic – if flying at or near alphamax with a falling airspeed the last thing one wants to do is allow changes that might take the aircraft over that limit and nearer to alphastall.

The “job” the EFCS was being asked to do has been stated as “Provide the commanded alphamax”, but although at first reading that seems a straightforward objective, it is in fact simplistic. A more accurate task description would be “Provide the commanded alphamax in a controlled manner so as to minimise the risk and potential magnitude of overshoots above alphamax”

The details vary a little depending on the timing of thrust and sidestick applications, but basically when starting from a condition of level flight in the HAP operative AOA range with idle thrust and a reducing airspeed and applying maximum thrust and full back stick the sequence of events would be as follows:

Because the speed is initially reducing, the HAP logic requires that a down elevator signal be added to cancel the pilot’s nose up command. At this point the thrust is low and increasing only slowly, so the pitch remains constant whilst the speed builds up slowly.
As soon as the thrust has increased enough to arrest the deceleration, the HAP logic changes to allow the aircraft to pitch up. By this time though,the thrust has increased enough to provide a noticeable nose up pitching moment so the pilot’s demand can be satisfied without much change to the elevator command. At the end of this phase the speed is still building up slowly and the aircraft has just started to climb. [Note**]
The engines are by now accelerating quite rapidly, being on the steep part of the “S” curve, and if left uncorrected the associated pitching moments would increase the pitch rate to a level where there would be a very real risk of overshooting alphamax. The HAP therefore applies corrective elevator (actually a reduction of ‘up’ elevator) as shown on the graphs.
The aircraft, at this point, is pitching up towards alphamax and starting to climb more steeply.
As the engines near TOGA power their acceleration tails off along with any increase in pitching moment. The HAP elevator command depends on the details of the pitch rate and the proximity to alphamax at this point. If it seems that the pitch rate could be safely increased then the HAP might apply a small nose up correction, but if the pitch rate means that the aircraft is approaching alphamax too rapidly it might need to do the reverse to avoid an overshoot.
It is quite difficult to see exactly what is driving the elevator at this time because it is trying to control the difference between pitch and flight path angle, but we don’t have direct information on either alpha or FPA from the simulator records, although it could in principle be calculated from the data available.

Under this line of reasoning the only substantive difference between any of the four “flights” would be that F-JFKC’s was truncated (literally!)

[Note**] It was at about this point in the sequence that F- GFKC entered the trees.

Not quite - as OG says:
This is because it's an airliner, not a fighter - HAP mode is designed to maintain stability and trajectory, and Alpha Max is the upper AoA limit of that mode - it is *not* necessarily for use as an escape manoeuvre. In fact it can only really be expected to perform that function in concert with either sufficient airspeed, sufficient manual thrust applied (and available) or with Alpha Floor enabled. Asseline set the situation up so as to have neither.

As the graphs demonstrate (and OG has helped describe), Bechet initially got to a higher AoA in less time, but the overall performance was more or less similar. Whichever way you slice it, the fundamental aspect that cannot be ignored is that, possibly as a result of task saturation, Asseline did not recognise the danger in time and therefore did not act swiftly and decisively enough. That in itself is not the main reason he shoulders the responsibility he does - it's more to do with his decisions prior to then, when he had ample opportunity to turn around and do the run with more margin for error - but instead elected to press on and continue improvising with an ever-narrowing safety margin.

Airbus's own Alpha Max demonstrations were performed with sufficient thrust to achieve and maintain Alpha Max while preserving trajectory, and they were properly prepared such that they had a clear path ahead of the aircraft while in that state, because in that mode and at higher alphas, the room for evasive manoeuvre is significantly reduced.

Bechet got no restriction to obtain more than 17 deg of pitch even if he was under high AoA protection 1 sec after selecting TOGA.
True that speed was bizarrely not falling ... especially compared to Asseline who kept his sidestick in the same position for 3 more seconds ...
If flying at or near alpha max, there is no such thing as "falling airspeed", but there is flying at or near Valphamax.
"Falling airspeed" would be associated to rapid increase of alpha.
It would do that but brief temporary overshoot of alpha max is part of the protection too as demonstrated by the Airbus test pilot.

To the contrary it is specifically designed with that in mind.
Alpha max is necessarily associated to "sufficient airspeed" called Valphamax.
Anything between 5 and 10ft is a lot of performance ... if it's all it takes to survive the bush ...

Are you sure? Annexe X - page 9, right?

If so, then I'm seeing from "Remise des gaz"/full back-stick:

• An immediate increase in pitch for approximately 1 second (about the time it takes to transition between pitch command and HAP mode)
• The speed continues to decay from approx. 120kts to 113kts
• As the mode transition finishes (at approx. 115kts), the pitch increase stops, then actually decreases slightly as the speed decays
• As the speed builds up from the lowest value of 113kts (presumably due to the thrust kicking in), the pitch angle starts to increase again

Only in conjunction with sufficient airspeed and/or thrust. Alpha Floor is intended to provide a degree of fail-safe functionality in the event that airspeed/thrust is insufficient, which is why turning it off or otherwise preventing its function is not advisable unless precautions regarding minimum altitude and a clear path ahead of the aircraft are strictly adhered to.

Yes, but unless you know how that's calculated, it's something of a moot point.

Page 9 indicates that Bechet's altitude was in fact slightly lower than Asseline's at the point of impact, but even if you transpose it to match it doesn't really suggest that it would have made much difference.

[EDIT : Actually, hold that thought - I just remembered something from a while back (cheers for this info Chris)...

The RA of Bechet's pass diverges significantly below that of Asseline's roughly around the same time Bechet gets his initial "bump" in pitch (before HAP mode/damping arrests it as a result of an airspeed delta of approx. -5kts/sec). I'm wondering if this increase in divergence is down to the higher pitch angle and consequent lower physical altitude of the RA antennae. ]

Also, as others have pointed out, the increased pitch angle would have meant that the empennage made contact with the trees lower down and at a more acute angle, increasing the risk of the airframe breaking up before it came to rest and a significant increase in casualties as a result.

Yes I am sure that speed was bizarrely not falling ... especially compared to Asseline who kept his sidestick in the same position for 3 more seconds ...
And obviously you don't have any explanation to justify that so different attitudes obtained by Bechet and Asseline are supposedly still producing an identical speed decrease ... ?

Asseline applied TOGA before alpha floor would have kicked in ... what's you point again ?

Knowing that Bechet started the procedure 10ft lower than Asseline did, it does suggest that it could have made all the difference.

Just another typical unsubstantiated catastrophic scenario à la Airbus.

On the timescale of the chart on page 9 of BEA's 'Additif' (synchronized at the time the flight path passes through 100 ft RA ?), Bechet advanced the thrustlevers between 1 and 1.5 seconds earlier than Asseline.
Actually, at nominally 1g, with IAS falling at 1.7 kt/second, AoA is increasing at 0.5 degrees/second.
The accident report puts the impact at about 5 seconds after the thrust levers were advanced. Bechet's radio altitude was 27 ft when he advanced the thrust levers, and 5 seconds later it was again 27 ft. Asseline's radio altitude was 32 ft when he advanced the thrust levers.

Finaly, which was the math model ? :}

I thought the graph was supposed to be a "Recoupement from Habsheim" but are you now suggesting there is in fact not much to be 'recouped' ... ?

I thought you had earlier established the gain at 10 ft ... ?

And if you increase your AoA by 5 degrees in 2 seconds what would be the IAS falling rate ... ?

@CONF - I notice you're avoiding the question over whether the slight increase in pitch would account for the marginally lower RA value given that the increase in pitch angle would cause the rear-mounted RA antennae to be physically closer to the ground.

The IAS drops from 120 at the point Bechet set TOGA to 113kts 5 seconds later. How is that "not falling", let alone "bizarrely"?

And regarding "unsubstantiated catastrophic scenario[s]", it's no such thing - it's basic physics. A flat-ish sheet of metal subjected to an opposing physical force will bear a greater degree of that force as the angle becomes more acute.

@roulis - I'm mystified as to what you actually mean there.

The report discusses the difficulty of reproducing simultaneously all elements of the accident flight. My understanding of "Recoupement" is that the objective of Bechet's simulator exercise was to 'replay' the accident flight. The point you are criticising does not concern Bechet's simulation as such, but is about how Asseline's trajectory has been plotted on the graph for comparison with the simulated flight.

Actually I said 'less than 10 ft' here. I do not recall exactly how I arrived at that number, but I may have meant to say that Bechet gained 'less than 10 ft' on Asseline in those 5 seconds. Apologies if my wording was imprecise.

If you increase your AoA the loadfactor increases. The IAS continues to fall until the thrust has increased sufficiently to accelerate the airplane.

mystified by me is surely to much. And what about in my posts ? Math model of june 1988 A320 ? Metalanguage ?
Aren't you from the World best Country in logic ? Charles Babbagge, Ada Lovelace, Lewis Carroll, Alan Matison Turing ! France is it for math !

I have actually a LOT to criticize :

1. All the graphs are of the lowest standard. I would not have wasted any time on them if you didn't mention the one on page 9. I do think the BEA made its best effort to make sure nobody would be tempted to read them.
2. Those flight and simulator tests were purely smoke screens - what was needed was only the DFDR data to be compared with the most detailed programming of the FCS.

Load factor increase should reveal a change of path, from level flight to ... climb.
I still disagree with your concept.
Kinetic energy is transformed in potential energy until the thrust has increased sufficiently to confirm the early but short term positive climb as IAS now remains stable at Valphamax.

Indeed, as shown below.
No. The airplane will start a phugoid motion at alphamax as shown earlier, unless the pilot relaxes the sidestick and maintains the appropriate pitch attitude.

In the following graph KEht and TEht are the kinetic and total energies, respectively, expressed as a height. Total energy is the sum of kinetic and potential energy.

http://i.imgur.com/Revjj8s.jpg

@roulis - I've explained at least half a dozen times how the software development work was done, most recently in post #740.

The chances of there being a logical error due to a mis-key - as you theorise - are practically zero because the code is not keyed in manually. The chances of there being a logical error aren't much greater because of the pioneering work on testing, regression and reliability metrics. After that there's the fact that every major system "block" was implemented twice using syntactically different methods, and each is cross-checked against the other.

Even CONF iture seems to be accepting the possibility that it might just be a known feature of the system at this point, even if he doesn't much like how that particular mode functioned.

Between OG and HN39's sterling work, we're looking at a very reasonable explanation of how the aircraft functions would have behaved in that scenario.

@roulis

I have to say that I share DW's puzzlement when trying to understand your point. From previous postings:

Quote:

---

A simulator stays a simulator today, since they always have commands which don't exist on the plane and use metalanguage

---

Quote:

---

In the simulator a hidden mistake ...... may modify the behaviour of the simulated system (plane, inertial system, aso) without you know it, and you have a bad surprise when you do the same action on the plane, despite your aerodynamic algorithm is OK.

---

Quote:

---

Finally, which was the math model ?

---

You seem to be saying that you believe there could have been a mistake in programming the simulator [Dozy has been commenting however on errors in the flight EFCS units]


However, I cannot relate to the simulator having "commands" which don't exist on the aeroplane. The simulators at Toulouse are linked to the "Iron Bird" which uses actual flight standard hardware (and its associated software) so the processing of pilot commands is identical on the aircraft and in the simulator. The only difference is that the simulator uses a mathematical model of the aerodynamics and processes the pilot commands in conjunction with that model to produce the aircraft motions which are fed back into the flight standard EFCS units rather than those emanating directly from aircraft response.To quote from the Airbus FAST article on the iron bird:

Quote:

---

From the flight deck, the Iron Bird can be flown like a standard aircraft, with a computer generating the aerodynamic model and such environmental conditions as air density, air temperature, airspeed and Mach number.

---

Since you seem to be accepting that the likelyhood of error in the aerodynamic representation is small, the only source of difference between simulator and actual aircraft that fits your argument is, so far as I can see, the solution of the six degree of freedom equations of motion. Such an error would surely not be confined to the particular case we have been discussing, and in any case the correspondence between the actual flight records and the simulated version of the last few seconds of flight (page 13 of Annexe X of the BEA report) says that no significant error existed.
Also of course the method of solution of these equations has been been around a long time in various simulators so there is no innovation there.


Could you perhaps be a little more specific regarding the reasons why you think the simulator results to be suspect?

So according to Bechet the airplane has no issue going to alpha max but then, what do you make of the Airbus statement that "the flight protection system operated perfectly and prevented the aircraft from crashing nose first" ?

Also not too sure how you get Valphamax at 113kt ... ?

Sorry, I should perhaps have written "phugoid motion at approximately alphamax". The phugoid damping terms will reduce the AoA slightly below alphamax when the airplane is decelerating, and increase AoA when the airplane is accelerating, as conceptually illustrated in the chart below.

Well, the flight protection system certainly 'prevented the aircraft from crashing nose first'. As to 'operating perfectly' the BEA report notes:
In short, the recorded parameters are too few and too coarse to permit a reconstruction of the operation of the flight control system in a complex situation with variations of windspeed and angle of attack encountered by the airplane as it flew below treetop height in the wake of the forest.
I stand corrected: Valphamax should have been the Vs1g of 110 kt.

http://i.imgur.com/kwTBtKZ.jpg

In addition to HN39's remarks, I should add that "operating perfectly" in this context seems to refer to the fact that it operated as designed - and based on the analysis both of the report and the work done on this thread, that looks like a reasonably accurate statement.

What Bechet seems to have proved (and others here have explained how and why), is that the aircraft will attain Alpha Max as long as speed is sufficient, but the time taken to do so depends on the flight conditions and the mode. Specifically, the time taken to achieve it will be longer if the command (i.e. full back-stick) is given with the aircraft already in HAP mode and decelerating than it will if the aircraft is in pitch command mode when the command is given.

From a systems perspective this makes sense as, when presented with a decelerating aircraft, HAP mode has to constrain rate of movement in the pitch axis (and elsewhere) in order to fulfil the part of its design brief that demands flightpath stability and trajectory be paramount. Pitch command mode is obviously free of those constraints because airspeed deltas are immaterial if pitch (as opposed to AoA) is what's being commanded by the stick.

As to what impact the earlier increase in AoA might have made in that situation - well, we can only speculate. But my speculation based on reading of the graphs (aided immeasurably by other posters' explanations) definitely indicates that there would still have been some impact with the trees, and at that point there are just too many variables involved (particularly with regard to what part of the aircraft hit the trees, at what angle and what damage that would cause) to make even an educated guess. That said, based on the photographic evidence, I do think that the actual path of the aircraft caused the main gear and later the main spar to absorb more of the impact force from the trees, lessening the subsequent forces on the more fragile empennage and tailcone.

But again, why do you still persist equalling Valphamax and stalling speed ... ?
And if you do think Valphamax is Vs1g at 110 then what is Vstall ?

True that all these speeds, all of them, including Vls Valphaprot, should have been published in the report for the weight config altitude at the time ... Where are they ?

For the graph, things don't add up.
How do they or you get identical speed traces from so different attitudes ?
An obvious penalty on the speed there must be by pulling the nose up ... but also a benefit to the altitude ... Where are the ?