@Chris Scott:

I don't know for certain, but all the credible sources I've encountered state that flare mode was not a factor in the aircraft's behaviour. The oft-repeated claim that "the aircraft thought it was landing and wouldn't let the pilot pull up" was a complete fabrication of the press*.

Thinking about how the systems were designed to interact, I suspect that the engagement of flare mode would only happen if the descending "ramp" from the RA sensor was consistent over time, as any system responding instantly to transient changes would not be appropriate in an aircraft.

Airbus have changed code many times over the years (in fact the ability to fine tune aircraft qualities without requiring mechanical work was one of the factors in favour of civil airliner FBW), but even by 1988 they had a pretty good handle on this kind of basic behaviour - having tooled their modified A300 around for several years.

* - And also the opening salvo in terms of a lot of people misunderstanding FBW as a concept, by erroneously conflating it with autoflight. Given the usual short shrift accredited to journalists among pilots, it's surprising how long that particular rumour has lasted and how many were willing to believe it.

Hi DW,
I agree with you there.
The baulked landing procedure (Select TOGA power and rotate to 10 degs pitch) allows you to fly away from any attempted landing - even after touch down.

Some pilots seem to forget that the only thing that makes an aircraft climb is thrust (when you have no more kinetic energy to swap for height).
Why on earth they were so close to Alpha Max AND Low Height AND Idle Thrust is beyond me.

Indeed. A bit of background - The very first Software Engineering module lecture I attended in my first year at Uni had my late Prof. showing us the infamous video of the accident - he then took a show of hands to see how many of us thought it was an issue with the computer/software implementation - quite a few went up. He then proceeded to explain why it wasn't what so many of us believed, and provided an overview of how the systems were designed/implemented - finishing up by pointing out that it only takes a small mistake to cause a disaster, and just how much work and effort it takes to keep those mistakes to a minimum.

I've said it before, but I should reiterate that said Prof. was originally a dyed-in-the-wool sceptic when it came to digital FBW in civil aviation, and was well-known on the old Risks list for holding people's feet to the fire!

At least some of the answers are found in the lesser-known "Other factors" section of the report:

(Emphasis mine. Please excuse ropey Google translation - it was the best I could do in the time!)

In short - the airline and crew forgot the old "5 Ps" maxim*, and thus fell victim to the consequences.

* - i.e "Proper Planning Prevents P*ss-poor Performance".

** - @CONF iture - could you please point me to the page/section where you're getting the 2.5deg value from? Thanks.

3.2.2 . other factors:

The pilot was known to his Air France colleagues as "Rambo".

r r r
"Why on earth they were so close to Alpha Max AND Low Height AND Idle Thrust is beyond me".

One guess is that the crew wanted to keep the aircraft in view for a longer time by taking advantage of high AOA protection to slow it down to minimum speed and maintain it/AOA by adding thrust. The computers adjust alpha max to stay below Vs1g stall, may be that slight adjustment was enough to cause a descent from 100ft to 50ft. When pilot decided to go round from twin evils of idle thrust and max angle of attack the aircraft performance was less than desired in the situation. One thing is certain unplanned manuevres at lower altitude is asking for trouble. Perpignan for example.

vilas
From the link to the accident report I posted yesterday:
"The first officer informed the captain that the aircraft was reaching 100 feet at 14:45:14. The descent continued to 50 feet 8 seconds later and further to 30-35 feet. Go-around power was added at 14:45:35. The A.320 continued and touched trees at the end of the runway at 14:45:40 with a 14 deg. pitch attitude and engine speed being 83% N1. The plane sank slowly into the forest and a fire broke out."

I would suggest the aircraft sank below 100 feet because they didn't apply any power for 21 seconds, and hence they deliberately flew below 100 feet.

Villas, please explain why you think it was the computers that were not able to keep the aircraft airborne for over 26 seconds with idle power from 100ft at a speed close to the stall.

Hi DW, May be some confusion with 2.5%?
See FCB 17
"TOLERANCE OF FAC COMPUTED SPEEDS
Due to the data accuracy used to compute the characteristic speeds, and specifically the AOA accuracy, the precision of the computation is specified to be within ​2.5 %.
During acceptance flight, the tolerances are as following:

Clean aircraft
Green Dot ±​5 kt
VLS ±​4 kt
Vαprot ±​5 kt
Vαmax ±​5 kt

Conf full
VLS ±​3 kt
Vαprot ±​5 kt
Vαmax ±​5 kt"

vilas
In the case of Perpignan this was a planned manoeuvre but at a wrong altitude
Methink if they had made the planned manoeuvre (it was a test) at a higher altitude the result was to be the same .. splash in water .... they were engaged in a deadly yoyo game

For DozyWannabes benefit.....Prior Planning Prevents P*ss Poor Performance is actually not the '5 Ps' as advertised but, actually 6!! Hopefully the performance will be better next time with a little prior planning.....?!!!

r r r
I do not have access to English version of the report. From what I read in the posts,I consider the following. The pilot wanted to fly as slow as possible by flying at Valpha Max by holding the stick back. Alpha floor gets activated between Valpha prot and Valpha Max and if it was instantly disconnected before speed increase beyond Valpha prot then it will be
deactivated till the speed has increased beyond Alpha prot before dropping below again. He did not seem aware of this that is why he was surprised by the lack of alpha floor response and moved thrust levers manually. Now he was at alpha Max and idle thrust at 100ft.Considering the response time of the engine and for the speed to recover from back side of the curve descent from 100ft and ground contact seems possible.

villas

The French report, page 35:
12h 46' 26'' CDB "Bon Je vais bien la debrayer l'auto-manette." (Google translate = "Good I'm fine to disengage the auto-throttle"). Radio Altimeter shows 40 / 50 / 40 feet.

The Captain is aware the auto thrust is disconnected, yet he doesn't apply TOGA thrust for another 10 seconds with a plane full of passengers. Incredible!
I think you are right. It is the best explanation so far.

As was also the claim that : "had it been a 737 no one would have survived but thanks to the Airbus protections, almost all survived"
Not more surprising than most of you who have read or not the report are still pretending that the airplane was at alpha max.

OK, I'm going to duck for cover after I post this, but....


There were reports that the DFDR and CVR didn't jibe - that there was a 3 second discrepancy. The implication was that the DFDR had been 'altered' to 'remove' a 3 second delay in the engines responding to the GA command http://images.ibsrv.net/ibsrv/res/sr...y_dog_eyes.gif. Basically, that there was a cover-up of some shortcoming in the aircraft and blame it on the pilot.


Based on an 'Air Disasters' program about the crash, the pilot is still claiming he was framed, pointing at the 3 second gap. http://images.ibsrv.net/ibsrv/res/sr...s/confused.gif


So, knowing relatively little about this accident (and most of what I do know is based on the press and TV reports), is there anything to the alleged gap in the data?http://images.ibsrv.net/ibsrv/res/sr...lies/worry.gif

One dedicated site for this accident (in french ..from a journalist who has followed the case since the first minute ... because he was a passenger on that plane)
Crashdehabsheim.net
So it is an analysis among others, and which are often contradictory :)

BEA Final Report - Extracts
 

Quote from Conf_iture:
Originally Posted by BEA [see its Habsheim final report of 1990/04/24]
1.16.1.2. Lois de pilotage de l'Airbus A320
Cette loi de pilotage assure en particulier une protection automatique empêchant l'avion d'atteindre une incidence supérieure à 17.5 degrés, pour conserver une marge suffisante par rapport au décrochage, même si le pilote maintient sa demande au plein cabré.

In case it helps anyone, this is my translation into received English:
This flight law provides a special automatic protection preventing the aeroplane from reaching an incidence [angle of attack] greater than 17.5 degrees, to conserve a sufficient margin with respect to the stall, even if the pilot maintains a full climb [pitch-up] demand.

Note that this BEA description does not specify that an alpha of 17.5 deg will be achieved if the pilot maintains full back-stick.

An earlier part of 1.16.1.2 sheds light on the question of whether any engagement of Landing Mode might have at any stage affected the ability of the pilot to achieve Alpha Max. Many of you will prefer to read the original in French, but for those who don't and to save space I'll simply offer this translation:

During all flight-phases prior to the moment the machine reaches a height of 50 feet, measured by the radio altimeter, the flight law is the usual one, called C*.... [there follows a description of the latter] ...
During the phase of descent between 50 and 30 feet, the flight law is modified progressively to take into account (*), instead of the term of load factor [normal G] , a term in pitch (difference between the pitch recorded passing 50 feet, called the reference pitch, and the instantaneous actual pitch);
when passing 30 feet, a supplementary order intended to simulate an effect of conventional landing is introduced to complement [modify] the previous pitch law: this order progressively reduces the the reference pitch (established at 50 feet) to -2 degrees in 8 seconds, creating a dive [pitch-down] moment that the pilot must counteract ("derotation").
At all times, if the angle of attack reaches 14.5 degrees, the flight law is modified and the term of load factor or the term of pitch (whether modified or not by the derotation order) is replaced by a term of incidence [Alpha Prot] (difference between the current angle of attack and 14.5 degrees). This flight law provides a special automatic protection preventing the aeroplane from reaching an angle of attack greater than 17.5 degrees, to conserve a sufficient margin with respect to the stall, even if the pilot maintains a full climb [pitch-up] demand.
This latter flight law, by the name of Alpha Prot (angle-of-attack protection), is a priority mode once the angle of attack reaches 14.5 deg. It does not constitute a degraded mode and cannot be de-activated by the crew.
[The section continues with a description of Alpha Floor.]

(*) This transition is progressive: the change of law is effected in one second.

The reference to Alpha Prot being a priority mode suggests that it would take priority over all others, including Landing mode. The report states that the modes/laws of engagement were specifically recorded by the DFDR as follows, where the time base is in seconds relative to the time of "impact", notated as "t" (see also my previous post). These are listed as follows:
Before [and including?] t - 22, Normal C*;
between t - 21 and t - 20, in transition to landing mode;
between t - 20 and t - 18, progressive return to C*;
between t - 18 and t - 04, landing mode (a reference pitch of +6 deg having been measured passing 50 ft);
at t - 4, switch to Alpha Prot, the angle of attack having exceeded 14.5 degrees; this law maintained thereafter.

Confit and others,
Please let me know soonest of any anomalies in my translations...

Please excuse (or ignore) my intrusion into this discussion - I'm the least qualified to comment here, but I do have a question:
Would the extra couple of degrees of AoA, that are presumed to be held back by the s/w (is that your point, CONF iture?), have changed anything for the better in the outcome?
I understand that the lift coef curve is mostly flat near stall as it is. In addition, IF the extra increment in lift extended the flight long enough for the engines to spool up, wouldn't the go-around thrust-pitch couple just push the airplane into a stall? The crash would then be tail-first, perhaps.

If the angle of attack had been greater, and the slowing with the same power had thus been more alarming, then perhaps the power would have been added earlier, and the trees would have been avoided. The trees would also have been further away in time, allowing the engines to spool up more before they turned into chippers.

Crashing on the airfield might also have been more benign than crashing in the forest. There'd probably have been less chance of smashing open all the fuel tanks, and it would have been easier for whatever rescuers were available to get to the wreckage.

As it was, it was close. Perhaps with three fewer feet of treetops in the engines… it might have flown away. The aircraft wasn't dragged to a dead stop - it was moving through the forest for five seconds before it stopped and burned.

balsa - we did this topic to death on a previous Habsheim thread, but the view is that had the a/c been a 'traditional' non-fbw type then the trees might well have been cleared with the extra degree or two of 'alpha', but conversely if the crew had over-rotated in their anxiety they could well have stalled and possibly dropped a wing which would almost certainly have caused far greater loss of life. The jury, as they say, remains out.

Given that they were where they were...
 

Hi balsa model and awblain,

Reading your posts, a couple of points spring to mind.

(1) Pitch rose through +10 deg at about t -13. No particular significance in +10, but my guess is that, assuming the pilot's eye height was adjusted (using the seat-height adjustment) to the recommended level, the trees would not have been visible through the windshields after that. Also, not many pilots are used to the perspective at that kind of attitude - except on T/O. At t -7 pitch was about +14. Unfortunately I don't have an A320 AWOPS guide to hand, which might help with the relevant geometry.

At about t -8 the co-pilot warned the captain of some pylons ahead. They were very much further away than the trees, so one can assume that either the co-pilot could not see the trees, or that the steep deck-angle caused him to think that the a/c was higher than the treetops.

(2) Some readers may be surprised to learn that at t = 0 (defined as impact) the stick was still not fully back. IIRC, full deflection is 20 degrees. The last recorded stick position was -17 deg (17 deg nose-up command), rising rapidly from -5 deg at about t -3. What happened after that is not recorded, because the power supplies to both the DFDR and CVR were simultaneously cut (by severing of shared conduit).

Between t -9 and t -4, the stick command was between -6 deg and -7 deg, but this was relaxed slightly at t -4, falling to -5 deg.

ALPHA PROTECTION

As mentioned in the BEA report (see previous posts), the flight-control law changes from Normal Law to Alpha Protection (in effect a sub-law of Normal Law) if the angle of attack rises to an arbitrary figure known as alpha-prot. Alpha Prot "law" tries to maintain that angle of attack if the stick is neutral. A higher angle of attack, known as alpha-max, can be achieved with sustained, full back-stick. Alpha-max provides a small margin from the stall (the latter usually defined as alpha-CL-max), and cannot be exceeded. Intermediate angles of attack are commanded acording to the amount of back-stick applied by the pilot.

The BEA report states that, in their configuration (Flaps 3 and L/G):
alpha-prot was 14.5 deg;
alpha-max was 17.5 deg.

At t = 0 ("impact") both pitch and alpha were about +15. The latter represents the apparent discrepancy of about 2.5 deg that Conf_iture has called into question. As stated above, alpha-max can only be achieved by sustained, full back-stick.

The trees being out of sight under the nose is interesting, which might have contributed to a lack of urgency - although the approach of the line of the trees should have been perceptible in peripheral vision, even if they were below the sill directly ahead. From the video, the whole of the flyby appears to have been done at a substantial deck angle, so any visual impression of height throughout the whole pass would have had to have been from the side. It's interesting that the first officer was able to see the pylons 8-s from impact though - distant 30-m-high pylons (which look like they're 3km away on Google Earth) - and nearby treetops are not likely to be at very different elevation angles from 8-s (~350m?) away from the trees. Looking forward, it would be trees all the way from the base of the pylons to the sill, and with the ground whizzing by at 40 feet or so to the side and the tree line approaching, it seems to be no place for a confidence-building visual illusion.

Isn't it all navel-gazing anyway? - the plan for the show presumably didn't have any tree surgery in it, and the arrival at the treetops was presumably at the end of a substantial deviation from the intended plan.

Prompt cutting of the power to the recorders implies a substantial impact - rather more than from twigs hitting the rear fuselage - perhaps a few extra feet wouldn't have made any difference. With more angle of attack, the rear might have been thumped into that conduit-slicer even harder (3 degrees being about a meter at the tail from the center of mass), helping to pitch back down and further into trouble.

Would you agree that the prime human factor is that no-one would ever have dreamed of trying this in a non-FBW airliner? Perhaps the same sort of overconfidence factor that has been claimed to account for the accident statistics when ABS systems were first fitted as options to cars, and the serious accident rate was higher in the otherwise identical cars with the ABS than those without.

I fly Airbus types, inc. 320, and I used to fly out of Habsheim in a previous job. (Not A320's) It is a small airfield surrounded by forestation on 3 sides.

The CM1 was taking an enormous risk in flying too low and slow in an aircraft he clearly did not understand well. (Parallels with the Costa Concordia accident exist in Human Factors terms)

5 dead are on this plonker's conscience. Forget nationality, or background. On the day, he showed off, screwed up, and killed people.

The BEA does not elaborate at all but applying full back stick is what it takes to go to alpha max.
Full deflection in roll is 20 deg but 16 in pitch. The stick was fully back.

So to get to alpha max, one has to apply sustained full back stick. I'm guessing that this means that as the full back stick is applied, the alpha limitter progressively increases its limit value from alpha prot to alpha max.
Out of curiosity, how much delay would this entail?

Also, I recall something about Airbus fbw going to "direct law" at expected landing radar altitudes, and that this mode gives the pilot direct stick-to-pitch control. Could that have been the pilot's motivation for going so low? To have a better feel over the remaining pitch authority?

To be clear, I'm questioning why BEA+Airbus kept absolutely silent on the fact that the airplane had no intention to deliver anything more than alpha prot despite the pilot request.
But to answer your question, my opinion is that it would have made the difference considering that according to the report the engines have been registered at 91% N1.
No, alpha max is part of the protection, and so whatever the thrust setting.

Dozy, Chris r r r
I think unnecessary lengthy technical discussion is going on when there are some simple aviation facts staring in the face. I do not know what was planned but you can see what was executed. The pilot decided to slow the aircraft to minimum speed taking advantage of the AOA protection, fly level and go around. In any aircraft primary instrument of flight path change is pitch. The thrust maintains speed. The pitch up caused by thrust is secondary effect. Incidentally it is dampened in A320 by FBW and you need to pitch up. Not doing so was a possible cause of another crash. When pilot was late in setting the precise thrust to fly level at 100ft the aircraft sank. He could not pull back because he was at MAX or near MAX AOA so unable to change the flight path. Thrust was the only alternative but being at idle for a while it takes about 4 seconds to get out of idle and when you are sinking from 40ft, 4seconds must have seemed like a life time. So he panicked and thought ATHR was not behaving and moved the thrust levers manually. Alpha floor should have come between alpha prot and alpha max. Now the question is how and when exactly was it disconnected? There are three possibilities.
1. It was disconnected permanently before slowing down started. This does not seem probable as the pilot expected thrust activation.
2. It was disconnected as it got activated between alpha prot and alpha Max. In this case alpha floor will remain dormant till the speed increases beyond Valpha prot.
It is possible pilot did not know this considering the technology was new and that is why he was surprised by lack of response.
3. He may have been holding on to the disconnect button to prevent alpha floor till speed came to alpha max and inadvertently exceeded 15 seconds because he was preoccupied visually and disabled it.
In any case he needed quick response to gain those critical extra 50ft which was not possible because of the max angle of attack.
Why should a line pilot who only has access to FCOMS indulge in manoeuvres which even the test pilot did not, in radically different aircraft? I am unable to comprehend that.

ATHR disabling (by holding disconnect buttons for more than I-forgot-the-exact-number seconds) was planned but not executed. Alpha floor didn't activate because it's inhibited below 100 ft per design, in order not to spoil the landing.

Showing off. Careless planing combined with sloppy execution. Chances are they never meant to fly that low, which does not imply it is acceptable to make high alpha pass with planeload of passengers at 200 instead of 20 ft.

Some widebodies stop autotrim, narrowbodies add automatic pitch-down command to facilitate the flare but going to direct law happens only with gear extension when aeroplane is already in alternate law and that was definitively not factor here. Aeroplane was totally sound just before controlled flight into trees.

vilas
We don't need to discuss that - because as Clandestino points out, "Alpha Floor is available, when the flight controls are in Normal Law, from lift off to 100 ft RA at landing." (FCTM)

Alpha Floor was never going to activate whilst they were below 100 RA.

r r r
If the speed went below alpha prot only when they went below 100ft then offcourse alpha floor was disabled. Did the pilot know that? The Airbus design is such that it is possible to fly hundreds of normal routine operations without much knowledge. I consider that as a positive but the pilots have to understand that if they try out something beyond normal they could be asking for trouble because that requires much deeper study of the design and its implications which is beyond the scope of FCOMs and line pilots. Protections on civil transport aircraft are not built to routinely fly the aircraft on the brink but to save the situation when forced into it by abnormal factors. At Perpignan they planned it then abandoned it and last moment executed it at low level and were not able to handle the consequences.

vilas
From page 40 of the BEA report, at time 1245
100 RA Speed 151 kts.
48 RA Speed 141 kts.
40 RA Speed 137 kts.
30 RA Speed 116 kts.

It appears to me that the aircraft was deliberately flown below 50 RA with the speed allowed to wash off, apparently waiting for Alpha Floor to "save the day".
Probably he did not know that, as the FCTM was published later, and I still can't find a reference in FCOM.
I agree.

Given the briefed game-plan...
 

vilas,

As you know, this thread was started from the transfer of a few posts on the AF447 Thread No. 11. (Not my idea!)

If you look again at post #1, you may be reminded that - in an earlier post on the AF 447 thread - I had opined that the crew had been relying on Alpha-Floor to initiate the G/A (i.e., when the AoA reached +15), but that they had allowed the a/c to sink below the Alpha-Floor inhibition height without realising the consequences. That assumption on my part was naive, and on reflection would have made it very difficult for the captain to go around at a position (in relation to the crowd) of his choosing. Alpha-floor (+15 deg) is only half a degree above alpha-prot.

As CONF_iture pointed out, however, the captain had specifically briefed that he would be inhibiting Alpha-Floor, in order to continue pitching up to alpha-max. His plan was to maintain alpha-max (therefore necessitating full back-stick) in level flight (he said at 100ft), using manual thrust to maintain height. (Note that, at a stedy AoA, thrust controls VS, not speed - rather more like a light piston-engined a/c on the approach.)

The two key defficiencies in the execution of the briefed game-plan seem to have been:

(1) Rushed, straight-in approach, arriving over the airfield boundary (inbound) with too much energy to allow a reduction in speed to the planned Valpha-max during the transit of an unfamiliarly-small airfield. This may have tempted the PF to delay the go-around while he waited for the IAS to decay to an acceptable (in his terms) value.

(2) Descent below 100R. From the time they were approaching 100 ft on the approach until about t -3, the PF consistently did not pull hard enough on the stick to maintain or recover to the briefed height. This apparent reluctance to pull harder is all the harder to explain, because the PF was looking for the highest-possible deck angle to show the crowd.

Quote from CONF_iture:
Originally Posted by Chris Scott:
"Note that this BEA description does not specify that an alpha of 17.5 deg will be achieved if the pilot maintains full back-stick."
The BEA does not elaborate at all but applying full back stick is what it takes to go to alpha max.

Yes, we are in accord on that one. :ok: However, in the earlier post you've quoted, I was just trying to point out that the BEA seems to have carefully emphasised that alpha-max (in this case 17.5 deg) will not be exceeded, without stating that it will necessarily be precisely achieved.

Quote from CONF_iture:
"Full deflection in roll is 20 deg but 16 in pitch."

Thanks, I haven't found that figure yet. The DFDR trace seems to shows a rapid rise to about -17, at which point the trace ends without becoming steady.

Quote from CONF_iture:
"The stick was fully back."

As I've already said:
"Between t -9 and t -4, the stick command was between -6 deg and -7 deg, but this was relaxed slightly at t -4, falling to -5 deg.
"The last recorded stick position was -17 deg (17 deg nose-up command), rising rapidly from -5 deg at about t -3."

The back-stick reached about 17 deg (presumably maximum), but not for a measurable period prior to impact. That's the reason for my observation in (2), above. Why he did not pull harder from t -26 to t -3 is inexplicable, if only because it was delaying the desired attainment of alpha-max. The modest back-stick up to t -4 would, as you know, never achieve alpha-max.

r r r
I am unable to paste the report in google for translation. Below is what you wanted.
DSC-27-20-10-20 P 4/6
The αfloor function is available from lift-off to 100 ft RA before landing.

FCOM information at time of accident
 

Quotes

From rudderrudderrat:
"It appears to me that the aircraft was deliberately flown below 50 RA with the speed allowed to wash off, apparently waiting for Alpha Floor to 'save the day'."

From vilas:
"If the speed went below alpha prot only when they went below 100ft then of course alpha floor was disabled. Did the pilot know that?"

Response from rudderrudderrat (my emphasis):
"Probably he did not know that, as the FCTM was published later, and I still can't find a reference in FCOM."

Firstly, the evidence strongly suggests that he was not relying on Alpha-Floor; contrary to what I originally thought.

Secondly, I think he should and would have known of its inhibition below 100R.

Regrettably, I have mislaid the Airbus FCOM volumes dished out to us BCAL (British Caledonian) pilots on arrival at Blagnac for our conversion course on 1/1/1988. Prior to that, we had perused the BCAL Ops Manuals (our own FCOM) dated August 1987. After finishing our ground course and simulator (we were just a week behind the first Air France course), BCAL issued a wide-ranging amendment, dated 17FEB1988, which included considerable changes to the Flight Controls chapter in the Technical Manual. The changes were partly necessitated by changes in FBW logic (Dozy please note), and partly an improvement in the explanations and diagrams.

At both 25AUG1987 and 17FEB1988, the BCAL chapter on Flying Controls describing the Alpha protections aparently fails to mention that Alpha Floor is inhibited below 100R.

However, the BCAL chapter on Power Plant - which includes a description of A/THR, and which remained unchanged from 25AUG1987 in the 17FEB1988 amendments - includes the following:

A/THR can be engaged:
- Manually, by.....
- Automatically, when the pilot initiates a T/O or G/A....
or - if there is an alpha-floor detection after lift-off and down to 100 ft (R.A.) on landing.
In the particular case of alpha-floor detection, the MAX T.O. thrust is automatically selected whatever the position of the thrust lever.

That's because there isn't one - as I've said before - all I've had to work with over the years are extracts - but I've managed to OCR and translate some of the lesser-known aspects of the report recently.

To the best of my knowledge, no-one's claimed that, and we've already confirmed that the FCTM does not state that pulling back in High AoA Protection mode will definitely give Alpha Max - just the closest to that value that the systems can give with the flight parameters at the time. If a pilot assumes that it will give them Alpha Max precisely, then they are in error.

Nope - that was based on a misinterpretation of the data by the retired investigator the lawyers used to give a second opinion. Ray Davis was an excellent investigator, but he had no prior experience with DFDRs.

Posted a while back:
Additionally, as the (admittely poorly-)translated "Other Factors" section I posted earlier confirms, the official BEA report does not find that the factors leading to the crash lay with the flight crew alone - the sequence began with poor preparation and briefing materials on the part of the airline. The BEA's report does not explicitly apportion responsibility - because like other agencies that are nominally independent, yet still civil service (like the UK AAIB, ATSB etc.), their remit does not extend far enough to allow them to do so. Of course, the legal teams were counting on the press they were briefing to be unaware of that distinction.

Because the crew's lawyers were arranged by the union, it could be argued that they tried to paint a picture of a cover-up on AI's behalf, because to draw attention to the report's actual content - i.e. implicit but robust criticism of AF - would be biting the hand that fed the union's members.

For their part, AF's defence during the criminal and civil proceedings involved falling back on an old document that specified the airshow "hard floor" (i.e. minimum altitude) to be 600ft. This raises the question of how, if that rule was still in effect, they were able to sign off the Habsheim display in the first place - and it also demonstrates that it was in fact AF who were primarily responsible for the effort to have the crew "thrown under the bus".

As for "how did they end up so low and slow?", as I understand it the chain of events was set in motion during the (rushed) approach. It wasn't that the PIC was waiting for an "acceptable" (as in sufficiently breathtaking for the spectators) altitude/speed during the flypast, it was because they were so high and hot at the start of the final that they chopped off too much power.

Fast process - The protected aircraft takes advantage of the electronics to get the maximum performance in the minimum time and outperform the non protected aircraft.

I have some unofficial references for now, but I will try to locate and post some official ones ... Wilco
I think it was all about the show ... Even if the planned altitude was for 100 ft AGL and the pilot pretended he thought he was maintaining just that, I would not be immensely surprised if his real intention was to go lower ... (?)
Pulling harder early in the sequence would have made the aircraft that was too fast climb far too early to his liking.
Late in the sequence, the pilot, now fully aware of the approaching trees, but well aware that thrust was not coming as he expected it, delayed as long as possible the pull up request.
I certainly would not blame you for courageously making space ...

Real Time process to be more precise. Actual (as opposed to theoretical) Alpha Prot, Floor and Max boundaries are calculated constantly in real time. The values are functions - not hard-coded constants.

I'd be as interested in the unofficial values (and where they came from) as I am in the official ones.

I'd be very surprised - as the Airbus test pilots who came up with the scenario were very specific about not going under 100ft RA to maintain a reasonable safety margin.

With Alpha Floor disabled, the aircraft would maintain current altitude at calculated max AoA up to theoretical Alpha Max - it wouldn't climb, if the documentation is accurate.

Can you confirm in the FDR trace?

(I'm still waiting for the source that gives you 2.5deg, by the way...)

Additionally, if the PIC was expecting thrust sooner than it was provided, then he was clearly ignorant of the properties of high-bypass turbofans. Either that or ignorant of the consequences (namely allowing the engines to spool down) of the thrust settings he ordered to make the approach.

It will only do that at constant airspeed, i.e thrust equal to drag. With thrust less than drag the aircraft decelerates and AoA has to increase progressively to maintain lift equal to weight, i.e. the sidestick has to move progressively backwards. When alpha-max is reached and the aircraft is still decelerating it will descend.

Correct - but in this case the aircraft had finished decelerating before it crossed the grass strip threshold. If the aircraft's forward momentum was still subject to cutting power then it would continue to decelerate, but it did not - it maintained the airspeed determined by the approach settings.

Flyover altitude
 

When the accident happened just in front of my homebase, we fast jet pilots discussed the possible traps of this failed display long hours. That short time after the accident we had no official information available except the location and environment of the nearby accident site. We could look at the crash site when departing visual from our base.

Any pilot of my outfit was familiar with low flying down to 100 feet and up to 540 KIAS in Labrador, and we all agreed that flying an airliner at 100 feet or below over a small airfield at minimum speed was suicidal planing.

We discussed, why the crew even went considerably below that planned altitude and came up with the suggestion, that it might not have been the intention of the crew, but happened due to the perspective of the small little airfield. Flying a visual approach to a small little runway / airfield like Habsheim when being used to bigger airfields and buildings like Basel just minutes before gives the visual illusion of being at a higher altitude above ground than actual. Which raises the question, why the information by the Radar Altimeter was neglected. When you expect in advance that the thing will give altitude warnings you have no intention to obey to (as the intention was to do a visual pass and not one based on inside cockpit information) the information is filtered to zero as non essential background noise by the brain.

This flyover should never have happened, we would never have gotten the permission to execute such a flyover with our jets. In my view all the speculation about possible technical aspects is noise to cover up the fact, that the crew f** ed up badly and didn't register the descent below 100 feet. Only altitude information comes from the Radar altimeter, Captain and FO did neither acknowledge nor react to those warnings.

Not even that. As far as I can tell from the report, AF signed off on the profile provided that the flypast was over the paved strip (which had no obstructions in the run-off area) and the crew were comfortable with the profile. The briefing materials provided were inadequate - specifically the photocopies of the airfield charts provided to the crew effectively deleted the graphics indicating the trees.

In the event, the crew spotted the airfield late, and noticed that the spectators were lined up on the grass strip, not the paved strip on which they had been briefed. At this point the crew would have been well within their rights to abort the flypast altogether, and press on to the sightseeing trip over the Pyrenees which made up the latter part of their flightplan. Instead, the PIC elected to perform an unauthorised approach maneouvre to match the grass strip, even though they were considerably high and fast to do so.

I'm not sure what you mean by that. Are you referring to a point where the airspeed bottomed, changing from decelerating to accelerating while the engines continued to spool up from idle to TOGA?

I'm referring to the constantly changing variable of airspeed throughout. The airspeed did not increase enough to have a significant impact on calculated maximum alpha until a point where they were just about to make contact with the trees. The engines spooled down well before the aircraft crossed the threshold. The aircraft maintained airspeed based on that initial value, and maintained pitch attitude equivalent to maximum AoA available. The airspeed didn't increase substantially until after the engines spooled up again.