airtren and others, if meatware pilots are so darned good, why do you and the others believe the FBW aircraft are consistently showing very significantly lower accident rates when it has just been demonstrated that current levels of flight training have deteriorated significantly? Could it be that the automation actually provides a serious added benefit?

The one that keeps things simple, always :
In manual flight, don't expect anything to trim for you - You, the pilot, are responsible for it.

Leave to the pilot the responsability for this type of action ... and if he does actually choose to trim up ... then I won't show up to defend his action.

No please, not even more automation.
At the earliest sign of disagreement between the probe values, Airbus should say :
As I'm not sure exactly what's happening, I auto cancel all my wonderful features, and I give you back a conventional aircraft in direct law.

Brown soft stinky material such as emanates from the South end of a North facing fertile male bovine.

The inertial and the GPS systems are still working. They may not know your air speed within 60 kts and your altitude likely well within 100'. BUT, it does know the plane had better not be touching the ground when the ground speed is over say 200 kts or even only 120kts and if the AoA is excessive for the given ground speed politely slap the pilot with a dead fish and tell him he's stalled. (Which would have done no good because the PF thought he was doing the correct stall drill, apparently. Where he dreamed it up, nobody quite knows.)

Furthermore, if the last pitot reading was 275, the pitch of the aircraft is about normal, and the thrust is about normal you can pretty decently presume 5 minutes later you're still going roughly the same speed at roughly the same altitude even if the GPS set has gone toes up.

Now, the design of the plane may have hidden some of this data from the PF or the PF had not been trained to find and use it. But the plane bloody well knows in one of its computin' thangs.

infrequentflyer789, you and others may be on to a distinct problem with the THS concept. A clacker might be a good idea.

But, in the case at hand I don't think it contributed anything to the problem other than making bad a little worse. Track the elevator position from the peak of the climb to ocean surface. Did it ever, even once, go nose down rather than slightly less nose up? Had the PF gotten the elevator past neutral into ND territory the THS would have started to unwind, fairly smartly. And we'd be arguing if it had unwound as fast as it should have or whether it should have wound itself up to the stops. But the problem visible is that PF had nose up TOGA on his mind and nothing else penetrated.

That is why communications and team work are needed in the cockpit. The team members must communicate with each other what they are doing and what they are expected to be doing. (And 2 day old pizzas must be kept in stock for waking pilots out of their trances.)

JD-EE
 

You are correct, and nobody doubts the benefit of automation in itself.
But it can and must further improve and subjects asociated with automation must be looked at with more attention than before..

Or are you saying, automation is at the end of its developement, that is as far as we can get, human machine interface is perfect and that will be for the next 100 years?

AlphaZuluRomeo, thanks for your reply, and ideas.

The reasoning for returning the THS to a Stall Recovery Optimal Position - I picked Neutral as that seems the best candidate - is that from other BEA reports it seems that in other Stall incidents, unlike AF 447, where the THS was started the move NU after the Stall, the THS was further NU, or max NU already before the Stall.

A THS Stall Recovery Optimal Position is one, which yields the most effective Elevators ND, and NU actions, which are needed in a (quite) quick sequence during Stall Recovery .
As long as the Stall is ON, as it is a slow move/reacting surface, I would not risk interference with the Elevators, which need be quickly very effective, and for short time intervals.

Manual control of course remains. Sound alarm can become easily a disturbance, so agree. A visual - a LED - would, IMO, be useful.

The Elevator NU would have been less effective, while the Elevator ND would have been more effective. Which means different pitch angles and AoAs - less NU, more ND. That we know. This could be simulated. Would they have taken advantage of it?

JD-EE:
JD-EE, you are spot on.
Communication IS the solution : communication between pilots AND communication between the plane and the crew.

What do we have (see BEA's #3 report page 29) :
- at 02:10:05 speeds are OK and Otto decides to quit (why ?) ;

- at 02:10:06 speeds are OK ; plane starts banking ; PF : "I have control" ;
Wouldn't a 'bus pilot suspect some sort of FBW computer(s) malfunction and start "aviating" ?

- displayed speeds start to go wrong at 02:10:07 : after the, so far unexplained, FBW malfunction. (Cause or consequence of the FBW malfunction ?)

Now look at pages 45 and 46 :
- page 45, BEA tries to make you think that the "NAV ADR DISAGREE" message came immediately after the "AUTO FLT AP OFF" message. This is not true. "NAV ADR DISAGREE" came in only at 02:12:XX (why XX ?)

- page 46, order of messages :
1) "AUTO FLT AP OFF" ;
2) "NAV ADR DISAGREE" suggesting "IF SPD DISAGREE -> ADR CHECK PROC... APPLY" ;
is only shown to the pilots at 02:12:XX when situation is already largely out of control.

Questions :
- why should the PF call for unreliable speed drill at 02:10:05 when Otto quits and speeds are OK ?
- in an event leading to AP disconnection, why is such a smart AP/FD system unable to maintain for a few seconds the average pitch of, say, the past 5 or 10", until the proper ECAM alert message is displayed ?
- am I the only one to think that the "NAV ADR DISAGREE" ; "IF SPD DISAGREE -> ADR CHECK PROC... APPLY" message displayed at 02:10:08 THEN Otto disconnection at 02:10:10 plus a stick shaker instead of an aural stall warning could have saved 228 lives that night ?

Better communications and smarter design are solutions for a better flight safety.

@ rudderrudderrat : My pleasure :)

Regarding your comment:
The thing is AoA probes (needed for stall warning & FPV) are (or deemed) unreliable when IAS<60 kts. I'm not sure an unreliable FPV and/or stall warning is better than none at all?

About the PFV: if I read correctly the annex 4 (parameters) of the 3rd interim report, HDG-V/S was selected on AF447, never was TRK-FPA asked by the crew. Therefore, the unavailability of the bird, although damageable in absolute terms, would have changed nothing in the case of AF447.

Hi airtren

I understand your point, it is valid but I still feel uncomfortable with it, because:
- it adds another layer of complexity to be aware of (KISS)
- it may be dangerous if stall warning isn't 100% reliable (and it's not)
- the crew must react to the stall by pushing ND. That would give ND elevators, then ND THS if the latter was NU by far.
(note : on AF447, if one accepts that the flight control surfaces acted accordingly with the crew inputs, the crew never pushed enough on their sidestick to make the elevators go ND, only less NU)

I don't think I understand which interference you may be refering to? I didn't suggest to limit the elevators in any way, only to prevent THS NU move.
I agree that if THS stays where it is, the recovery may be a bit longer than with the THS neutral (or ND), but as the crew has to push SS ND, elevators will go ND and eventually THS too.

jd_ee,

Benefits of technology progress are so pervasive that IMO go without saying. Your reminder is welcome. It is also an opportunity of another reminder:

Somebody already said this on these threads a lot better than me: Technology progress changes the safety parameters practically in every field. Technology progress is manifesting itself not only in new systems, but in improvements of existing ones as well.

Would I be reading too far in your post, that your thinking is that existing automated systems don't need improvements? for an improved safety?

Who reduced the Thrust from TOGA to Flight Idle for a few seconds near the top of the climb, when the pitch of the aircraft reduced, slightly ?
Then TOGA was restored, for the all that remained of the flight.

PF held/ had held a French Gliding Licence from a few years earlier. I do not know how active he had been or still was. A Brevet "B" only required a couple of "S Turns" and a safe landing. I imagine ( but I do not know) that our PF went well past this level, to Brevet "D" or beyond...

(AF encouraged some former members of Cabin Crew to become Pilots - our Captain had been one, earlier in his career.)

The PF could have become a gliding Instructor. He probably would have had aero-tows with the cable fixed to the nose of the glider. This would have given him enough height to practice stalls and spinning. He would have been winch launched, sometimes, where the cable might be fixed lower down, perhaps under the Pilot's seat, to get the best height possible, rather like a kite.

Underslung engines have an effect on the pitch of an aircraft, normally advantageously " more power=nose up..... less power= nose down"

At this moment, for AF447, the nose ought to come down.

Someone else said that only Nostradamus would really know what was in PF's mind. But who did alter the Thrust, twice?

Hello GerardC
Did you read §1.16.4.1 of the 3rd interim report?
Also remind that:
- recorded speed are from pitots/ADR 1 & 3
- AP2 was ON, it uses IIRC pitot/ADR 2 as primary

I don't quite understant your question. :confused:

See above ; I agree with you if you replace "displayed speeds" (there was 3 of them) by "recorded speeds" (only 2).

BEA tries what? It's written plain & simple:
The purpose of this table is to show which message(s) will be directly seen by the crew, as the screen cannot contain them all.
That's why on the next page, with the hypothesis that no message was ever acknowledged/erased, the BEA shows simulated printscreens on a chronological basis (other purpose).

From various posts:

FPA/TRK was selected at some point or they would not have had FPV FLAGS reported on the PFD.

FPV was flagged because all three ADR's were simultaneously unreliable at various times. With Airbus you need at least one good ADR to get an FPV. It is not totally inertial dependent. At any time at least one ADR became reliable, the FPV would have returned (possibly not visible), if selected. On a B737 you can fail all (both of 2) ADR's and still have a full-time FPV. It is totally inertial.

The FD does not have be turned off to select FPA/TRK. When FPA/TRK is selected, the HDG/VS dual cue steering is replaced by the FPV FD symbol and the "bird" (FPV) is "displayed".

If the FPV is offscale of the PFD when it returns, how do you know what its status is?

It is not "ghosted" or caged at the lower limit (bottom) of the PFD like a HUD FPV. It is GONE.

My mistake, then. What you write is consistent with the text of the 3rd report (§ 1.16.6.3, just re-read it), but there is an inconsistency with the annex 4 (parameters) on p. 108 (bottom) which shows only HDG-V/S selected. Perhaps the sampling period isn't tight enough for this parameter? Or the "for EIS2" mention means something I don't get at the moment (any help appreciated)?

@GerardC:
 

This 3rd report is an interim report like the 1st and 2nd report.
You need to read al reports!, some questions you have are already answered in the previous reports.

Nothing to explain here, there wasn't a FBW malfunction.

but what if a smart design is not understood and not properly used by the user? like AF477.
One can say there is a design flaw or not smart enough systems during the design phase or after the first years of operation (like DC10 aft cargodoor).
But not after so many years of operation, by then there are other issues,
and that may be clear to all of us by now.

Pilot error due lack of training, absence of CRM and TEM.

Isn't there room for technical improvements?

Yes off course there is, but not tactile feedback (which is of no use in FBW) or introduce other protections (THS inhibit at high AoA) because there you ask for other problems.

A. already made changes to AoA BEFORE this event and offered this as option. 'BUSS'
Svoice 'STALL STALL' would have sounded until impact.

Would this have prevented this accident?
proberly not because it wasn't understood in the 54s it was present!

AF (like most operators) didn't opt for that mod because there wasn't a reason to do so before.
Now things have changed and this 'BUSS' option may become standard (like it is on A380 and will be on A350).

AlphaZuluRomeo, thanks for the follow up.

The Stall Warning reliability is among the concerns raised with the AF 447, here on this Forum, as well as the BEA report. I am confident, or perhaps just hoping that it is going to result in a BEA recommendation, and will be mandatory to address.

I understand your perspective, and I perceive it, as being in the same direction.

Perhaps with the risk of repeating myself, I see in general the time constraints of the Stall Recovery as a very important parameter. There is very little time for such a Stall Recovery - we know it took about 3 minutes to loose 38K ft of altitude - and with the THS being a slower moving control surface, I see it beneficial to have the THS down to Neutral sooner, rather than latter, and let the Stall Recovery be handled with the Elevators as a main element.

I am sorry for not being clear, or not using a better word. Let me try to clarify - sorry if there is any repetition.

The use of "interference with the Elevators" was meant as "diminishing the effectiveness of the Elevators".

Specifically, it was in reference to the effect of a THS NU, versus a THS Neutral when summed with the Elevators ND, for the first phase of the Stall Recovery (ND command, gain speed, loose altitude),

efficiency THS NU + ElevatorsND < efficiency THS Neutral + Elevators ND

respectively the effect of THS ND, versus a THS Neutral when summed with the Elevators NU, for the second phase of the Stall Recovery (NU command, level off, stabilize and start regaining altitude).

efficiency THS ND + ElevatorsNU < efficiency THS Neutral + Elevators NU

In both cases, the THS Neutral is more "neutral" :) than the others.

An important consideration was that while it is true that the non-neutral effect of the THS may mean "amplifying", as opposed to "diminishing" - for instance THS ND with Elevators ND, and THS NU with Elevators NU - for the duration of one of the two phase of the Stall Recvery, it is also true that the Slow speed of the THS move, is a factor that may transform the "amplifying" during phase 1, into a "diminishing" in phase 2, at the transition from phase 1 or phase 2 of the Stall Recovery.

The short time available for the Stall Recovery, requires a very quick. and very effective ND to NU transition from phase 1 to phase 2 (described above), with fully effective Elevators - any "diminishing" is undesired.

I hope it is clearer.:)

How low must one's head be to not notice the attitude and altitude on his PFD? Not to hear "STALL STALL STALL"?

Stick pushers are not there to deal with crew unaware of what goes on around them. They are potentially very dangerous devices and are fitted only to aeroplane that are considered to be more dangerous without then with them. DP Davies has written an excellent treatise on stick-pushers, pages 130-140. His analysis of risks and benefits connected with pushers is amazingly applicable to any other envelope protection too.

And give you direct stick-to-elevator? Half up elevator at mach 0.8 would give pretty much the same outcome we have now though the path to it might be somewhat different and perhaps include a lomcevak or two.

There was nothing to communicate except utter bafflement in the cockpit. Crew got way behind the aeroplane, completely lost SA and never regained it during final minutes.

Absolutely. There are two dominant views on implications of "Swiss cheese" accident model. Optimistic theory claims each and every cheese slice has to be as hole-free as possible to reduce the possibility of accident to minimum. Modern management theory is that as any cheese layer stops the accident as well as any other, it is important to first make cheaper slices thicker and less porous. Others can be thinner, with more holes if number of the dead when all are breached falls below the statistically acceptable.

Automated aeroplane with competent pilots is safest of them all but do the additional costs of proper pilot training justify the increase in safety? If you really believe that life is priceless, they do but that's not the way thing work in our day and age. Yours, mine and everyone else's life have a price tag on them.

Inputs in direct law ...
 

Non sense - Why would you pull the sidestick half way ?
Don't you adapt your inputs depending how your 'direct law' aircraft respond ?

Why would you pull half-way in ALTN2 when encountering UAS? The one who could answer that is unable to talk to us and I strongly suspect he would be unable to coherently explain what was he thinking and doing even if AF447 were somehow timely recovered from stall.

Don't you adapt your inputs to achieve desired attitude, no matter what control law are you in?

So again, a question. In AL the RTL protects the control, the Rudder. From your "Half elevator up at Mach.8." I assume you propose an inadvertent elevator input (or commanded, either way), might cause serious problems (lomcevak).

ROLL is DIRECT, RUDDER is DIRECT, but PITCH is NOT DIRECT, and it is UNPROTECTED.

The logic here escapes me, could you explain to me? I can understand the need for deflection protections, but why not in the elevators?

On the one hand, the airframe defends the controls, on the other , the Flight Path (elevators). Why?

So here: In a degradation to Alternate LAW, the a/c anticipates (with its logic) control inputs that may be excessive. Obviously, the need is to MANEUVER, NOT CRUISE. Why in Heaven's name is TRIM allowed at all.

It is TRIM, and not a primary FLIGHT CONTROL. keep it firmly at 0 degrees...... Throughout.

If the TRIM is active, it absolutely compromises the elevators' authority.

If ACTIVE, it is also sluggish (behind), and the Pilot must form a different response to variable combinations of TRIM/ELEVATOR, which he cannot see, feel, or "hear". This is not a recipe for disaster? One that can be blamed on "Lack of Handflying?" POOR TRAINING? ETC?

Hi Clandestino,

Yes you do. But suppose you are "overloaded" by warnings as you struggled to maintain wings level. Consider these two alternatives.
1) In Direct Law, the stab trim would not have moved. If PF relaxed the back pressure, the aircraft would have nosed down naturally whilst it attempted to regain it's trimmed speed.
2) In ALT LAW, when he relaxed back pressure, the aircraft maintained it's nose up attitude as the speed washed off.

In which Law do you think is easier to actually stall?

@AlphaZuluRomeo,
The IAS was grossly under reading. The acute angle of attack to the pitot tubes rendered them useless. The fact that the aircraft is airborne should be sufficient logic to maintain stall warnings and Angle of Attack.

Well, duh. It is supposed to be that way. I don't mind writing for a zilionth time that DP Davies has it all neatly explained.

Just when did he relax the backpressure? You are acquainted with sidestick traces from 3rd intermediate report, aren't you? A couple of times stick goes forward but quickly gets behind neutral again and stays there before elevators even have the chance to get to neutral.

A33Zab,

The better understanding of possible problems later in the life of a complex system is somewhat contradictory with discounting the possibility of uncovering flaws later in the life of such a complex system. The latter calls for some reminders:

- the probability of uncovering all flaws/shortcomings/bugs during tests, or in the first year or years of operation of a system, is decreasing with the complexity of the system.

- a shortcoming may stay hidden for a good amount of time, as long as its hosting path in the system's algorithms is not operated, or fully operated - the type of AF 447 Stall is not happening often.

Can you elaborate on "THS inhibit at high AOA", in terms of description, and the problems incurred? I am not sure if you refer to the elements that were the object of several earlier posts on this thread, but either way, elaborating would be helpful, and would be appreciated.
Are there any reasons for the BUSS not to have been adopted? particularly for a route that has a higher risk? like the AF 447's?

Hi Clandestino,

Yes thanks.

See Page 74.
"The PF copilot said “I have the controls” and made rapid and high amplitude lateral, almost stop to stop, inputs. He also made a nose-up input that increased the airplane’s pitch attitude
up to 11° in ten seconds……."

The nose up request on the side stick rotated the aircraft by about 1 deg per second. If they had been in Direct Law, as the speed washed off, the nose would have wanted to drop and the back stick pressure would have been less effective. The aircraft may have stabilised at a speed above the stall whilst still holding the same back stick pressure.

Do you think it is easier to stall in Direct or Alternate LAW?

Great. Now we'll deepen our acquaintance with sidestick and controls positions on page 108 which are raw data behind words on page 74 that you cling to. You have certainly noted that despite right sidestick hovering around halfway nose-up input, elevators that are delivering that one degree per second pitch-up are barely off neutral. What do you think would happen if FBW went into direct law and tried to move elevators to half-deflection at 0.8 Mach? I don't know whether it would be even faster zoom climb to stall at higher pitch, dynamic stall or overstress but it would certainly be uglier than 11° in 10 seconds pitch-up.

I have seen no valid argument on which to base my decision on the matter, therefore I'm undecided for the time being.

Hi Clandestino,
I don't know either - but I bet they would have felt it.
Instead of an unnoticed, increasing pitch up - all he would have had to do was let go and the aircraft would have naturally nosed down to recover any lost speed. It would still have been trimmed to fly at M.08.

Clandestino, Ruderrat,

An interpretation that the pilot has intentionally, in full knowledge of the situation entered NU commands, calls for a reminder of the confusion shown by the CVR transcript in the BEA report.

Furthermore, there is additional data to consider - such interpretations were advanced before on the AF 447 threads, but do not recall them being documented this way.

The combining of the Pitch and Roll control BEA graphs - see bellow - show a significant coincidence and persistence of Pitch and Roll commands.

As I think it is normal that not every Pitch command required a Roll, and vice-versa, this can be interpreted as:

a). a lesser familiarity with the separation of the two types of commands on the stick, and furthermore:

b) a lesser familiarity with the Neutral position of the stick.

Consequently, it seems that what would have been a perceived Neutral position of the stick for Pitch and for Roll commands, was in reality a OFF Neutral position, in reality a NU command, and respectively a Roll command.

In conclusion, this can be interpreted that the persistent NU commands were not intentional, but just a simple consequence of the handling of the stick.

If the NU commands were not intentional, than the Autotrim of the THS to max NU was not intentional.

Furthermore, the THS was positioned to the max NU position during the Stall Warning time interval, contrary to what the computer logic would have asked for, if the two logical paths (Stall, and Autotrim) were linked.

Note: if we expect the pilot to conclude that in STALL a NU commands is a NO, NO, why shouldn't we expect the computer to arrive at the same conclusion???

It is possible that the BEA work on the Human Factors and a future report will add more analytical elements, interpretations, conclusions, and recommendations that may intersect with elements presented in this post


http://farm7.static.flickr.com/6207/...7d8a4571_b.jpg

Clandestino

It is NOT 'intended' to compromise the elevator's authority. Its intent, as you well know, is arguably out of place in Alternate LAW 2, when Pitch is unprotected, and the Pilot hasn't a clear knowledge of the actions of the THS.

Further, in a recovery, what the THS does more than anything, is FRUSTRATE the Elevator's authority, and you also know that.

To Stall in DIRECT? or ALTERNATE? Like clandestino, a toss up.

This I do know. To recover from a STALL? given 447's data, DIRECT. WHY? Because without a fully up THS, the elevators could not have kept her in the STALL (caveat: pending a final decision by BEA re: CG). She'd have dropped her nose, something these gents were not granted as a cue that STALL was underway, (and just broken).

If, after the nose dropped, the PF kept holding full back, a slow repetition of the same thing. Then if he eventually did not figure things out, perhaps the rollercoaster may have prompted one or the other worthies to sit down.

Clandestino,

I read your post as saying that "an active TRIM is supposed to be absolutely compromising the elevators authority".

Can you explain that in your own words, interpretation and logic?

The question should really be, "Did the elevator have ND authority during the period when the aircraft was on the wrong side of the stall warning?" The answer is yes it did, and indications are that it would have had control up to around 180 KCAS. If a Side Stick max ND command had been made and held for about 2 seconds, the THS would have started neutralizing the elevator demand. Any further ND would have provided increased control as THS followed and airspeed ramped up. The whole process could be sped up by use of the Manual Trim Wheel.

The only real problem I see in the way the THS operates is, the use of the Manual Trim Wheel appears to have been absent from the training regime, or at least discouraged. Why has this happened? The THS is a major control surface, and where it is positioned should be part of the instrument scan. OK, in Normal Law it is taken care of automatically, but in Alt Law the situation changes. Did the PF ever understand how the THS operated in Alt Law? We will never know, but if you don't understand a STALL WARNING, nor understand that consistently pulling the nose toward the heavens is not going to help you on this planet, then what chance does a trim wheel turning constantly for a minute within your periphial vision have of getting noticed.

As for the THS doing its 3°NU to 13.6°NU thing; it had nothing to do with 'autotrim'. It was operating in an integrated demand/time manner to neutralize the elevator input demand - nothing more. The elevator demand was wilful.

The A310 TAROM approach zoom climb/stall/recovery incident at Orly on 24 September 1994 provides some insight into the movements of the THS. Though I note the PNF made some manual adjustment to the THS following the stall recovery while setting up for their second approach, and without the PF being advised. That doesn't mean that the PF was unaware that the THS was moved to provide better trim. Also, the incident was marked by NO stall warning, and the reason given was that AoA SW thresh-hold had not been reached before the IAS had dropped below 60 KTS and the control logic inhibited it. Sound familiar?

Essentially the same logic with minor changes has been around for a long time. Unfortunately it requires incidents/accidents before everyone realizes how some of this control logic works.

Yes.

Trimmable horizontal stabilizer, on any such equipped aeroplane, is always the most powerful control surface and easily overpowers the elevator.

Get this book:

http://covers.openlibrary.org/w/id/701216-M.jpg

and read from page 35 onwards for details.

mm43
 

What does change in Alt Law?
According to my references and also posted here from others in Alt Law the autotrim is working as well.
What are you getting at with "the situation changes"?

Hi,

Very little change ..
No more pitch protection
Autotrim is working as well .. but the change is that the elevators are now commanded by the pilot SS .. no the autopilot
As we had seen in the AF447 case .. this can make a difference

No, jcjeant, the ss' inputs go to the computer, which controls the elevators. You are describing PITCH DIRECT, not part of AL2. PITCH DIRECT would make possible a lomcevak, perhaps, as the elevators are not "protected".

Hello mm43,

I've noticed in your post a number of differences in the use of words, that are perhaps just semantics? There are also a number of adjustments to be called. For instance:

Your "THS followed" .... is the THS being moved NOT MANUALLY, but under electrical control by the A/C's PRIM computer controls - which I would call - following the documentation - "autotrim".

In Alternate Law, the "autotrim" is still active. See page 75 of BEA Report (English version), second paragraph of Phase 3 Section, in two sentences: "THS began a movement... It should be noted that in Alternate Law the auto trim is still active."

The NU move from -3 to -13 degrees was controlled electrically, as the Autotrim was active - see the BEA Report, same section, and more.

You're using the word "neutralize", while some documentation is using the word "compensate".

As the THS's role is in stabilizing the pitch attitude that has been reached by means of the Elevators - that's why the name - perhaps "compensate" is closer to the definition of the function? although I can see how "neutralize" can be used with the same meaning in mind.

Once the THS is in a NU at a certain angle, a further Elavator NU at a certain angle is summing the NU effects of the two, while if the Elevator goes ND at a certain angle, the effect is a difference as long as the THS is at an opposite (pitch, or angle) position.

It is generally accepted that the CVR transcript shows confusion, which puts a certain doubt if such a demand was in full awareness of the situation, and with a clear defined goal.
I am familiar with the Tarom case, as well as some other successful Airbus Stall Recoveries, as I've read several reports, watched 3D renditions, but a while ago.... For the Tarom case, the BEA English version of the report, which you've pointed to, has the CVR transcript in a mix of French and English - with several instances of "alarme decrochage-cricket" for "Stall Warning" at page 54.

Despite their mistakes, they've shown their airmanship, and pilot talent, achieving quite a recovery from only 4100ft to 800ft (250m), 60 degree AOA and 30 knots Stall, landing shortly after.
That's so true...

Yes, they are (potentially dangerous), which is no doubt why RRR mooted a stick shaker, and I (knowing someone would bite) extended the argument to a stick shaker... in a specific context.. that is where a plane can easily be held in a stall by the crew with a neutrally stable trim - AF447

Also bear in mind that D. P Davies was writing quite a while ago now... technologically speaking.

On ISIS info, from A33Zab
 

Thank you, A33Zab, for that detailed info on the ISIS. My reservations are disarmed, with just one small niggle: one wonders why yet another generation of standby instruments don't maintain an internal backup power source, good for 10, but ideally 15-20 mins of self sufficiency.

But as the question relates to AF447, this little device should have been more than adequate to coarsely validate any suspicions or doubts concerning the primary displays.

Thanks again.

Yes, and he made a weary aside in the book that some pilots were complaining about the presence of stick-pushers as potentially unsafe and unnecessary technology usurping their authority.

Then, a month after the final edition of the book was published a Trident crew comprised of a senior Captain and two relatively junior co-pilots (both S/O) on climb out from LHR retracted the droops too low and slow, approached stall and inhibited the stick pusher. The result was a full deep T-tail stall, pancaking into a field in Staines and 118 people dead.

[EDIT : On a quick fact-checking browse, I decided to have a look at Wikipedia's entry on BEA548/G-ARPI, and I have to say it's probably one of the most impressively researched articles I've seen on the site.

Now, superficially there are at least as many glaring differences as there are similarities between AF447 and BEA548 - the command gradient was very similar, and both incidents involved a loss of control following inappropriate handling, however the former was cruising, the latter was on climb-out, and while the Trident was probably the most advanced airliner in service at the time, the A330 is something else entirely. However what struck me when looking at the Flight articles in the wake of BEA548 was how similar the questions being asked and the debate over automation and warning systems is.

Check this out (apologies for the C&P, but I'm truly gobsmacked by the similarities - emphasis mine):

From 1972 | 3235 | Flight Archive

Here's one for the force-feedback/straight to Direct/Manual Trim supporters to think about, also note the trim situation :

And from 1973 | 1189 | Flight Archive :

Plus ça change indeed! ]

Clandestino,

This succinct rephrasing of the sentence I asked about reads and means different, as you are well aware.

In the rephrasing, your wording "overpowering" is an element that is at the core of the reasoning behind why to have, or not to have an automatic move NU of the THS during Stall, when Elevator action need be immediately fully efficient.

I should clarify that I was looking for your own words, and your own supporting explanation, as short statements alone are often too brief to be a platform for a discussion, and so can be a book reference.

This last book reference is illustrative - you may find an appropriate appreciation. Unfortunately, I don't have the technical means to share the collection of excellent documentation on theoretical and practical aspects of the workings of the THS and Elevators which I have, for being able to reciprocate.

AlphaZuluRomeo;

Thanks for the info I didn't know that the FPV would go away, but it makes some sense, or at least did to some design engineers.

I do have a few questions about this. If the FPV gets "kicked out" by the system, how long does it take to come back?

The constraints that you wrote were that one of those parameters hat to have been met, by ALL ADRs, at the same time. The 60 knot parameter should have only been met spuriously, and transiently. The 20,000 fpm would have also been transient only, as the average was less than 15000 fpm.

Was there any indication about how long the FPV was unavailable?

Thanks