AF 447 Thread No. 12 [Archive] - Page 6

alf5071h

18th Jan 2017, 15:27

Surprise represents the difference between expectations and reality.

Fear is a natural response to perceived danger, which usually depends on prior knowledge.

'Startle response' is an unconscious reaction to a sudden or threatening situation (fight or flight). Startle involves automatic (subconscious) reaction and reduced cognitive ability; the focus of attention is towards the perceived threat leading to tunnel vision and the need to act. The startle response could continue if the actions do not effect a recovery, deepening the startle and reinforcing the chosen action, even if, in hindsight, this is wrong.

Startle could be reduced by avoiding surprising situations, by understanding and enhancing the recognition of startle, and being prepared (experienced) to manage an undesired state. Like error, startle cannot be irradiated, thus avoidance, detection, recovery and mitigation aspects apply.
Self-confidence and experience are important defences, particularly those which improve the perception of surprising situations and time available for actions.

Self-confidence could be improved with exposure to surprising' situations, but this may require 'real surprise'. Are simulators (instructors) able to generate sufficient realism to induce startle or fear.

Avoidance would involve improving system reliability - avoid grandfather rights, and reconsider the assumptions in certification. System failures are a probability; we tend forget that extremely improbably events can and do occur, and we often assume too much about pilot capability in extreme situations.

With increasing levels of safety the industry needs to adjust its view. Instead of attempting to identify all threats and regulate people, accept that in rare circumstances the outcomes are only a probability. Pilots should be encouraged to be adaptable, helped to judge situations and be allowed to deviate from the norm, and even encouraged to make (small, inconsequential) errors. Training has to enable pilots to manage the uncertainties in flying, not just the few 'certainties' in procedures.

Greater depth of basic knowledge could help pilots form a more accurate perception of startling events to help reduce the effect, the magnitude and/or duration..
Experience as in 'know-how' could be improved by re considering basic procedures:
e.g. operators claim to have good CRM practices by involving crew in decisions. However, which view offers greater learning:
Capt - "re weather ahead, we should deviate left 15 deg?" ( a tick in the CRM box) or
Capt - "re weather ahead, what would you suggest we do?". The latter exercises the crews' mind and decision process; it adds experience of actually doing something in a real situation.
Perhaps this aspect in some small way applied to the AF447 accident; I recall a telling graphic of the track deviation of other aircraft at the time, compared with the smaller deviation of AF447.

Instead of active recovery training, the focus should be more on awareness and the need to change the course of action. e.g. disciplined behaviour to use what little cognitive resource remains to reconsider why the situation may not be improving:- "am I using the correct action", or "do I really understand the situation".
Stop, rethink, break tunnel vision; but that may require realistic startling events.

Think slow, but faster. (http://www.skybrary.aero/index.php/Hindsight_15)

http://www.skybrary.aero/index.php/Unexpected_Events_Training_(OGHFA_BN)

Concours77

18th Jan 2017, 16:05

Stimulation: Visual(PFD). Aural(alerts, warnings, airstream, buffet) voice(CRM) G

Observation: intensity, (rated normality, comparison, rejections)

Recognition: level of threat, immediacy, communication, optionals,

Task: timing, action, review.

SORT

These are all categories of the Executive function of the brain, imo.

Once ingrained, and trained, it remains to test how far each candidate can "compress" these categories into the correct action.

A computer can do all these. But a human can do them better. What remains impossible for computers to get, (at present) is what starts to look like "intuitive" work. It is not intuitive, it is the extreme skill that results from intense training. It has been called "luck", or "genius", even the "zone".

When the current crop of over valued computational machines grok "intuition" what will follow will be the inevitable presence of pilotless aircraft. Till then, occasionally we need to compute "risk/benefit" and whistle through the cemetery.

KayPam

18th Jan 2017, 19:26

I sure hope there is still enough time to make a career in aviation..

We could debate this in other parts of the forum. Is there already a topic for us to discuss about that ?

Winnerhofer

18th Jan 2017, 21:19

Couldn't find anything on the topic:
http://www.pprune.org/9644344-post1258.html
Would be great if 45989 could elaborate.

KayPam

18th Jan 2017, 23:03

KayPam
What does any A320/330 do when it overspeeds Autopilot engaged?
(usually due to turbulence)
Clearly you have never flown either.
With AP/ATHR on, the ATHR will gradually reduce its power to flight idle (slower than if you put it on idle notch manually)
(In a wholly different context: In final approach, the ATHR gains are lowered in order to avoid a too "lively" ATHR when closer to the ground. So one should pay all the more attention to their speed, and never rely entirely on the ATHR. It can do a better job than a pilot but not always)
However, the ATHR will (in any case) have much trouble managing wind gradients higher than 2kt/s
If the speed increases, the ATHR will reduce but not fast enough.
The pilots can notice the increase in speed and deploy spoilers.
Another possible reaction (but less academic) is to pitch up. I even see some pilots reducing to idle notch (and some others forgetting to put it back to cruise thrust when required)

In any case, if an airbus with AP ON is accelerating, the normal law will start to pull up in order to reduce speed, once just above MMO.
Full forward stick while in overspeed will make the airplane stabilize at MD - Mach Dive (which is 0.07 above MMO on all airbus aircraft if my memory is correct, .82-.89 for the 320, .86-.96 for the 380)
Neutral stick will give you MMO (in stabilized conditions)

The High speed protection starts to really worry and to really pull up more when you're about halfway between MMO and MD or more.

In fact I am not (yet!) a qualified Airbus pilot but I do work in the very building where integration tests are carried out for the A380 and the A350, with integration simulators (Airbus factory at Toulouse Airport)

I am about 80% sure that AP will disconnect if high speed protection engages (well, you don't care about that question because in the high speed prot, wings are levelled so you would lose nav capability and you would obviously lose altitude holding as well)

So I would be very interested in knowing how easy/hard it is to fly the speed with the attitude in a wind gradient. Would there be a risk of oscillations around the target altitude due to overcorrection ?
Are pilots trained to operate manually at higher altitudes ?
A A320-pilot-friend told me it was very difficult to transition from climb to cruise manually at high cruising altitudes.

FCOM will confirm most of this (maybe not the 2kt/s value), mainly in DSC 27-20-10-20, see page 111 here : http://nicmosis.as.arizona.edu:8000/ECLIPSE_WEB/TSE2015/A320_DOCUMENTS/A320-FCOM_DSC%20Aircraft%20Systems_part2.pdf )

When pilot saw he was not over the runway threshold, he reverted to muscle memory, an unfortunate one. "Pull the stick, firewall the throttle." But he was not flying a Corsair, he was flying a Beech twin....

The aircraft made a small hole in the roof, not a long gash. He should have pulled the stick, and firewalled the throttles......arse about.

As to 447, the reason this discussion is eight years on, and twelve threads in, is because we yak about the part of the flight path that is fundamentally irrelevant. What was the status and attitude of the aircraft at the most important moment in the flight? As the A/P quit, and the a/c was four hundred feet low, Nose Down, and the Stall Warn was active? Oh, and rolled right?

It is the interface, Machinbird, as you say. The human is being evolved out of the equation, replaced by ever more "dependable" automation. Emotion and intuition are poison, data and speed are paramount.

Are you implying this corsair pilot pulled too much and stalled his beech ?

About AF447, going from FL370 to FL366 (there is a debate among our team of engineers about whether we can say FL followed by a number not finishing by 0 or even 5) in a short time span (as short as the one between cavalry charge for AP disconnection and the moment you look at your altimeter) would be really feelable through vertical acceleration, and the crew should have realized that.
They should have realized that they were actually in straight and steady flight without the need for touching anything. (CF the post that I wrote the other day about "it does not take exceptionnal flyings skills to do nothing")

As for attitude indication, IRS do not freeze ! (They do, however, suffer from laser lock, ATPL monkey knowledge here)

As for the Airbus stall warning.... AOA is considered invalid under 60kt (CAS invalid under 30kt, the ADR do not even try to compute it), and the stall warning was based on an AOA higher than a treshold. So invalidity of the AOA would make the stall warning stop.
According to one of our teachers in engineering school, that behavior is illegal. I hope that Airbus management decided to solve this ***slight*** problem.

Concours77

19th Jan 2017, 15:20

Edifying, thank you.

"As for the Airbus stall warning.... AOA is considered invalid under 60kt (CAS invalid under 30kt, the ADR do not even try to compute it), and the stall warning was based on an AOA higher than a treshold. So invalidity of the AOA would make the stall warning stop.
According to one of our teachers in engineering school, that behavior is illegal. I hope that Airbus management decided to solve this ****slight**** problem"

This aircraft was never flying at (velocity) sixty knots save for a few seconds of ballistic flight at the top of the arc. Loss of computed (indicated) airspeed then merged into computed but (erroneous) and air speeds remained unreliable the whole four minutes to impact, imo.

The intermittent StallWarn may have begun at the loss of Computed Airdata when the aircraft quit A/P.....and this resulted from ".....WindShear...." (ACARS).

It is not possible for mass to demonstrate a vertical velocity of (17,000fpm) and have an accurate and reported AirSpeed of sixty knots....

So the StallWarn, to a savvy crew, would be rejected in any data driven solution to recovery, imo.....at the outset.

The reported "< sixty knot" trigger for (inhibited) StallWarn, if true, shows a shortsightedness at the programming level. It also suggests a blunder that may have been repeated in other ways with AutoTrim.

The THS, in its travel to the Max NU stop shows a "programmatic" impetus, not pilot induced, or even "noticed" by flight crew.

In any case, it is Auto, so there is no argument. My guess is the aircraft FCM was looking for (aircraft commanded) NU authority to meet load (computed) requirements of the airframe, independent of crew input.

45989 comment? Also, reference to Escape(CFIT) Normal Law, does StallWarn activate, even though the aircraft cannot Stall if the computed AoA is valid?

@KayPam: Re: Corsair/Beech sending PM

alf5071h

19th Jan 2017, 16:11

KayPam, if the altitude (ADC) is referenced to the 'standard pressure setting, then the display is 'Flight Level' irrespective of the numerical value.

Re inhibition of AoA; refer to regulations on preventing the display of 'hazardously misleading information'; in every operating situation.

Re seeing values, feeling acceleration "...the crew should have realized that."
This might be a reasonable assumption without the effect of startle, but where sensory awareness is disrupted and automatic responses triggered due to surprise, then inability to realise is to be expected.
Similarly the reasonable advice 'sit on your hands, do nothing' may not be recalled from memory because of the overriding subconscious startle response.
Thereafter, as cognitive capacity is restored, the do nothing advice may not apply in the changed situation.
The brain could be behind the drag curve for some time, particularly for conflicting demands to 'assess the situation' and 'do nothing' advice; a clash of objectives (cognitive dissonance) (https://en.m.wikipedia.org/wiki/Cognitive_dissonance). Resolving these problem requires great mental effort - forget 'this', do 'that', pilots have to be adaptable .

One training task is to embed knowledge such as the maximum rate of change of altitude to be expected - even in upsets, and without associated accelerations or other instrument indications (VS). Also the need to view the wider picture, multiple instrument scan, integrate body senses, and compare this with previous experiences.
Training has a great responsibility in this area, the choice of sudden situations (rarely instantaneous or extreme), knowledge of aircraft systems, accuracy of simulator / CBT situations, knowledge of the atmosphere, of human behaviour.

The purpose of training is to embed specific knowledge in memory so that it can be accessed by the fast 'system1' thinking which takes over during startle.
A vital aspect would be to teach 'know-how' opposed to know-what. This is the training debate about knowledge recall - checking vs education - how to learn and gain meaningful experience.
This is an area which Airbus has considered and may have embodied into their training.

And as for all the other 'monkey knowledge', it may be irrelevant if the industry addresses the initiating contributing factor ('root cause') instead of outcome symptoms. Fix the pitot problem before you try to fix the crew, and even then consider the crew as a resource not a threat.
The regulator has significant responsibility in is area, but may be hampered by their own safety system: - retrospective hazard identification and dependency on regulation to control; a lengthy bureaucratic process.

Concours77

19th Jan 2017, 17:21

That may be the most objective, dispassionate, and reasoned essay on the topic.....(alf)

However, for those of us who still "question" the 'theory', some conclusions are not absolute....

The recorder data is "interpretive", BEA are not committed to absolutes....(bravo), and these threads have a somewhat skewed bias.(imo). Not even pitot failure is a lock....where do we see the identified ice blockage? Computer actions are suggestive of it, not based on data? Evidence of flight programming errors are patent, all we know is Airdata is NCD, by definition.....Wind Shear is far more plausible than simultaneous identical failure across three triplets?

That the CVR seems incomplete is actually a benefit, some of us entertain divergent views. For instance, when do we know crew recognized the change to AL? Eleven seconds after the Warning, not immediately, only when Robert declares it so. At 02:10:19?

I am not convinced the crew was incompetent; neither do I believe there is
certainty about "startle", or surprise. They were well aware of the weather to expect prior to loss of A/P, that was in the BEA report.

thanks for you post.

KayPam

20th Jan 2017, 17:38

"Re seeing values, feeling acceleration "...the crew should have realized that."
This might be a reasonable assumption without the effect of startle, but where sensory awareness is disrupted and automatic responses triggered due to surprise, then inability to realise is to be expected."

I meant something and did not express it very clearly I think. Here is what I meant :
Say you're in steady level flight and you loose 400ft in less than 5 seconds.
The only way this can happen is if you feel gigantic vertical acceleration. Maybe something like 0G for 2.5s and 2G for 2.5s.
I'm not gonna make a calculation but you see the idea.

So, since the crew did not feel such gigantic (relatively speaking) load factors, it must be because they did not actually lose 400ft in less than 5s.
It was only an altimeter artifact.

Concours77

20th Jan 2017, 17:57

"It was only an altimeter artifact."

You've had six and a half years to see and conclude that, if true. Similarly UAS was an artifact of AirData. It also fooled the aircraft, but the FCM wasn't sensing the DFDR, either. Was it static sensing?

The culture and twenty years of flying have cultivated "trust the machine".

Anticipation or Skepticism? What difference? Be ready for anything, or start the recovery (too?) late?

Four hundred feet in 5 sec is 4800 feet per minute. Compared to what happened right after, that's docile. The soon to be climb hit 7000 fpm? Turbulence? W/S?
Both reported. By pilots, and ACARS.

KayPam

20th Jan 2017, 18:42

Well, maybe the most reliable way of allowing the crew not to trust this altimeter is to include in their training that methods of calculating altitude will change if available input data will change.

Hence if any probe freezes, the indication will vary, in a non physical way.

Concours77

20th Jan 2017, 21:34

The crew were well aware of Wx, they phoned CC and warned them, they had deviated, and they Expected rough. They got it. I'm at a loss how this thread conversation turned to startle. I also recall the initial report said nothing was recorded on the right side of the cockpit.... Not indications, but nothing got recorded. So we end up with stick traces? Mystery.

If no indications were recorded, how do we know about the 400 ft low? If it was real, then fine, but how could it be an artifact and spurious but end up on the DFDR? From the right side?

There was no CVR data that showed any discussion about the AP loss, only "I have it..." ? Right?

Startle? The a/c kicked out the AP. Lacking any remarks, it's like that was expected. "we tried everything....!" Except for nose Down, or handing off to the "good" side? Or maybe having a chat about what this "everything" was?

Only initial remarks about ascent, then they quickly terminate..... Followed by everything except Nose Down?

Ever the helper, did the aircraft input some NU? Very touchy about Overspeed, this program?

KayPam

20th Jan 2017, 21:50

"I also recall the initial report said nothing was recorded on the right side of the cockpit.... "
If it said that, it's just plain wrong. There is a ****load of sensors related to the right side (only some of them frozen or impacted by the freezing), and all parameters related to anything other that what had frozen was still valid..

A 400ft low could appear on the right PFD. Then, the DFDR records from the DMC.
This low could appear due to a change in available data for computing altitude.
More precisely, TAS and Mach allow you to correct for position error. Without them, position error correction is lost.

I don't think this bus would be touchy about overspeed. It has a high speed protection law in normal law that would save the aircraft in close to 100% of situations with normal law.
However, I have no idea what the THS did during the incident.
The THS position is a truly important flight parameter and I do believe airbus should display it more clearly.

Concours77

21st Jan 2017, 13:50

Hi KayPam,

"However, I have no idea what the THS did during the incident.
The THS position is a truly important flight parameter and I do believe airbus should display it more clearly."

What it did is critically instructive. From a position of 2? Degrees Nose Up it cycled, "...smoothly and consistently Full Nose Up, and remained in that position until impact."
The THS trims automatically, and cannot be manipulated effectively (it can be "held" manually, but when released it keeps moving). Only in Direct Law is it a legitimate Flight control, in fact, it is the only way to control Pitch "Manual trim only".

The BEA report relies almost exclusively on one foundational "fact". From the instant of the abnormal, the pilot flying held ".....mostly Nose Up stick...."

So, the Trim is full Nose Up, the aircraft is Stalled, and descending quickly. The pilot's have tried everything, "try climb (Captain)" "I have, many times....." Pilot flying.....

Aircraft attitude, Stalled, in rapid descent.... In the Stall, the aircraft is in "established" descent, though no pilot would call it that, look at the ROD!! But the computer, with NCD AoA, no reliable airspeed, and VS also wild, might call it "stable", no?

Is there an "airstream audio data channel" for the computer to sense!? Is the computer's best solution to lock its commanded Pitch where it is, not to be overridden by pilots? The pilots could hear the noise, and arguably knew the descent was certainly fatal, not to be locked in, but to be corrected!!?

Back to the stick. What is this control, really? It can "command" attitude, but not directly, it can only send a request to the FCM, to be analyzed, and "normed", then modified, and applied.

The stick, actually, is nothing more than a "suggestion box" with a handle.

So WHY, when Robert was pestering Bonin to "you climb, so go down...." Did Bonin not descend? It made no difference, the aircraft was already climbing, and nothing Bonin could do would arrest this climb. What is this feature? Not Overspeed Protection. Not a mistake either, the THS would continue this auto climb when the elevators lost authority, as we see in the THS trace, and the BEA statement of fact.

Why would this happen? This aircraft's flight control system is programmed to not let the Nose drop. The Airframe is designed to exhibit neutral stability in Pitch approaching the Stall......it is "longitudinally stable". It makes no difference that there is poor annunciation of the THS travel. And as I say, this NOSE UP is not negotiable. This aircraft does not drop its nose at Stall. By design. I think by the time the crew decided to get serious and boot Direct Law (".......PRIM/SEC.....fault") the Tail was stalled, the elevators were completely ineffective, and there was no time to get the Nose to drop via Direct Law; it is a laborious process.

Winnerhofer

25th Jan 2017, 21:55

https://www.youtube.com/watch?v=4WuPoVjOXLY

Concours77

29th Jan 2017, 17:17

At 3:54 of the video, compare the four official "cues" of Stall with the reported attitude and aspect of AF 447 at the time of AutoPilot OFF...and review the pilot's actions. Nose up, not immediately responsive, uncommanded Roll, Stall Warn active, and from the DFDR, (inertial record) buffeting.

Question. In Overspeed, with Autopilot active, is Stall possible?

Machinbird

29th Jan 2017, 19:23

In Overspeed, with Autopilot active, is Stall possible? Realistically, it doesn't matter whether or not the autopilot is engaged. For any flight condition that is a valid overspeed at an authorized altitude, for 1 g flight, you will be above the 1 g stall speed. The worst cases are near the aircraft's ceiling. (Think of the U-2 flight envelope at altitude)

When you start talking about accelerated flight (more than 1 g) then an aircraft can be stalled up to the point where you break the airframe first, but an Airbus FBW system will g protect the airframe in Normal and Alternate law, (but not in Direct or Mechanical law.) For an autopilot to be engaged, you must be in Normal or Alternate law, so you won't be breaking an Airbus FBW airframe with over g while on autopilot barring an encounter with something like a massive thunderstorm or mountain wave rotor.

Assuming that the autopilot is receiving valid inputs. the answer to the question is no, as long as the autopilot is engaged, being in overspeed condition precludes stall in 1 g flight.

Caveat! I've never flown the Airbus, and am at heart a steam gauge pilot, but I've stalled aircraft from near ground level up to over 50,000 ft.:} It will not hurt my feelings if you find a flaw with my logic.

Concours77

29th Jan 2017, 20:22

"Realistically, it doesn't matter whether or not the autopilot is engaged. For any flight condition that is a valid overspeed at an authorized altitude, for 1 g flight, you will be above the 1 g stall speed."

I am trying to establish some possibilities related to Normal Law, Alternate Law, and loss (or add) of protections. Especially as it may pertain to FCM response to two flight modes: Stalled, and Overspeed (simultaneous).

......As it applies (may apply?) to a discussion of the forty seconds surrounding the loss of AutoPilot by the crew. Because of the conditions established by the report, and the training video, I want to have an understanding of how the pilots took the situation in, and responded, (knowing what we know, and entertaining what they may have known)?

Probably need an A 330 pilot? I asked a friend, a Captain on the 320.... As a ten year Captain, I asked him how many times he had flown in Alternate Law?

His answer: Zero.

KayPam

29th Jan 2017, 20:52

"Several flights per year" end up flying in alternate law.
The most common cause for that is either manual disconnection of 2 ADRs (there's even an airbus procedure recommending this in some specific cases), or the freezing/loss of two (I think) pitot or static or aoa probes.

New question tonight : do you think the ambiant noise could have told the AF447 crew that they were at a slow speed rather than a high speed ?
The copilot thought they were fast. Maybe that was due to unusual noise, because of the wierd airflow around the airplane ?

Concours77

29th Jan 2017, 22:48

There are questions that arose from beating the ACARS to death for two years! As to ambient noise, which is likely given "turbulences forte", ACARS "WINDSHEAR", and "do you think we have some crazy speed...?" Etc.

If due to an unusual sound of airstream, it is recorded on the Cockpit Area Microphone...
To my knowledge, few people have heard that recording, with its nuances, intonation, alerts, etc. but an easy take once heard, I should think.

Also, by 'crazy' Bonin could mean slow, fast, or sideways (slip)..... To include the turbulent airmass of cruise in the ITCZ.....

One would need experience of flight at or near Stall in high speed, actual Overspeed, and the "personality" of the airframe in jet upset.....

If Wind Shear occurred, it might help an understanding of corrupt AirData, and altitude reporting. The ingredients were present for fluctuations in performance leading to A/P quit?
Trigger a protection?

KayPam

30th Jan 2017, 00:09

In French, crazy would likely refer to fast, with no certainty of course.
I don't think there was any windshear involved. AP quit due to loss of anemo data only.

Machinbird

30th Jan 2017, 01:27

It was really unfortunate that Robert came down so hard on Bonin when he put out the speed brakes thus causing them to be immediately stowed.

You would think that someone would have tumbled to the fact that they were not hanging on their shoulder straps following deployment.

That should have lead to a productive line of thought about being slow, but given the level of fear in that cockpit, who knows?

Concours77

30th Jan 2017, 19:44

"That should have lead to a productive line of thought about being slow, but given the level of fear in that cockpit, who knows....?"

Indeed, who knows? I venture to say anyone who listens to the record, the CVR!!

Now this speed brake issue happened after the initial Stall, and mushed descent?

It underscores why the aural record is so critical. The transcription is so abridged, it even casts doubt on the report....?

Why did Robert so easily abandon his position re: climb? With the g, the altitude, and the reduction of airstream noise, one would think Robert would have gotten apoplectic? Instead, he joins in to tell the Captain they have "... Tried everything...." Evidently, something satisfied Robert that A) the climb was not subject to pilot arrest, or B) Nose Down had been "tried".......and failed, repeatedly......

That two pilots would disagree so vehemently about spoilers meant they had at least two divergent views on recovery? Where is the follow up? This lasted four minutes, I would expect some chatter, not the apparent "restraint" of voiced "concerns"?

KayPam,

"AP quit due to loss of anemo data only."

That's interesting.... What about The Stall Warning, and uncommanded Roll, plus unresponsive control?

This aircraft will not Stall in Normal Law. It wants to be In Alternate Law to Stall...that had nothing to do with loss of Auto Pilot? I repeat my question: if at Vs, (past alpha Max (and Vmax) , and already in Alternate, wouldn't the AP drop via the FCM? And, if this is so, and Pitch was commanded Nose Down, via Protection, isn't it quite possible the result may have been Overspeed?

Winnerhofer

4th Feb 2017, 17:07

Disable Autotrim in Alternate Law
AF447 | formercaptain.ca (http://www.formercaptain.ca/category/aviation/af447/)

Concours77

4th Feb 2017, 18:05

"First the airplane stalled (quit flying because the Angle of Attack was too great). Then, because of the steady back pressure on the sidestick, the autotrim wound the Trimmable Horizontal Stabilizer (more powerful than the elevators) to full nose up."

Disagree, strongly....

Follow the stick traces (both sides) then show us how the THS was "responding" to stick inputs. Instead, it initiated and sustained a smoothe, even travel to the stop...and remained in that position until impact....

Further, the Horizontal stabilizer stopped almost a full degree shy of "full travel". This suggests perhaps a mechanical issue....

If the THS were relying wholly on the stick to conform this automatic travel, it would have articulated in synch with the stick, per Alternate Law, Pitch..... (Not smoothly). To reconcile this movement would imply the FCM somehow "knew" the Pilot wanted full travel, or it was programmed to independently input full Nose Up.

"because we must know not only why F/O Robert stalled the aircraft, but much more importantly why he didn’t know he had stalled it, why he had a totally inaccurate picture of what was happening, and why there was a complete absence of situational awareness on that Flight Deck."

False. Robert did not Stall the aircraft, Pilot flying was Pierre Cedric Bonin.....who was F/O and RHS.

(Paraphrase): this author claims the a/c flies just as any other, that it has "positive longitudinal stability".
If it had, it likely would have been recoverable, instead of remaining nose high at the Stall....(the Nose would have dropped significantly, signaling the Stall, and cueing recovery....)

What about the Trimmable Horizontal Stabiliser? Calling it "Trim" is misleading. As it cranks in Nose Up, it is fundamentally changing the Angle of Incidence of the Stabiliser, not its trim. Any deviation from neutral Angle of Incidence changes the neutral point of the Stabiliser and its ability to provide a consistent downforce. In short, the character of the maneuverability of the airframe in Pitch is altered, imparting a stubborn bias to the Pitch control. At full THS Nose Up, the aircraft cannot alter its Pitch away from Full Nose Up, the elevators are essentially useless.

Winnerhofer

10th Feb 2017, 16:59

Just in:
INFO FRANCEINFO. Crash du vol Rio-Paris : la justice ordonne une nouvelle contre-expertise (http://www.francetvinfo.fr/faits-divers/accident/info-franceinfo-crash-du-vol-rio-paris-la-justice-ordonne-une-nouvelle-contre-expertise_2056213.html)
http://www.lemonde.fr/societe/article/2017/02/10/accident-rio-paris-les-juges-d-instruction-demandent-une-nouvelle-expertise_5077960_3224.html

Concours77

10th Feb 2017, 18:45

the justice ordered a new second opinion.....

As expected, nons? They can borrow mine, if they wish....s'il vous plait?

Publish 10 fevrier, 2017, cette Les familles espèrent un procès bientôt

The families expect the trial soon....

m'aider monsieur....

Winnerhofer

11th Feb 2017, 09:48

Never is this going to end.
The other day I heard some attorney say on different case that court action too long after an event has little value.

Concours77

11th Feb 2017, 17:59

Never is this going to end.

Don't be discouraged.

While "defensible", the report is not conclusive... If the evidence remains covered up, or worse, destroyed, there is no statute that runs on manslaughter.

Or fraud.....

Machinbird

12th Feb 2017, 20:45

What about the Trimmable Horizontal Stabiliser? Calling it "Trim" is misleading. As it cranks in Nose Up, it is fundamentally changing the Angle of Incidence of the Stabiliser, not its trim. Any deviation from neutral Angle of Incidence changes the neutral point of the Stabiliser and its ability to provide a consistent downforce. In short, the character of the maneuverability of the airframe in Pitch is altered, imparting a stubborn bias to the Pitch control. At full THS Nose Up, the aircraft cannot alter its Pitch away from Full Nose Up, the elevators are essentially useless. Oh it is trim all right. Trim refers to the effect on the aircraft as a whole, and is used to control the aircraft pitching moment within the limits of its trim authority.

There are any number of aircraft that use this method of trim. Virtually every airliner in use today trims the horizontal stabilizer angle of incidence. Many Piper aircraft trim in this manner, as well as a number of military aircraft.

The thing that did not make sense about AF447 trim behavior was why was it possible for the aircraft to continue trimming nose up (In Alternate Law) after reaching stall AOA?

KayPam

12th Feb 2017, 21:20

Concours77

12th Feb 2017, 23:31

Your French really makes no sense

My spelling, but the translation comes from my niece, a PhD in French linguistics.

Machinbird:

My definition of trim is mine, and it comes from flying aircraft whose Horizontal Stabiliser is fixed. In such a traditional platform, "trim" is accomplished by deflecting a "trim tab", and is used to reduce the need for constant pressure on the yoke. The tab is cranked in to establish a "trimmed" aspect for cruise.
My first flight instructor cautioned against using trim for maneuvering. For obvious reasons, imo, and 447 is a prime example of "runaway" trim.....again, automatic, no pilot input. In fact, once at the stop, it's bias NU prevented Recovery....

AF 447 was in jet upset, out of control, and auto trim cranked in full Nose Up, in and through aerodynamic Stall....once at the stop, the THS didn't budge; it held that full Nose Up "Trim" until Impact with the Sea.

In an exchange with an AE whose employer was at one time Airbus, I got a very frank admission that the THS program was a huge mistake, and needed to be changed....if the recorded data was accurate... these professionals, always with the "caveat", yes?

Machinbird

13th Feb 2017, 02:38

Concours77, be very careful of home grown definitions in the broader context of modern aviation.
Before you can understand the Airbus FBW flight control laws, (and the AF447 accident) you should understand C* flight control and how it operates.
Similarly, to understand Boeing FBW flight control laws, it would help to understand C*U flight control.
Check out this link for a quick explanation of the concepts:
Fly-By-Wire A Primer for Aviation Accident Investigators (http://cf.alpa.org/internet/alp/2000/febfbw.htm)

So how do you think we trimmed the F-4 Phantom with a single all moving stabilator at the back end and no elevator or trim tabs and electricity only needed to change the trim setting? When you understand that, you will understand that your trim definition is impossibly restrictive.
My definition of trim is mine, and it comes from flying aircraft whose Horizontal Stabiliser is fixed. In such a traditional platform, "trim" is accomplished by deflecting a "trim tab", and is used to reduce the need for constant pressure on the yoke. The tab is cranked in to establish a "trimmed" aspect for cruise.

Concours77

13th Feb 2017, 15:38

Load factor and pitch rate demand is not relevant to this particular point. It is sufficient to base the discussion on "AutoTrim" and the need to fly manually whilst another axis is C*.

I politely reject your contention that there was "panic" or excess "fear" on the flight deck.

I thought the CVR (that released by Otelli) demonstrated that the profanity, and the reasonable questions: "But what is it doing....?" Show an engagement that belies panic.

I also reject the "PIO" determination when the roll axis got "challenging", when other evidence points to an approach to Stall dynamic: "uncommanded roll, unresponsive controls, buffeting, and an active Stall Warn" (both audio and ECAM). That the aircraft then entered an uncontrollable climb also suggests other, and patent derivations: Air Caraibes, Indonesia, Metro, etc. instead of "pilot pulled aft stick....

The report's record is derived from evidence that is subject to considerable interpretation, and there is no conclusive causation here.

Can you help with your memory of the early ACARS data? Reported by French employees of the airline, there was this: "TURBULENCES FORTES..." The system reports via satellite. The crew knew they had poor radio comms, can the crew type a message to Paris via Satellite, concurrent with mechanical reporting?

IcePack

13th Feb 2017, 17:01

I hate this conjecture that their was FEAR.
After 40 + years I can say that I have never been subject to fear during an event/incident.
BUT I have for sure had the shakes after the event/incident once one the ground.
In the air just get on with the job!
IMHO they were not frightened in this incident but obviously confused.

Machinbird

14th Feb 2017, 00:45

IMHO they were not frightened in this incident but obviously confused.Actually this was an accident, and if they were not experiencing fear on the way down with their aircraft not responding in the way they were expecting it to, then they were not human.
A big clue that they were experiencing fear related stress is that they were not hearing the stall warning alarm while it was sounding (other than right at the beginning when it chirped at them a couple of times). The ears are one of the first things to shut down under stress.
. After 40 + years I can say that I have never been subject to fear during an event/incident. If you can close your eyes and see the event in graphic detail, you probably experienced fear related stress and time dilation at the time.

I can vividly recall a low level jet wake turbulence encounter that rolled the aircraft ~90 degrees at 50 feet above the runway, for example but I was too busy to perceive fear at the time. Doesn't mean that the stress hormones did not kick in, because they did.

Fear is a natural human condition that creates a strong hormonal response in the body. Let us not pretend it does not exist or is a sign of weakness. It is a hidden factor in too many accidents that we seem to be tap dancing around rather than confronting.

IcePack

14th Feb 2017, 08:37

but I was too busy to perceive fear at the time.

That is what I meant. I am sure stress hormones were active hence the shakes after the event.
Fully aware that this crew possibly were not hearing the stall warning & were suffering from stress effect. But the CVR indicates to me they were not fearful per-say.
Still wonder what was meant by "we have no indications" as if I understand correctly when that was said the airspeed indications had returned.

Uplinker

14th Feb 2017, 09:27

I get that after a particularly challenging landing. I relish max conditions, crosswinds, etc, and really enjoy the challenge of controlling it all and landing safely, (or throwing it away if it gets too bad). I don't feel scared during this, just engaged and focussed, but I can feel the fight or flight hormones in my system as we taxi in.

Concours77

14th Feb 2017, 15:14

Machinbird,

"A big clue that they were experiencing fear related stress is that they were not hearing the stall warning alarm while it was sounding (other than right at the beginning when it chirped at them a couple of times). The ears are one of the first things to shut down under stress."

You say that, but how do you know this? How is it you "know" they heard the Stall Warn the first time, at AP quit? How do we "know" they either "did not perceive" the following alarms, but instead were only "ignoring" them, perhaps having rejected the warnings as spurious?

This is the problem with "knowledge". Sometimes (often?) it is equated with facts....what we know is based on input....

We do "know" for instance, that the CVR data is not complete. I "know" this because the investigative agency has said so.

So you might respond, "if the crew were discussing recovery and mentioned a "Stall", that would of course be reported...."

You may assume the crew was cognizant of degrade to Alternate Law immediately? In point of fact, the degrade to AL was not memorialized until eleven seconds AFTER loss of AP and speeds.

"We've lost the speeds, Alternate Law......." (02:10:21)......

Do you recall the reported status of cockpit data? "Nothing was recorded from the Right Side of the Cockpit"?

To my knowledge, there is but one accident involving Airbus equipment where the pilots are suggested to be completely at fault.....(447)

There is on record an accident where flight data recorders were switched, the replacement recorder had falsified data.

The official record of 447 can be reasonably defended. But this reasonable defense is dependent on data that is ostensibly unavailable?

IcePack

14th Feb 2017, 15:25

Still note that many on here still do not understand airbus FBW. Note when not in direct law stick fore & aft movement is a G demand. So I suspect the software interpreted the back stick as a request for x g. So as the aircraft could not produce the x g it tried its best so ran the elevators full up & still not sensing the required g ran the stab full up. (ie followed up)(trimmed is not exactly a correct term)
In theory say a little aft stick requesting say 1,1/4g will end up with full up elevator & full up stab if that is what is required to produce the g demand of 1,1/4 g.
Not relevant here but roll when not in direct law is a roll rate demand so same applies if a small roll demand can not be met full aileron & full roll spoilers could be the result.
I will say however the real aeroplane does have some delay in producing all this.

Concours77

14th Feb 2017, 15:42

IcePack

"Still note that many on here still do not understand airbus FBW. Note when not in direct law stick fore & aft movement is a G demand. So I suspect the software interpreted the back stick as a request for x g. So as the aircraft could not produce the x g it tried its best so ran the elevators full up & still not sensing the required g ran the stab full up. (ie followed up)(trimmed is not exactly a correct term)"

That has been the point right along. The major issue for me is not C* but its pairing with Roll DIRECT. We don't know the aircraft's timing in the degrade to this obscure Law, but it May have been delayed by eleven seconds from the initial upset (StallWarn, Cavalry Charge, Master Caution).

If so, do we know the uncommanded roll was weather, wind shear, ham hand, or approach to Stall? We don't.

So after hours in AutoFlight, the aircraft splits its personality, and requires an unannounced reversion to manual? In (expected) turbulence, and bordering on jet upset at loss of auto?

Yes, the "Stab full up" is not exactly "trim"....

"I will say however the real aeroplane does have some delay in producing all this."

Precisely. Perhaps the root cause of this tragedy? Timing is everything?

Owain Glyndwr

14th Feb 2017, 16:51

Concours77

It might be a good idea for you to get your niece to translate the definitive (French) version of the Final Report which differs from the English version in several respects.

In particular, in section 1.16.3 it states that the two ADRs failed between 2:10:3.5 and 2:10:05 and that the FBW reverted to Alternate 2B at 2:10:05 and stayed in that mode thereafter. So we do know the timing of reversion to direct law in roll - no supposed eleven second delay.

Then in section 1.16.4.1 it states that " lorsque le pilote automatique se déconnecte, un gradient de vent latéral concomitant (20 kt en 4 s) engendre le départ de l’avion en roulis à droite ;" so we do know the source of the uncommanded roll. Fig 64 of the French version shows a simulation of what the lateral response of the aircraft to this turbulence would have been with and without the actual pilot input. Note that this data does not exist in the English version.

Concours77

14th Feb 2017, 18:18

"In particular, in section 1.16.3 it states that the two ADRs failed between 2:10:3.5 and 2:10:05 and that the FBW reverted to Alternate 2B at 2:10:05 and stayed in that mode thereafter. So we do know the timing of reversion to direct law in roll - no supposed eleven second delay."

WE know. Because we have the DFDR. When did the flight crew know? All I can find that was reported by the investigators was the CVR: "We've lost the speeds.....Alternate Law...."

That was Robert's remark, at (I believe) 02:10:21.... Per the CVR Mike 1....

I submit that you knowing, and I knowing, and we knowing, means less than nothing...

When did THEY know, and what's missing from the CVR?

I apologize for giving you the "we".... I have a hard time not putting myself in the cockpit, and trying to suss what "they" knew, and "when"?

Concours77

14th Feb 2017, 18:29

" lorsque le pilote automatique se déconnecte, un gradient de vent latéral concomitant (20 kt en 4 s) engendre le départ de l’avion en roulis à droite ;" so we do know the source of the uncommanded roll. Fig 64 of the French version shows a simulation of what the lateral response of the aircraft to this turbulence would have been with and without the actual pilot input. Note that this data does not exist in the English version.

What did Robert know, and when did he "know" it?

Do you have an opinion on the Trimmable Horizontal Stabilizer cycling "Full Nose Up" but only reaching -13.2 degrees? Is there any chance that the jackscrew got stuck short? Any chance of an "Alaskan" type fatal Pitch?

KayPam

14th Feb 2017, 18:36

I can vividly recall a low level jet wake turbulence encounter that rolled the aircraft ~90 degrees at 50 feet above the runway, for example but I was too busy to perceive fear at the time. Doesn't mean that the stress hormones did not kick in, because they did.

If this was true you should be dead by now.
Except if you were flying some sort of highly maneuverable aerobatic or jetfighter aircraft.

Owain Glyndwr

14th Feb 2017, 21:03

When did They know and what's missing from the CVR?

All this was described in second by second detail in the FIRST expert's report, but that has never, to my knowledge, been translated into English.
You have to be careful to differentiate between when they could have known of the law change and when they actually spoke about it. The expert's report shows an ECAM page timed at 2:10:08 that says "Alternate Law (Protection lost)" but then at 2:10:22 it says:"02h 10.22 Le PNF continue la lecture de I'ECAM : « Alternate Law, protection slo.." so they could have known about it 3 seconds after the actual law change.
The intervening time seems to have been taken up by other activities, because as the experts concluded " Face â l'incompréhension de la situation, le PNF cherche dans la lecture partielle et désordonnée de I'ECAM une justification â ce qu'il perçoit, et revient à son projet d'action initial de prévention des conditions givrantes" - loose translation "not understanding the situation, the PNF resorted to a partial and confused reading of the ECAM to find a justification of what he was seeing and went back to his initial actions for prevention of icing conditions"
From other remarks one can infer that the experts attributed the low level of cockpit conversation to the increase in stress of the moment.

With respect to your other posting, I would have thought that the last thing a pilot, flying in turbulence and faced with a sudden aircraft movement would want to know would be how big was the gust that hit him. He "knew" there was a roll diversion immediately..

I don't know where you got 13.2 degrees from; the published DFDR graphs are really to small to get that much precision unless digitised; but in any case the THS did not "cycle". Its position is determined by a time integral of elevator deflection and without knowing the integration constant and doing a careful integration with the actual elevator input one cannot say what the final THS deflection should have been.
But no, no chance of an Alaskan type pitch.

Machinbird

15th Feb 2017, 00:50

If this was true you should be dead by now.
Except if you were flying some sort of highly maneuverable aerobatic or jetfighter aircraft. At the time of the event, I was seriously concerned about dying as you suggest.
The aircraft was a North American T-2A which was a straight wing jet trainer. I was number 6 to roll with 10 seconds interval between takeoffs as briefed.
With gear and flaps up, accelerating through 200 knots at about 50 feet up, the aircraft began to roll right against full left aileron and then full left rudder too and reached about 85 to 90 degrees of bank.
I remember thinking, what do I have left???:eek:
The thought came-Aft stick! The aircraft then popped out the side of what must have been a multi-aircraft vortex and began to respond to control. With a wingspan of 38 feet, there wasn't much time or altitude to play with. The ejection seat was useless in that attitude.

Concours77

15th Feb 2017, 13:52

"You have to be careful to differentiate between when they could have known of the law change and when they actually spoke about it"

With respect, that is my point, precisely. You also state that the second ADR failed at 2:10:05...and that AL was instantaneous. That leaves two seconds before the Auto Pilot quit, and perhaps another two seconds for the crew to observe the alarm, and institute input. The "gust" likely complicated a crisp decision, perhaps adding another two seconds of distracted focus, and stick input. Six seconds to start manual flight, and stabilization of flight path.

You leave unaddressed my question about when they were cognizant of loss of Protections and a major change in handling (Roll DIRECT). Did they not lose both PFD's?

Do you fly this aircraft? I have an acquaintance who flew the A320. He flew as Captain for ten years. I asked him at one point "how many times have you flown this plane in Alternate Law exactly?" He answered, "Zero".

I asked him if he knew what AL2b is? He answered: "I have no idea."

I repeat, the first time we know absolutely when the pilots were aware of the Law degrade is "...We've lost the speeds......Alternate Law...." Time: 02:10:22.

Seventeen seconds perhaps of Mode Confusion. It is my belief that it is in this initial time period the aircraft was lost....do you disagree? It is certainly within this time frame that we see the "commanded climb" ?

That the THS deployed to Full Nose Up, in the Stall and the Stall Warning was inhibited whilst airborne are but two extraneous conditions that are inexcusable even though not material.

Finally, I need to repeat my thought that though we all can take some ersatz authority from the data post mortem the flight crew had no such luxury. This is the truth, for me, and I make note of this "data" approach by folks who are without the empathy to place themselves wordlessly in this flight deck "on the day"...

Many thanks, Owain Glyndwr.

Are you connected in any way with Airbus?

Owain Glyndwr

15th Feb 2017, 15:36

@Concours77

Look, I'm not going to get into a fruitless discussion on things which have already been covered time and time again in the twelve AF447 threads and the relevant official documents. If you were to read the accident reports and expert analyses carefully you would find the information you seek.
I will quote just one point to illustrate what I mean. You have just hypothesised that there was a delay of six seconds to start of manual flight and stabilisation of flight path.
But if you had read the BEA Final report you would have seen on Fig 26 the following:
2:10:05 A/P disengaged
2:10:06 First Officer (on the right) "I have controls"
2:10:07 read from chart 1st application of pitch control: 1st application of roll control
Bear in mind that there may be a delay between action and recording of that action because of DFDR characteristics

If you had read the official report you would know that your remarks are incorrect.

No, I do not fly the A330

"It is my belief that it is in this initial time period the aircraft was lost ....do you disagree"

Yes; it is my view that the aircraft was lost at 02:10:50 when, from an attitude of 6 deg in more or less level flight and an airspeed of 216kt the FO initiated a pull up to 17.9 deg.

Am I connected with Airbus? Check my age - at 81 I don't work for anyone!

My view is that "what" happened is adequately covered and not really in dispute. "Why" it happened that way is best left to the PROFESSIONAL airline pilots that contribute herein

Concours77

16th Feb 2017, 15:28

From OG

"Bear in mind that there may be a delay between action and recording of that action because of DFDR characteristics"

Thank you.....I have allowed for that. Unless crew were expecting a Law Degrade with loss of autopilot, the recorded data suggests this exact thing (delay in recording).

I repeat that the only (first) evidence we have of the crew's recognition of these important aspects is seventeen seconds AFTER the DFDR (sic) reporting of them.

I believe I can make a reasonable statement relative to the (recorded) difficulty in managing Roll... Turbulence? Possible. Patent aircraft roll response as sensitive in Alternate Law? Certainly, Airbus is explicit about that. Uncommanded Roll as a result of approach to Stall? Again, possible, the StallWarning demands we consider that.

"...We've lost the speeds....Alternate Law...." At 02:10:22, spoken by David Robert, PNF (pilot not flying......)

Seventeen seconds after the first reported manually effective control inputs by Pierre Cedric Bonin, and the defining moment of onset of "confusion....." We know that they are at odds with the annunciation PFD data, and each other, concerning ascent...

That is all completely patent, I believe. The last vocalization I believe was from Captain du Bord duBois:".....Pitch ten degrees...." The purpose of this dying man's final words? Remarkable in that he does not mention his mother, utter terrified profanity, or other recorded last words.

He is trying to tell us something. With two seconds to live, he knows the DFDR has recorded Pitch, and Angle of Attack is not available, the aircraft doesn't tell the pilots this, only the DFDR gets the AoA data. He wants us to know they know attitude, that they are without a solution, and he wants posterity to know what the problem is.

He knows the aircraft is nose high, he knows the rate of descent is fatal, and he may as well have said, although discretion may have prevented this: "She is not responding in Pitch...."

You don't care about "WHY". Nor do I, nor do most professional pilots, I would say...

"WHY" is for Priests, the word we concentrate on is "HOW".

My initial conclusion remains that the pilots did not know, nor were they privy to how the aircraft was behaving, and confusion ensued. Once confused, reason becomes difficult, and solution development becomes perhaps impossible.

Owain Glyndwr

16th Feb 2017, 16:56

The delay I was referring to is the internal DFDR delay - maybe quarter to half a second, no more than that. It was simply to explain why it might be read that there was a whole second between his announcement of taking control and evidence that he did so.

Please don't put words in my mouth. I did NOT say I don't care about "WHY". On the contrary, I care very much and I am amazed to hear your opinion that most professional pilots don't care either! I just happen to think that professional opinion outweighs that of enthusiastic amateurs every time.

Most people would agree that the pilots did not understand what was happening to them, but not perhaps with your argument on the reason.

KayPam

16th Feb 2017, 18:30

DFDR recording is VERY complicated.

For instance, some parameters will be refreshed 5 times per second in the DFDR, and be recorded only 4 times per second, so you skip one in every 5 possible recording.

Parameters are not at all refreshed as much as you would expect them. The best ones being refreshed 8 times per second (they're very rare)

For instance if you push your button "event marker" in the cockpit, in order to mark an event in the DFDR, it will only work if the parameter is refreshed (written) while you're pressing it. Since it is (say) at 1 point per second, you could be unlucky, press it for 0.9s and miss it !

To finish with, some parameters will be refreshed very regularly but the parameter itself can be late due to some reason (gear squat parameter can be as long as 2s late)

roulishollandais

17th Feb 2017, 19:21

Why is it so bad?

Owain Glyndwr

18th Feb 2017, 11:39

roulis
It's difficult to get a litre of wine into a standard 75cl bottle!

Ian W

18th Feb 2017, 13:20

roulis
It's difficult to get a litre of wine into a standard 75cl bottle!
It is a pity that these days when electronics are far more capable, smaller and cheaper that the DFDR/CVR and communications links to them are of such antediluvian design. The only assumption that can be made is that these recordings are not considered important enough to spend time and money on.

it will only work if the parameter is refreshed (written) while you're pressing it.

Are there any other push button selections in the cockpit that have such a hit and miss design? Of course not - "but this is only DFDR so it doesn't matter"?

Concours77

18th Feb 2017, 14:53

"Are there any other push button selections in the cockpit that have such a hit and miss design? Of course not - "but this is only DFDR so it doesn't"

Likely assumed to be the cynic here, there is this:

DFDR is basically "default quality control". CVR is sufficient, and generally is more efficient in post accident conclusions, since the interface is a driving metric?

An onboard "fire" is required to have a probability of "once every one billion flight hours"

Since there are demonstrably more hull losses than chunks of fleet flight hours in the billions, a fire is less common than losing a hull full of people....

The first bit of wreckage (447) pulled up, and spirited immediately away to Toulouse was the avionics equipment bay contents. "What's that smell?" We are to believe it was St Elmo's fire, a common source of O3, the aromatic that can prompt "What's that Smell?"

Obviously no post flight fire, due to its position in a sea of extinguishing fluid, the wreck had important digital data to give up...

"Command and control" is not limited to the military.

There are no, repeat NO unbiased people present at the scene of an airplane crash....

Only police, military, and "invited parties". Assuming an accident might lead to losses, including economic, political, and prestigial, it is only reasonable to see this as common....

At the inception of each hull loss, a representative of the flying public, (the Raison d'être of the industry) must be present, call this person(s) an ombudsman if you will.

If a United States President can concoct a story to allow an immense invasion of a foreign country (pick one of many, Iraq, Syria, Vietnam?) does one believe it is outrageous for a multi trillion dollar industry to merely "collect and protect all evidence, then issue a report"?

And be honest about it? What are we smoking?

tdracer

18th Feb 2017, 19:30

The only assumption that can be made is that these recordings are not considered important enough to spend time and money on.Ian, it's not just the flight data recorders - most of the avionics on an aircraft are several generations behind the electronics in your phone. The reasons are simple - it's insanely expensive to certify new aircraft avionics, and more critical the system, the more it costs (the certification costs to change something in FADEC software is north of a $1 million USD - and that's just the certification costs - it doesn't include actually making the s/w change). Further, if you 'upgrade' something you need to make sure it's a drop in replacement - otherwise all the systems it talks to have to change as well. That's why most 747-400s are flying around with the same flight deck display system that was designed 30 years ago.
Further, while there are occasional 'block' changes of avionics, unless the regulators mandate it, they are seldom retrofit. As a result, there are still lots of commercial aircraft out there that still have the old analog foil tape recorders. I was involved in investigating a 747-200 freighter crash about 5 years ago that was the result of multiple engine failures after takeoff - foil tape FDR, the only engine parameter was EPR :ugh:
I've looked at dozens of DFDR files over the years - usually incident investigations but occasionally accident investigations. Trust me, having something like the DFDR in an A330 or 777 is wonderful - they are head and shoulders better than the stuff from even 10 years earlier. Yes, they have their limitations but they are not that difficult to work with once you understand those limitations.

tdracer

18th Feb 2017, 19:35

There are no, repeat NO unbiased people present at the scene of an airplane crash....
Concours, until you've actually been involved in investigating the cause of death of hundreds of people, I suggest you shut up.

Concours77

18th Feb 2017, 20:10

I have, Except for the hundreds part. On one MVA, our defendant was prosecuted by a District attorney who withheld evidence, and by investigating police who sat on an eyewitness's testimony. The testimony was explicitly exculpatory, and when another investigator discovered it, the case was dropped.

This case in France is one of manslaughter. I have seen principals in manslaughter cases violate law. The defendant in the case I describe was looking at fifteen years in prison....yet the "authorities" wanted a conviction, at any cost. Don't lecture me....

tdracer

18th Feb 2017, 20:59

Concours, you're talking about suppressing the cause of an accident that caused hundreds of deaths, and it doing so putting additional thousands at mortal risk.
I've worked with perhaps a hundred other aviation professionals who have been involved in crash investigations at one time or another. They all had one overriding concern during the investigation - finding the root cause so corrective action could be taken and no one else need die.
Stop slandering those people...

Concours77

18th Feb 2017, 21:23

As an investigator, I am familiar with the profession. My comment you cite has to do with on scene; an emotional, raw, and highly challenging format.

My problem is not the dedicated professionals to which you refer. Examination and interpretation of evidence is a fine art. My issue is with the "after the fact" partisans, the agencies, the politicians, the investors, etc. and the lawyers, not to mention the spinners.

I cast too broad a net, and I apologize....

IcePack

18th Feb 2017, 21:29

Tdracer wasn't it a Swiss company that proved the FDR was switched during an early Airbus crash investigation?
Methinks in this day & age their is too much money involved to have absolute reliance on ALL investigators ethics. Concours I am sure is not slandering, but just being sceptical.

tdracer

18th Feb 2017, 23:47

My issue is with the "after the fact" partisans, the agencies, the politicians, the investors, etc. and the lawyers, not to mention the spinners.

I cast too broad a net, and I apologize.... Fair enough - apology accepted. It's just something I've very sensitive to - the accusations than invariably occur whenever the cause points to something other than the aircraft - that Boeing/Airbus/etc. 'rigged' the data. While the manufactures have dedicated air safety investigators, they regularly pull in subject matter experts from the various engineering areas. I was only intimately involved in one really bad accident - the Lauda 767 that crashed when a thrust reverser deployed during climb. It was perhaps the hardest thing I ever did in my 40 year career - and the reverser wasn't even my system. At first the investigation wasn't that bad because everyone thought it was bomb, but that changed. The DFDR was destroyed and didn't yield any useful information, but we were able to get a printout from the FADEC non-volatile memory. That memory dump was the smoking gun that the T/R had deployed at 24k/Mach 0.78, and I was one of the first people to see the evidence :eek:. A deployment it flight wasn't supposed to be able to happen, but somehow it had and 223 people had died because we'd missed something.
I went home that night and put away the better part of a bottle of Scotch :uhoh:. I honestly don't know how my friends who do crash investigations for a living do it...

Concours77

19th Feb 2017, 15:53

"I went home that night and put away the better part of a bottle of Scotch . I honestly don't know how my friends who do crash investigations for a living do it..."

You're very gracious to respond. The final straw for me in the business was a homicide. Clearly and demonstrably perpetrated by a police officer, in uniform, the web of complicated conspiracy necessary to exonerate, and not even charge the suspect angers me to this day.

So, the suppression of evidence gets my blood to boil.

If I were given the job of writing a synopsis of 447 and the Report by BEA, I would likely have to experience the same sort of frustration....

In this accident, the technical, the scientific evidence has great representation. There were three (at least) eye witnesses of the entire four minutes; their voice record is not available.

In a capital case in this country, to withhold material evidence from the Court at trial is a felony, and would likely be charged and pursued. Keep in mind that those who retain it in this accident and prevent its propagation, are not even the "Police".

This is not complicated, and for those in the business who see it happening, well, I would hope they are as upset as I am.

My hope is that at trial, sanity prevails. A Subpoena by the Judge, and it's done. The recording is released, and since it bears so heavily on the Public interest, it likely would be made available to all.

If the evidence has been "lost", "modified", or destroyed, well, let's hope it remains available.

As a professional in the business, are you concerned about the doubt of the accuracy of the Report? It taints all the work done on the Report by everybody, it casts doubt on all...

Thanks also to IcePack....

Machinbird

19th Feb 2017, 22:10

Concours77, I am glad that we have your motivation and background out in the open. In a PM earlier I noted that I perceived that you were attempting to steer the narrative of the accident. The problem with that tactic is that you obviously did not have sufficient aviation background to do that successfully.

I have investigated aircraft accidents, witnessed aircraft accidents, and read thousands of accident and incident reports over the years and one thing I have learned is that there are extremely few new ways to have an accident. The addition of technology between the pilot and the aircraft opens up new possibilities for misunderstanding what is happening, but aerodynamics is till at work in the background to make things fly.

When you take an aircraft through the maneuvers depicted on the AF447 DFDR readout, it is obvious what put the aircraft in the water so the question I have, is what factors were influencing the crew to allow them to grossly mis-understand what their aircraft was doing. I would like to have a discussion what influence fear may have played in this accident. I am not considering the typical movie depiction of fear, but rather the built in physiological response to fear that any pilot worth his salt has experienced and overcome in training and operations. In my experience, professionals will typically attempt to keep solving problems right up until the end. The problems occur when the physiological response to fear/stress interferes with perception and with orderly thinking.

Concours77

20th Feb 2017, 00:48

I appreciate your level of experience. I would be interested still in your opinion regarding the Roll Direct issue at 02:10:05. Still PIO?

Stick and Rudder is what killed them, no doubt, but my interest is in their eye witness commentary on the way down.

Why do you make no complaint about the "CVRFile" being kept in the dark? You want progress in interface? You think Fear would be an interesting data set?

What do you expect to learn without the most valuable evidence available? I think you're on to something; do you not think the eyewitness record is or should be public domain?

What the hoarders of the record owe the public is clearly apparent. That they continue to block access is criminal, IMO.

Machinbird

20th Feb 2017, 04:15

do you not think the eyewitness record is or should be public domain?

What the hoarders of the record owe the public is clearly apparent. That they continue to block access is criminal, IMO. Concours77, there exists an uneasy relationship between pilots and things that record what they do and say in the cockpit.
In order to have CVRs in the cockpit, the authorities have had to agree that pilots last words will not be made public in raw form, otherwise pilots have means of defeating such recording devices in order to maintain their privacy. In unusual circumstances, raw recordings have been made available to the public, but I for one am willing to forego someones final expressions of dismay in order to have access to the bulk of what was said in written form. I know other clues to look for to draw the bigger picture.

I would be interested still in your opinion regarding the Roll Direct issue at 02:10:05. Still PIO? I have had extensive discussions with Owain Glyndwr who possess much more detailed aerodynamic knowledge than I will ever hope to have. He has mathematically demonstrated that it was not a classic PIO, however I have enough physics to know that any system with feedback and too much gain will go unstable. A pilot is a variable gain feedback device and a highly excited pilot is very likely to increase the rapidity and level of his feedback if he perceives the aircraft is not doing what he mentally expects it to. Add interesting effects such as time dilation to the pilot's time perception and who knows what the result can be. These effects are extremely difficult to generate for scientific study. I do know that two Airbus aircraft have been lost after the PF inexplicably pulled back on the stick and pretty much held it there after experiencing roll instability at the transition to Roll Direct in alternate law. (AF447 & QZ8501)

Concours77

20th Feb 2017, 13:42

Hello.

"Concours77, there exists an uneasy relationship between pilots and things that record what they do and say in the cockpit."

Colgan gave us the first officers final scream. Some doomed pilots have uttered infantile and guttural sounds. So let's be honest. An "uneasy relationship" is a political expression of an adversarial discussion....

At some point, one needs to judge whether public safety is more important than politics....I believe it is. Your position seems that it is "negotiable".

Post 447, the pilot group at Air France threatened a strike unless the Thales pitots were changed out on a more urgent basis....remember? That is "public safety" as an expression of a professional group with an informed and common position....

So we appear to disagree, fundamentally....

I do not suggest that the record be exposed on some ridiculous reality show, but shared respectfully with unbiased and neutral professionals.

I find it interesting that virtually all of the "transcribed" CVR releases conform with what amounts to a consensus informed with data that is not complete.

Without any bias whatever, an investigator could (would)? challenge the secret CVR as suggestive of fraud; something that would certainly be added to the other data as a matter of obvious duty?

Either the Report is true to its mission of public safety, or it is not.....Censorship is not only inappropriate, it should be an embarrassment to the mission....

Concours77

20th Feb 2017, 13:46

Did you miss the Captain's command to PF much later in the chronology?

"....Watch your Lateral!!...."

What do you make of that?

"I do know that two Airbus aircraft have been lost after the PF inexplicably pulled back on the stick and pretty much held it there after experiencing roll instability at the transition to Roll Direct in alternate law. (AF447 & QZ8501)"

"Inexplicably"? My first assumption would be that pulling back stick kept the aircraft "controllable".

That remains my working theory with AF447.....and,

, however I have enough physics to know that any system with feedback and too much gain will go unstable. A pilot is a variable gain feedback device and a highly excited pilot is very likely to increase the rapidity and level of his feedback

Do you include the aircraft in this supposition? Or, just the pilot?

Machinbird

20th Feb 2017, 15:33

Do you include the aircraft in this supposition? Or, just the pilot? In this case of AF447, just the pilot as in gross over-control.

Did you miss the Captain's command to PF much later in the chronology?

"....Watch your Lateral!!...." No, didn't miss it. He is being thrown around in the cockpit as the aircraft experiences wing drop in the stall, a logical speculation as to the meaning of the comment.

"Inexplicably"? My first assumption would be that pulling back stick kept the aircraft "controllable" Probably not too far from the truth. Once stalled, as the aircraft became slower, the wing drops likely became less violent. (speculation again.) However, initial pull up into the stall was due to a fear response (more speculation) caused by rapid oscillatory roll rates (AF447 & QZ8501)

Regarding CVR records, I do not suggest that the record be exposed on some ridiculous reality show, but shared respectfully with unbiased and neutral professionals. So how do you propose that can be done without losing control of the raw audio?

As an investigator in an accident (military), I have sometimes been asked to consider a particular viewpoint.. That is an undesirable position to be in when the person making the request also writes your personnel evaluation. The more independent parties to an investigation that there are, the better the likelihood that the truth will out.

Concours77

20th Feb 2017, 17:09

"Probably not too far from the truth. Once stalled, as the aircraft became slower, the wing drops likely became less violent. (speculation again.) However, initial pull up into the stall was due to a fear response (more speculation) caused by rapid oscillatory roll rates (AF447 & QZ8501)."

Let's start here,
I sense some common ground....

Do you know our Pierre Bonin? Of course not. From what I derive from Lo these many threads my conclusion is different than your supposition that the initial pull up was a response to fear. It is highly unlikely.

My suppose is his inputs were generated from anger...not fear. From Owain Glyndwr, we know his control inputs were immediate, and fear takes time to develop. Now it is possible that his fear had presented prior to manual control, but if so, I suggest his emotions were supportive of action, Not patience.

Patience is the cure for panic, as well as other unwanted emotion....if one is healthy, and understands his emotions, his patterns.

Fear is basic, the mother of all emotion, even Love. To reach the kind of fear you are suggesting takes input, observation. the lizard brain demands data, it cannot think on its own.

Would you consider broadening the discussion, without judgment? I do repeat however, the only real data that would be instructive is inside that sequestered chip.....?

Machinbird

20th Feb 2017, 17:56

and fear takes time to developWell, I think I will take issue with this statement. From practical experience, the acute attention physiological response (Fear response)takes about 1 heartbeat. You know when it hits you because your heart violently contracts (like it did the time another formation interleaved the formation I was in at 90 degrees to our heading).

Can you quote your source for this physiological observation of yours?
To reach the kind of fear you are suggesting takes input, observation. the lizard brain demands data, it cannot think on its own.

Concours77

20th Feb 2017, 20:33

Stimulus, Response. No Stimulus, no Response. That is the role time plays in the emotion called fear.

"(like it did the time another formation interleaved the formation I was in at 90 degrees to our heading)."

What caused Bonin's "Response"?

I have postulated that his initial Pitch up was a result of the aircraft's nose down attitude...why would that create (result from) fear? To me, it was the correct response. Similarly, as he struggled (and mastered) the Direct Roll, he likely noticed it came about in conjunction with his back stick? You admit the docility he may have experienced in Roll might be due to his conclusion that Pitch Up made the a/c more controllable?

Now. We know that the first time the crew demonstrated a knowledge of loss of speeds and the Law degrade was at 02:10:22. Seventeen seconds AFTER the DFDR posted the data.

It is not logical to assume that because we have the DFDR, and a timing of the changes, that the crew did also.

In fact, it is preposterous. Why? Because we have a pilot who is struggling, and convinced that Pitch Up is necessary to maintain controlled flight? Do we even know if he is aware that the aircraft is in Roll Direct? The evidence shows that he probably does NOT recognize Roll Direct, his first Roll input was made to correct for turbulence!! Why is he expected to be able to differentiate turbulence from Roll Direct?

At this point, my working hypothesis would be "Split Mode, Roll Direct, disguised as turbulence". Throw in a surmised solution of Nose Up controls flight path, and for seventeen seconds, he has done the wrong things; we know it, he couldn't have?

Machinbird

21st Feb 2017, 04:09

Concours77
Stimulus, Response. No Stimulus, no Response. That is the role time plays in the emotion called fear. I'm not sure if we are on the same page, Concours. Do you now agree that an extreme fear response can occur virtually instantly or do you hold a viewpoint that it takes a significant amount of time to develop? From my own experiences, it can hit you like a hammer blow.

I am pleased to see that you are attempting to look at the AF447 event from the the "inside" view rather than as a judgemental external viewer. I think we will be able to do some thought experiments to validate/invalidate your concept.

From my personal experience again, any time an aircraft does not appear to be following your control inputs for reasons that you do not understand or cannot control, it will immediately trigger a strong physiological fear response in the pilot flying.. By fear response, I am referring to the typical fight or flight reactions.

I would like others who have also encountered this situation to either confirm or refute this observation so as to confirm if it is inherent to general pilot behavior. I would not expect every pilot to necessarily have had such experiences, however.

Life on top

21st Feb 2017, 04:43

Concours77

21st Feb 2017, 13:45

"From my personal experience again, any time an aircraft does not appear to be following your control inputs for reasons that you do not understand or cannot control, it will immediately trigger a strong physiological fear response in the pilot flying.. By fear response, I am referring to the typical fight or flight reactions."

Biochemistry describes these responses accurately. Can we agree that the kind of fear we are discussing wants an observed (experienced) stimulus?

If so, then I propose one that might fit your parameters. At loss of autopilot, the a/c was reporting a deviation in altitude of (-) 400 feet. It also, via FD, showed a roll to starboard.

The pilot, probably in concert with ".....I have the controls....", made inputs to climb, and roll left. The aircraft did not immediately respond in Pitch (BEA). In fact, the record shows it took eleven seconds for "....the aircraft began to climb..."

Does that qualify as a stimulus sufficient to gain the pilot's concern?

Life on Top

Don't forget the Captain's exit from his seat to disable the ELAC? There is record on the ACARS of 447 of what looks like an attempt to gain Direct Law by disconnecting "....Prim/Sec......" Also 447's "uncommanded roll", "unresponsive controls" and "Stall,Stall" as the autopilot quit? "Buffet"?

Hamburt Spinkleman

21st Feb 2017, 14:07

Concours77, isn't this the 5th or 6th username you have used to engage in a circular, obtuse and amphibolous style of debate on this subject?

Winnerhofer

21st Feb 2017, 19:46

Concours77:
1) No ELAC on A330
2) Dubois was always standing

KayPam

21st Feb 2017, 20:07

I must say after watching the air crash investigation episode of Air Asia A320 over Java sea, the similarities were striking. Yet the French BEA investigator or the episode failed to mention 447 by a word. As if Airbus is covering up known weaknesses with stall at high altitude. Any other with thoughts around this?

It is not the fault of Airbus if an airplane stalls when pulled up at a high altitude !!
On the contrary, Airbus does everything in its power to help airplanes keep their normal flight laws and associated protections.

Same flying technique as AF447 but in normal law would have resulted in a perfectly normal flight !

Concours77

21st Feb 2017, 20:09

Winnerhofer
My reference was to Air Indonesia A320, and not DuBois.

Hamburt Spinkleman
No.

Machinbird

22nd Feb 2017, 02:17

Concours77, we know you are a lawyer (with light aircraft experience) trying to make sense of the AF447 accident. Others are also interested in the accident and what can be taken away and used. Many are not primary English speakers. You would do everyone a favor if you would try to suppress the lawyer lingo and use simple sentence structure. Also, this is not an adversarial proceeding where you must hide your hand and then spring it on the other side at the most opportune time. Just relax and lets see what we can figure out about this accident.:8

_Phoenix

22nd Feb 2017, 03:09

On the contrary, Airbus does everything in its power to help airplanes keep their normal flight laws and associated protections.
There was "alternate 2B law", the roll is direct but pitch is still a g load factor law or "normal'' but no stall protection.
After autopilot disconnect, the aircraft banked to the right and lost in altitude. Then possible Bonin grabbed the sidestick instinctively from a reclined seating position. The "normal" flying technique (mayonnaise stirring) put him quickly into PIO with large lateral inputs and an average(30%) nose up. It took about 10 seconds to stabilize laterally, but meanwhile the aircraft changed flight path from horizontal to climb. During next 30 seconds, before stall warning blared into cockpit, the pitch input averaged around neutral = "0" change in flight path (climbing). Now, here is the catch -> Low Energy Awareness: "Past experience on airplanes fitted with a flight-control system providing neutral longitudinal stability shows insufficient feedback cues to the pilot of excursion below normal operational speeds. The maximum-angle-of-attack protection system limits the airplane angle of attack and prevents stall during normal operating speeds, but this system is not sufficient to prevent stall at low-speed excursions below normal operational speeds. Until intervention, the pilot has no stability cues because the aircraft remains trimmed"

Machinbird

22nd Feb 2017, 04:42

Concours77, you may not have realized how different hand flying in the mach number range at altitude is from your experience in hand flying light aircraft at lower altitudes.

The very high true airspeed causes the aircraft to generate significant rates of climb/descent with extremely small pitch changes. During normal level flight cruise, typical pitch inputs would be on the order of 1/2 degree, with 1 1/2 degree pitch change being a large correction. To do this requires a high level of concentration on the attitude indicator.

At the same time, the high true airspeed reduces the aircraft's turn rate significantly and thus requires less scanning effort on the aircraft heading since that changes slowly. The piloting strategy is then to keep the wings dead level which will stabilize the heading and concentrate on the pitch indication almost exclusively. The ratio of pitch scanning versus heading scanning is probably in excess of 85-15 whereas down low, it is probably more like 50-50.

Concours77

22nd Feb 2017, 13:36

Can we say: "aircraft at altitude fly very fast. Why? They have to, or they won't fly"

Is that a different way of stating your opening above?

May I offer a way to look at high altitude performance and the Airbus logic of "Stall"?

The THS went full Nose Up, ostensibly to provide a (wing) loading the elevators could not?
The aircraft is neutral in longitudinal stability, it resists dropping its Nose, even at Stall?
The Stall Warnng is inhibited at air speeds (indicated) of sixty knots, or less?
A symptom of this aircraft's approach to Stall is "uncommanded Roll"?
Another symptom at Stall is "unresponsive controls"?

This looks like an excellent performance envelope for an aircraft at altitudes below four hundred feet AGL. An aircraft about to land.....

Do we know why the Thrust was maintained for the entire descent? Was it commanded, or Autothrottle?

Given your description of high altitude handling qualities, does the aircraft's design comport with high altitude Stall?

Did the aircraft know where it was? Did its designers consider that some excellent design features for a landing aircraft might not be optimal for a Stall at 37000 feet?

I would like to say that except for descent rate and the lack of extended landing gear, the aircraft was in excellent attitude to land?

Thanks to Machinbird, and also Phoenix...

Winnerhofer

22nd Feb 2017, 16:34

At 30kts it doesn't compute.
A bit like reversing at 3km/h, the ABS doesn't cut in.

Concours77

22nd Feb 2017, 16:43

Hello Winnerhofer....

"A bit like reversing at 3km/h, the ABS doesn't cut in."

Why would it? The phonic sensor is live, the wheel is rotating?

Is ABS available in reverse? Why would it be?

Winnerhofer

22nd Feb 2017, 17:52

The crew had loss of AP, a short Stall Warning, and an attitude “approaching” upset.
Also degraded to AL2B.
They entered a climb as the Auto Trim motored smoothly to full NU, where it stayed until impact.
Crew had no AoA indicator, neither did they have the optional Artificial Horizon, or BUSS.
They noted the climb, though their CRM lacked a concurrent discussion of recovery.
They tried to regain the “bird” in the display, and the F/O had desperately tried to move the FCM into “Direct Law”.

Concours77

22nd Feb 2017, 18:16

They entered a climb "as rapid as 7000 fpm" as the Auto Trim motored smoothly to full NU, where it stayed until impact. (full Nose Up. = -14 degrees)
Crew had no AoA indicator, neither did they have the optional Artificial Horizon, or BUSS.
They noted the climb, though their CRM lacked a concurrent discussion of recovery. "There was no reduction in climb rate, post discussion..."
They tried to regain the “bird” in the display, ("to "see" flight Path, or to calculate AoA is not known") and the F/O had desperately tried to move the FCM into “Direct Law”. " Possibly by defeating the FCS by opening the Breaker?"

Alterations included....

Machinbird

23rd Feb 2017, 04:57

Can we say: "aircraft at altitude fly very fast. Why? They have to, or they won't fly"
Is that a different way of stating your opening above?No, that was not the intent of the post.

If Bonin had used a strategy of control such as I described, the aircraft would have arrived in Paris. Since that is not what happened, it means he used an inappropriate control strategy. The question is why?
Did he have any experience hand flying at altitude? I am thinking he did not since he was flying extensively in RVSM airspace on autopilot. If he had any exposure to hand flying, it was almost certainly in Normal Law in a simulator.

Did he have experience flying in Alternate law with Roll Direct? As I understand, the answer is no. That training was reserved for Captains.

Did he have confidence in his abilities to hand fly? Judging from his performance, he did not. CRM went immediately out the window, and his PM was clearly distressed by his performance. This is the type of situation that could be expected to create strong fear in both individuals right at the start of the non-normal event. First Bonin, then Robert.

Winnerhofer

23rd Feb 2017, 10:24

http://www.pprune.org/tech-log/555473-stability-wars-why-did-relaxed-lose.html

Machinbird

23rd Feb 2017, 13:37

Stability Wars: Why Did Relaxed Lose?Winnerhofer
Perhaps you provided the link so that Concours could better inform himself.
With regard to AF447, the trim tank was full, and that meant that the CG was at or near the aft limit which provided lessened trim drag.
The down side of that CG location was that once stalled, it was easier for the aircraft to reach extremely high angles of attack.

Chris Scott

23rd Feb 2017, 13:58

Quote from Machinbird:
"Did he have any experience hand flying at altitude? I am thinking he did not since he was flying extensively in RVSM airspace on autopilot. If he had any exposure to hand flying, it was almost certainly in Normal Law in a simulator.
Did he have experience flying in Alternate law with Roll Direct? As I understand, the answer is no. That training was reserved for Captains."

Surely it will come as no surprise that I'm in agreement with that line of argument, and that probably goes for many others lurking in the background - particularly those of us that were used to hand-flying subsonic jets at the same speed and altitude as AF447 in the cruise. But we seem to be going over familiar ground...

IcePack

23rd Feb 2017, 14:40

With regard to AF447, the trim tank was full, and that meant that the CG was at or near the aft limit which provided lessened trim drag.
The down side of that CG location was that once stalled, it was easier for the aircraft to reach extremely high angles of attack.

Maybe the trim tank was full but i believe the CG was not near the aft posn. Due freight in fwd hold (i am told)
In the airline I flew the 332 with the trim in the cruise was around 38 to 39 which is getting nearly full aft.

Owain Glyndwr

23rd Feb 2017, 15:41

The BEA Final Report states that at the time of the accident the CG was 28.7%

Machinbird

23rd Feb 2017, 16:07

Icepack and Owain, thank you both for the correction.:O
From the BEA final report (English version),
The balance corresponding to the aeroplane’s takeoff weight and shown on the final
load sheet (after LMC) was 23.3% of the MAC (mean aerodynamic chord), which was
within the limits.

The recorded data indicates that at the time of the event, the aeroplane’s weight was
205.5 tonnes and the balance was 28.7%, which was within the limits.
From a A332 CG chart, the max inflight aft CG for 205 kg x 1000 (is that the same as 205 tonnes?) is about 39%, so obviously much more aft CG was available to AF447.
The trim tank was apparently able to move the CG aft ~5%. Probably Owain can provide a more complete estimate.

Machinbird

23rd Feb 2017, 16:20

Surely it will come as no surprise that I'm in agreement with that line of argument, and that probably goes for many others lurking in the background - particularly those of us that were used to hand-flying subsonic jets at the same speed and altitude as AF447 in the cruise. But we seem to be going over familiar ground...
Yes, familiar ground until we get to this part of the statement:
Did he have confidence in his abilities to hand fly? Judging from his performance, he did not. CRM went immediately out the window, and his PM was clearly distressed by his performance. This is the type of situation that could be expected to create strong fear in both individuals right at the start of the non-normal event. First Bonin, then Robert.
I think that if we look within ourselves, we will agree with this statement also, and that is an opening into a discussion of fear in the cockpit.
Again, by fear, I do not mean screaming fits, mearly the physiological response to fear.

Owain Glyndwr

23rd Feb 2017, 17:33

Machinbird

The TO CG was 23.3%, so that would tie up with your approx. 5% from the trim tank.
Yes, 205kg x 1000 is 205 tonnes. Trim tank holds 4800 kg which would give a bit more than 5% shift at 205T

Machinbird

24th Feb 2017, 18:00

First, thank you Owain Glyndwr for the confirmation of the A332 trim tank aft cg contribution.

I believe it is necessary to discuss the physiological fear response to understand the human side of what happened to AF447. The most universally recognized name for this response is the Fight or Flight response.

Since we are not issued an FCOM for "Human Being, MK1 Mod0, we have to pick up our understanding of the special operating modes of this highly complex device through personal experience and personal curiosity. Just as our aircraft can surprise us as it switches control laws unexpectedly, your own body can surprise you with unexpected and unrequested automatic mode shifts. The Fight or Flight Response is one of those mode shifts than catch you out if you are not prepared for it.
An explanation of Fight or Flight response can be found here:
The Fight or Flight Response - NeilMD.com (http://www.thebodysoulconnection.com/EducationCenter/fight.html)

Concours77

24th Feb 2017, 22:31

Machinbird,

I haven't studied it, but I have given it a speed read. Thanks Evelyn Wood.

I might not be on the same page as you are relative to fear on the flight deck of AF447.

The thrust of the book after a quick look is that "fight or flight" is deep within our DNA, a relic of the survival default when facing the "saber tooth tiger". Its prescription is to "blunt" the reflex, since there are no longer "saber tooth tigers" challenging our survival, and there are ways to relax and reason around the "sub saber tooth" realm of modern challenges.....

So what do flight crew have to deal with that is actually a "saber tooth moment"?

Asseline knew he was going to crash into the trees, he didn't lose it, he crashed, and survived.

Haynes lost his vertical Stabiliser along with his number two fan. He not only didn't panic, he enlisted help to make a certain crash survivable. They found a dead heading Captain, and had him lie down and work the "steering" (differential thrust, manual.)

Perpignan? Captain knew they were gone, but he kept pulling the stick, pissed off he couldn't get more "g".

Sullenberger? Amazing. So where do we look for what you diagnose as panic?

Colgan. Captain heard a Stall Warn, because the bug was not reset after De-Ice was switched off, a faulty and premature alert.

He lost it, though he had a good twenty knots to lose before the actual Stall. He pulled, because his training was to "lose minimum altitude" at Approach to Stall. When that ate up his margin, the stick pusher volunteered to help, but he kept pulling, likely forgetting the pusher was the good knight, ready to save them.

That qualifies as panic that killed.

I don't see panic on AF 447, nor do I see evidence of flee or fight, a sub set of panic. I see anxiety, lack of confidence, confusion.... All things that can be overcome if the level of training and personal development is sufficient.

I would like to recommend a book by a friend of mine, Sylvia LaFair.
"Pattern Aware"

We can learn to trust our calm and qualified self. The pilot is a computer, well in advance of any Valley branded mother board.

Making best use of the equipment is what flying requires. Pilots have skills that are impossible to reproduce in any computer, abstract thought, intuitive problem solving, and very nearly the kind of calm detachment that comes with the actual computers only advantage, emotionless RAM.

Winnerhofer

25th Feb 2017, 21:35

Flug AF 447 - Kollaps der Team-Struktur im Cockpit könnte Airbus-Absturz ausgelöst haben (http://www.deutschlandfunk.de/flug-af-447-kollaps-der-team-struktur-im-cockpit-koennte.676.de.html?dram:article_id=379703)
Flight AF 447
Collapse of the team structure in the cockpit could have triggered Airbus crash
In June 2009 an Airbus from Air France crashed across the Atlantic and killed 228 people. The reason for this was frozen sensors, but now crises investigate the disaster again: they see fundamental problems with the handling of people with highly automated board technology.
June 2009, flight AF447 on the way from Rio de Janeiro to Paris. The Air France aircraft has been in the air for over three and a half hours and is already far out across the Atlantic. The captain is resting. In the cockpit of the Airbus the two copilots. Outside stockfinstere night. Suddenly the autopilot turns off.
"I have control," says the copilot. But that will change drastically in the next seven minutes. Important exterior sensors of the Airbus are frozen. That's why the instruments spin! They indicate that the aircraft loses a lot, but this is not true. The copilot at the wheel believes the error message and rips the machine up. But now the airbus nose is too steep. It threatens the dreaded flow tear, a complete loss of the lift.
Giving gas and nose down! That would be appropriate now. But the alarm and the instrument display are contradictory. Is the machine now rising or falling? The pilots keep the climb, there is a flow break. Even the captain, back in the cockpit, can no longer avert disaster.
Lack of emotional distance to the onboard computer
"The last few seconds are characterized by the fact that people have only tried to take over the control by means of the joysticks, but this was not coordinated at all, which can be traced using the flight recorder evaluations," says Gordon Müller-Seitz. He is a professor of strategy and cooperation at the TU Kaiserslautern. One focus of his research is on crises arising when dealing with technologies at the interface between man and machine. Therefore the interest in flight AF447. Müller-Seitz shares with an expert colleague, French study scientist Olivier Berthod from the Freie Universität Berlin: "When the machine no longer reacts as usual, the emotional stress for the copilot is so great that everyone is just as bored to pay attention to what The onboard computer. At this point, organized action collapses."
"The breakdown of the team structure, the communication structure - that would be what was interesting in the case," says Gordon Müller-Seitz. He and Olivier Berthod are now presenting a new analysis of the misfortune and come to the conclusion that this is a fundamental problem in the way people deal with highly automated technology. The pilots lacked a critical distance to their onboard computer. In a confusing situation they were fixed on the instruments instead of pausing and thinking together what was going wrong at the time.
"It is all the more important," says Gordon Mueller-Seitz, "that the people - we would call it - have a certain vigilant, attentive neutrality with regard to technology Master of the situation, and that was not the case, because the interplay between the man and the machine broke. "
It was indeed dark and the pilots practically on the way. But would not they have had to feel what their machine was doing?
"This was also the reason for the fact that it was an Airbus aircraft, because the Airbus cockpit and the instruments did not convey a sense of how much the flight was actually flying. When one had flown a Boeing aircraft in comparison, You would have felt the movements from the outside, because they are electronically transmitted and simulated while you were simply in a closed cockpit in the Airbus. You did not know how to move, whether up or down Down, because it was night."
As a consequence of the crash, pilots are now training in their simulators the failure of the autopilot in cruising altitude. And Olivier Berthod emphasizes that the number of accidents with Airbus machines has not increased, but decreased. Nevertheless, the ability to work in the cockpit should be better trained, as he recommends:
"It's always easy to sit down at the desk, but we think that in critical situations, pilots should understand themselves as a team rather than a team, looking for a solution together, which should be a standard procedure and trained."
The new study has quickly moved around in aviation circles. And the researchers were already given first invitations to lectures before pilots.

Chris Scott

25th Feb 2017, 23:40

Quote from Winnerhofer (post #1345) :
"They entered a climb as the Auto Trim motored smoothly to full NU, where it stayed until impact."

Not quite...

The function of any auto-trim system is to remove the necessity for the PF or AP to continue to command the deflection of a primary flight control. In this case the auto-trim is concerned with pitch control, and adjusts the incidence (angle) of the THS (trim-able horizontal stabiliser) to enable the elevators to return to neutral in a few seconds after they have been deflected to comply with a command from the pilot or AP for a pitch-change (actually, in the case of C*, a change in normal G).

So in AF447 the THS "motored", as designed, in reaction to persistent pitch-up inputs from the PF's sidestick; inputs which were inappropriate once the aircraft had returned to the correct indicated altitude and which led in due course to an aerodynamic stall. That was allowed in turn to progress to a deep stall which the crew did not identify as such.

Quote from Machinbird:
"CRM went immediately out the window, and his PM was clearly distressed by his performance. This is the type of situation that could be expected to create strong fear in both individuals right at the start of the non-normal event.
I think that if we look within ourselves, we will agree with this statement also, and that is an opening into a discussion of fear in the cockpit."

Yes, I concur with that.

Machinbird

26th Feb 2017, 01:18

I have cherry picked the Neil piece for physiological information that might be applied to AF447. Neil's emphasis was on preventing and controlling over-activation of of the fight or flight response. In AF447, we had an accute invocation of that response. Normal emergency training is intended to give a direction to our actions, thus avoiding stress inducing situations.
Excessive stress creates an automatic protective reaction within the body that initiates nerve cell firing and chemical releases (adrenaline, noradrenaline & cortisol) to prepare us for running or fighting.
When our fight or flight system is activated, we tend to perceive everything in our environment as a possible threat to our survival. By its very nature, the fight or flight system bypasses our rational mind—where our more well thought out beliefs exist—and moves us into "attack" mode…….Our thinking is distorted. We see everything through the filter of possible danger. We narrow our focus to those things that can harm us. Fear becomes the lens through which we see the world.

Has the fight or flight response become counterproductive?
In most cases today, once our fight or flight response is activated, we cannot flee. We cannot fight. We cannot physically run from our perceived threats. When we are faced with modern day, saber tooth tigers, we have to sit in our office and "control ourselves.

How do we elicit the relaxation response?
Because the relaxation response is hard-wired, we do not need to believe it will work, any more than we need to believe our leg will jump when the doctor taps our patellar tendon with a little red hammer. The relaxation response is a physiologic response, and as such, there are many ways to elicit it, just as there are many ways to increase our pulse rate (another physiologic response).
1. 1. Focus on a word or phrase that has a positive meaning to you
...........................
3. Deep diaphragmatic breathing exercises, with a focus on the breath, can trigger the relaxation response.
(The last two items are methods that might be practical in a cockpit while managing an emergency.)

Concours77

26th Feb 2017, 14:32

From Chris Scott:

"The function of any auto-trim system is to remove the necessity for the PF or AP to continue to command the deflection of a primary flight control. In this case the auto-trim is concerned with pitch control, and adjusts the incidence (angle) of the THS (trim-able horizontal stabiliser) to enable the elevators to return to neutral in a few seconds after they have been deflected to comply with a command from the pilot or AP for a pitch-change (actually, in the case of C*, a change in normal G)."

A question? I asked Owain Glyndwr at one point why the graph in the report of the THS movement looks "smooth"? Yet the graph of the stick trace looks anything but? The trace is full of bumps, up and down....

If the THS moves as a result of pilot command, wouldn't the system itself be representative of the pilots "choppy" stick movement?

Owain Glyndwr responded that he did not have the integration constant, so could not comment why the graphs were "seemingly" disparate?

Wouldn't this work have been done by the report? It would seem obvious to show the system worked as designed? If it is in the report, please disregard my question....

Owain Glyndwr

26th Feb 2017, 15:25

You are putting words in my mouth again!
I said nothing about the graphs being "disparate". I simply said that without knowing the gains one could not calculate the final deflection.
As a lawyer, you probably do not appreciate that integrating a variable results in a smoother variation than you see in the original, unintegrated, variable. So the smooth recorded THS movement is entirely consistent with the "jerky" elevator commands - which, by the way are not just the stick movements but include the autostabilisation commands, another item for which the gains are not known.

However, it doesn't need a genius to work out that if you maintain back stick for a long period the THS will move steadily towards its maximum nose up deflection. The experts who analysed the DFDR will have known the details of the laws and so could, if they thought it necessary, have calculated the THS response. For all we know they did just that, but since it is clear to (almost) everyone that the system did work as designed they made no comment other than to record the facts.

Concours77

26th Feb 2017, 16:15

"Disparate" was my word, I did not intend to imply you believed they were.

"Maintain" back stick? My comment was that back stick seemed not to be maintained, but was "choppy". I assumed that since you didn't direct me to the report, that indeed the report did not do the integration you suggested, and that I would have thought that the report should have done that, to educate those of us who are not geniuses?

I won't paraphrase you again, and I am sorry it irritated you.

Are autostabilized commands of any import to a conclusion about why the THS acted so?

If the THS continues to trim Nose Up, after the Stall, is that a "Protection"? It would seem counterintuitive that in a Stalled condition, the aircraft acted, automatically, against what might be considered "recovery" of aerodynamic flight?

Machinbird

26th Feb 2017, 16:54

Bruce Tognazzini wrote this blog on panic some time ago. His specialty is software design however he is a pilot and diver as well.
Panic! How it Works and What To Do About It (http://www.asktog.com/columns/066Panic!.html)
Suggest you follow the link before reading the rest of this paragraph.

This particular paragraph explains what I believe happened to the crew of AF447 right at the beginning of the event:
The natural role of the anxiety leading to panic appears to be to guide us toward immediate evasive action, be it flight or fight. Panic ensues when we are unable to formulate an effective evasive action, we choose the wrong evasive action, the evasive action is ineffective, or the evasive action goes terribly wrong in ways we do not understand. From this, we see that development of the panic state is a two step process.

Activation of the Fight or Flight response
Inability to formulate/execute an effective evasive action.

This parallels the initial AF447 experience:

Autopilot drops out inside a turbulent cell while crossing the ITCZ=Activation of Fight or Flight
The aircraft roll response is strongly stimulated by the PF's initial correction and he cannot get it quickly under control as it continues to oscillate in roll= cause for panic.

Owain Glyndwr

26th Feb 2017, 17:40

As I said, the THS takes its commands from the elevator position. Look at Fig.63 of the report. When the THS was moving towards a NU trim the elevator was ALWAYS negative (nose up command). I assumed you had read the report.
However, I think you are using the report in an unintended manner. I believe accident reports are written to inform not to educate.
The autostabiliser commands are in this case relevant only to reinforce the point that one cannot judge the THS movement solely on the basis of stick position.
Of course the THS movement seems counterintuitive, but the THS control system knows nothing of the aircraft's stall state. I repeat, it only reacts to the elevator deflection it sees. In this case the elevator was driven almost entirely by the pilot's command, the contribution from pitch damping being very low as the pitch rates were very low. In normal law of course it would be a different story and the THS would be prevented from further NU movement by the down elevator applied as stall protection.
As Machinbird said in an earlier post, the puzzle is why NU movement was not inhibited in alternate law when stall protection became active.

Concours77

26th Feb 2017, 17:51

Thanks for being patient. My understanding is that the report is written and published "to the public".... I don't consider it overly technical, but my expectation is that any "study" undertaken in the investigation would not include "assumptions should be made when the study is incomplete?"

So I consider the THS "study" incomplete.

You state:

"As Machinbird said in an earlier post, the puzzle is why NU movement was not inhibited in alternate law when stall protection became active."

At the risk of tarnishing my non genius status further, aren't "protections lost" in alternate law? IOW, what does "when stall protection became active" have to do with this initial, and ultimately unrecoverable Stall?

And in discussing this wreck, how can the pilots be at fault?

I have to be missing the plot.

Thanks

jmo

(When AP, AT, FDs, and other automated systems are lost, why would one "Automatic System" be retained? THS......)

Concours77

26th Feb 2017, 18:09

Machinbird,

"From this, we see that development of the panic state is a two step process.
Activation of the Fight or Flight response
Inability to formulate/execute an effective evasive action."

I would disagree, in that it also takes two additional steps to activate the fight or flight response. Fight or flight does not initiate without two precursors that ennable the response. Fight or Flight is not a spontaneous condition, save for an individual who is predisposed to spontaneous panic? That is actually discussed in the DSM IV? Panic disorder.

"Stimuli"

1. Recognition. (stimulus)

2. Awareness (the conscious evaluation of the threat)

Which create the chemical flow that enables the conflict? (Fight or Flight)

The conflict then potentiates the panic, which flows from "unresolved anxiety/stress"

The state of panic can then prevent resolution, as the thought process degrades.

The PF had no opportunity to engage the only prevention of panic: "Assessment"? He had to move the controls, as we agreed to that earlier?

Owain Glyndwr

26th Feb 2017, 18:58

IOW, what does "when stall protection became active" have to do with this initial, and ultimately unrecoverable Stall

You are correct, in that protections are lost in alternate law, so my remark was perhaps misleading and I should rephrase my comment to be "inhibited when stall warning became active".
If it had been so inhibited the THS would have been frozen at 3 deg NU. That would not have prevented the accident because the pilot's continued pitch up command would have resulted in the application of full up elevator which is quite enough to drive the aircraft into stall.
It would of course have made recovery easier, and incidentally would have prevented the aircraft from developing a 50 deg angle of attack so the position error would not have gone haywire, the indicated speed would not have dropped below 60 kts and the stall warning would not have been inhibited.

Others (pilots) will have to tell you if and why the pilot was at fault. I don't feel myself competent to comment on piloting affairs.

The THS "system" is retained because it is an integral part part of the basic C* system. The other systems you mention are self contained and separate.

Machinbird

26th Feb 2017, 19:58

Fight or Flight is not a spontaneous condition,
Now I have personal experience that refutes that statement.
I went from normal alertness while flying formation to an adrenaline heart slam as I was looking to spot and avoid flaming wreckage (that fortunately did not materialize) when that other formation flew through our formation.

Is your source of information credible? Can you cite it? DSM-IV is not relevant since being crazy enough to fly jets is not a disorder.

Concours77

26th Feb 2017, 21:51

Hello. Owain Glyndwr

"It would of course have made recovery easier, and incidentally would have prevented the aircraft from developing a 50 deg angle of attack so the position error would not have gone haywire, the indicated speed would not have dropped below 60 kts and the stall warning would not have been inhibited."

The inhibited "StallStall" cricket created what might be argued as a "bar" to understanding that they were Stalled.

The Full Nose Up can not be defended, IMO, regardless the design consideration.

Did BEA do flight test to determine the extent to which the Taiilpane prevented or seriously inhibited recovery? If not BEA, then AI? The manufacturer has what is called a "duty of care". It is not to be glossed over... As With Concorde, we see a verdict that "apportions" responsibility, including jail?

I say again, the THS study is incomplete, and if the occasion to develop a rational foundation for safety sake was not addressed, more than incomplete, perhaps negligent.

Machinbird,

Quote:
"Originally Posted by Concours77
Fight or Flight is not a spontaneous condition,"

"Now I have personal experience that refutes that statement.
I went from normal alertness while flying formation to an adrenaline heart slam as I was looking to spot and avoid flaming wreckage (that fortunately did not materialize) when that other formation flew through our formation."

"Is your source of information credible? Can you cite it? DSM-IV is not relevant since being crazy enough to fly jets is not a disorder."

My source of information is credible. If you would like a cite, I can do that, otherwise I would ask you to trust that my statement is accurate.

I don't aim to be definitive here. I read, ponder and write quickly. What you read from me is a first draft, mistakes and all. I look to be corrected, that is a plus, an opportunity to learn from some one with more knowledge and experience...

I doubt what you call fight or flight happened spontaneously. The conflict itself is a product of sensation. Again, you cannot experience something you don't sense.

My proof would be my near miss over LA. I was piloting the Skylane, and my passenger grabbed my right arm. "Did you see that"? I said no. He said, "it was a twin, going "that way" he almost hit us!!"

I stayed calm, my immediate response was to check the instruments, reassure us both that we were straight and level, and that we experienced no contact.

My instinct was something to feel good about. I had no fear, no panic, no fight or flight....

I hadn't seen it. If I had, well, I like to think I would have told myself what I told myself in the moment. "We're OK, no contact, we're safe." The Skylane has no potty...but I checked later, any way...

Machinbird

26th Feb 2017, 22:07

Sorry Concours, your example is not comparable. You didn't even see the threat.
No wonder you didn't get a fight or flight response. I saw the image of two planes (in the midst of my formation!) going from right to left. I had to then tell myself, "Its over, turn off the response," so that I could keep flying smooth formation.

Please cite your reference.

Concours77

26th Feb 2017, 22:10

My reference is my memory of a study in Psychology at the University. I remember the year, but I may have trouble locating the textbook....for now, will you agree that Fight or flight is a conscious and internal conflict?
My guess is you were well and truly startled, but your solution interrupted the more toxic binary dilemma?

Chris Scott

26th Feb 2017, 22:12

In the midst of his discussion with Owain Glyndwr, Concours77 has quoted a paragraph I wrote in post #1359 (http://www.pprune.org/tech-log/539756-af-447-thread-no-12-a-68.html#post9688143):
"The function of any auto-trim system is to remove the necessity for the PF or AP to continue to command the deflection of a primary flight control. In this case the auto-trim is concerned with pitch control, and adjusts the incidence (angle) of the THS (trim-able horizontal stabiliser) to enable the elevators to return to neutral in a few seconds after they have been deflected to comply with a command from the pilot or AP for a pitch-change (actually, in the case of C*, a change in normal G)."

That was a half-decent explanation of auto-trim, mainly for the benefit of pilots who haven't used it. But perhaps it can be improved in relation to Airbus FBW aeroplanes like the A330. It may also be helpful to reflect that auto-trim is merely an automated version of the various trimming systems with which virtually all aeroplanes have been fitted since the early days of aviation.

So here goes:
The function of a flight-control trimming system is to remove the necessity of a PF or AP to apply a continuing command to deflect a primary flight control in one direction. Pitch trim has been achieved traditionally by a hinged trim-tab which forms part of the trailing edge of an elevator. The pilot can adjust the position of the tab, which then exerts an aerodynamic force on the elevator as a substitute for the force previously exerted by the pilot's elevator control, which will then maintain the desired position "hands-off." Most large jet transports use a different system, in which changes of the angle of incidence of the "trimmable" horizontal stabiliser (THS) allow the elevators to return to neutral. On aircraft with conventional flight-control systems the elevators are controlled by the PF or the AP. In manual flight the PF uses a trim wheel or piccolo switches to move the THS, but with the AP engaged an auto-trim system moves it. In Airbus FBW with the AP disengaged the EFCS interprets the PF's sidestick position according to C* logic, which at cruise speed effectively means normal acceleration, and any resulting displacement of the elevators is reduced in due course by the auto-trim slowly moving the THS in the appropriate direction.

Please don't hesitate to inform me of any errors or possible improvements.

Concours77

26th Feb 2017, 22:21

Machinbird,

From the Harvard Medical School, paper on "the physiological reactions to stress" date not known.

"This combination of reactions to stress is also known as the "fight-or-flight" response because it evolved as a survival mechanism, enabling people and other mammals to react quickly to life-threatening situations. (The carefully orchestrated yet near-instantaneous sequence of hormonal changes and physiological responses helps someone to fight the threat off or flee to safety.) Unfortunately, the body can also overreact to stressors that are not life-threatening, such as traffic jams, work pressure, and family difficulties."

So my point is that fight or flight is a response triggering what I include in parenthesis, above.

Stimulus. A-4? "Conflict in flight path, bad, dangerous, or Jesus!!" A response, dependent on the stimulus, and the physiology of the result, the "conflict" I don't mean to parse words, but to say Flee or Fight is spontaneous ignores the physiology the body describes.

Concours77

26th Feb 2017, 22:34

Thanks Chris, it gets clearer and clearer....

My criticism remains in place though, since the elevators return to "neutral" and the THS has actually "supplanted" the elevators as primary flight control?

My concept of trim, even high altitude heavy jets, is that trim is a replacement for deflection, and is extremely suitable for Cruise. To the extent that aft loading of fuel helps fuel economy, it also challenges the stability of the airframe?

I fall back on the first lesson of trim, "not for maneuvering". But for tuning the attitude to allow continuous flight without constant correction, or deflection?

So I see the tailplane at -14 degrees as not a good idea when the purpose is to maneuver, to recover. At a time when Nose Down is a critical need, that immense aft "wing" is at its most powerful, and opposite to the appropriate input?

Imagine, "briskly Push the controls Nose Down, hold a descent, and carefully ascend when the risk of secondary Stall, is mitigated?"

I maintain the flight crew were cheated of that opportunity.... Perhaps a recovery was impossible, but I would quote the above post, where it is said "would have made recovery easier...."?

Owain Glyndwr

26th Feb 2017, 22:38

I wasn't defending anything, merely trying to answer your question as to what effect THS inhibition might have had.
I should have known better than to offer facts to a lawyer - a mistake I won't make again

Concours77

26th Feb 2017, 22:46

I admit to a fear response when I see you have responded....

No, I take everything you say as Gospel. My comment is an opinion, and I did not sense that you were defending a position. Your position needs no defense.

Chris Scott

27th Feb 2017, 00:09

Quotes from Concours77:
(1) "... the elevators return to "neutral" and the THS has actually "supplanted" the elevators as primary flight control?"

No, the THS remains the secondary flight control, having merely backed-up the activity of the elevators, which remain always the primary. If at any time the PF gives consistent inputs in the reverse sense, the THS will in due course travel in the appropriate, opposite direction. The auto-trim has no bias in one direction or the other, and it is certainly not a ratchet-type device.

(2) "I fall back on the first lesson of trim, "not for maneuvering". But for tuning the attitude to allow continuous flight without constant correction, or deflection?"

The first lesson of trim is ALWAYS to use the primary control first, and then unload the primary control with trim. Never use trim as the primary control, except (once in many lifetimes) when the primary control fails.

(3) "To the extent that aft loading of fuel helps fuel economy, it also challenges the stability of the airframe?"

No. Life is a compromise in regard to safety and stability, or we would never get out of bed. And so is aircraft stability.

(4) "Imagine, "briskly Push the controls Nose Down, hold a descent, and carefully ascend when the risk of secondary Stall, is mitigated?"
I maintain the flight crew were cheated of that opportunity...."

First of all, as far as we know the two co-pilots never recognised that the aircraft was stalled, which is what Machinbird's hypothesis is investigating. AFAIK they never attempted a stall recovery.

Had they attempted a stall recovery, would they have been cheated of it? IIRC, Owain has previously calculated that, even with the THS at full nose-up (NU) trim, there is enough elevator authority to pitch the A330 down. And there is evidence that the A330, height permitting, is recoverable from extreme alphas as in AF447. But it's true that the rate of pitch-down would be lower with full NU than a lower angle.

Setting that aside, there comes a point in any control-departure when an aircraft cannot be recovered before impact. This crew took the aircraft to that point, and then well beyond it. They seem to have misdiagnosed an overspeed when it should have been evident that the (presumably unintended) rapid climb of no less than 2000 ft would have depleted the vast majority of the aircraft's kinetic energy.

Machinbird

27th Feb 2017, 02:30

carefully orchestrated yet near-instantaneous sequence of hormonal changes and physiological responses Concours
There is a triggering sequence for activation of fight or flight, but as your own reference indicates, it is near instantaneous, at least within the body's own internal measurement of time. Once triggered by visual, audio, or by physical impact, activation of the fight or flight response moves at nerve impulse velocity to prepare the body for action.

The BEA in their final recommendations noted the effect of "Startlement" as the cause of the accident. If you substitute triggering the fight or flight response for "startlement" you come pretty close to my own assessment of fight or flight response triggering and leading to panic when the roll became unstable.

The startle effect played a major role in the destabilisation of the flight path and
in the two pilots understanding the situation. Initial and recurrent training as
delivered today do not promote and test the capacity to react to the unexpected.
Indeed the exercises are repetitive, well known to crews and do not enable skills in
resource management to be tested outside of this context. All of the effort invested
in anticipation and predetermination of procedural responses does not exclude the
possibility of situations with a “fundamental surprise“ for which the current system
does not generate the indispensable capacity to react.
The rapid increase in crew workload in an unusual and unexpected situation led to the
degradation of the quality of communication and coordination between the pilots.

Machinbird

27th Feb 2017, 03:25

Chris,
That is a good summary of the trim function. It was surprising how stable AF447 was in the stall. I initially expected that such an aircraft would drop a wing and progress into a spin, but that did not happen. I have to attribute that to the automatic action of the yaw damper.

In Normal Law THS trim is limited by AOA protection activation.
From FCOM
When angle of attack protection is active, THS is limited between setting at entry in
protection and 2° nose down (i.e. further nose up trim cannot be applied).For some reason, in Alternate Law, there is no inhibition on nose up trim related to angle of attack. It would seem logical to inhibit THS trim at stall warning activation when in Alternate Law. From Owain's comments recovery from stall would have been greatly enhanced.
If it had been so inhibited the THS would have been frozen at 3 deg NU. That would not have prevented the accident because the pilot's continued pitch up command would have resulted in the application of full up elevator which is quite enough to drive the aircraft into stall.
It would of course have made recovery easier, and incidentally would have prevented the aircraft from developing a 50 deg angle of attack so the position error would not have gone haywire, the indicated speed would not have dropped below 60 kts and the stall warning would not have been inhibited.
The BEA did not address the lack of THS trim limits in Alternate law in the accident recommendations. I have to assume that there were good engineering reasons for not adopting limits on the THS trim system in Alternate law, but I have no clue what they might be.

vapilot2004

27th Feb 2017, 09:49

A question? I asked Owain Glyndwr at one point why the graph in the report of the THS movement looks "smooth"? Yet the graph of the stick trace looks anything but? The trace is full of bumps, up and down....

The traces released by the BEA from the 'readout' of the DFDR on AF447 were rather coarse in comparison to those released from other crash investigations.

Chris Scott

27th Feb 2017, 11:47

Quote from Concours77 [my emphasis]:
"I asked Owain Glyndwr at one point why the graph in the report of the THS movement looks "smooth"? Yet the graph of the stick trace looks anything but? The trace is full of bumps, up and down...."

Here is a video of an A320 co-pilot handling the sidestick on what is probably a fairly average day:

https://www.youtube.com/watch?v=vBuoA9qkKi4

(Several other similar videos are available on line.) The aircraft is presumably in Normal Law, but the pilot is consistently over-controlling the sidestick; behaviour that I often saw from the jump seat during many years of line-checking on the A320. I doubt that the pilot concerned was even aware he was doing it.

In AF447, the control laws were C* in pitch, but Direct in roll. That makes for a bad combination, because a lot of firm** movements may have to be made to keep the wings level, while only small movements are appropriate in pitch. With the Airbus sidestick it is more difficult to avoid roll commands affecting pitch commands (and vice-versa) than it is on the traditional column/control-wheel combination.

** [EDIT, in deference to comment by IcePack - below]:
(larger than those needed for pitch)

IcePack

27th Feb 2017, 12:45

PJ2

27th Feb 2017, 14:55

Icepack, I do agree with your observation that one should be gentle with the controls at high altitude. One should be gentle at all times with transport aircraft! It was this same, sage advice that D. P. Davies offered in Handling the Big Jets, (editions 1967 - 1971). I believe that most experienced pilots on these aircraft know this and respond appropriately.

"Criminal" may perhaps be a bit strong regarding simulator fidelities. Also, a lot has changed in simulation over the last decade including heightened fidelity for stall performance.

We have to remember that prior to AF447, there were 31 other UAS events on A330s and every one was a log-book entry.

Concours77

27th Feb 2017, 14:56

Re fear, flight.

"02:10:06 (Bonin) I have the controls.
02:10:07 (Robert) Okay."

Within one second of AP quit, Bonin has acted correctly, and was acknowledged by PNF Robert.

He then quickly input stick back, and roll left. The record as regards Roll shows an inheritance of roll right, and an "over control" left. In the ensuing seconds, he established roll stability, and the aircraft had started to climb....At this point, Bonin "owns" what is to follow.

This should rebut any discussion of paralyzing fear, the flee fight syndrome, or other theories indulged to establish abnormal reaction/behaviour?

As to startle, Bonin had contacted the CC and told them "you should be careful".
Startle implies he was unprepared for the loss of AP and the consequent alarms.
His actions on the record would confirm, at least at this stage, that entertaining a discussion about physiology and fear is not supported?

Next? When did the crew recognize and acknowledge the cause of the problem, and the aircraft's response to it?

Lonewolf_50

27th Feb 2017, 15:13

Are we back to explaining what an instrument scan is?

Chris Scott

27th Feb 2017, 15:43

Quote from Concours77:
"This should rebut any discussion of paralyzing fear, the flee fight syndrome, or other theories indulged to establish abnormal reaction/behaviour?"

It might at first seem to rule out the startle factor, but I can assure you that the sudden, unwanted sound of the "cavalry charge" (audio signal of AP disconnect) is not conducive to relaxation on a dark night. Add to that some turbulence, a partial loss of primary flight-instrumentation, and ECAM warnings, and none of these physiological/psychological factors can be ruled out.

The sidestick needed to be used with the utmost care, as others confirm above. Fear, or even tension, make that more difficult. The muscles of the forearm and hand may tighten, which could well have caused the PF to pull on the sidestick unintentionally (see my previous post), particularly if he was preoccupied with trying to keep the wings level in unfamiliar, roll-direct law.
Another possible difficulty controlling the sidestick would have arisen if the PF' s seat was too far back, or if his sidestick armrest was not deployed correctly.

The bottom line is that this crew lost situational awareness, or they would never have allowed the aircraft to climb 2000 feet without specific comment. That alone suggests mental processes associated with fear and/or overload. During that climb, they were not sitting there drinking coffee or reading a magazine.

PJ2

27th Feb 2017, 15:43

Lonewolf_50;

Re explaining scan, ;-)

We may be chatting with & explaining to a new generation who were just starting out eight years ago or otherwise too young to remember the details of AF447 and are newly-curious.

I think the twelve AF447 threads are a goldmine of thought and, like Davies, are all well worth spending the time reading through - they're an informal "book", rabbit-trails and all, on primary topics for aviators like the one you've touched upon.

Machinbird

27th Feb 2017, 16:32

Concours77
This is not intended as a put down, but you are lacking sufficient aviation experience to properly understand the elements of the AF447 accident. You have almost certainly not hand flown at night in the feathery tops of a complex cumulus based storm system looking at your radar screen for indications of bad areas, with St Elmo's fire flickering around your windscreen with occasional larger balls of discharge forming on parts of the aircraft ahead and alongside of you, while listening to the screech of static discharge in your headset. There are many experiences in the corners of the flight envelope you have not seen. Your mental picture of the events of AF447 is too glib.

In the ensuing seconds, he established roll stability,This statement ignores the fact that it took almost 30 seconds of frightening overcontrol to establish roll stability, and what enabled that stability was the reduction of roll gain resulting loss of airspeed..

Concours77

27th Feb 2017, 16:49

Chris Scott

27th Feb 2017, 17:09

"Icepack, I do agree with your observation that one should be gentle with the controls at high altitude. One should be gentle at all times with transport aircraft! It was this same, sage advice that D. P. Davies offered in Handling the Big Jets, (editions 1967 - 1971). I believe that most experienced pilots on these aircraft know this and respond appropriately. "

Does that still apply, when many younger pilots of FBW transports now have no experience of hand-flying any jet at high altitude, even with a fully-functional EFCS ?

Lonewolf_50

27th Feb 2017, 17:16

When did the crew recognize and acknowledge the cause of the problem, and the aircraft's response to it? Shortly before impact, it seems. If you have read the transcript in the BEA report, Captain DuBois recognized that something had gone horribly wrong with his "impossible" at 02 12 43,8 on the CVR. As they went through their problem solving efforts, clear identification of the problem seems to have eluded the crew.
Extracted from the CVR Trascript provided in Appendix 1 to the report (https://www.bea.aero/docspa/2009/f-cp090601.en/pdf/annexe.01.en.pdf)
2 h 10 min 03 2 h10 min 04,6 Cavalry charge (autopilot disconnection warning)
2 h 10 min 06,4 Bonin | I have the controls
2 h 10 min 11,0 SV | stall
2 h 10 min 22,1 Robert | alternate law protections- (law/low/lo)
2 h 11 min 01,2 Robert | Above all try to touch the lateral controls as little as possible eh
2 h 11 min 25,7 Robert | Do you understand what’s happening or not?
2 h 11 min 32,6 Bonin |(…) I don’t have control of the airplane any more now
2 h 11 min 34,7 Bonin | I don’t have control of the airplane at all
2 h 11 min 42,5 DuBois | Er what are you (doing)?
2 h 11 min 48,2 Robert | We lost all control of the aeroplane we don’t understand anything we’ve tried everything
2 h 12 min 23,0 Dubois | The wings to flat horizon the standby horizon
2 h 12 min 43,8 DuBois | (…) it’s impossible
2 h 13 min 39,7 Robert | Climb climb climb climb
2 h 13 min 41,2 Bonin | But I’ve been at maxi nose-up for a while
2 h 13 min 42,7 Dubois | no no no don’t climb
2 h 14 min 05,3 DuBois | Watch out you’re pitching up there
2 h 14 min 06,5 Robert | I’m pitching up
2 h 14 min 06,5 DuBois | You’re pitching up
2 h 14 min 07,3 Robert | I’m pitching up
2 h 14 min 07,3 Bonin | Well we need to we are at four thousand feet
2 h 14 min 23,7 Bonin | (!) we’re going to crash
2 h 14 min 24,2 Bonin | This can’t be true

Note: there is quite a bit more on the transcript, but I cut these bits out to illustrate from initiation to almost impact some of the what they were saying as they tried to resolve their problem.

KayPam

27th Feb 2017, 17:21

I wouldn't recommend firm control inputs at high altitude in direct law in roll either. Direct roll law rate of roll is something like 60deg a second. (Not published)
As I have said before it is criminal that the simulators do not simulate control responses at high altitude correctly. (Sims fly the same at 150 &350)

However it could be quite easy to compute an approximate value of this roll rate.
Only "confidential" input required is aileron deflection obtained with full lateral sidestick in direct law. However, it should be the maximum deflection of both ailerons as well as roll spoilers (someone might be able to confirm/infirm this).
The full deflections are easily obtained if you have the real aircraft in front of you (which pilots have).

Then it's just an equilibrium between Clp*pb/2v and Cldl*dl
As I was saying on the ATPL theory questions topic, the TAS will increase the roll rate, so 450KTAS must give a very high roll rate.

PJ2

27th Feb 2017, 18:42

Does that still apply, when many younger pilots of FBW transports now have no experience of hand-flying any jet at high altitude, even with a fully-functional EFCS ? No, by definition it wouldn't apply to new/inexperienced pilots. I was more thinking about, and referring to industry experience with FBW/automation/protections today vice when the Airbus/FBW was introduced around thirty years ago. I don't know whether or not high altitude, high Mach Number, swept-wing flight aerodynamics is taught seriously to airline pilots today. As you know there is plenty of information for budding pilots that provide great information for keen pilots. Today, I''m not sure what "keen" means - it used to mean digging through everything that was available to one, without anyone suggesting it or requiring it.

That said, I believe that "FBW" and "Protections" are often conflated, and that the two subjects remain a point of disproportionate misunderstanding among many including Airbus pilots both experienced and new. I believe that some discussions particularly regarding the Airbus, suffer because of this.

Winnerhofer

27th Feb 2017, 19:13

A Critique of Airbus (http://www.vision.net.au/~apaterson/aviation/airbus_critique.htm)

PJ2

27th Feb 2017, 21:20

The "Critique of Airbus" is nine years old. A more recent article (Flight International, Learmount), can be read at the link below by just signing in or creating a free account.

The technology is transparent to an atrophying of piloting/thinking/programming skills, which is largely a voluntary matter although individual airline automation policies may (and in my view, have), hinder(ed) the retaining of such skills. The success of the design and the incident/accident record are both now well beyond such arguments as represented by the "Critique...".

ANALYSIS (https://www.flightglobal.com/news/articles/analysis-how-a320-changed-the-world-for-commercial-433809/): How A320 changed the world for commercial pilots

20 February, 2017, Flight International, David Learmount
As the world’s first digital fly-by-wire (FBW) airliner, Airbus Industrie’s A320 was positioned to bring commercial flying and flight management into the 21st century when it was rolled out in 1987.

The question at the time was: how was 21st century flying going to differ from the way it had been? The question now is: did Airbus get it right?

For Airbus, the A320 was more than just a FBW airliner. It was the still-young company’s debutante in the narrowbody marketplace. But above all – in the company’s strategic perspective – it was its first product in a planned family of FBW airliner types that would, as a result of their control technology, have very similar flying and control-system characteristics.

Nearly 10 years after the A320’s entry into service, by which time the type’s market acceptance was obvious, former Airbus president Roger Béteille admitted the decision to use FBW flight control was one of the most difficult he had ever made. He explained: “Perhaps we were too bold, but we had no choice. Either we were going to be first with new technologies or we could not expect to be in the market.

Cont'd at the link above

gums

27th Feb 2017, 21:56

I have to throw in with 'bird, Chris, PJ, Wolf and others concerning flight dynamics and basic airmanship.

I do not understand the newguy questions - Confours or whatever the callsign is.

I question if the newbie has gone thru thousands of posts on this thread and seen the very lucid and accurate descriptions and discussions of aerodynamics, flight control laws, design philosophy, personal war stories.... and the beat goes on.

The 'bus control laws have been dissected over and again.

- When all the data was published it was obvious that the crew was not well-prepared and the most experienced aviator did not assert authority.

- The side stick position is not and was not visible to the "other guy".

- The jet has really great aero to get into a stall without obvious shaking, buffet, wing rock and so forth.

- The chimes and sounds and such did not direct the crew to a useful procedure or flight control input

- High altitude dynamics are lots different than down low. Not only is the TAS much higher, which makes even a slight control input result in fairly pronounced changes in pitch and roll, but the mach effects become apparent.

I hope this newbie will go back as far as possible and see all the outstanding discussion most of us here had, especially once all the recorders were made public.

I respectfully send....

_Phoenix

28th Feb 2017, 03:16

I'm just a lurker, but sometimes it's just hard sitting while "the party" gets hot again.
I'm trying to have a look, once again, from AF447 "pilot eye" and making abstraction of all knowledge about accident.
Imagine the scenario, well known, of that flight deck at the moment of the autopilot disconnection. The aircraft banked right rapidly and vario showed slight descent. "I have control!"; "D'accord!"(1)
Bonin moved the sidestick immediately, he applied the correction in lateral, but at "regular/normal" amplitude, as for an approach phase(2). Also, maybe he pulled unintentionally, as I and others presumed earlier here. We have to admit that in that short period of time, in seconds, all the important info, actions and communication were done. Both acknowledged the UAS. Robert read loud the ECAM messages: engine THR MOVE, Alternate law, meanwhile Bonin was absorbed in lateral control. Then Robert changed view from ECAM to vario, he noticed the huge climbing rate "ATTEND...", before he finished the sentence "Fais attention a ta vitesse!", the sidestick was pushed nose-down. The N1 was exceeding 100%.
Now, at 2h10m41s apparently Bonin was in control, he checked from his memory, UAS items: (THR) "yeah we’re in climb" then corrected the pitch to 5-7 deg, all seemed stabilized, but was only an apparent calm, before the disaster. Pilots had no physical cues whatsoever about the aircraft dramatic loss of speed and energy(3)
I read posts that zoom in BEA graphics, trying to show the novice hand flying, PIO, startle, panic etc.
I invite you to watch again the simulation, it happened much faster than this post reading up to here... watch the real deal, 40 seconds again and again, up to Stall at 2h10m52s (4).

https://www.youtube.com/watch?v=BR5kFOHVnUU

That fast they lost it.
(1) "No, I have control!"
(2)/(3) Training for flying at high altitude/Sidestick design, something to learn from little brother CSeries. The soft stops, pusher that "talks" to you about low energy, trim for speed, keep the pilot in the loop, see at 1:08

https://youtu.be/-Y2plnzdqPs?t=68

(4) next 20 seconds, stall + healthy positive vario?! I guess Bonin heard about "persistent false stall", BEA annexe 08. THR was mostly in excess of 100%, then TOGA, for 1 long minute before vario changed to descent. The noise and buffet of the fall, at 280 kmh(174mph). It was quite impressive, louder than a hurricane category 5 "I have the impression that we have some crazy speed"

"ERR, what are you doing?!" and stall warning miraculously went silent.

Machinbird

28th Feb 2017, 04:43

Would you classify that thirty seconds as "jet upset"? If so, I would agree, and acknowledge that as the beginning of the Loss of Control? Especially so if the focus on Roll recovery cost airspeed and Pitch awareness? Where was FO Robert? Aside... Was Roll ever effectively managed? Captain remarked on it....
Concours, the word jet upset normally invokes an aircraft in a bad attitude such as the CRJ that crashed in Northern Sweden. This was a bit different. It was an oscillation that the PF was fighting and devoting excess attention to.

Most pilots have not experienced situations where their aircraft is acting contrary to their control inputs except perhaps situations which results from stalls. Those that have experienced this contrariness will remember the experience as very jarring and alarming. Although the AF447 roll oscillation was not particularly extreme nor rapid, it was contrary to Bonin's piloting intent, and he fought it vigorously and he was alarmed. At the same time, his trust in his control system was damaged.

Was AF447 ever stabilized? Yes, briefly in the 10 seconds before the stall. Afterwards it was again destabilized. Was Bonin in good control of himself, probably not. Why didn't Robert intervene? Perhaps because Bonin was assigned as PF by the Captain. Perhaps his personality was indecisive. Perhaps Robert's understanding of just what had happened to his aircraft's energy was lagging because of his own fear that Bonin had generated.

One thing is fairly certain in the period just before the stall. Panic within the AF447 aircrew was just below the surface. They had lost track of where the aircraft was within its flight envelope. They did not understand what had just happened to their aircraft to cause their difficulties.

From the Tognazzini blog on panic comes this little jewel:

3. Panic Desensitization A third approach to reducing or eliminating panic is through desensitization. You don’t hear a lot about it, because we don’t do much panic desensitization. Instead, we do nice, safe simulations that we think work as a substitute. They don’t.Looking back at my own training to land jets aboard ships, I find that it was all extremely challenging and almost every flight during training took you out of your comfort zone. One effect of this training was to desensitize you to hazards. You knew that the hazards were there but you knew you could handle them.

Perhaps we should deliberately throw panic inducing exercises at aircrews in the simulator to create some of this desensitization?

Winnerhofer

28th Feb 2017, 13:26

ANALYSIS: How A320 changed the world for commercial pilots

20 FEBRUARY, 2017 SOURCE: FLIGHT INTERNATIONAL BY: DAVID LEARMOUNT LONDON
As the world’s first digital fly-by-wire (FBW) airliner, Airbus Industrie’s A320 was positioned to bring commercial flying and flight management into the 21st century when it was rolled out in 1987.

The question at the time was: how was 21st century flying going to differ from the way it had been? The question now is: did Airbus get it right?

For Airbus, the A320 was more than just a FBW airliner. It was the still-young company’s debutante in the narrowbody marketplace. But above all – in the company’s strategic perspective – it was its first product in a planned family of FBW airliner types that would, as a result of their control technology, have very similar flying and control-system characteristics.

Nearly 10 years after the A320’s entry into service, by which time the type’s market acceptance was obvious, former Airbus president Roger Béteille admitted the decision to use FBW flight control was one of the most difficult he had ever made. He explained: “Perhaps we were too bold, but we had no choice. Either we were going to be first with new technologies or we could not expect to be in the market."

Asset Image
Livery styles may have changed since 1987, but much of the original aircraft christened by UK royalty lives on
Airbus
From the pilot’s point of view, the fundamental change in the A320 was the addition of flight envelope protection (FEP), which all aviators hope – and most would like to believe – they will never need.

The most visible difference was the replacement of a control yoke with a sidestick. The stick has a relaxed central position such that, when released to it during manual flying, no roll or pitch input is demanded of the pilot.

Control inputs to the sidestick and to the power levers in manual flight are intuitive, even to pilots trained on a mechanically controlled aircraft, but initially it feels strange not to have to follow up a manually commanded pitch change with trim inputs. There are no trim switches, and the conventionally positioned pitch trim wheels on the centre console are not used in flight except as an emergency back-up pitch control system. Pitch change demanded manually via the sidestick is delivered by the elevators, and the act of centring the sidestick commands the stabilisers to trim to the selected flight profile.

In 1997, one of Flight International’s test pilots, Peter Henley, benefiting psychologically from the knowledge that the A320 series had been in successful service for nearly a decade, flight-tested the new A319. He had this to say about flying the aircraft manually: “The sidestick works in the conventional sense and produces a rate of aircraft response which feels right to a pilot accustomed to a conventional aircraft. A comforting feature of the system is that the apparent response to the control and the feel remain constant throughout the flight envelope.”

FEP as a concept was difficult, at first, for flightcrew to get their heads around. In the A320 (and all subsequent FBW Airbuses) it works like this: with its flight control computers selected to normal law, the pilot’s manual inputs, when the aircraft is flying within the flight envelope, are transmitted direct to the control surface actuators unaltered by the computers, so pilots get what they are asking for.

If, however, the pilot allows the aircraft to get close to the edges of the flight envelope, warnings are triggered. If it continues right to the edges, the aircraft will be prevented from stalling, overbanking, overspeeding or overstressing, no matter what the pilot input – or the lack of pilot input, if that happens to be the problem. The FEP also provides an automatic reaction to the effects of windshear.

Meanwhile Airbus’s long term plan – completely visible in the fleet today – is that all FBW Airbuses (that is all Airbus types except the A300 and A310 series) would have so much commonality in terms of human/machine interface and systems control philosophy that for a pilot trained on one of the types, cross-type qualification on the others would be achievable with minimal training time and cost, even across the widebody/narrowbody divide.

FBW as a technology was not a new idea in the early 1980s when the A320 was in gestation. The military had used it extensively, and Airbus’s Toulouse forebear Sud Aviation (later Aérospatiale) had installed analogue computer-driven FBW in Concorde, its supersonic joint venture with British Aircraft Corporation.

To put the Airbus FBW venture into the context of its era, only one other airliner manufacturer was actively considering FBW control. In the mid-1980s, Boeing had proposed a FBW-controlled narrowbody designated the 7J7. It was to be fitted with twin aft-fuselage-mounted unducted fan engines (“propfans”), and intended for service entry in 1992. However, problems with the propulsion technology ultimately defeated the manufacturers, and a propfan has still not been successfully developed.

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Popularity of the A320 has been the payoff of an existential choice: be first with new technology or, likely, be out of the market
AirTeamImages
Boeing introduced FBW seven years after the A320’s service entry in its hugely successful 777 widebody, but the company’s direct narrowbody competitor for the A320, the perennially successful 737 series, is still selling well despite having conventional mechanical controls. The 737’s flight deck is just as highly automated as the A320’s in terms of its autopilot/autothrust and flight management system capabilities, but it does not have active flight envelope protection, just warnings and a stickshaker.

The question 30 years after the A320 series’ service entry is: did Airbus get it right? The market says yes, and so do the accident statistics (or lack of them). But have the original flight laws/software that defined the A320’s flying characteristics at service entry in 1988 had to be changed in the light of experience? Soon after entry into service the manufacturer added a low-energy warning to the system, but otherwise the simple answer seems to be no.

Certainly no fundamental changes have been needed, but there have been a few adjustments to take account of higher gross weight or aerodynamically modified versions – like engine nacelle changes. Airbus also admits blandly: “A rotation law has been implemented for better take-off performances. The crosswind landing is made easier thanks to a new decrab law.”

The cockpit in the latest versions looks remarkably similar to the original, but its capabilities have been updated like those of other airliner types over the past 30 years. These updates take account of the drift away from navigating by radio beacons toward global navigation satellite systems. For example, they include precision area navigation, required navigation performance, vertical navigation, autopilot-flown traffic alert and collision-avoidance manoeuvres, runway overrun warning and prevention systems, and electronic flightbags. The company says there have been no changes to its A320neo cockpit.

So, despite all the initial apprehension about the A320’s FBW/FEP systems, they have proved themselves to be remarkably durable.

Cockpit automation

Airbus Industrie’s ambition to design a flight control system that would help pilots do their job better and more safely than purely mechanically connected controls drove it, in the early 1980s, to conduct a fresh examination of how pilots’ roles were changing in the modern commercial aviation environment. The company concluded that pilots would definitely remain essential, that the cockpit design would reflect their primacy as decision-makers, but that also they would need more back-up in the age of highly automated cockpits, busier skies and an expectation of zero accident risk.

The new cockpit automation philosophy first launched in the A320-series anticipated an imminent era when pilots would hardly ever trip the autopilot out, and aircraft could rely largely on flight management systems for navigation, because their computational capabilities, speed and accuracy far exceeded the mental capacity of pilots. These things are taken for granted now, but then they were unfamiliar.

Autopilots combined with autothrottle had long been a useful pilot tool, but they work equally well with FBW or the old mechanical control systems. The latest variant of the venerable 737-series is a good case in point, and it still competes commercially with the A320 series.

There are times, however, when the autopilot – only capable of operating when the aircraft is within its flight envelope – is designed to trip out if it approaches the limits of its operating capability for whatever reason. This is the point where the pilots are expected to take over, using their flexibility, ingenuity and training to take charge of a situation that might be surprising, complex and confusing.

At this point, a glance at 1970s/1980s military control technology can aid understanding of the philosophy behind the extension of FBW capability to encompass FEP. In the 1980s there was direct cross-fertilisation of ideas between the computer-controlled dynamic (CCD) system of the Dassault Mirage 2000 fighter and the Airbus team, some of whom had flown it or military types like it.

CCD, which would now be called FBW with FEP embedded in the software, enabled a combat pilot bent on obtaining maximum performance from the aircraft to be able to demand it at any speed by moving the joystick and throttle on to the stops with no fear of overstress or damage. This liberated the pilot to concentrate on mission tactics, and enabled the airframe to be designed with “relaxed stability” without fear of loss of control, making the aircraft much more manoeuvrable.

FEP keeps the aircraft operating within safe parameters even if the pilot mishandles or neglects to control it, and the full authority digital engine control system does the same for the powerplants.

Airbus’s ultimate reason for moving into digital FBW was that it was now a sufficiently mature technology for use in the commercial arena, and the safety benefits of FEP were so obvious that it simply did not make sense not to use it.

Testing the prototype

In 1984, when Airbus Industrie was flight-testing its FBW system – some three years before the first A320 was rolled out – the manufacturer’s then senior vice-president for engineering, Bernard Ziegler, invited Flight International’s air transport editor David Learmount to take the controls of the FBW testbed A300B2. The aircraft carried the FBW flight computers linked to a single sidestick control that was mounted at the left-hand seat. The right-hand seat pilot had a conventional yoke with mechanical control runs.

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Airbus named its A350 assembly line after A320 champion Roger Béteille, speaking
Airbus
In a short pre-flight briefing, Ziegler explained that, although the aircraft might feel as if it was acting in response to a direct connection between the sidestick and the elevators and ailerons, the relationship was more subtle. The spring-loaded sidestick, when relaxed to its central position, commanded – via the flight control computers – a 1g flight profile and a zero roll rate. When displaced in pitch the stick commanded a proportionate change in the vertical acceleration by operating the elevators, but the computers would limit the positive or negative acceleration to the maximum allowable g load if the stick was pushed or pulled on to its stops.

Ziegler explained that sideways stick displacement commanded a proportionate roll rate up to a maximum of 15°/s. And, he added, the system would not let the pilot stall the aircraft. He told his ingénue co-pilot he could try it when airborne.

In the testbed A300, the sidestick’s signals were sent to the computers which, in turn, sent signals that activated control surface servos according to the stick displacement and the flight laws embedded in the system software.

The purpose of this flight was to demonstrate the system’s FEP in action. Learmount took over the sidestick seat when the aircraft was at a safe altitude, Ziegler gave him control and invited him to try to stall the aircraft in clean configuration. The throttles were set to idle, and Learmount chose to let the aircraft slow down in level flight. When the indicated airspeed was approaching the stall at about 100kt (185km/h) the nose began to dip to maintain an angle of attack just above the stall. Learmount pulled the stick back to raise the nose and induce a stall, but the nose continued to dip and the airspeed continued – marginally – to reduce until it reached what Ziegler later explained was “alpha-floor”. This is the stalling angle of attack. At that point, with the stick still fully back on the stops, the engines wound up automatically to take-off/go-around power. As the airspeed increased and the angle of attack was just clear of the stall, the nose began to rise steadily and the aircraft powered upwards out of its brief descent.

The FEP limits the angle of bank more simply: a pilot roll input on the stick simply stops being effective at a maximum of 67° bank. Overspeed protection is provided by raising the nose to keep the speed within flight envelope limits, even if there is nose-down pilot input.

Pilot mental appreciation of how the FBW laws work in practice seems to be just a matter of familiarity. Manual flying in the A320 series feels perfectly intuitive, so it should not matter whether the pilot thinks of a pitch-up displacement of the sidestick as a demand for a proportionate elevator deflection, or as a demand for a proportionate increase in vertical g (which is how the FBW system delivers it), because the effect is identical: the nose-up attitude increases as demanded by the pilot. Likewise, it should not matter whether a pilot displacing the sidestick to the left is demanding a proportionate aileron deflection or a proportionate rate of roll, as the effect is identical.

Having experience not only of developing Airbus’s cockpit automation philosophy but of introducing conventionally trained line pilots to it in the early days, experimental test pilot Etienne Tarnowski remembers how it felt persuading them that the A320 was not taking control away from the pilots and giving it to a computer.

Tarnowski says it was useful to provide them with analogies they were familiar with. Pilots do not complain that yaw dampers or turn co-ordination systems take control away from them, he suggests, but rather see them as assistants. FEP in pitch loading does not take control away from pilots hit by a storm downburst on final approach, but liberates them to pull fully back on the stick knowing it will provide absolute maximum aircraft climb performance without fear of stalling.

Most questions from trainees, says Tarnowski, were not about manual flying or the flight controls, but about getting the most from the flight management guidance computer via the autopilot, autothrust and flight management system: managing the automated systems and choosing the best autopilot modes for any particular phase of flight. This happens to be the same in highly automated cockpits that do not work with FBW/FEP.

Tarnowski believes there would have been an early days benefit for new A320 crews if Airbus had merged its design and training teams earlier in the design process, but says: “I am not convinced that an earlier merging of the test and training communities would have changed the design of the A320.” It would probably have helped the instructors, however.

Lonewolf_50

28th Feb 2017, 13:46

Winnerhofer: the last paragraph is about the only comment worth noting, at this point. I find it interesting that Learmount wrote about himself in the third person. (Well, that's how your Cut and Pasted article presents it ...)

Winnerhofer

28th Feb 2017, 13:50

To be frank, I don't rate Learmount much.
He's long long passed his sell-by date.
I think this was ghost-written.
This is the full version no editing.

Concours77

28th Feb 2017, 15:01

Here,

"ERR, what are you doing?!" and stall warning miraculously went silent."

When the Commandant du Bord entered the cockpit, finally, only one of the three had any experience flying this airliner in Alternate Law 2b. Bonin.

In that sense, he was "senior" in "type". Robert had criticisms, but made no attempt to take control from Bonin.

I have a theory about this phase of the flight.

gums,

"- The jet has really great aero to get into a stall without obvious shaking, buffet, wing rock and so forth."

I think that is intended as a compliment.... I think it is actually an indictment.

As most experienced pilot in 2b, Bonin may have gained sufficient mastery to understand the jet was comfortable in Stall. The "sweet spot" as it were. Attempts to lower the nose caused the Stall Warn to activate and may have actually re introduced "buffet", a signal that lowering the nose was the "wrong" thing to do.

Whatever buffet there was was likely encountered when the aircraft "began a recovery", iow, there was buffet on either side of the Stall, entry, and escape.

Did Bonin purposely defeat the Stall Warn (by pulling back the stick) to demonstrate to the Captain they were not as bad off as might be surmised? Thinking they were on the "right side" of the Stall?

I think none of these three experienced aviators had ever actually flown in Roll Direct before this flight. Or experienced the "great aero" that may have led them to their demise...

As to the THS: There seems to be no discussion in the report of the logic that produces Automatic trim into and through the Stall, which also served to make recovery difficult, if not impossible.

Airbus has no duty to discuss this issue. Bringing it up is not necessary, and would only serve to put into question the design. In the record, on the CVR, Robert is quoted: "loss of Protections," or similar. That is sufficient to satisfy the duty Airbus has to inform pilots of a particular design feature. There is no liability to provide a Protection if it is known that none are available in this flight Law? Inhibiting AutoTrim would IMO qualify as a protection...

Lonewolf_50

28th Feb 2017, 16:00

When the Commandant du Bord entered the cockpit,
With respect, sir, their names are:
David Robert, Pierre-Cedric Bonin, Marc Dubois (the captain) As most experienced pilot in 2b, Bonin may have gained sufficient mastery to understand the jet was comfortable in Stall. The "sweet spot" as it were. Bonin, also a glider pilot, was experienced enough to know that He Does Not Want To Be Stalled and that Being Stalled Means That You Aren't Flying, You Are Falling. My provisional conclusion was that Bonin was never aware -- in the cognitive sense -- that the aircraft was stalled. (until perhaps some seconds before impact). I have seen nothing to make me revise that conclusion. We discussed at length, in previous threads, the issue of the trained maneuvers, which is stall prevention focused with the cue of a stall warning. Stall recovery was not a training maneuver for the A320 type. Please note that, when you are stalled, your stall prevention procedures most often are not going to solve your problem but your stall recovery procedure usually will. (I spent a few years teaching spins and stalls, half of a lifetime ago).
Attempts to lower the nose caused the Stall Warn to activate and may have actually re introduced "buffet", a signal that lowering the nose was the "wrong" thing to do. ... Whatever buffet there was was likely encountered when the aircraft "began a recovery", iow, there was buffet on either side of the Stall, entry, and escape. ... Did Bonin purposely defeat the Stall Warn (by pulling back the stick) to demonstrate to the Captain they were not as bad off as might be surmised? Thinking they were on the "right side" of the Stall? What brand are you smoking? I'd like a taste.
Based on the feedback/cueing Robert was providing to Bonin as the latter tried to get his hand flying up to scratch, Bonin's instrument scan was somewhere between slow and non existent, and it is difficult to ascertain whether or not he was trying to follow the flight director or to try and keep the AH level ... go back and read the reminders/feedback Robert is providing. Bonin is Behind The Aircraft from a few seconds after he announces that he's go the controls, and as I read the timeline, something like six seconds after he starts to manipulate the side stick the first stall warning voice message is logged in the CVR.
2 h 10 min 06,4 Bonin | I have the controls
2 h 10 min 11,0 SV | stall
Have you read the full report and all of the appendices?
Have you read the tech log forum discussions (here at PPRuNE) that began with the release of the first CVR, and the subsequent FDR, information that came out in one of BEA's interim reports. While there's a bit of noise, there is some superb exposition on how that system works, and where some of the "gotcha" bits are.
I think none of these three experienced aviators had ever actually flown in Roll Direct before this flight. That was discussed at length, and speculated over, during the series of threads on this crash. One more opinion is now offered. The discussions on training took up a lot of space in the PPRuNe threads.
As to the THS: There seems to be no discussion in the report of the logic that produces Automatic trim into and through the Stall, which also served to make recovery difficult, if not impossible. If you keep pulling the stick back, and the flight control surfaces keep trying to do what your control inputs call for, the THS isn't going to change its orientation since it keeps trying to trim to account for the latest commands to the elevators.

The extended discussion in the PPRuNe threads arrived at a number of very sharp folks concluding that you'd need to make a nose down command -- and hold it for a while -- so that the THS would move (albeit slowly) in the other direction away from a trimmed position that was "pro stall."
In the record, on the CVR, Robert is quoted: "loss of Protections," or similar. That is sufficient to satisfy the duty Airbus has to inform pilots of a particular design feature. There is no liability to provide a Protection if it is known that none are available in this flight Law? Inhibiting AutoTrim would IMO qualify as a protection... In what flight regime? Inhibiting auto trim might also create handling problems.

KayPam

28th Feb 2017, 16:44

"From the pilot’s point of view, the fundamental change in the A320 was the addition of flight envelope protection (FEP), which all aviators hope – and most would like to believe – they will never need."

Lol.
If you knew how often they come into play :p

"Pilot mental appreciation of how the FBW laws work in practice seems to be just a matter of familiarity. Manual flying in the A320 series feels perfectly intuitive, so it should not matter whether the pilot thinks of a pitch-up displacement of the sidestick as a demand for a proportionate elevator deflection, or as a demand for a proportionate increase in vertical g (which is how the FBW system delivers it), because the effect is identical: the nose-up attitude increases as demanded by the pilot. Likewise, it should not matter whether a pilot displacing the sidestick to the left is demanding a proportionate aileron deflection or a proportionate rate of roll, as the effect is identical."

Let's totally disagree on that.
If you fly, especially at a high altitude, without consideration for whether or not you're in normal law, you're in for a sur-prise !
My opinion is it should be made very obvious whether the A/C is in normal law or not, with HUGE red signals when it is not. The small amber and red crosses are, imho, not enough.

Simple example : windshear recovery.
ATPL theory tell us you should pull up to the stick shaker. Airbus FCOM replaces stick shaker with full back stick, thanks to alpha protection.
Now try to apply this normal procedure when in direct (or even just alternate) law and tell us if stalling during a windshear recovery help or if it didn't.

Chris Scott

28th Feb 2017, 17:24

Quote from _Phoenix
"Now, at 2h10m41s apparently Bonin was in control, he checked from his memory, UAS items: (THR) "yeah we’re in climb" then corrected the pitch to 5-7 deg, all seemed stabilized, but was only an apparent calm, before the disaster. Pilots had no physical cues whatsoever about the aircraft dramatic loss of speed and energy(3) "

Hi, I don't know your background, so I don't want to seem patronising. It may or may not be surprising for you to imply that lowering the nose to a pitch of between +5 and +7 degrees would be a sufficient correction. In fact, it would remain outside the acceptable envelope of pitch at that altitude.

To illustrate the point, the cruise TAS of an A330 is - let's say - 480 kt. That's 8 nm/minute, or 48640 ft/min. Starting from level flight (pitch around +2.5 deg), a pitch-up of just one degree gives a VS of about +800 ft/min. Pitching up to +6 at cruise altitudes would give an INITIAL VS of about +2800 ft/min. But even at Climb thrust the aeroplane would be simply trading kinetic energy for altitude. The climb rate would be completely unsustainable, so the IAS and Mach would decrease rapidly, and consequently the VS also.

The initial pitch-up remained uncorrected, and was the first bad move that led to this tragedy - as you know. Of course you are referring to a later phase, by which time nearly all the surplus kinetic energy had been squandered. This would have been evident to any jet pilot experienced at hand-flying climbs at high altitude. The clue would have been in the altimeter. IIRC, they had earlier discussed the possibility of climbing (gently) by 2000 ft, and had decided the aircraft was a bit too heavy. Yet - inexplicably - Bonin had mishandled a "zoom" climb of about that amount.

Finally if the aircraft was flying level, a pitch of +6 would give an AoA of +6, and the wing would probably be stalled, depending on the Mach. Some people contributing to this thread are simply unaware of the limitations of jet-transport handling near the top corner of the flight envelope.

Concours77

28th Feb 2017, 17:26

In the record, on the CVR, Robert is quoted: "loss of Protections," or similar. That is sufficient to satisfy the duty Airbus has to inform pilots of a particular design feature. There is no liability to provide a Protection if it is known that none are available in this flight Law? [B]Inhibiting AutoTrim would IMO qualify as a protection...[B]

Lone wolf:
"In what flight regime? Inhibiting auto trim might also create handling problems."

In the Stall...where the THS "created handling problems." Point being, the THS performed as you describe, and as advertised....

Winnerhofer

28th Feb 2017, 17:56

Mon Cher Concours77,
Here are the missing pieces of what really happened on the flight deck.
1) Remember that Bonin only had a Frozen Licence.
2) This is why Dubois asked him as he left the flight deck: "T'as le PL, toi?
This is a strange question.
When I hail a taxi, I do not ask the driver if has a licence.
He asked because he knew damn well that Bonin only had a Frozen Licence.
The BEA confirmed this.
The BEA also hashed the DFDR.
An argument ensued following Bonin's answer which is more than just "Oui".
This is where Robert had just entered.
3) All 3 crew failed their recency in 2007.
4) Bonin was a F/A who in 2008 was fast-tracked on to the RH-seat due to
pressures from the Unions.
F/As were exempted from psychometric testing.
In 2008, there were 30 F/As who were fast-tracked at AF.
5) Dubois himself a former F/A only knew too the story as he had become CM1
very late and reluctantly so.
6) The least incompetent was Robert but he was the odd-man-out in Rio as the
other 2 had their respective partners with them.
7) Dubois was standing the whole time because Bonin's wife was in the observer
seat.
8) The whole CRM was just lopsided from the beginning.
Dubois was listening to classical music and commenting an article about tax
havens.
9) Bonin had no idea what ozone and St Elmo's were nor where the Equator was.
https://www.youtube.com/watch?v=jM3CwBYX-ms

Winnerhofer

28th Feb 2017, 21:06

Commandant de Bord is abbreviated CDB.
It is not du but de.
I know French is difficile but that should be your next challenge.
It also gives a way better understanding of AF447.

_Phoenix

1st Mar 2017, 04:06

Hello Chris,

Yes, that pitch was too much in the coffin corner. But possible he targeted a pitch around UAS procedure: FL100 and up -> 5 deg/CLB (annexe.06)
However, the background of the subject is that "Pilots had no physical cues whatsoever about the aircraft dramatic loss of speed and energy" (apart the altitude reading, that came too late)
You know well that the pitch control movement of the sidestick is normal load factor or g command. The elevator movement is followed by the stabilizer to automatically trim the airplane to a neutral, 1g, stick-free stability. Naturally, if kinetic energy (speed) decreases then the Lift < mg, hence nose goes down (CG within limits). The natural longitudinal flight path was override by FBW trim setting change for constant flight path attitude, as initially commanded.
Airbus considers that no additional alerts about low speed/energy situations is needed at high altitude because large altitude loss due to stall cannot occur on Airbus Fly-By-Wire aircraft.
Well this accident proved that all the sky is not enough.

Concours77

1st Mar 2017, 17:49

For Phoenix,

- "The jet has really great aero to get into a stall without obvious shaking, buffet, wing rock and so forth." gums

"Airbus considers that no additional alerts about low speed/energy situations is needed at high altitude because large altitude loss due to stall cannot occur on Airbus Fly-By-Wire aircraft.
Well this accident proved that all the sky is not enough." Phoenix

Are these quotes related? The jet ended up with full authority (HS) Nose Up, and full thrust on both engines. (One assumes elevators were still available, though not of equal "authority..")

Are those two conditions conducive to maintenance of "horizontal" aspect? Failing one, or both, would the jet have dropped its nose and become easier to recover a controllable flight path?

Does that relate to an approved (regulatory) performance at Stall? I ask because you state "Airbus considers...no additional alerts (cues?)....(are) is needed at high altitude....etc.)?

Because what is suggested is even though the aircraft may be stalled, "no large altitude loss can occur on Airbus FBW"

I guess I'm putting you on the spot. This aspect of the accident, IMO, is not addressed.

I think that if most posters are satisfied that "the aircraft performed as commanded", then the investigation is not complete. So many legitimate conclusions are foreclosed with the lack of design consideration discussion, regulatory expectations, and a solid basis for "safety takeaway" is not possible?

Machinbird

1st Mar 2017, 19:42

I think that if most posters are satisfied that "the aircraft performed as commanded", then the investigation is not complete. So many legitimate conclusions are foreclosed with the lack of design consideration discussion, regulatory expectations, and a solid basis for "safety takeaway" is not possible? Concours,
Yes, the aircraft did perform as designed, however in retrospect there was room for improvement. Aside from the pitot system that was overly sensitive to ice crystal blockage, the stall warning shutting down while the aircraft was still stalled, and the THS continuing to run in the aircraft nose up direction after aircraft reached a stall warning AOA, (in Alt 2b), there were a number of human interface factors that should be addressed. The crew was slow in recognizing the change in flight laws, they stopped hearing the stall warning due to the stress of the moment, and, frankly, the method of presenting altitude on the PFD is not as friendly as an old fashioned steam gauge altimeter, thus leading to slow understanding of just how fast they were falling and what levels they were passing. Some means of better telling, under stress, what the other crew member is doing with the controls is probably appropriate since that was a factor in at least 2 accidents.

The "fix" for the accident seems to have been more in the aircrew training direction rather than in making improvements in the actual aircraft. Those presently flying the aircraft are in a better position to say how comfortable they are with the training adjustments that were made subsequent to the accident.

Lonewolf_50

2nd Mar 2017, 02:04

Lone wolf:
"In what flight regime? Inhibiting auto trim might also create handling problems." In the Stall...where the THS "created handling problems." Point being, the THS performed as you describe, and as advertised.... When you are carrying passengers, you aren't supposed to be stalling the aircraft, so that handling parameter is hardly what my "what flight regime" question was aimed at.

I repeat: what we learned during that overly extended discussion is that before that accident, stall prevention was the trained response, not stall recovery. "stall handling" doesn't enter into it.

Nothing further, out. :ugh:

_Phoenix

3rd Mar 2017, 02:39

I ask because you state "Airbus considers...no additional alerts (cues?)....(are) is needed at high altitude....etc.)?

Actually, it is an excerpt from an FAA report:
lessonslearned.faa.gov (http://lessonslearned.faa.gov/IndianAir605/ASHWG%20LAA%20Report_15%20March%20Final%20Version_Appendix%2 01.pdf)

I see Manchinbird answered graciously to your question. In general, I embrace same views, but a small exception though. Instead of startle effect, I see "rabbit between headlights effect"
I like Airbus. It is a marvel, aerodynamics, endurance and safety, all great. However, FBW laws need to be simplified and "improved". It can be done quietly through a substantial software revision. I think the best is Bombardier's approach, with only two control laws, normal and direct. FBW philosophy is a combination of the older guys, the series C = A+B. Side-stick as Airbus, but C*U flight laws as Boeing, also in addition, Bombardier brings original cutting edge innovations regarding the human-automation interaction and the situational awareness.

Winnerhofer

24th Mar 2017, 16:26

40 Questions Rejected By Investigating Magistrates:
http://www.association-af447.fr/wp-content/uploads/2017/03/Questions-aux-experts-DA.pdf
There will be no FURTHER counter-submissions as well re-assements prior to court date:
Crash du Rio-Paris : une enquête difficile - Le Parisien (http://www.leparisien.fr/faits-divers/crash-du-rio-paris-une-enquete-difficile-17-03-2017-6769446.php)

Winnerhofer

1st May 2017, 18:40

New documentary for 01 June 2017
https://www.scoopnest.com/fr/user/W9/856828133810556929
W9 reconstitue le crash du vol Rio-Paris (http://tvmag.lefigaro.fr/programme-tv/w9-reconstitue-le-crash-du-vol-rio-paris_24607fce-2b4b-11e7-8979-77d59280982b/)
Can be watched for free online just by signing on.
6play : Replay W9 et direct des émissions et séries (http://www.6play.fr/w9)

KayPam

1st May 2017, 19:48

Could you please keep us posted when it becomes available ?

Fursty Ferret

2nd May 2017, 10:04

I'm not defending the incompetence of the handling pilot in this incident. But if you're an armchair flight simulator jockey you need to understand a few points about Airbus FBW at high levels.

For a start, despite what Airbus tells you, you're in a different subset of Normal Law. At low speeds (<220 knots) side stick directly commands elevator in the first instance, and then a feedback loop integrates a load factor demand. Without this the lag at low speed would be unbearable.

At higher speeds side stick directly commands load factor, but due to the higher speeds response is far quicker, and the effect more pronounced. Handling the aircraft at high flight levels is actually quite challenging if you don't want to make the passengers sick.

Even small load factors and pitch changes can have a pronounced effect on flight path. Couple this with the startle effect and a hamfisted grip on the controls and you have an aircraft out of control very quickly.

If you've never flown the aircraft manually in (or to) the cruise (and you'd be astonished at the number of people who haven't, blaming RVSM), I urge you to try it.

KayPam

2nd May 2017, 11:21

At low speeds (<220 knots) side stick directly commands elevator in the first instance

-> that's probably because under 220 knots in cruise there is every chance that you're already in alpha protection law

vilas

2nd May 2017, 16:44

Even small load factors and pitch changes can have a pronounced effect on flight path. So, leave the stick alone till you figure out what changes in pitch you want. Startle or otherwise they effected huge change in pitch but never checked the result.

Concours77

3rd May 2017, 17:18

Hello Vilas,

"...So, leave the stick alone till you figure out what changes in pitch you want. Startle or otherwise they effected huge change in pitch."

Yes, cerrtainly. In reading the CVR, two things are very notable.

No Pilot commented on PITCH, ever. The one and only comment on Pitch was by Captasin DuBois, two seconds before Impact... The PM only spoke "...You go UP, so go DOWN..." PITCH unaddressed. Bonin only: "...but I have been pulling back..."

(DuBois) "...PITCH, TEN DEGREES..." the last words spoken, but should have been first....?

The second even more remarkable absence is this: None of the pilots mentioned the word STALL. Ever. There were two mentions of STALL, by the aircraft itself, seconds after the loss of Autopilot.

As the Captain returned to the cockpit, the aircraft had stalled, and the Pitch was around fifteen degrees NU. That makes it a steep climb up the aisle, no? Yet he says nothing about orientation or attitude?

Fursty Ferret

3rd May 2017, 17:42

So, leave the stick alone till you figure out what changes in pitch you want. Startle or otherwise they effected huge change in pitch but never checked the result.

Completely agree!

However, as the pitot probes iced up the indicated altitude dropped by about 200 feet. The report suggests this is what led to the initial nose up command and someone who is unfamiliar with high altitude flight has potential to overcontrol in this situation (also: armrest in correct position? Seat all the way forward? All these things influence sidestick input - for me, half a turn on the angle adjust can be the difference between smooth flying and not).

Linktrained

7th May 2017, 23:33

Near the TOC the Thrust was reduced for few seconds. The Pitch lowered a just few degrees (as it must). Then TOGA was restored for the remainder of the flight.

All without any comment on the CVR. (Apparently)

Concours77

9th May 2017, 00:40

Hi Linktrained,

The thrust issues are bizarre, indeed.

At one time, Bonin: "...But we have the engines, what is happening...?"

Also in re TOGA: Again, I think Bonin (PF) "...We are in TOGA, Eh...?"

Right along with no comments on STALL, what in the world can a pilot be thinking if he fears Overspeed, but stays in either Max Climb, or TOGA?

So I still think important bits are missing from the record....

jmo

_Phoenix

9th May 2017, 03:04

Then TOGA was restored...
All without any comment on the CVR. (Apparently)

Right along with no comments on STALL
IMO they acknowledged the stall condition. As per CVR transcript, after 3-4 stall warnings and noise of vibration in cockpit the throttle levers were advanced to TOGA. That's enough, no comments necessary.
However the best reconstitution out there is "Pieces a conviction AF447". It looks like the actors listened to real CVR: "apparently" in this reconstitution the word "Stall" was mentioned. Listen carefully at 4:01 at the moment the throttle levers are advanced in the video:
https://youtu.be/e_VuBMoZoo4?t=241
In CVR transcript we have the translation: (!) at 2 h 10 min 54,9

Winnerhofer

13th May 2017, 18:05

FINALLY DCVR REVEALED IN FULL!!!!
NRJ12 prépare un comedy game inédit pour cet été (http://www.europe1.fr/emissions/le-journal-des-medias/nrj12-prepare-un-comedy-game-inedit-pour-cet-ete-3326789)
From 2:58"- 4:05"
New upcoming documentary for 01 June reveals all!

KayPam

29th May 2017, 20:09

I don't think there is anything new in this newest documentary...
They said they based their re enacment on a transcription of the CVR.
Not anything that we didn't have.

Linktrained

30th May 2017, 00:04

SURELY If someone accidentally KNOCKS THE THRUST Levers ... Someone ought to say

" SORRY ! ..SHALL I PUT THEM BACK AGAIN ?"

( They were over the Atlantic... The Captain may have noticed something... He DID reappear on the Flight deck shortly after TOGA had been restored.)

Winnerhofer

31st May 2017, 08:27

Just sign-up and watch doc:
Vof Af 447 : que s'est-il vraiment passé ? : Documentaire - 6play (http://www.6play.fr/vof-af-447-que-s-est-il-vraiment-passe--p_6870/Documentaire-c_11689280)

Winnerhofer

31st May 2017, 09:55

Just finished watching it.
Nothing new.
Nothing special.

Concours77

31st May 2017, 17:24

Not unexpected sir....

Any material deviation from the established dogma would be A) Denounced in high dudgeon by the adherents, or B) Launched with excruciating fanfare by the families' attorneys.

Nothing to see here, move along?

MaverickSu35S

4th Jun 2017, 07:14

...
But hey, if everybody is happy when the dead pilots are blamed, then lets not learn anything from this and move on to the next event that will look more or less like this one.:ugh:

This is probably the way you see it! Then who is to blame if both pilots did everything wrong with their controls? That is the pure truth and we must face it, not try to deviate it! The only 2 reasons why Airbus could be blamed for being a contributor to this is because:

1. The stall alpha protection was not doing it's job or have not been implemented at all on A-330s. The stall alpha protection should control the horizontal stab, more than just the elevators, by not allowing "X" AoA to be passed, yet by looking at the DFDR the horizontal stab was moving freely towards increasing the pilot commanded elevator input until it reached -13 local angle, having the alpha reached more than 50 at some point during the fall.

2. The idiotic philosophy of having a left mounted side stick for captain and right mounted side stick for co-pilot, having both invisible from one pilot to the other was and still is "a remarkable achievement" for this disaster! Even with that option (which is kind of intriguing) to set "priority left", "priority right" or "dual input", the only pilot (on the left seat) who was sometimes pushing forward still couldn't command the horizontal stab towards a more positive value. Even on 787s, Boeing knows why they want both pilots to think and do things in the same way, not allowing conflicting data or inputs.

But anyway..., even with these kind of challenging Airbus planes problems, the pilot should've listened carefully to the strong "STALL" alarms (both aural and sound) and know what a stall actually is. I'm very convinced they both misinterpreted the definition of stall and thought that it's related to airspeed only, as many dummies behind the stick do. They were only juggling the throttles all the time, but not ONCE ever thought of listening to that stall alarm more thoroughly and get the idea of pushing full forward for a little while and see what happens, not once they have thought about it (except for the captain) until too late.

Here's the DFDR video:

https://www.youtube.com/watch?v=BR5kFOHVnUU&t=73s

* Stall = flow separation *

Flow separation has nothing ever to do with the relative speed between a fluid and a contacted solid material or with the indicated IAS or TAS. The only thing it can be triggered from is by having a relative angle between the flow and the surface exceeding "X" value above which the fluid cannot follow the surface, even if this angle may vary with speed.

It's always been and will always be the alpha that you command to get into or out of stall. For some reason though, depending on how the pilots learned or interpreted this, the term of stall is more generally or almost always seen as a lack of airspeed, which is totally totally wrong. Even if the plane can no longer sustain 1G below a given combination of airspeed and alpha, the plane is perfectly controllable even with reduced response rates, but no matter the airspeed (can be Mach 1), the plane's wings will always get flow separation (aka stall) above "X" angle of attack and the controls (especially lateral control) get almost non-responsive, which ANY PILOT must learn about in flight school before encountering it alone for the first time.

In the end, it proved that the pilots were more incapable of staying away from trouble or recovering from it than the plane itself. Nobody said "let's not learn anything from this", but the crude truth regarding the pilots should not be altered.

vilas

4th Jun 2017, 07:35

The stall alpha protection was not doing it's job or have not been implemented at all on A-330s.
The aircraft was in Alternate 2. There is simply no protection as per design in Alternate 2. Anyway even Alt1 cannot prevent stall if pilot holds full back stick.

alf5071h

4th Jun 2017, 13:09

A critical weakness following an event is that we continue to seek blame - the human, opposed to considering what could (should) be learnt. Additionally, the focus remains on the crew at the time of the event opposed to considering influencing factors such as training and regulation; and then there is automation, which of course is specified by the human.

Consider why the regulator required more training for unreliable airspeed (UAS), a procedure already trained for, opposed to avoiding the real threat - ice crystals. Compare this with safety activity for engine roll-back in a similar timescale. Warn crews to avoid cb's by a greater margin, use the wxr, do what is done every day, but do it better.

How was the training conducted, did the outcome match the intent. Where UAS procedures involve immediate actions, were these overemphasised opposed to the follow up actions more applicable to the cruise conditions of this and previous events.
Was the training simulation realistic, with multiple effects, systems and control degradation, or was only airspeed considered. Also, was the malfunction pre-announced, thus little benefit for training surprise and startle reported in other events.

If immediate actions require manoeuvring are Captains expected to take control, thus other crew members have no opportunity to experience degraded control systems. (if indeed that was simulated).
Did the requirement for additional training actually contribute to this event ?

And simple lessons learn't. Shared decision making for avoiding weather - is it better to ask what avoidance should be taken, forcing other crew members to actively consider the options; opposed to "is 15 left OK?" which is easily agreed with, but without any learning value for cruise pilots or future Captains.

Many automation lessons have been learnt. The pitots were being changed before the event, this negates many subsequent system issues. Revised assumptions about human ability to manage flight without ASI resulted in BUSS, not a requirement, but chosen after the fact.

So maybe we are learning that the human is not as good as assumed, but the human is still very capable. We should not expect a human to solve an automation malfunction, particularly where the function was automated because the potential situation was one which human might not be able to resolve (catch 22) - dual pitot error and ADC comparison in a triple mix system.

Have we still to learn that we should not build complex systems which rely on human intervention in case of failure, and then blame the human for failing to resolve the issue.
Blame or error in this sense is the gap between the expectancy of human performance before the event and that after the event, the difference and root problem, is in our initial assumption, which of course may be unforeseeable at that time.

misd-agin

4th Jun 2017, 13:46

This is basic high altitude flying -

We cruise at 2.5. -3 degrees NU since jets airliners have been flying.

Approaching TOC our pitch attitude is perhaps 1 - 1.5 degrees NU higher(800-1200 FPM climb). So 3 - 4.5 degrees NU would be expected.

Putting an airplane in a position contrary to basic flying rules, and then blaming the airplane, isn't the right path either. Ten, 15, or 20 degrees NU at altitude is crazy. And the total time of total air data failure was under 25 seconds, and both were fully recovered in approx 45 seconds(?).

This is basic attitude flying. Flying isn't a game. Chasing a FD for 2,000 hrs isn't flying, it's playing a video game. Lord help us is the video game doesn't work correctly.

KayPam

4th Jun 2017, 13:55

2. The idiotic philosophy of having a left mounted side stick for captain and right mounted side stick for co-pilot, having both invisible from one pilot to the other was and still is "a remarkable achievement" for this disaster! Even with that option (which is kind of intriguing) to set "priority left", "priority right" or "dual input", the only pilot (on the left seat) who was sometimes pushing forward still couldn't command the horizontal stab towards a more positive value. Even on 787s, Boeing knows why they want both pilots to think and do things in the same way, not allowing conflicting data or inputs.

You all really really (really) need to stop with that nonsense.
Have you ever stepped foot in an airbus cockpit ?

If you had seated at a pilot's seat, you would have immediately seen that.. you CAN see the other pilot's sidestick from your seat !

alf5071h

4th Jun 2017, 15:42

re 'contrary to basic flying rules, perhaps this overlooks the influence of surprise and reversion to 'most recently' refreshed training.
If First Officers experiences' were limited to observing the Captain handling UAS procedure, and that was the most recent but irrelevantly trained immediate action, then we should not be surprised when startled pilots attempt to copy that procedure. Otherwise we need to revisit our assumptions about human performance.

Compare this with Colgan. Recently training for irrelevant tail stall, 'stall' warning given, surprise, procedures for tail stall executed simultaneously by both crew.
Lessons learnt; identify and revisit assumptions, consider what is taught and the context of instruction.

Concours77

4th Jun 2017, 17:02

You all really really (really) need to stop with that nonsense.
Have you ever stepped foot in an airbus cockpit ?

If you had seated at a pilot's seat, you would have immediately seen that.. you CAN see the other pilot's sidestick from your seat !

Seeing is one thing, understanding what is input is another. No Airbus pilot stares at another's sidestick to ascertain input. PM, initially, commented about VS, or altitude, not "stop pulling, we climb...!" Besides, the sidestick is not articulated as a wheel, but nudged, released, and 'stirred'......

Each stick moves independently, they are not connected, and trying to suss manual movements of the opposite stick is not appropriate?

A climb can be sustained, and is, by the aircraft with the stick mostly in neutral, hence "nudge"? The stick commands an attitude. Once selected, the "climb" is self sustaining, and must be countered with forward stick. The climb reached a rate of 7000fpm at one point, 1.75 G?

Is this about right, KayPam?

As to Colgan, the "surprise", the STALL warning, occurred because the Stall bug speed was set to anti ice ON, and had not been selected correctly; Captain had a great deal of excess room to maneuver, the Stall warn was bogus. It sounded at fully twenty knots high. Sad.

misd-agin

4th Jun 2017, 17:10

FO's stick was full back for most of the event.

A confusion factor might have create into the event when the stall warning stopped due to excessive AOA. Forward stick was applied which reduced the AOA into the normal (expected) envelope which re triggered the stall warning.

Perhaps aerobatic experience with zero G, and an unloaded wing and very low, or no airspeed, might have helped in analyzing the situation and made someone realize zero G was their friend.

Concours77

4th Jun 2017, 17:51

Linktrained

4th Jun 2017, 23:06

We need to ponder why, given seventy two "STALL STALL" alerts, none of the pilots thought to address AoA? No one has come close to explaining this fact... Also, why would any trained pilot not associate STALL with the dire need for airspeed, which can only be acquired by Nose Down? If they reacted to the re acquisition of lower AoA (and the Stall Warn) by pulling back, simply to silence the Alarm, why did they ignore it the rest of the four minutes? Associating Nose Down with STALL is counter indicated.

I am NOT AB Rated, so,

A look at # 1119 shows what CAN happen with an experienced Captain - on a Sim. before it was frozen.

A THS reading at this point might have been interesting , too. ( Who ever looks, normally ?)

Perhaps a repeated STALL warning becomes just another noise, even before the 72 repeats. A changing voice with vocal pitch rising, might draw attention, as well !

CONF iture

5th Jun 2017, 14:45

You all really really (really) need to stop with that nonsense.
1- Far to be a nonsense - Try with table trays out as it is most of the time in cruise, or simply at night time.
2- If Airbus wanted the PM to see how the PF is manipulating the flight control command, they would have built things differently ...

Concours77

5th Jun 2017, 16:55

In a very real way, the two manufacturers have approached abnormals and manual flight with very different approaches. The sidesticks play no part in passive CRM cues. The wheels do, and score one for B. AB fits no shaker or pusher, having been granted a waiver at certification, (because it won't Stall in Normal Law). Boeing does have these emergency devices.

With an automatic degrade (AB) into an unfamiliar mode, the pilots are at a disadvantage, as the AB flies diferently, and must be controlled with a different protocol.

Stall entry can be completely benign (AB) as the stability "accomodates" departure, instead of emphasizing it, in the interest of notifying the crew that the AC has departed....

What remains in reality is that emergency procedures are almost never needed, so much of the apparent disadvantages are moot.

Except when they're not?

Lonewolf_50

5th Jun 2017, 17:24

We need to ponder why, given seventy two "STALL STALL" alerts, none of the pilots thought to address AoA? As the A330 on that particular evening did not have a display for AoA as it does for airspeed, vertical speed, attitude, etcetera, the more cogent question (raised during 10 of the 12 447 threads here on PPRuNe) appears to be why the more basic "pitch and power" were not the foremost concerns, in terms of being directly addressed. That question is not answerable other than by inference and guesswork, since neither of the two gents in the flying seats is alive to share with us their thoughts.
(I recall from one of the thousands of posts, memory sketchy, that on one of the pages a non-flying pilot can sort through(page 6 or 7) one will eventually get a value for AoA. I think you can appreciate why neither of the pilots went paging through that system -- their attention was on trying to fly the aircraft).

Concours77

5th Jun 2017, 17:27

As I recall, the AoA can be approximated using the FD, the "bird", (FPV), and a quick mental numerical subtraction? Not easy, and probably not trained?

Since this exercise utilizes computed data involving the AoA, one wonders why, if the FCM knows the AoA, how difficult or expensive would it be to display it to the only two who can save the flight?

Lonewolf_50

5th Jun 2017, 17:30

KayPam

5th Jun 2017, 18:37

Concours77

5th Jun 2017, 20:01

If it is your belief that they were trained to do that, or that the FD was fully operational even with unreliable airspeed, fine, but I think you've wandered into some Monday Morning Quarterbacking at this point.

If it is, or was trained it would be what is called an "admission against interest..." For AB or the line to explain how to reach an AoA value without supplied kit, it is an admission that the value is important for flight, and the Gauge is not optioned, possibly creating unsafe flight....

Likely if the practice is known, it is an informal "workaround", shared informally amongst A330 crew who are rostered on one of the cheaper models.

A football player or coach who does not review film and stats after the game, on ANY day, is not a winning player or coach. imo.

galaxy flyer

5th Jun 2017, 21:55

This, on the other hand, is a real problem.
The other real problem is that stall warning stopped when CAS went under 60kt. This design, I don't know if it has been corrected since, is completely against regulations.

I'm not sure 'bout that--the Bombardier business aircraft cancel the stall warning at 60 knots and are FAR 25.

KayPam

5th Jun 2017, 22:18

There is a line in the certification specifications that is very specific indeed :
The stall warning should not stop until the airplane is clear of the stalling situation.

Concours77

5th Jun 2017, 23:43

In defense, an aircraft which is exempted by demonstration does not have to adhere to that which is exempted, nor to related prose in the regulation.

IOW, AirBus aircraft demonstrated an aversion to aerodynamic Stall sufficient to satisfy the Regulator. This also takes into account the airframe's static stability, longitudinally, to and through Stall.

Given that, it is a short step to assume the requirement to maintain the Stall aural warning below 60 knots is less stringent than the rather important exemption from shaker/pusher.

I have found "Low Energy Awareness Program", and it is related, but cannot load it, perhaps it is proprietary.

There may be, at the root of this apparent warning "failure", a very good reason the Stall Warn is inhibited below 60 knots IAS. EFCS, once Stalled, may have an exemption related to "recovery" that requires the Warning be inhibited. Whether or not it is related to Low Energy warnings, I have no idea?

Bidule

6th Jun 2017, 06:08

There is a line in the certification specifications that is very specific indeed :
The stall warning should not stop until the airplane is clear of the stalling situation.

I do not think this is a correct statement, at least in FAR 25. Effectively, as per FAR25.207(c): "Once initiated, stall warning must continue until the angle of attack is reduced to approximately that at which stall warning began."

mono

6th Jun 2017, 13:10

It may be different now. But only a few years ago every aircraft I had worked on cancelled the stall warning below around 60kts. That's Boeing, Airbus, Cessna, all of them.

The understandable assumption was that you should know that you're stalled below 60kts. Further to this, at below 60kts, the airflow over the vane is not reliable enough to provide accurate AoA information and also I was told, to stop erroneous stall warnings on, for example, undulating runways during TO.

I know Airbus has introduced a MOD to keep the stall warning below 60kts.

KayPam

7th Jun 2017, 15:55

I do not think this is a correct statement, at least in FAR 25. Effectively, as per FAR25.207(c): "Once initiated, stall warning must continue until the angle of attack is reduced to approximately that at which stall warning began."

The wording is a bit different but the idea is the same.
Thanks for digging that out.

In the case of AF447, the stall warning stopped even though the angle of attack had increased way further than stall warning aoa.
This is in contradiction with the abovementionned statement.

Even if Airbus was authorized to design it like that, this can be criticized.

Mono : thanks for this info.
However, a better idea than a below 60kt condition for deactivation would have been a weight on wheel condition.
If you're in flight below 60kt with your airbus, you're almost 100% sure that you're stalling (or in 0G flight but that seems unlikely) so I think it would deserve to ring..
Aoa is not reliable under 60kt ? if you stall so deeply that your CAS goes under 60kt, that's a very good reason to make the stall warning ring. Not stop it.
(if no weight on wheels)

Concours77

7th Jun 2017, 17:46

Would have been interesting to be present at the last programmer's meeting prior to certification trials.

"Yeah, at less than 60 knots, the aircraft is taxiing, right?" AoA vane inop, so Stall Warn is inhibited.

Logical, but as with all things, the exception breaks the "rule".

So as with "Low energy awareness program", the committee thinks similarly....

Low Altitude only. Sometimes the 'committee' is an ass. Otherwise bright people defer to "consensus".......

tdracer

7th Jun 2017, 18:25

It is standard design practice to inhibit indications when that indication is considered to be unreliable - and the AOA below 60 knots is not considered to be a reliable indication. That a "professional pilot" might manage to stall the aircraft so badly that airspeed dropped below 60 knots while stalled was probably not considered to be a credible scenario.
Until it happened...
Now that the designers know that there are "professional pilots" out there that will stall an aircraft that severely, the designers can take that into account with creative logic - e.g. when stall warning "true" and airspeed greater than 60 knots, if airspeed drops below 60 knots while stall warning remains true, keep the alert active.

However my personal opinion is that Bonin simply shut out the stall warning indication - literally didn't hear it - because it didn't fit what he thought was happening. If correct, something like a stick shaker would have been more effective...

tdracer

7th Jun 2017, 21:16

It didn't happen. The actual 'airspeed' never 'dropped below 60 knots' only the ADR sensed airspeed.....Fair enough, I should have specified indicated airspeed...

.....Would you give them credit then for being at least 'semi-professional'? No, not Bonin. What he did demonstrated a complete lack of understanding of basic aerodynamics.

Note that I spent ~40 years on the design side of things - and prior to AF 447, if someone had told me I had to design my system to account for an aircraft that was in air and was stalled so badly that indicated airspeed dropped below 60 knots (and with the PF taking no corrective action to get out of the stall), I probably would have laughed out loud...

Goldenrivett

7th Jun 2017, 21:51

if someone had told me I had to design my system to account for an aircraft that was in air and was stalled so badly that indicated airspeed dropped below 60 knots (and with the PF taking no corrective action to get out of the stall), I probably would have laughed out loud...

Looking at your location, it appears you didn’t design an aircraft system without feed back between the pilot's controls, and with a stabiliser auto trim system which continues to trim whilst stalled.

Concours77

8th Jun 2017, 00:45

Owain Glyndwr

8th Jun 2017, 05:14

@tdracer
You have a slight advantage over me in that I only spent 37 years on the design side, but I would have been laughing along with you. With the caveat that it was allowing the aoa to develop to over 50 degrees that caused the indicated airspeed to drop below 60kts I agree with everything you wrote

john_tullamarine

8th Jun 2017, 07:39

CONF iture

8th Jun 2017, 13:25

With the caveat that it was allowing the aoa to develop to over 50 degrees that caused the indicated airspeed to drop below 60kts
Only active participation of the Autotrim was allowing the aoa to develop to over 50 degrees ... Not much to laugh on that one.

Concours77

8th Jun 2017, 15:11

Neither of the other two could have done any better, using available data from CVR.

.. many of us would have thought that it just needed someone to look at the AH for a moment (obviously, there was no semblance of an instrument scan in the cockpit at the time ..) and wonder why the body angle was up where it was ... not rocket science for those who have a good grounding in stick and rudder I/F, I would think.

It is my surmise that it was the Horizon to which PM was pointing: "Here, and here, you go up....so go DOWN"

Also, Captain DuBois: "Take this.......Watch your lateral!!"

From the CVR... Wondering about what was working and what was erroneous was their plight, they hadn't the benefit of Recorders, and seven years on.....

Just what the situation calls for, Autotrim into a non recoverable Stall. As if....all was normal? Autotrim, in its insidious way, foreclosed recovery; every second of Nose Up bias it supplied cemented their doom. Trim is for cruise, not for maneuvering out of unusual attitudes....

tdracer

8th Jun 2017, 18:29

Machinbird

8th Jun 2017, 19:02

People seem to seek clean-logical data that logic and engineering can explain. Life isn't like that.

The best explanation for AF447 are the first three sentences of this quote from Frank Herbert's "Dune".
“I must not fear. Fear is the mind-killer. Fear is the little-death that brings total obliteration. I will face my fear. I will permit it to pass over me and through me. And when it has gone past I will turn the inner eye to see its path. Where the fear has gone there will be nothing. Only I will remain.”

Vessbot

8th Jun 2017, 19:40

What I can't understand (and can't forgive) is why Bonin didn't know that basic fact...

To me, the answer is easy. There are 2 types of knowledge in play.

First, there's academic knowledge, like the facts recited by your hypothetical aero student. For the lazy, it amounts to little more than flashcard-type question and response that's unconnected to anything. Sometimes, for a more diligent pilot, some of these facts can start getting processed into logical relationships and connected into some small webs of theory. And maaaybe, if we're lucky, sometimes even connected to... the physical realm of actual flight!

Second (and, unfortunately, a world apart) is the other type of knowledge, which isn't really a type of knowledge, but I'm talking about the gut-level, split-second urges to make various control inputs in response to aircraft states. For the most part, these urges aren't at all informed by any theory of flight from the first type of knowledge, but rather quick-reacting, unthinking, "twitch" type responses that are either instinctual, or drilled to a level where they might as well be instinctual. Now in some areas of flight, this is fine. If you're flying straight and level, the gut response to a slight bank upset is to roll the wings level. If a gust of turbulence knocks the nose up, you push it back down. If it knocks it down, you pull it back up. If you're rolling down the centerline and the plane starts coming left, you push on the right rudder, etc.

(Note that this drilling for the responses of these simple situations can come not just from the beginning of that person's flight training, but since they are a child. The pertinent example of this is the general principle that you control a vehicle by pointing its front end in the direction you want to go. We know (and have internalized this) since we were children and learned basically how cars work.)

But in other areas, this gut-level instinctual knowledge will lead us astray. If have a large attitdue upset, that leaves you upside down and with the nose below the horizon, the drilled response of the "pull the yoke back" (which is normally the go-up control) will of course only exacerbate the situation. A successful outcome requires an application of the first type of (academic) knowledge, an understanding of the lift vector and its manipulations (I wrote more about this here (http://www.pprune.org/tech-log/594994-inverted-unloading-reducing-angle-attack-modern-jet-aircraft-2.html#post9781526) in the recent thread about upset recovery). Understanding aerodynamics is not just for answering test questions for getting your license, it really really applies! But too many only take it as far as it satisfies the licensure task.

This yoke-pull go-up response is unfortunately drilled into us way too far not only from the common-sense notion that vehicles go where you point their noses (outside aviation) but even inside aviation-

- from the 99% of our flying time which is spent on the front side of the power curve and therefore the airplane indeed does go up when the nose goes up

- from lazy and unknowledgable instructors that don't explain the real-life ramifications of the drag curve and the relationship between excess thrust and flight path angle

- from lazy application of technology, i.e., autothrottles that also hide that same ramification, ...

- from all those things that suffuse a pilot's career and drill the yoke-pull go-up response so deep into a pilot't gut reaction. Considering all these factors, it's absolutely unsurprising that when this pilot was suddenly faced with mismatching info, and every alarm under the sun going off at once, that he was too wide-eyed and unable to use some dim factoid he used to pass a written test decades ago, to override the gut-level reaction to pull the stick back.

You just can't overcome this starting with when the **** hits the fan in flight. It starts with an intellectual drive to deeply understand the mechanics of flight, and to apply that academic knowledge into thinking (on the ground) about what and why the airplane is gonna do when this and that happens, and what and why would then the proper pilot response be. It's a process that starts when you first crack your student pilot manual, repeats itself continuously throughout your career, and doesn't end until your last flight.

One of the chief tasks of a good instructor (for other peoples minds) and a good learner (for one's own mind) is to bridge the gap between these 2 types of knowledge. The first one is useless without application to the secondd, and the second is deadly without application from the first.

Vessbot

8th Jun 2017, 19:57

Anytime I get on this topic, I think of this very illustrative passage by Richard Feynman about a long visit to Brazil and his experience of their physics education system. Here (http://v.cx/2010/04/feynman-brazil-education) is the entire chapter from his book, below is a shorter excerpt. (A little malformatted, unfortunately)

In regard to education in Brazil, I had a very interesting experience. I was teaching a group of students who would ultimately become teachers, since at that time there were not many opportunities in Brazil for a highly trained person in science. These students had already had many courses, and this was to be their most advanced course in electricity and magnetism – Maxwell’s equations, and so on.
The university was located in various office buildings throughout the city, and the course I taught met in a building which overlooked the bay.
I discovered a very strange phenomenon: I could ask a question, which the students would answer immediately. But the next time I would ask the question – the same subject, and the same question, as far as I could tell – they couldn’t answer it at all! For instance, one time I was talking about polarized light, and I gave them all some strips of polaroid.
Polaroid passes only light whose electric vector is in a certain direction, so I explained how you could tell which way the light is polarized from whether the polaroid is dark or light.
We first took two strips of polaroid and rotated them until they let the most light through. From doing that we could tell that the two strips were now admitting light polarized in the same direction – what passed through one piece of polaroid could also pass through the other. But then I asked them how one could tell the absolute direction of polarization, for a single piece of polaroid.
They hadn’t any idea.
I knew this took a certain amount of ingenuity, so I gave them a hint: “Look at the light reflected from the bay outside.”
Nobody said anything.
Then I said, “Have you ever heard of Brewster’s Angle?”
“Yes, sir! Brewster’s Angle is the angle at which light reflected from a medium with an index of refraction is completely polarized.”
“And which way is the light polarized when it’s reflected?”
“The light is polarized perpendicular to the plane of reflection, sir.” Even now, I have to think about it; they knew it cold! They even knew the tangent of the angle equals the index!
I said, “Well?”
Still nothing. They had just told me that light reflected from a medium with an index, such as the bay outside, was polarized; they had even told me which way it was polarized.
I said, “Look at the bay outside, through the polaroid. Now turn the polaroid.”
“Ooh, it’s polarized!” they said.
After a lot of investigation, I finally figured out that the students had memorized everything, but they didn’t know what anything meant. When they heard “light that is reflected from a medium with an index,” they didn’t know that it meant a material such as water. They didn’t know that the “direction of the light” is the direction in which you see something when you’re looking at it, and so on. Everything was entirely memorized, yet nothing had been translated into meaningful words. So if I asked, “What is Brewster’s Angle?” I’m going into the computer with the right keywords. But if I say, “Look at the water,” nothing happens – they don’t have anything under “Look at the water”!
Later I attended a lecture at the engineering school. The lecture went like this, translated into English: “Two bodies… are considered equivalent… if equal torques… will produce… equal acceleration. Two bodies, are considered equivalent, if equal torques, will produce equal acceleration.” The students were all sitting there taking dictation, and when the professor repeated the sentence, they checked it to make sure they wrote it down all right. Then they wrote down the next sentence, and on and on. I was the only one who knew the professor was talking about objects with the same moment of inertia, and it was hard to figure out.
I didn’t see how they were going to learn anything from that. Here he was talking about moments of inertia, but there was no discussion about how hard it is to push a door open when you put heavy weights on the outside, compared to when you put them near the hinge – nothing!
After the lecture, I talked to a student: “You take all those notes – what do you do with them?”
“Oh, we study them,” he says. “We’ll have an exam.”
“What will the exam be like?”
“Very easy. I can tell you now one of the questions.” He looks at his notebook and says, ” ‘When are two bodies equivalent?’ And the answer is, ‘Two bodies are considered equivalent if equal torques will produce equal acceleration.’ ” So, you see, they could pass the examinations, and “learn” all this stuff, and not know anything at all, except what they had memorized.

Concours77

8th Jun 2017, 21:17

Concours, what you postulating may be true once the stall was completely developed - my point is that it should never have gotten that far.
Ask any first year Aero student this question:
"You're at a stable 35k cruise, then pull full nose up and leave it there, what will happen?"
They'll respond along the line of "you'll climb - trading airspeed for altitude".
And if you keep the stick full back, what then?
"Why would you do that, you'll stall!"
What I can't understand (and can't forgive) is why Bonin didn't know that basic fact...

You make conclusions with insufficient evidence, and do not allow for facts established!

At loss of Autopilot, along with cavalry charge and Master Caution, there was.....STALL STALL....

May I then ask your question of the aircraft: "It should never have gotten 'that far' "

The pilot had nothing to do with the initial warning, save perhaps his initial input of NU.

If you fly this aircraft, and have an explanation for "mayonnaise stirring", enlighten us as to the link between this first Stall warning and the aircraft's attitude?

FLEXJET

8th Jun 2017, 21:45

In descent, 447's airspeed (velocity) was seldom below 300 knots. Indications were what put them in the grinder in the first place. So any discussion of indications or "How bad was the Stall", are meaningless.

She impacted with a velocity around 240 knots.

"sixty knots" is extraneous information. A pilot who confuses a reoccurring Stall Warn and increasing velocity with decreasing Pitch such that he pulls back, is too in the weeds to fly. Neither of the other two could have done any better, using available data from CVR.

jmo

From the BEA final report:

"Les dernières valeurs enregistrées sont une vitesse verticale de - 10 912 ft/min, une vitesse sol de 107 kt, une assiette de 16,2 degrés à cabrer, un roulis de 5,3 degrés à gauche"

So I understand that VS and GS were the same 107 KTS at impact.

I am wondering why would a Ground Speed be only displayed on the ND, and not on PFD? Isn't it a strange design?
A glance at GS and you can guess if a stall condition might exist, at any altitude. To have to look at the ND is not optimum in such a scenario.

Vessbot

8th Jun 2017, 22:21

Even in the jetstream? No, there are plenty of air-data sources there to diagnose a stall. Groundspeed cluttering the PFD would be absurd.

misd-agin

8th Jun 2017, 23:11

FLEXJET

9th Jun 2017, 17:33

Vessbot

I meant that if you see, say 250 GS at FL350, and you have a stall warning, it might help to recognize a stall. If a crew is mislead by multiple failures, Ground Speed is there to give an independant speed data.

When GS is not on PFD, it is not in the primary scan. I am wondering if this could be a contributing factor. Like the side stick thing : proper design ?

Concours77

9th Jun 2017, 19:28

Nonsense. They never got to 300 kts. They got to 160 KIAS and 130 KIAS. They hit with zero and unknown. The unknown readout had been 0-30 KIAS just prior to impact.

Page 93 of the report -

https://www.bea.aero/docspa/2009/f-cp090601.en/pdf/f-cp090601.en.pdf

Hi. With great respect, there is an element of nonsense about the report, in that it purports to display actual in the moment data. Nothing wrong with that, but without a studious representation, inclusive of actual audio, blanket statements are not iron clad.

From data in the report, many explanations can be supported, but remain conjecture.

Was there not a data point that showed 15,000 feet per minute descent? Now that is 150 knots in the vertical, and suggests that with the concurrent horizontal velocity, a value approaching a velocity of 300 knots is supportable.

Without reliable IAS, I put more faith in the report of "crazy speed" than any numerical value of record?

As to loss of Stall warn below "sixty knots"? Would the pilot believe they had regained aero flight with the display con current with the re invigorated Stall Warn? If in fact the aircraft was reporting accurately, wouldn't the pilot misread Stall cues as something other than Stall?

In other words, as the aircraft AoA reduced, and Stall was announced, the associated buffet, roll problem, and increase in noise level was understood as overspeed, rather than Stall? His move to spoilers would suggest that.

So, again, with respect, the dynamic flight cues are missing from the report, and I choose to keep my conclusions open...

Vessbot

11th Jun 2017, 14:49

Vessbot

I meant that if you see, say 250 GS at FL350, and you have a stall warning, it might help to recognize a stall. If a crew is mislead by multiple failures, Ground Speed is there to give an independant speed data.

I understood that from your previous post. I don't know your background, but your premise forces me to spell out what's obvious to trained pilots: groundspeed has no effect on stall. Airspeed (the aircraft's movement through the airmass that it's in) determines that. If you're flying into a 250 knot headwind at a 250 knot airspeed, the groundspeed will be zero and that indicates nothing at all dangerous. I have personally "hovered" a plane like that.

To use that data meaningfully, first the crew would have to convert the winds aloft to a head/tailwind component, next add it to the groundspeed to get a true airspeed, and finally convert that to an indicated airspeed at attitude. This is the kind of stuff there used to be a 4th crewmember for. The notion that someone already as task saturated and confused as the crew in question, be able to quickly do that problem off the cuff successfully and use it to get themselves out of the pickle, is ludicrous.

GS would not have helped, and would only be unnecessary clutter on the PFD.

FLEXJET

11th Jun 2017, 17:12

Concours77

11th Jun 2017, 17:41

Although it would be a reach, it would not necessarily be wrong to say the crew confused attitude with altitude, and power with airspeed.

Though unlikely, that would explain their obsession with power, and the "need" for Nose Up?

misd-agin

11th Jun 2017, 20:27

They had reliable airspeed indicators except for a very short time. One was only reliable for 47(?) seconds, both were u reliable for about 29(??) seconds.

"Nose up" was the low altitude training procedure for stalls. Assumes a higher thrust to weight ratio, denser air, and Normal Law. Piloting 101, and physics, especially high altitude physics, disagree.

Concours77

11th Jun 2017, 22:09

Actually, it was the procedure for "approach to Stall", no? This aircraft cannot be Stalled in Normal Law?

Halfway through the descent, Captain suggests to Bonin: "...Try Climb..." Bonin replies, "...But I have tried that for some time now...!"

Captain did not respond, as I recall... Whatever the attitude at that specific moment (it could be determined with CVR indexed to NU graph) the Captain thought Nose Up was appropriate!!

That would be instructive, at least as to Captain's efforts to recover?

@Winnerhofer. Was there ever a conformed video representation of attitude, controls, VS, etc.?

markkal

13th Jun 2017, 11:35

This topic, transcending the peculiarities of stall recovery with the airbus family of a/c, notably the use of trim, raises the same issue over and over again relating to Uprt-Loc phenomenon which did not exist in the past.

The whole point, is how the crews can revert to " Back to basics" and with their situational awareness and visual cues they get from proper scanning and understanding from their instruments and basic pitch and power setting comprehension, do the right things, and save the day and instead of digging holes in the ground or splash at sea..

But what does " Back to basics" involve ?

For the previous generation of pilots, moving to the new generation of fully automated aircrafts, it meant applying their skills both mental and motor, to fly the aircraft the way they used to fly a Constellation or a 707 or a DC8 or aDC9

They had an extensive experience with "Classic" jets they had flown for decades and they were able to step back into known territory,

They successfully terminated the flight managing situations that their automated systems were unable to cope with.

In 1995 pilots flying the new generation aircrafts still had extensive experience with the older jets

Ten to fifteen years after this was not the case anymore. We saw the advent of a new generation of pilots trained and rated with the new automated aircrafts lacking the experience of their predecessors.

To them, "Back to Basics" has no meaning at all, they cannot revert to "Basics" they dont have.

The rule "Back to basics" is no longer applicable
In case of need, we find pilots trained on the new generation of aircrafts having to deal with scenarios that were the daily bread of older generation of pilots and here they are clueless.

They find themselves in situations they are unable to either comprehend or analyse, which however "basic" they could have been for the older generation,
have no meaning for them, hence the numerous accidents.

This is the major issue involving crews which have never known neither flown the old generatuon of aircrafts.

How newly introduced Uprt-Loc training, involving limited on air exercises and sim sessions will solve the problem escapes my common sense and understanding.....

atakacs

13th Jun 2017, 19:23

I can see your point but unless I'm mistaken Bonin was an experienced glider pilot. He must have sensed something was not adding up...

_Phoenix

14th Jun 2017, 05:24

His glider experience didn't helped with the stall of a swept wing, at cruise altitude.
The stall warning was not triggered continuously during the stalled condition, but it was triggered when not suppose to. I believe this aspect was never discussed.
On the A330 as on other aeroplanes of the same generation, the threshold of the stall warning varies with the Mach, in such a way that it is triggered - in alternate or direct law – before the appearance of buffet.
The stall warning was triggered at 2 h 10 min 51, 10 seconds later the variometer indicated a solid climb of 2000 ft/min and the vertical acceleration was around 1g. In less than a minute, the aircraft vertical speed exceeded -15000 ft/min with associated aerodynamic noise of the increased airspeed (in wrong direction).
Now, the conventional stall of a glider: almost zero aerodynamic noise, clear buffet, 0 g, the natural drop of the nose, the aerodynamic noise rapidly increased. An experienced glider pilot estimates the speed by aerodynamic noise.

https://youtu.be/7QpUj7wiPDI
Well Bonin never recovered from his steep dive.

markkal

14th Jun 2017, 07:02

Yes Atakacs and Phoenix, you have a point there, but am still puzzled, pitch & power = performance, and "power" for a glider pilot comes from gravity, so the nose has to go down e.g. the yoke forward....
And what about "Tunnel vision" or the lack of instrument scanning....ASI malfunction alone should not cripple a pilot, worse a crew...

From the transcripts and reactions of the crew, it appears they did not panic so fear was not a crippling factor at least at the beginning..

Concours77

14th Jun 2017, 14:23

Fear of Fear. Bonin's initial actions were not delayed by time spent in assessment. It is easy to say, "...the aircraft Nose was down, and it was in right roll..." So. Immediate inputs? Perhaps. Was stress level high?

It is common for our "survival" response to react quickly, to not allow a situation to "get away from us...." Additionally, abnormals are almost always experienced in the sim, where the expectation is for quick solutions....

It is not uncommon for one to act quickly, precipitously, to avoid fear "taking over".

The A330 does not Stall like a glider... Not at all like a glider.

A question other than "How could the pilot input so much nose up?":

How did he keep it right side up, directionally stable the entire time? The Stall Is benign, so much so....

Not only does it stall gently, it is so easy to fly whilst Stalled....

Is Recovery from Stall in the A330 more frightening than descending right side up at 7000 fpm? Does it present such an intimidating prospect in recovery that falling is the preferred option? Is recovery impossible, regardless the altitude available?

Winnerhofer

30th Jun 2017, 18:04

https://www.wired.com/story/boeing-autonomous-plane-autopilot/

“Airbus tries to avoid human error; Boeing tries to take advantage of human capability.”

“AF447 is the quintessential example of what can go wrong with automation,” says Balog. .

The flight crew didn’t understand the automation system, they simply trusted it.

The captain could have saved the flight with a few simple actions, but made exactly the wrong decisions.

Winnerhofer

12th Jul 2017, 22:15

https://blogs.crikey.com.au/planetalking/2017/07/02/jetstar-others-avoided-crash-similar-air-france-af447/

KayPam

12th Jul 2017, 22:24

An incident in which pilots will inexplicably pull on their stick at cruise altitude, climb and be saved from a stall and dive to the ground* only by the airplane's protections is actually very very common.

Multiples occurences per year. My best estimate would be around 15-20 worldwide.

*When a crew comes to a point where their actions on the flight controls cause a transition from normal flight to stalling without them noticing this transition, they generally are unable to recognize and save the situation on their own.

Concours77

13th Jul 2017, 22:34

There are precise values in attitude, both in rate and deflection, that trigger a definition of "Jet Upset".

It is arguable 447 was beyond those values almost immediately post Auto Pilot drop. Seconds after loss of AP came the first Stall Warn from the aircraft. One assumes an aircraft alerting an aerodynamic Stall is beyond Upset, and closing in on Loss of Control (Stall, By Definition).

Perspective.

Vessbot

15th Jul 2017, 02:58

I am a bizjet guy, EASA/FAA. While in cruise, I usually see a GS range of 380/620KT.

In the case of AF447, while stalling for 3 minutes, would you agree that their GS was much below that range?
Would you agree that a quick look at the OFP will give the expected and accurate GS to be compared with?

The crew checked engine parameters but I never read in the report that GS was mentioned or discussed.
I am just wondering if checking / discussing / comparing GS could have reversed this tragic fate, i.e. could have made someone finally push the stick (again, Airbus design, sorry to insist...).

Considering their heading wandered more than 180 degrees off planned, I say that no, a quick look at their flight plan would not give a GS useful for comparison.

I maintain that the FPD is for immediate, basic aircraft control type information. Am I gonna stay right side up, hit the ground, or go off course?
Anything beyond that is clutter. GS is generally for navigation problems. Should the unique occasion arise that would make it useful for more immediate aircraft control due to an unusual circumstance, I think that if a pilot has the mental space to make meaningful use of that information, he has the mental space to look one screen over.

Concours77

15th Jul 2017, 15:51

did you mean "PFD"? Relying on GS, or including it in scan, is arguably ridiculous, given the "g", other instrument indications, and loss of altitude. The VSI is sufficient? It too, is "airspeed"? They knew without looking at GS that they were in deep ess?

Ranger One

16th Jul 2017, 02:13

Concours77

16th Jul 2017, 16:52

Ranger One.

I'm betting it was discussed. Just at the first STALL WARN from the aircraft, was Bonin's stick forward? His very first Pitch input (post AP loss) was Nose Up, but seconds later, as the aircraft climbed, could the SW have activated based on erroneous indicated (calculated AoA) airspeed? In spite of correct elevator input?

I have never associated the first SW with the much later reversed activations of the alert. If his first Nose Down was met with the STALL STALL, could it have set the stage for repeated and chronic Nose Up, which eventually put them in the Ocean?

One can "learn very quickly" under extreme stress.

At Captain's entry to the cockpit, the Horn ceased. Had false adaptive behavior caused Bonin to pull to silence the alarm? Very counter intuitive, but the Aft Stick is itself very counter intuitive?

Has anyone ever synched Bonin's stick with the timing of the SW?

Goldenrivett

16th Jul 2017, 18:25

Originally Posted by _Concours77
Has anyone ever synched Bonin's stick with the timing of the SW?
Have you actually bothered to read the accident reports?
Page 29, 30 & 31.
https://www.bea.aero/docspa/2009/f-cp090601e3.en/pdf/f-cp090601e3.en.pdf

Turbine D

16th Jul 2017, 19:04

Ranger One:

I think you need to go back and carefully review the BEA Final Report:

https://www.bea.aero/docspa/2009/f-cp090601.en/pdf/f-cp090601.en.pdf

There, I believe you will see that the first stall warning occurred almost immediately after the autopilot disconnected, the cause being ice crystals in the pitots and had nothing to do with any PF stick input. The auto thrust went to thrust lock nearly at the same time. While the two pilots were trying to diagnose what was happening a gust caused the aircraft to start to roll, and the PF spent a good deal of attention and time attempting to stop that roll. Then you can read what took place after that.

Keep in mind you are posting on Thread #12. The previous 11 threads are easily accessible and contain a great deal of information and discussion, some coming from experienced A-330 pilots, engineers and fly-by-wire experts in other aircraft. There is also significant discussions and information as to what reliable data and protections were available as the transitions to alternate law and alternate 2 law occurred.

A recent question was if the aircraft was recoverable once it was in the stall. The answer is, nobody really knows for sure as it has never been examined in the way it happened using an A-330 aircraft from that altitude. However, there are two reports of attempted recovery in flight sims that resulted in the idea recovery was possible if the stall was recognized early and the stick was pushed all the way forward and held for a fair period of time. As I recall, the recovery occurred at about 22 to 25K feet and some other caveats were noted to keep from stalling again...

Concours77

16th Jul 2017, 20:15

Goldenrivett.

At 2:10:09. Bonin pushes stick forward.
At 2:10:10 STALLSTALL
At 2:10:11 (at 52 kts.) Bonin pulls back,
At 2:10:12 STA.....

Bonin does not push forward again except in "mayonnaise".

Thanks for reviewing this with me.

Turbine D.

"...two pilots were trying to diagnose what was happening a gust caused the aircraft to start to roll, and the PF spent a good deal of attention and time attempting to stop that roll. Then you can read what took place after that...."

If memory serves the attitude of the a/c just after the loss of Auto Pilot was 15 degrees right roll, minus two degrees ND. That is almost five degrees too low, and 15 degrees more than level wings. So it did not "start to roll" whilst the two pilots were "diagnosing" their situation?

Your diagnosis of the cause of STALLSTALL is not germane, and is meaningless to the pilots at the time. The warning happened just after Bonin input Forward stick. The STALLSTALL may not have been related to the input, but was concurrent with it. Similarly, the 52 knots was a nonsense, but absolutely may have been related to the warning....we aren't discussing your conclusions, only what might the pilots have done relative to what was happening That they could experience

Turbine D

16th Jul 2017, 22:32

Concour77,
Your posting:
If memory serves the attitude of the a/c just after the loss of Auto Pilot was 15 degrees right roll, minus two degrees ND. That is almost five degrees too low, and 15 degrees more than level wings. So it did not "start to roll" whilst the two pilots were "diagnosing" their situation?

From the Final Report:
The first disturbances in speeds 1 and 2 occurred at about 2 h 10 min 04, causing the autopilot to disconnect, which was signalled by a visual and an aural (cavalry charge) warning. The crew did not necessarily perceive these transient losses of speed information and the associated losses of altitude.

In addition, the crew’s mental resources were already taken up by turbulence avoidance maneuvers and the plan to climb during the minutes that preceded the autopilot disconnection.

When the autopilot disconnected, the roll angle increased in two seconds from 0 to +8.4 degrees without any inputs on the sidesticks. The PF was immediately absorbed by dealing with roll, whose oscillations can be explained by:
ˆ A large initial input on the sidestick under the effect of surprise;
ˆ The continuation of the oscillations, in the time it took to adapt his piloting at
high altitude, while subject to an unusual flight law in roll (direct law).

Following the autopilot disconnection, the PF very quickly applied nose-up sidestick inputs. The PF’s inputs may be classifed as abrupt and excessive. The excessive amplitude of these inputs made them unsuitable and incompatible with the recommended aeroplane handling practices for high altitude ight. This nose-up input may initially have been a response to the perception of the aeroplane’s movements (in particular the reduction in pitch angle of 2° associated with the variation in load factor) just before the AP disconnection in turbulence. This response may have been associated with a desire to regain cruise level: the PF may have detected on his PFD the loss of altitude of about 300 ft and loss of vertical speed of the order of 600 ft/min in descent. The excessive nature of the PF’s inputs can be explained by the startle effect and the emotional shock at the autopilot disconnection, amplified by the lack of practical training for crews in fight at high altitude, together with unusual fight control laws.

Although the PF’s initial excessive nose-up reaction may thus be fairly easily understood, the same is not true for the persistence of this input, which generated a significant vertical flight path deviation.

There remain a number of possible explanations:
ˆ The crew’s attention being focused on roll, speed or on the ECAM;
ˆ The initiation, more or less consciously due to the effects of surprise and stress,
of the action plan (climb) desired by the PF prior to the autopilot disconnection;
ˆ The attraction of “clear sky”, since the aeroplane was flying at the edge of the
cloud layer;
ˆ A saturation of the mental resources needed to make sense of the situation, to
the detriment of aeroplane handling;
ˆ The presence of turbulence that may have altered perception of aeroplane
movements in response to his inputs.

In answer to your final comment, the things they could have done, was to correct the roll, adjust the pitch angle and pause, doing basically nothing, until diagnosing the problem rather than reacting immediately to something not understood.