The AD certainly makes one stop and think, that's for sure.

PIO/APC
 

Clandestino wrote (about PIO/APC) :
Indeed, when the aircraft is fully stalled and mushing, and PF is holding full deflection left-up on his sidestick, and he is not touching the rudder pedals, yaw damper does give orders. After some time looking at these traces, I still cannot make sense of them. This is an area of interest which I hope will be investigated.

However, more akin to the APC definition which you suggest is the start of the sequence, right when PF takes control. Roll and yaw are mixed up in an oscillation, which appears to the pilots as a pure roll movement, but where in fact rudder is actuated and lateral accelerations are measured.

Surprisingly, no trace of gyros is provided. Yaw rate gyro would be interesting to look at. Heading traces are insufficiently detailed to extrapolate yaw rate from them.

Moreover, I am greatly interested in aileron authority and response to SS inputs. It appears that right inboard aileron maximum deflection remains limited to a modest amount. This maximum available deflection decreases significantly within the first seconds after A/P quit. Such limitation is surprising in the context of a Direct Roll flight law, which is part of Alternate 2B global flight law.

Interesting elements of comparison are available with the D-AXLA accident report. FDR traces show a large number of fascinating bits of information. Such are not provided in the 3rd interim report which is our subject matter. Maximum aileron deflection appears different in this report. However, the exact type of aircraft is different of course. Expert input welcome.

Well, perhaps A33Zab (or other knowledgable people) may help here. I would have thought that that kind of ECAM would also trigger an ACARS message, for the maintenance teams to check the vanes after the flight. Am I mistaken, here?
If not, given that we know there wasn't such an ACARS message, we may safely assume that the ECAM/warning was not triggered.

I was answering upon DozyWannabes remark
and tried to find an explanation for it. It is not relevant for the start of the upset and stall, but it is relevant information, as it is a typical stall behaviour for a swept wing aircraft. Known to the crew it should have helped to recognize the stall (if they missed everything else) and to react more adequate to the rolling tendency by using manual rudder instead of aileron to roll wings level.

Yaw damping was active, also according to manual, but not side slip estimation.

Honestly i don´t know how this missing sideslip estimation influences the behaviour of the rudder in a stall, or how the functioning yaw damping influences it in a positive or negative way. But hopefully somebody can explain.

That compilation does not help, as it reflects the pitch attitude, the rudder position and the bank angle, but not the input from stick or rudder. Would be interesting to compile those with the input from SS and Rudder, the difference then would be the FCPC input (would do it myself, but am too dumb for it).

You’re not without noting that ADs are usually and conveniently not 'linked' to any accident …

Fully applying to the facts is actually my main purpose, but what do you imply by stating the BEA has changed ?
Is it how finally the awaited independency and transparency are upon them, so how do you see how things were managed 20 years back ?
I can’t remember you ever publicly doubting the official line …



This, is a relevant piece of observation that I could hardly refute.
Thanks A33Zab.

Re 'verbalisation', is it still correct to think that BEA have not released all the cvr transcript so more may yet come ?

CONF iture etal

I'm puzzled by the arguments involving ADs, DGAC and the BEA :confused:

ADs are specific and the responsibility of the regulator to enforce

Accident causes are general (multiple layers of swiss cheese) and the responsibility of the BEA to dissect

What am I missing in understanding the arguments ?

lack of ADs don't cause accidents, but the presence of ADs may minimize future accidents

Good call. I lost sight of that. ALT LAW occurred at the outset when AP off.
PF immediately 3/4 stick back for no known reason. After 20 seconds PNF states "ALT LAW, Protections Lo"(st). By then the speed had decayed and they were dancing the edge of the flight envelope.
PF was over controlling from the get go. Large scale stick inputs, thrust set at TOGA and then idle, Air Brakes deployed. Ignoring PNF directions. Did he panic?
Sadly if PF had left the controls alone and sat on his hands it could have been a different story. Near the end he verbalizes his desire for max nose up thus confirming it was intentional SS input. This would fit him not being aware of ALT LAW or not understanding it.

décrochage
 

Can a french aviator clarify the extent of usage of the word "stall" in their training.
Is the english "stall" widely used in French aviation training or is the native "décrochage" used?
Is hearing "stall" a routine part of stall avoidance training in the sim?

Hi xcitation,
If he'd done that - it would have continued to roll right wing down until it was inverted.
They were struggling to keep the wings level in ALT LAW from the outset.

I think that BEA should be informed about your concerns. There's a faint possibility they believe that two agreeing AoA probes outvoted the third. It is of utmost importance to discover which version is correct.
Yup, my mistake. It wasn't 32, it was 33 before and four between the accident and publication of interim 2. Thank you for pointing me towards the more reliable source.

Yup, because that made the difference between 37 happy landings and one crash. Other crews may not followed procedures, but they kept the aeroplane aloft.

If you look closer it seems that it's not just right inboard aileron. Left inboard aileron also goes only to about 5° up and no more. Is it normal to have ailerons with different maximum up and down deflection? Is it usual? Is it only Airbus specialty? We have the right to know!

Regarding the aileron authority: do you remember what aileron authority you had when stalling your first trainer? Widebody plummeting oceanwards at AoA higher than 35° is bound to have it even worse than that.

Well maybe you hit the nail on the head. That is about the only thing they all focussed on. Forget speed, stall, attitude, THS and just focus on the roll. Amazing that they had such roll control once they stopped flying and became a falling 200 tonne piece of metal. If anything from all this the airbus is an awesome forgiving airplane at low speed. Would you expect to have control of liner at speed as low as 30kts in chop? If you asked me I would say it tumbles and break up.

Have I missed something? What would cause three pilots to know that the last thing they should do is put the nose down?

Are you sure? The initial roll could have just been a nasty bit of turbulence - everything after that could be PIO/ADC - the lateral control inputs from the PF certainly seem in excess of those required at cruise altitude.

The airplane rolled through seven degrees in two seconds, not really an alarming rate (the 'second' hand on your analogue wrist watch 'rolls' twice as fast). Upward gusts alternated with downward gusts about every five seconds.

I would not mind if someone would explain to me how releasing the SS in roll direct results in the aircraft rolling inverted, but more importantly explain this to the RAF who just sub-leased 2 of these aircraft and are probably not aware of this.

Lookng at the likelyhood of the reasons for that tendency to roll it seems pretty obvious to me that we can assume that turbulence played a or the major role in this.
If that was the case the probability of a stable continued role to one side until inverted is rather low.
Looking at the outcome I'm with excitation on this one.

even the interpretation of a medical monitor needs big experience, hehe we discuss since many weeks the lines of less minutos..... but in this case a trendline of the altitude, wouled helped the captain a lot to spot the situation (maby with a future-line calculation for different pitch or powers....?)

Hi OK465, DW, henra,

Unless the aircraft was trimmed exactly to balance any asymmetric thrust (due TL moved in response to thrust lock), it would tend to roll one way and continue to roll, unless counteracted by pilot or Auto Pilot input.
Since it was in Alternate Law, there was no AP or FBW roll input - only pilot input.

At what attitude do you think it would stop rolling if left by itself?

I, by choice never flew the Airbus but friends that do say if you leave the plane in a bank it maintains it forever. Even in alternate law. If that is true it wouldn't roll inverted but I am sure a pilot would correct it if this information is wrong. I am so happy I only flew Boeings. They always do what you want.

Hi Triple R:

Thanks for the explanation. :)

I see now that releasing the SS in this situation while continuing to manipulate the thrust levers is fraught with potential peril.

Rudderrat
With an aircraft stalled the roll would lead to yaw in the direction of the roll. As the 330 is swept wing the wing on the downside would then be more directly into what airflow there was and generate slightly more lift and the aircraft would nod up and start rolling back the other way to repeat the yaw and roll on the other side. As I believe Dozy has said this is relatively standard swept wing behavior. Like a long period dutch-roll

However, into this action PF was putting in as much aileron as he could, often apparently full SS. The result of this would be to make the low wing AOA higher so less lift so a tendency for the aircraft to apparently do the opposite of what was wanted until the wing sweep effect was larger than the aileron AOA effect.

Perhaps someone with spare time could check - but if the total time with the SS held to the left is larger than to the right then that could explain the overall right turn in the descent track as the right wing was being held deeper in the stall by aileron AOA.

Speculation now - but for a pilot sitting in the right hand seat, just pulling the stick directly toward the pilot would be a Nose Up - Left Roll input. This would maintain the stall and result in a track that turned to the right.

Hi Ian W
I don't know the physics of stalled aircraft behaviour, but I think the stability was a result of dihedral rather than sweep.

When stalled, if one wing is lower, it presents a greater plan surface area to the airflow than the higher wing, resulting in a levelling couple.
I think PF's roll input would help level the wings because the lowered aileron would present more drag. (edit in the same way that down elevator lowered the nose and reactivated the stall warning)

However, I will probably agree with Owain's analysis.

Quite a few folk here just a bit confused about aircraft, and in particular swept wing, stability, but I don't actually think any of this is relevant to this thread.

What is a fact relevant to this thread is that attempts to lift ANY stalled wing with aileron will result in the wing going further downwards. This can be seen on the PGF AB320 traces as well.

Absolutely unbelievable but true...:ugh::

AF447's initial altitude drift went virtually unchallenged

I think it was the increased drag and not the higher AOA, i agree though that it looks like it did not help in leveling the wings.

I tend to agree. Dihedral helped, sweep back did not help.

Here i disagree again. See my post from few days ago Adverse yaw



Would somebody be able to explain on my followup question concerning the function of yaw dampening and missing side slip estimation in Alt2?

I agree inthe way, that it did not play a role causing this upset.

But i strongly disagree in general.
The aerodynamic behaviour of the aircraft seems to be a blanc card in nowadays training and knowledge base. We wonder, wy the pilot pulled the stick despite being in a stall. We might also wonder, why he applied full left aileron and not using rudder to level the wings. It might have the same reason: Not knowing, what the outcome in an aerodynamic point of view) theses actions would be. He wanted to stop the descent and climb up again, therefore pull back on the stick. That worked probably more than 99% of his flying career. Tell the aircraft what to do, point the nose up and apply sufficient power, and the aircraft will follow the orders. Same with bank. If right wing is down, put the SS to the left. When the wing is level, put the stick to neutral and it will stay there. That worked again more than 99% of his flying career.

Unfortunately there are situations, when you have to switch from normal behaviour to "trouble shooting mode", and for that you have to know the performance envelope of your aircraft and how it behaves, if you touch that envelope or go outside of it.

Military fast jet pilots do that on a day to day basis, therefore they know exactly how the aircraft will behave and and how to react by flight control input to get the desired result.

This crew had no clue what might have helped to get out of the situation they themselves flew (stalled) into. Agreed, they should not have gotten into this situation first hand, but that´s what ´s happening in our non perfect technical and human world.

Therefore again, i tend to say, that it is also very important to look into those issues after the stall happened instead of exchanging arguments about tactile feedback and yoke Vs.SS the 50th. time. We placed those statements and they stand from either side.

Gentlemen,

I have read EVERY post here regarding AF 447. I remember June 2009 like it was yesterday. I am not a pilot. The intelligence and opinions here have been beyond enlightening. From takata believing the plane turned around (which it did but under different circumstances) to spot on weather examinations......all class work.

Unfortunately there are facts and the facts involved with AF 447 are disturbing. A STALL is a STALL. The plane was telling them that, the altitude was telling them that, buffeting was telling them that. OK... I get it...the pitots were clogged..there is confusion....the plane is confused....the pilots are confused. I hate to say it but the people on the flight deck were...morons. I know, it is terrible to say. How can a skilled aviator, make that 2, not know he is in a stalled position? We are talking about life and death and that is serious business. People are dead because 2 guys refused to acknowledge there was a problem.

What more is there to argue?

@John3775

Spot on!

But 3 morons?

Or does this "crash prooved", aeroplane simply put the pilot(s) out of the loop?

John3775: I've said it here before but no-one thinks it's shocking or surprising:

It's allowed (certified) for the AP to quit and make the pilots hand fly the plane at high altitude.

It's allowed for AF to use 'pilots' who have no training or experience in hand flying the plane at high altitude.

Not only for AF.

It's ALLOWED for the whole industry.

Money counts!

So do it at your next check ride with your company, FAA or whatever examinar @ FL 350 or so.

Have fun...

A good reason then, for having a proper stick shaker and pusher in ALT mode, as almost all other civil jet aircraft have and have had for many decades now.

There also appears to be little reason for allowing the THS trim system to assist a pilot to trim right into and beyond the stall at altitude and cruise speed...

Yes, yes, i know... bad piloting, inexplicable piloting but that is why stick shakers and pushers have been around for years - because it is known that pilots stall aeroplanes and the consequences are often that with a large swept wing jet a/c (however tailed), recovery cannot always be guaranteed in a set height lossor limit 'g' once badly stalled (c.f. stall netry just averted).

What was the argument then for certifying in Alt2 without a stick shaker and pusher ?

:D
@VGCM66 Is there much more to say?

p.s. for all the A haters from B factoryland....B jets are not without faults; many deadly; and had it not been for government cash injection it would not be the mega company it is today (protectionism as much as the US would like it to be is not exclusive)...therefore I ask those of you with issues to do your homework and perhaps have a bit of understanding, acceptance and humility before passing judgement.

QF72
 

Before you start attacking the dead pilots you need to do a bit more research here. Are you aware that QF72 was probably fresh on AF447 pilots minds which included false stall warnings and failed PFDs followed by a steep dive that was recovered by a continuous stick back! Note that QF72 had the benefit of visual references (day time + good weather).

The AF447 pilots probably had less than 60 seconds to get ahead of the aircraft that had run away from them. This was not an easy situation, totally untrained for. In this situation panic can occur quickly. You have to ask why did they behave the way they did. You need to dig deeper to find why they made the mistakes.

Training, experience, design philosophy
 

A few good points recently.

I hitch hike on RF4's comments, if you will excuse me.

The military guys here flew jets with vastly different operational requirements, and some of our jets had vastly enhanced performance characteristics than the 'bus. So we flew the things to the edge of the envelope and maybe beyond during training. When we encountered a "bad" condition, we usually had seen it before and responded according to procedure and training. This was not the case with the AF447 crew.

There is no substitute for experience. You can fly a simulator all you want, but until you see and feel the real thing in the real situation, you are not fully prepared. Simply following a rote procedure will work 90% of the time, but that remaining 10% can be, and often is, fatal. It is very hard, very expensive, and maybe foolhardy, to experience stalls and high AoA flight conditions in a big commercial jet. Only way around this is to have a small fleet of planes to see and feel the flight characteristics of stall entry, and recovery. Sorta like the Shuttle folks used to practice their approaches.

Another thing I saw when checking out folks in the USAF Reserve and Guard was how commercial airline folks could go from flying the Viper or SLUF or Thud or Double Ugly on weekends to a 737 or 757 for their "day" job. i would take those guys and gals any time in a big jet that had entered unknown territory. So there IS A WAY.

The design philosophy that assumes engineers can build a jet that "protects" the crew and SLF's from all possible contingencies is failing us. As with your auto, you must be able to master the beast without a plethora of control laws and "back up" modes, and such. You must first of all, and lastly, be a pilot.

I'll go back to my cave now....

Hi,

DB64
And what is your advise for all the A haters from A factoryland ?

Xcitation
You give yourself the answer ....
totally untrained for

Full Back Stick
 

There are a several QRH procedures that call for Full Back Stick.
WIND SHEAR:
SRS ORDERS .... FOLLOW
This includes the use of full back stick if demanded.
If the FD Bars are not available , use an initial pitch attitude of 17.5 degs with full back stick, if necessary.

WINDSHEAR AHEAD:
Thrust Levers ….. TOGA
SRS ORDERS .... FOLLOW
This includes the use of full back stick, if required.

EGPWS ALERTS
PITCH ….. PULL UP
Pull to full back stick and maintain in that position
THRUST LEVERS …. TOGA

The pilots will have practised all of those procedures in the simulator, and will have gone away with the association of TOGA and Full back stick seems to work OK. Piloting skills don't seem to be required, simply pull back and let the computer fly the aircraft in pitch.

It is not mentioned anywhere that the "piloting technique" of respecting Alpha Max should be employed, and to relax the back pressure when very close.

Is it reasonable to ask a pilot to fly one particular way when in Normal Law, and a different way when in Alternate Law?

If AB had fitted a side stick buzzer, which was activated when approaching ALPHA MAX in NORMAL LAW, then he might have had the opportunity to practice flying the correct pitch attitude / angle of attack during the Wind Shear and EGPWS Alerts, on the edge of the Stick Buzzer / Shaker.

It may have reminded him to respect the stick shaker, when at FL 350, rather than go for TOGA & FULL Back stick again.

One solution is to simply change the crew - but if they failed to recognise their predicament due cockpit design, training, QRH procedures, etc. then you can bet there will be another crew able to do the same somewhere else.

@gums
I agree 100%. :ok:

@ventus45
We had to do all our B707 emergency exercises in real life, Stalling, Emergency Descent, EFTO etc. Unfortunately we were writing off more aircraft during training than we did in normal passenger operations. There was no good reason to continue using the real thing once simulator fidelity came close. A crew learns far more by freezing the sim before impact than chatting to them in their hospital beds - or worse.

Reply to VGMC66 post #741 ... ref high altitude/weight buffet boundaries
 

VGCM66 - well said. And a fine Flight article too. AF447's initial altitude drift went virtually unchallenged

Please see post #1386 on 3 AUG 11 which seeks the figures for AR447 buffet boundary at the time of the accident. They were clearly exceeded and the inevitable aerodynamic upset resulted.

Has anyone listed these relevant AF447 Flight Manual figures yet?

http://www.pprune.org/tech-log/45687...no-5-a-70.html

Buffet boundary for AF447 weight at FL380 and 1 g is M=0.63.

John3775 #743

".. the people on the flight deck were morons.... 2 guys refused to acknowledge a problem... "

Whilst other modes of transport CAN stop and have time to think, this crew had just FOUR minutes...or less, and in Test Pilot country.

A test pilot might well have been flying by day, clear of cloud and anticipating the abnormal.

"Morons" is prehaps unreasonably harsh, especially as you have read all the other comments for two years.