AF 447 report out

[A-3TWENTY]

I think it makes sense what some wrote here. The sim behaviour is not reliable out of the tested airplane envelope.

Anyway I`ll answer the questions posted here:

- if you look back through the various threads you will note that many, including me, consider you needed -50 degrees of pitch to unstall. I doubt -10 would do it in time. Are you saying the sim would not GIVE YOU -50 or that you selected -10?

As it stalled the nose fell down from around 30º to 10º pitch down just like a small aircraft. And it stayed there. I applied full side stick forward but was unable to lower the nose more 10º down as well as recovering from the stall. At around 26000 ft I brought the thrust levers to idle to benefit from the pitch down moment with no effect.

does the simulator produce a log of flight parameters, like a FDR?
if yes, is it similar to the actual FDR data from AF447?

Didn`t tried , but I don`t think so.

Quote:
5.Then I pushed the side stick full forward and kept it there. NOTHING. Interesting to note that I was maintaining pitch 10º Down , but it never got out of stall.
NOTHING? When did it go from 30º Up to 10º Down?

P.S. At what point did you consider the airplane stalled, i.e. what criterion did you use to identify the stall?

As above: Just before it stalled there was a strong pitch up moment which raised the nose to around pitch +30º.I was doing some force puling the side stick to keep it at around 15º degrees up when just before the stall with the same force applied in the side stick it raised the nose to 30ºUP.
It stalled like a small aircraft.Nose fell down to around -10º and stayed there never recovering, and I was unable to increase the pich down.

Quote:
Originally Posted by A320
3.Just before stalling the airplane pitched up by almost byhimself to 30 degrees.
AF447 showed no tendency to do that.

Well, not really. Seems to be from what I`ve read that AF447 reached 30º UP or close at some point.

[HazelNuts39]

Originally Posted by A320

Seems to be from what I`ve read that AF447 reached 30º UP or close at some point.

Please see BEA Final report, FDR Chronology, between 02:10:58 and 02:11:22 -
The co-pilot sidestick is positioned:
- between the half-travel position nose-down and ¾ to the stop position nose-up with a nose-up position on average
- between 4/5 to the stop position to the left and 4/5 to the stop position to the right.
• The pitch attitude fluctuates between 17.9° and 10.5° (Period of 5 seconds).

EDIT: The point is that the real airplane showed no tendency to pitch up on its own, it pitched up and down in response the PF's sidestick commands.

[Lyman]

HazelNuts39

Thanks for the W/S data.

Also... You say: "EDIT: The point is that the real airplane showed no tendency to pitch up on its own, it pitched up and down in response the PF's sidestick commands."

Neither did the a/c Pitch down on its own, ref.: link to PDF of Link to
Airbus STALL;

"....the a/c g break is difficult to sense..."

Also re: FFS limitations, ".....it is difficult to present accelerations of long duration..." the answer being, IMHO, installing a FFS in the belly of a Wide body, to provide these "long duration accelerations"....

[TTex600]

Quote:
Originally Posted by TTex600
Is it your position that every system is acceptable provided that the operator is "trained"?

Originally Posted by Clandestino

No, this is your straw man argument. Not every system is acceptable. Those well designed, tested, certified and field proven stand very good chance of being so. That they can nevertheless turn out to be lethal in unfamiliar hands is just the way our universe is structured. And no, you don't get familiar just by adding the flight hours in the logbook or by hand flying whenever you feel like it. It's about knowing what your aeroplane can and can't do and how to return her into the heart of the envelope, when you have unwittingly chased her towards the edge, or beyond.

How is an airline pilot supposed to "know what your airplane can and can't do and how to return her to the heart of the envelope"? We are trained in simulators and kept in a certain limited flight envelope during that training.

Quote:
Originally Posted by TTex600
Next, you can't have it both ways. Which instruments are primary? Flight directors and FMA's, or attitude and power? The "it could never happen to me" crowd was quick to inform us that the ill fated AF447 crew needed only to fly pitch and power, and now you inform that FMA is important. [/sarcastic bad attitude]

Originally Posted by Clandestino

Not much sarcastic but I'll concur it's bad. Let's ignore the last part and assume post was made in good faith. In aviation it often is not case of "either-or but" "and...and...and". Pilot must always recognize when flight director is leading him along the optimal flightpath and so it is to be followed (99.99% of the time), or when it deviates so it must be disregarded. For those doubting the benefits of attitude flying, it is beneficial to remember FD displays attitude command.

I'm not faking the bad attitude.

But let us continue. One of Airbus' cardinal rules, at least as I was taught, is: "follow the FD's, or turn them off. Never fly through the FD's." Now you try to tell us that there is a time for the FD's to be "disregarded". Please cite your reference.

Quote:
Originally Posted by TTex600
It gets a bit annoying to have it implied that I the Bus pilot am an outsider to an airline pilots job, but this is a (basically) anonymous forum so I wont try to convince you otherwise.

Originally Posted by Clandestino

"Trust me, I'm a pilot", eh? Ad hominem is still invalid argument, even when it is self-inflicted.

Where did I say, "trust me I'm a pilot"? I said that I am an airline pilot and an Airbus Captain and I get annoyed when others post that I am an outsider to an airline pilots job. I also said that I won't try to convince you otherwise. That is somewhat the opposite of "trust me". The Ad Hominen appears to be emanating from your corner.

Quote:
Originally Posted by TTex600
focusing solely on the infalibility of his/her machine.

Originally Posted by Clandestino

Nope. This machine was not infallible, none is. It failed in utterly manageable way. Why minor fault resulted in catastrophe was puzzling even for BEA HF experts just piling up theories on top of each other.

So you agree that even experts are puzzled, everyone but you it seems.

Quote:
Originally Posted by TTex600
Explain why the stated on the CVR that they didn't understand what was happening.

Originally Posted by Clandestino

Because they did not understand what was happening.

I'll give you that one. Good answer. Now tell us why they didn't understand. You apparently already know exactly why this happened so tell us why they became confused.

Finally, you said that it is understood at the beginning of Airbus training that trainees are instrument proficient. Maybe so, but airline Airbus training beats that out of one quite soundly and in short order.
For that matter our initial tng and recurrent training is almost entirely focused on FAA Appendix required maneuvers. I will go so far as to suggest that an entire generation of pilots has been trained with the assumption they possess a skill vs verifying that such a skill is possessed.

To anyone still reading, I apologize. I've dealt with "super pilots" all my career. There is always one in every ground school who knows just how many light bulbs a ALSF II holds. They know the amperage draw of every tube and the exact sequence of gear retraction. They are quite annoying to those of us who are just "average joe" pilots. Obviously, we elicit the same feelings in them.
I've not tried to be an expert in these discussions, I'm more interested in shining a light on modern systems, the entire organism, that are becoming more and more pilot unfriendly. It's almost "startling".

[Lyman]

Mother Nature does not consider over confidence a skill set. It is a trap, only that. The preening is from the playground.... Imho

[A-3TWENTY]

Quote:
Originally Posted by A320
Seems to be from what I`ve read that AF447 reached 30º UP or close at some point.
Please see BEA Final report, FDR Chronology, between 02:10:58 and 02:11:22 -
The co-pilot sidestick is positioned:
- between the half-travel position nose-down and ¾ to the stop position nose-up with a nose-up position on average
- between 4/5 to the stop position to the left and 4/5 to the stop position to the right.
• The pitch attitude fluctuates between 17.9° and 10.5° (Period of 5 seconds).

EDIT: The point is that the real airplane showed no tendency to pitch up on its own, it pitched up and down in response the PF's sidestick commands.

Where to get the final report in english?

[RetiredF4]

Where to get the final report in english?

there from the BEA site.

[Clandestino]

Originally Posted by Retired f4

What a silly straw argument.

Lemme help you with this: straw man is fallacy of misrepresentation of an opponent's position. I was not targeting anyone in particular, i was just pointing that just based on outcomes, control architecture can not be considered to be causal in AF447 catastrophe as there were a) other cases of FBW Airbi that did not stall after UAS b) conventionally equipped aeroplanes that did suffer from stubborn pull into stall.

Originally Posted by Retired F4

How is your closed loop feedback ------ demand by pilot via control / thrust levers position versus effect crosschecked via instruments ------ functioning?

Perfectly well, thank you for asking.

Originally Posted by Retired F4

the PF might lack the demand (control position) and has to rely on the effect (instruments) only. The closed loop system is not available to him.

I suppose you meant PNF. Why should be there control loop for him? He is not supposed to be controlling the aeroplane, but monitoring her - aeroplane, not the other pilot.

Originally Posted by Retired F4

That didn´t go unnoticed during the analysis of BEA and is posted in their final report.

I disagree with their idea that the absence of natural horizon makes it more difficult to monitor and maintain pitch in an airliner.

Originally Posted by TTex600

How is an airline pilot supposed to "know what your airplane can and can't do and how to return her to the heart of the envelope"? We are trained in simulators and kept in a certain limited flight envelope during that training.

You make accidents where primary cause is pilot (in)action look inevitable. If the company or manufacturers have given you a bad training, it's all their fault, you are just the guy who does the dying. For Finnegan's sake, procedures are made to keep you flying even if the only envelope you know is the one your eBay purchases come in!

Originally Posted by TTex600

But let us continue. One of Airbus' cardinal rules, at least as I was taught, is: "follow the FD's, or turn them off. Never fly through the FD's." Now you try to tell us that there is a time for the FD's to be "disregarded". Please cite your reference.

Nice example of literal understanding. They are to be disregarded between the time you realise FD is in the wrong mode or has developed drift and your PNF switches them off. You don't really suggest you would follow the obviously wrong FD in a second or two it takes them to be switched off, do you?

Originally Posted by TTex600

So you agree that even experts are puzzled, everyone but you it seems.

To understand my reply, you need to know what HF means in this context. It is neither high fidelity nor high frequency. Technical experts were not puzzled a bit.

Originally Posted by TTex600

I've not tried to be an expert in these discussions

You've succeeded.

[RetiredF4]

Clandestino .. i was just pointing that just based on outcomes, control architecture can not be considered to be causal in AF447 catastrophe as there were a) other cases of FBW Airbi that did not stall after UAS b) conventionally equipped aeroplanes that did suffer from stubborn pull into stall.

And i was just pointing, that it does not prove the opposite either. I´ts no argument what so ever.

Clandestino
I suppose you meant PNF. Why should be there control loop for him? He is not supposed to be controlling the aeroplane, but monitoring her - aeroplane, not the other pilot.

Thanks for the headsup, will insert the missing "N" into the original post.

It´s your oppinion, that the PNF does not need the closed control loop to monitor and if necessary take corrective action?

Tell BEA, they seem to think otherwise.

BEA FR 2.1.2.3 Control of the flight path
It would also seem unlikely that the PNF could have determined the PF’s flight path stabilisation targets. It is worth noting that the inputs applied to a sidestick by one pilot cannot be observed easily by the other one and that the conditions of a night flight in IMC make it more difficult to monitor aeroplane attitudes (pitch attitude in particular).

Clandestino

I disagree with their idea that the absence of natural horizon makes it more difficult to monitor and maintain pitch in an airliner.

My expierience tells me the same. If we remove that point from the BEA statement, then remains

BEA FR 2.1.2.3 Control of the flight path
It would also seem unlikely that the PNF could have determined the PF’s flight path stabilisation targets. It is worth noting that the inputs applied to a sidestick by one pilot cannot be observed easily by the other one

I think, BEA was downplaying the above statement by adding the second part of the statement. But that´s just a guess over which i would not grind a ax with you.

Clanedstino
You've succeeded.

Although that post and similar others were not directed to me, i comment on them. They are very personal and disrespectful to the adressed poster, do not contribute to the thread and are not necessary at all. If you are annoyed over some posts, then disregarding them would be a better option.
The exchange of arguments should have some style and repect, and i start missing them in your posts. Posts might be wrong, inapropriate or out of the world, but to answer them with personal attacks is lowest level of discussion.

[bubbers44]

I think at FL350 we all know the airplane will stall if we pull up 15 degrees in any airliner. For some reason these two didn't.

[Linktrained]

Lyman's "Mayday" #610

Thank you for reminding me that Idlewild became JFK on 1st. Jan. 1964. Perhaps I ought to have given the QTH instead !

[TTex600]

Quote:
Originally Posted by TTex600
I've not tried to be an expert in these discussions

Originally Posted by Clandestino

You've succeeded.

OK, you get another one. I should have written that I never took an experts position in these discussions. Or, that I claimed any expert knowledge in these discussions.

I've made no claim to be the final word on anything Airbus. So you got me on that one.

Let's leave it at this, you be the expert and I'll be the line pilot. You type on your keyboard and I'll type on the MCDU. Til next time.

[A-3TWENTY]

There is no doubt pilots failed to comply with procedures , but in my opinion, the airplane showed three design failures, some known long ago.

1.The side sticks are not connected.

2.Pitots getting iced.

3. The stall warnings stops before you are reaaly out of stall.

My 2 cents.

[Tee Emm]

The latest Flight International article on the AF 447 crash reports from the BEA investigation that "the charged emotional situation combined with the workload might have led the pilot to trust the flight director independently of other parameters and he may have viewed the flight director crossbars as a means of maintaining cruise altitude....furthermore the cross bars orders were in contradiction with appropriate inputs and "may have troubled" the pilots.

"Troubled the pilots" Now that would be the understatement of the decade. All this is pure speculation and fails to consider the possibility that the pilots were simply right out of their depth when it came to flying a sophisticated jet transport by hand in IMC. Yet it remains a strong possibility a great number of the world's airline pilots are in the same boat; only saved from embarrassment by the reliability of superb automation.

Watch any airline crew entering a simulator prior to a recurrency training or conversion session. They have been carefully briefed and take their respective seats. Often with hardly time to adjust their seats and belts we see them almost simultaneously going heads down arse-up typing into their respective computers and switching on their flight directors. An observer can sense in the crew an almost a palpable sense of relief when the final finger pecking data inputs are made and the time has come for scans and engine starting. And that is just for a practice take off and landing.

There is something deeply troubling when airline pilots are unable to seamlessly switch from automation to instant raw data hand flying without running into the realisation they are ill equipped to cope safely -as witness AF 447. Manufacturers and various State regulators have a lot to answer for in their training philosophies.

[HazelNuts39]

Interesting questions

Originally Posted by Lyman (post#610)

At what point did 447 Stall?

In certification stall tests, an airplane is considered stalled when the buffet reaches “a magnitude and severity that is a strong and effective ‘deterrent’ to further speed reduction” (ref. FAR 25.201(d)(2)). Post-AF447 tests conducted by Airbus established “that the level of buffet was considered to be a deterrent by the test pilots when the angle of attack was about 10°, corresponding to normal acceleration amplitude of 1 g at the pilot’s seat. This angle of attack was reached at about 2 h 10 min 57 s during the accident flight.” (ref. Final report, 1.16.4.2). At the same time, the normal acceleration and lift coefficient started to decrease while the AoA continued to increase.

What is the relationship of the power ceiling, and the lift ceiling exceedances to the "climbing only due to her momentum"?

The power ceiling is the maximum altitude where the available thrust permits the airplane to maintain speed and altitude. The airplane can only exceed it by trading speed (kinetic energy) for altitude (potential energy). The lift ceiling is the maximum altitude where the airplane has a lift equal to its weight (1g) without exceeding alpha-max. At cruise altitude alpha-max is defined by buffet onset.

I have been trying to establish the cues available to the crew around the STALL.

The cues available to the crew were:

2:10:51 Begin of stall warning
2:10:53 Buffet onset
2:10:57 Deterrent buffet level reached
2:10:58 Airplane begins uncommanded rolling motions
2:11:02 Steadily increasing rate of descent while pitch attitude fluctuated around 15 degrees
2:11:32 Airplane rolls against full opposite sidestick, PF announces “no control”
2:11:45 Airplane pitches down from +15° to –10°, against full NU sidestick

She more or less just started to 'fall', rather than break? This suggests there was no immediate and drastic increase in drag.

The drag increased progressively with increasing AoA. Above about 9° the drag increase was ten times steeper than below 7°:

Time ...... AoA ..... CD
2:10:05 ... 2.3 ...... 0.020
2:10:49 ... 5.0 ...... 0.032
2:10:53 ... 7.1 ...... 0.046
2:10:57 .. 10.5 ..... 0.16
2:11:28 ... 25 ....... 0.54
2:11:37 ... 30 ....... 0.71

[A-3TWENTY]

The cues available to the crew were:

2:10:51 Begin of stall warning
2:10:53 Buffet onset
2:10:57 Deterrent buffet level reached
2:10:58 Airplane begins uncommanded rolling motions
2:11:02 Steadily increasing rate of descent while pitch attitude fluctuated around 15 degrees
2:11:32 Airplane rolls against full opposite sidestick, PF announces “no control”
2:11:45 Airplane pitches down from +15° to –10°, against full NU sidestick

Well , in this case it pretty much seems with what I experienced in the sim ...

[TTex600]

Originally Posted by A3Twenty

There is no doubt pilots failed to comply with procedures , but in my opinion, the airplane showed three design failures, some known long ago.

1.The side sticks are not connected.

2.Pitots getting iced.

3. The stall warnings stops before you are reaaly out of stall.

My 2 cents.

Yes, they failed to comply with procedure and the key lies in why.

Would you care to speculate as to why the crew failed to recognize the need to follow the UAS procedure?

I think the only real design failure is in allowing stall warning to stop while the aircraft was/is still stalled.

[Lonewolf_50]

Clandestino:

Originally Posted by Retired F4
the PF might lack the demand (control position) and has to rely on the effect (instruments) only. The closed loop system is not available to him.

I suppose you meant PNF. Why should be there control loop for him? He is not supposed to be controlling the aeroplane, but monitoring her - aeroplane, not the other pilot.

Wrong answer, amigo.

I used to teach this stuff (to some seriously ego endowed pilots) and had it taught to me (as a seriously ego endowed pilot) while in the Navy. We learned a lot of our CRM from commercial aviation, specifically the airlines.

CRM 101: if the other pilot is AFU, you have to recognize that and act to make the situation better. This may include actions like taking the controls in those {hopefully} rare occasions that it is necessary. Usually you help him get back into the problem and get back to flying right.

You can't do that unless you assess how well the other pilot is doing if things are not going well, or if he isn't flying right.

I am pretty sure that you know better than that off hand remark you made, in bold, since you do multi-place aricraft flying for a living, and IIRC, are a Captain.

[ap08]

I've been thinking long and hard on this:

If the sim really reproduces the airplane behaviour , the AF447 was is deep stall and they would never recover.

It does not. Covered many a time why it does not. Scrap the rest of the sentence.

2:11:45 Airplane pitches down from +15° to –10°, against full NU sidestick

Well , in this case it pretty much seems with what I experienced in the sim ...

and after much looking at the graphs in Annex 3 to BEA report, arrived at the following theory:

1. It is clear that the sim has no real data about the aircraft's behaviour at extreme angles of attack. However, some behaviour appears to be simulated, and the results do not appear to contradict reality. Is it a pure coincidence? IMHO, no one can answer this question with 100% certainty. Therefore, we should be open to all possibilities.

2. When the wing becomes stalled, the ailerons becomes useless. However, usually the pilot still has some pitch control at this moment, because the tail is supposed to stall later than the wing. Therefore, it is usually possible to break the stall by pushing the stick forward.

3. However, it is not impossible to get the tail stalled as well, if the airspeed is sufficiently low. Wouldn't it lead to complete loss of pitch control, just like it happened to both AF447 and A3TWENTY's simulator? If yes, doesn't this condition qualify as "deep stall", from which it is not possible to recover?

4. I would also suppose that the severity of stall is related to the aircraft's wing loading. If the plane has very low wing loading, like a Cessna or a glider, it can stall slightly but then chaotic aerodynamic forces flip it around, (much like it happens to a falling leaf). A330 is a heavy widebody, with very high wing loading, so when its speed has fallen sufficiently low for the tail to stall, there are simply no aerodynamic forces capable of disturbing its attitude(much like it happens to a falling rock).

My conclusion: any aircraft with sufficiently high wing loading can potentially enter "deep stall" - a freefall mode, from which it is not possible to recover...

[Lonewolf_50]

ap08:

A while back (one or two threads previous), some interesting graphs were presented that showed estimated characteristics of the airfoils (wing and THS/Elevator assembly) at increasing angles of attack.

This raised in my mind the matter of the lever arm between the THS/Elevator, the Cg, and the amount of lift the THS/Elevator can generate even if it isn't stalled. As V decreases the V^2 derived force (max potential) needed to tip the nose up and over may not be available.

Even if the THS / Elevator suite are NOT stalled, in terms of flow separation, control authority me be limited, or gone. (There was also discussed the matter of control rates, trim rates, and pitch rates).

It was something we kicked around.

I think Owain or mm43 or Henra or gums, or Retired F4 put up a few graphs on high AoA characteristics. It had two different spikes: at stall, and then a lot of degress AoA into deeper stall.

What I seem to recall from that discusion was that the lever arm was sufficient for most cases.
But
Since there isn't flight test data to back it up (is there?) this may remain one of those unanswered questions, with the basic operating theory being established as:

Don't Go There. (Literally, in the aerodynamic sense).