Hi,

That's unfortunate ... :uhoh:
I'm sure others will find better .. more brains .. more fun :)

You never noticed that the wheel is reinvented every year ? :ok:

Clandestino,
What I can see here is that you want to mix two things over and over :

1. Flying eyes closed can guaranty a LOC and you are perfectly aware of that. (average time needed seems to be around one or two minutes only ...)
2. But exiting a dive, to set things more obvious, be it in clear sky or in the clouds, can be done in many ways. From 10 deg ND to 10 NU can be down the hard way, the confortable way, or a variation of both. Only inputs will make the difference - Those inputs can vary on purpose during the manoeuvre depending what the pilot feels and is ready to feel. Wings are level. Sensation can absolutely be part of the elements that will guide adequately the inputs.

What don't you get here ?
Be explicit on your disagreement ...

I would not disagree as the altitude margin was confortable this time, but nevertheless, I see AF447 as a compulsory trigger to modify the UAS procedure to something that makes sense in any circumstances. What would or could happen if the 5 deg NU + CLB thrust is applied when the aircraft for any reason is already around the recommended max or simply at the FMS optimal a day when that optimal is pretty close to that recommended max ?

I like that 2.5 deg + N1 between noon and one (or whatever is the reference and general figures for cruise versus eng type) ...

JD-EE ^^ It appears from CVR excerpts that such was not the case.
I don't see the "climb away from clouds" as an instinctive reaction, since his initial control problem looks to have been controlling roll.

The more likely explanation is that as soon as he ran into that sloppy roll feeling, and was oscillating back and forth in roll, his hand got a bit tight on the side stick and he was pulling while he was rolling.
see the chart in post number 342, airtren,
perm link = http://www.pprune.org/tech-log/46062...ml#post6656578

My own personal experience with upset and being behind the aircraft on instruments (albeit not in heavies) is that when one is out of trim, it is easy to get a tight grip on the stick (Thought foremost is "GET BACK IN CONTROL, MAKE IT DO WHAT I WANT IT TO DO!") and end up fighting the aircraft a bit until closer to power / attitude / performance desired.

That catching up period (particular event I am recalling was a trim runaway) takes time and you really have to force yourself to get back to the basic instrument scan: attitude, performance, attitude performance. In the AF447 cockpit, the standard scan was not able to reference a key performance crosscheck, which is airspeed. The lack of that cross reference means that his scan (practiced and habitual) would not be serving him as usual: what he was looking for to inform a correction was simply missing. (Granted, his attitude should have told him, his PNF did tell him ... but I digress).

A number of members have pointed out over six threads the problem of dutch roll being a characteristic of swept wing jets. This may have contributed to his roll control problem, which raises tension (MAKE IT DO WHAT I WANT IT TO DO!) and result in inadvertent back pressure, back displacement, on SS.

Pilots who have flown A330, and who have posted on these forums, have pointed out that at high altitude, the aircraft requires a light touch to hand fly.

Occam's razor suggests a case of overcontrolling, even if the weather was indeed a concern for the crew during that phase of flight.

Is there really any pressing need to suppress it once the a/c is off the ground and once above a nominal (chosen) speed, until it's deactivated again upon landing

Yes, the AoA vane can malfunction (we know that), but its extremely rare, there can be cross-checks for that condition (e.g. a trouble shoot test soon after take-off could be applied)...

and additionally, why are more cctv, extrenal web-cam style devices, not used so the crew can - at a glance - inspect all around the aircraft for actual physical configuration and incipient or extant problems.

I seem to remember suggesting that such a (potentially low-cost) camera installation would likely have help avoid the Madrid take-off configuration accident. Sometimes the aircraft industry seems overly conservative, despite being knwon as a high-tech leader.

I think the industry should make its mind up how much accidents really cost and what that worth is in much better thought through systems and safety double-checks.

The Mk I human eyeball seems to have been sorely undererstimated as a troubleshooting device... ?

HazelNuts39,

Indeed, the graphs at page 41 and 42 with their granularity illustrate better the variations - thanks for pointing that out, and explanation.

Following the cause/effect chains a little further:

a) Pitch command -> Elevator action -> Pitch Attitude

The "integrated" angle of the Elevator NU is roughly 1 degree, perhaps less, in the time interval 2:10:08 - 2:10:16 in which the pitch attitude goes from approx 3 to 10 degree NU, which is a 7 degree delta.

b) Thrust -> Pitch Attitude

The thrust is on a decreased level, on a downward gradient variation rather than upward, if any gradient variation.

c) Elevator -> Normal Acceleration

The Normal Acceleration show 2 consecutive aggressive spikes of roughly 0.6-0.8g excursion upward/downward, corresponding to two spikes of roughly 1 degree in Elevator NU.

d) Turbulence -> Normal Acceleration

We don't have a graph of turbulence alone; it would be interesting to see.

But the variations in Elevator angle later on the time scale on the lesser granularity graphs - not present on page 41/42 - seem to correspond to lesser amplitude Normal Acceleration variation.

If that were indeed the case, would that leave room for the interpretation that the higher amplitude of the Normal Acceleration spikes between 2:10:08 - 2:10:16 indicates a turbulence contribution to that of the Elevators?

Not that it matters much in the larger perspective of the sad things happening during those 2-3 minutes....

Seems obvious to me so I must be missing something:

Once stall warning/condition is detected for more than 5 seconds (or other appropriate small number) latch the warning and do not remove it until valid (unstalled) airspeed and AoA are seen.

In other words once in a stall prove to me that we are no longer stalled.

Oh and while we are at it flash STALL on all displays every 10 seconds or so.

The graph on page 42 compares the recorded normal acceleration to that calculated from the control inputs without turbulence. That should give you a fairly good impression of the turbulence contribution.

NO ICE
 

ICING of the Pitot Probes as some explanation for UAS is a reach. It requires too much of a chaotic system by way of lined up cheeses.

At ~2:10:01, 447 enters a substantial UPDRAFT. Immediately, she does what all large (conventional planform) aircraft do when encountering a robust UPFLOW, she PITCHES DOWN, and DESCENDS. She has a LEFT WING displacement UPWARD due to TANGENTIAL ENTRY into the rising column. airtren's accel trace shows this at 2:10:01 - 2:10:05 from 1.3 down to .7.

This accounts for her aspect (NOSEDOWN) at a/p loss, and why the PF felt he had to ROLL LEFT, and CLIMB.

What about UAS? takata tells us the AD's three failed simultaneously. If so, that really makes icing suspect, but makes clear the loss of indicated airspeeds due to a consonant loss of AIRMASS to enter the Probes. All three started sampling ambients that had changed heading relative the airframe, and by 90 degrees. So the indications declined by > 30 knots in one second, and the ADs were rejected.



The PULL? The NOSE was down by three off 0, and 5.5 off cruise. That's nearly six degrees to make up, and he was too swift, STALLSTALL. Also, the a/p was actively inputting NU to counter the PITCH down. So PITCH is iffy at the a/p drop, and PF needs to fly, and he did. No judgment.


There is more, as I see it, and it is in airtren's graph.

That can explain the initial nose up, if the aircraft was not Straight and Level at the point of "you have it, robot taking a timeout, old chap."

It does not explain subsequent nose up inputs that lack successful counter-corrections toward a more level attitude.

Now explain why AoA vane #1 got stuck!

A seagull embedded on it?:}

Pilots who, actually, flew "ALT law" at high altitude, reported difficult control of the a/c.

From what we see, bank angle control required VERY large ss inputs.
In this situation, it seems difficult to criticize large ss NU inputs by PF.

Imho, the initial nose up is a reaction to the loss of 360' (35,024'-34,664') in just 4 seconds (02:10:05 / 02:10:09) that is "only" a 5400 ft/minute rate.
Any pilot flying an RVSM route will react very quickly to this kind of altitude variation.

I am afraid we will never have the answer to that question.

No. Just the opposite.

(my bold required)

Indeed, it's a fairly good impression. I should not be that conservative in equating the real plane with the theoretical/simulated model ran on the Airbus labs computers, and the would be values, with the corresponding values calculated by that model, based on feeding/running it with the known AF 447 command and headwind parameters.

It's also not that difficult "to imagine" based on the page 42 graphs, the graph of the vertical component of the turbulence; if I have time, I may try to generate one for my own curiosity....

By the way, this is an opportunity to mention and praise BEA for its professionalism in having these simulations, calculations, and analysis done, as they are extremely important in understanding and confirming that the plane acted within its intended design boundaries.

I respect your opinion, sir, but what about 4/5 ss deflection to counter a mundane 9° roll at 02:10:30 and a "right limit stop" to counter a 9° bank at 02:11:11 ?

Exactly.

The difference between "utilized" and "required".

If you let go of the SS in a 9 degree bank in ALT 2, the bank will actually tend to shallow out.

(It's not just an opinion.)

Posted on this before, and concur again.

Audio message can be continuously disruptive, visual can be too, if done in certain ways. Being disruptive once, or twice, to gain attention is perhaps enough. A certain very simple, small, visual message can be very strong without being disruptive. An A/C Error Status Panel with 3 color coded LEDs, to indicate and remind the type of Error messages that reflect the current state of the a/c.
(1) Emergency/Fatal - maybe RED , (2) Warning - maybe Yellow, (3) Informational - maybe Blue.

Lonewolf. It is on the graph, imo. The airframe was not S/L. The g accels, the PITCH, and Hazelnuts report of a .6 degree PITCH up moment/sec. So yes, I think safe to say the airframe was active, and on its way up, coincident with PF's first and emphatice NU pull. "Additive" controls, by happenstance, then.

No, I haven't gotten to the inter-relationships of command, result, deflection, TRIM, feel, etc. for the climb. But I believe it is all in there, and hang what PF thought, or BEA, or anyone. The traces are real, they don't lie, and they don't buy/sell/fly aircraft.

A thorough dissection of airtren's graph, then? If you need work in silence, I'll read only, and nort disturb. It IS that important to me. :p

Gerard C. I think the "initial noseup" started well before the frame you quote and was unrelated to the 360 foot "READ"/discrep in altitude. It had begun in A/P NORMAL, and the PILOT was responsible for piggybacking on the original .6dgree/sec. -imho. The g shows a sharp reduction, as the a/c descends ('turbulence/updraft').This descent: ap commanded, no?

mm43. Howdo. "Explain the stuck AoA vane....." WRG/FAULT ?:confused:?

PIO would seem to be the answer, but don't forget that post 2:10:51 the aircraft wasn't within a 'normal' flight envelope.

Worth looking at is the yaw damper, the rudder and the lateral 'g' traces. Once in the 'mush' the aircraft was 'nodding' and rolling/banking in a synchronized manner as well as 'fish tailing'.
http://oi56.tinypic.com/51dok5.jpg
Pitch Attitude, Rudder Position and Roll Attitude traces have been overlaid in the second trace in this graphic.

Well... perhaps it was too obvious for my deranged brain...:p
Good catch, thank you. So far I cannot find why it would not work (unless you freeze your 3 pitots during an actual stall... what a bad day, then) :ok:


Are you talking of the same pilot (still flying an RVSM route by the way) who (apparently) failed to react as quickly as before to a 2500-3000 ft altitude gain lasting "just" ~60 seconds with "only" a 7000 ft/minute (top) rate?
Sorry, I don't find the comparizon very conclusive...


---------

[edit/addendum] Self-quoting myself (sorry about that) but I just read (here) that the A380 apparently carry MFPs (Multi Function Probes) for Pt + TAT + AOA. Why this choice on the bigger bus? Are those MFPs something "new"?

Yes they are indeed something new. They use differential pressure data on a network of pressure ports to infer flow direction as well as total and static pressure 9hence airspeed and altitude). The probe body is itself fixed, though, so they don't have inherent high angle capability in the way a swivelling head might appear to - though even a swivel has to have stops beyond which it can't travel.

(Edit - ignore remark about static. Other manufacturers apparently integrate that ...)

@airtren & mm43:
 

Thx for your efforts to make this visible!
need some time now to study your valuable graphs and comments.

@ Machinebird:

Thx for the Fly-By-Wire A Primer for Aviation Accident Investigators
For the A3x series the - pitch rate - is indeed a input signal.

PJ2 posted this logic of A320 in the previous thread.

http://i474.photobucket.com/albums/r...tchChannel.jpg

@AZR:
 

The last I heard about this it was a testcase for Quantas only.
But some years had passed now, it could have been introduced by now.

http://i474.photobucket.com/albums/r.../PIOTCombi.jpg


http://i474.photobucket.com/albums/r...OTA380Test.jpg

Irrecoverable Stall
 

Reply to MM43:
An interesting quote from the document:

"It is important to know that if such a thrust increase was applied when
the aircraft is already stalled, the longitudinal effect would bring the
aircraft further into the stall, to a situation possibly unrecoverable."

An admission indeed. :ooh:

Color coded alerts.
 

Hi airtren:

AKA as ECAM.
LEDs are in Master Warning [RED] & Master Caution [Amber]
and comes with audible alarms & chimes.

http://i474.photobucket.com/albums/r...ab999/ECAM.jpg

mm43,

Thanks for the graph, it makes it easier to see.

Did you leave out the "roll commands" and "rudder commands" graphs intentionally?

They can help correlate visually the PF actions with the control surface deflections.

The "rudder" commands and control surface deflections on the graphs are confirmed by the CVR transcript's call to "attention with the rudder" by the Captain, in the same time interval with the graphs.

Ian W;
I believe that Airbus had worked out from the ACARS sequence the most likely scenario, and that statement is valid when compared with the Thrust and Pitch Attitude graphic shown on the previous page.

We now know that there was no escape as they didn't 'know' they were STALLED. :(

airtren;Yes I did. The rudder commands are all yaw damper commands, except in one instance where the pedal was jumped on. When looking at the Pedal trace and comparing it with the Yaw trace I noted that the algebraic sum was applied to the rudder and it recorded more than the RTLU restriction when the pedal was hard down.

Hello A33Zab

Thanks for pointing that out. Conforming to the existing color code scheme adds consistency to the a/c-human interface.

Elaborating further:

F - fatal --- most important, and highest priority -- ignoring may be fatal.
W - warning --- awareness of an abnormal condition is important, but ignoring it does not have fatal consequences
I - informational - information only, for pilot awareness.

The simplicity of a 3 LED Error Panel is a reincarnation of similar effective mechanisms used in the past.

Very interesting observations:

from http://fucampagne2008.unblog.fr/file...lprocedure.pdf

Originally posted by OK465 :
Do you mean you have first hand experience of (hand-)flying a 330 in ALT law2 at 35 000 feet ?

Sir, I am just an ordinary airline pilot and flying regional turboprop at that. I am not a psychologist, psychiatrist nor psychoanalyst so I really can not comprehend how can some PPRuNers, which I shall not name, suggest that technique that has been proven lethal for too many an aircrew could be used as an safer substitute for procedures we have now. I just can't get it. It is like someone suggesting potassium cyanide as a panacea for life's ills. Irresponsible at the very least.

One of the first thing a pilot who wants to learn how to fly an aircraft by reference to instruments alone must learn is to stop believing his senses and put his trust in instruments, lest he develops some illusion of attitude, turning or acceleration and kills himself flying. Only when this is lesson is mastered, one can progress on the next level: learning how the instruments can betray him and how to cope with it.

It can be done in many ways but many of them are plain wrong and some are plainly lethal. Proper way to rapidly exit a dive is to use maximum wings level pull that won't either stall or overstress the aeroplane. Pilots whose day at work involves pulling the extreme performance single-seaters out of dive, usually do it more precisely by referring to their alpha and G meters then by feel. Those who fly FBW aeroplanes can even do what Airbus pilots do when escaping windshear or terrain in normal law: pull the stick aft as it goes and let the electrons wring out the maximum performance out of the wings.



While the world outside is dangerous, it is not completely chaotic or anarchic. Industry does make up its mind about safety vs. costs and does it at almost daily basis. What we have here&now is the result of that compromise.

Since you have mention Spanair, configuration indicator in cockpit was working and showing just the wrong config for takeoff. Somehow Mk1 eyeballs, or rather central processing units behind them have seen what wasn't there. If the crew was in such a rush that they didn't read their instruments properly, what were the chances they would pause and use CCTV cameras to check the aeroplane from the outside?

@ Mad (Flt) Scientist & A33Zab:

Thanks for your answers. :ok:
Then, the MFPs on Airbus (A380) aren't the same thing I had in mind (re: The Rafale fighter probes).
On the latter, the whole probe (and not only the small "wing" at its external end) moves relatively to the air flow (AoA measurment). As the pitot is at the end of the probe, it too moves and it "always" pointing in the air flow direction. I think it's more accurate for IAS. Does anyone know if that sort of probes exist on any civilian aircraft? Is it only for high performances (fighters/aerobatics) planes?
That's maybe a bit too far off-topic at first glance, but in AF447's scenario, such probes would have maintained the speed above the 60kt limit, and stall warning would not have been inhibited.
Nevertheless, mods if you think it's better to discuss that specific point elsewhere, let me know and I will open another topic :)

Hi Clandestino,

Do you not use your sensation of deceleration to adjust the amount of braking to be applied, or the sensation of delta g when changing pitch attitude to make it comfortable?

I think you may be confusing spatial disorientation with sensed accelerations.

I suppose that depends on where the screens are, and whether real eyes prefer heads up or head down (psychologically speaking)... that is, a CCTV screen may present itself more in the heads up realm.
Is it not natural to (want to) have a look around the aircraft c.f. focus short in the cockpit on multiply diverse knobs, dials and intsruments...

Indeed, wasn't tghis just one feature of the trim-wheel.. not looked at, let alone noticed and responded too

You cannot keep ignoring the obvious.. there is something wrong with cockpit, systems and instruments, in a human interface fashion, when such obvious things as you say, are ignored, overlooked or found difficult... by all 3 crew (even in a crisis, indeed especially in a crisis which should have got that beady eye scan going quicktime!)

I absolutely do not, sir. For braking I use speed trend arrow, energy caret and ND groundspeed readout (GPS based) against outside visual reference to distance remaining to the exit I'm going after or the end of the runway. For pitch attitude rate I use that nice, big AH display on PFD in front of me. Sir, you heavily overestimate precision and usability of human senses of acceleration and balance in aviation.

The second one, if not corrected by visual references to instruments or outside world, inevitably leads to first one. It's a basic human limitation no eugenics crossbreeding programe will ever be able to eradicate.

And obscure part of instrument panel or outside view?

Position of the trim wheel is completely moot point. Crew needed not be aware of trim position at all. If they pushed forward on the stick, trim would obligingly go towards nose down. Pilot pulled. And stalled. Kept pulling till the vertical distance between his aeroplane and Atlantic ocean became zero. So died.

If none of alleged 32 losses of all IAS indications in high level icing conditions on 330/340s before AF447 ended in PPRuNeable incident (that is, incident discussed on PPRune), then your point of systemic error certainly can not be completely valid. Yes, there was problem with sensors. Yes, airlines and manufacturers were doing something to solve it but they were not in a great hurry, after all, there were 32 crews that coped with the problem successfully. Now we have one that did not and it is absolute imperative (categorical, if you speak Kant) to find out why. It is "the Comet mystery" of our day and age.

And yet there are many PPRuNers working overtime to prove this notion of yours wrong. I try not to ignore obvious but I do strive to ignore the oblivious.

What I find obvious from reactions on the PPRuNE is that the investigation of AF447 reminded some of the inconvenient fact that whenever they fly on the plane what keeps them alive is the knowledge and skills of the guys/gals up front.

Of course not.

But I have experience that takes the observations out of the realm of pure opinion. (You're welcome to discount anything I say, that's fair, no problem.)

But I would not make general sweeping relativistic statements like:

"Airbus pilots say the A330 is "difficult" to hand fly at altitude."

It's a big swept wing jet that "handles" and accepts proper pilot inputs like any other big swept wing jet in comparable situations, regardless of the active law. Not a "balanced on a pin" new concept out of Area 51.

In theory, yes. In practice, it is marked up for a reason, and this is not the first time time that a quick reference to it, when things aren't going according to plan, would explain all. How they got in that situation is another matter...

Sensed accelleration such as described by the pilot flying in AF 447, would have been a worse than useless perception.

The aircraft was nose up and the pressure being sensed in the back by PF was misinterpreted as possible overspeed...somatogravic disorientation.
The false sensation was then mistakenly responded to with persistent pitch up commands. The pilot seemed anxious and reverting to sensory habit rather than his training.

This aircraft was being hand flown without reference to the pitch aspect of the artificial horizon, and without reference to the altimeter or VSI in the phase leading up to stall.

No sense perception other than what he could see on his primary scan indications was of any use at all....



ps. I am also quite fond of the Categorical Imperative... when in doubt, duty alone will often rescue the day.

The crew of AF447 cannot have seen the latest Stall recovery advice from earlier this year (2011).

PF was/ had been a glider pilot, who must have had many winch launches, when the cable would have been attached under his seat. On releasing from a winch launch the glider would have been nose up, to get the maximum height from that launch and would have required the elevators to put the nose down to retain flying speed.

Someone reduced the thrust to Flight Idle for a few seconds on AF447 and the pitch dropped slightly but the SS stayed towards NU. Then TOGA was reselected.The stall was not recognised.

Would an old fashioned Rate of Climb instrument have helped them to realise that they were going DOWN... before the "passing 10,000 Feet..." on the CVR... The needle's change of direction might be clearer than a tape type display whizzing up/ down, too rapidly to be read. (Think what it might have looked like in Inches !)

Some of the French aircraft that I flew had metric instruments. We just flew the appropriate numbers.

Link....i have no doubt that moving dials trigger the brain better than moving numbers. The primitive visual reflexes for danger in the brain respond less acutely to numerate symbols than dial movement...there's plenty of research on that.

Its a safety issue in extremis, and i feel back up instruments should be live and analogue for that reason.