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AF447 final crew conversation - Thread No. 2

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AF447 final crew conversation - Thread No. 2

Old 11th Mar 2012, 15:43
  #141 (permalink)  
 
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The first clue of a possible impairment happened in autoflight. The V/select reported as 5000 fpm descent. If accurate (the a/c did not remain in this config, only commanded, rejected), the a/c was countering a 50 knot climb, or compensating for a chronic misalignment of THS and/or elevators.

As to RUDDER, I believe the pin is actuated within the fuselage; any "position" would be Pin Only, not necessarily to include the Rudder itself. So RTLU reports the drive portion position. Of course, the Rudder is assumed to be attached thereto.

HazelNuts39. At static deflection, yes. In cycling, the loads (calculated) can be much greater? The airplane's stresses are "independent" of a transiting aileron, yes? Are you assuming Still Air? In turbulence (again, calculated) the stress can multiply, of course.

And that is assuming a full complement of control surfaces at less than max deflection. At cruise, fewer surfaces are utilized, and at less deflection (small inputs). If all surfaces are not available, the ones remaining to accomplish the maneuver must be at max. (Spoilers locked out, eg).

Last edited by Lyman; 11th Mar 2012 at 15:58.
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Old 11th Mar 2012, 17:01
  #142 (permalink)  
 
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Lyman, before you go traipsing too far off into engineering La La Land, let me point out that the aircraft control systems were functioning as designed later in the flight, that the control gains were designed to be appropriate for that portion of the flight envelope and the aircraft was well inside its envelope, and the decision by the engineers was sensible since in Alternate 2 law, the aircraft did not require using as many spoilers based on actual flight tests results and calculations of spoiler effect on wing bending moments.

There is plenty of evidence to explain the performance of the aircraft as the effect of turbulence and pilot control inputs.

Take a look at the Cooper-Harper pilot rating scale located here:fig66
If you were to ask PF right then about flying qualities, he would have been in the 8 or 9 area, but in retrospect we can assign it a 10 (because he lost the plot in pitch)
(rudderrudderrat has the idea.)

Right about now, I anticipate that all the experienced Airbus drivers will have their hackles up and snorting a loud "Bull Sh&t." "I've flown in those conditions and you just have to be gentle with it." And you would be 100% correct. The problem is that PF had never been trained for that corner of the flight envelope and started off on the wrong foot with it. To be specific, he used an improper control strategy. That was the beginning of the end for AF447. There was time to save the day later, but by then, the crew was too rattled to work their way out of the situation.

At least, that is my take on the HF side of this accident.
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Old 11th Mar 2012, 20:25
  #143 (permalink)  
 
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Lost information like AS

Hi,

CONF iture

It is technically feasible (and not costly) to detect this type of failure (on the fly ).

In new designs and existing (easy retrofit). Sensing aerodynamic pressure "reflected" on actuators. No load (or light one) means less surfaces like your example.

Curiosity: info on this incident, please.
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Old 11th Mar 2012, 20:30
  #144 (permalink)  
 
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The beginning of the end and remaining chances

Hi,

Machinbird:

To be specific, he used an improper control strategy. That was the beginning of the end for AF447. There was time to save the day later,




the crew was too rattled to work their way out of the situation.
With a better man machine interface this HF "disaster" could be reverted?
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Old 11th Mar 2012, 20:40
  #145 (permalink)  
 
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Large stimuli to a System near limits

Hi,

RetiredF4

Using 20°/s roll rate at 5.000 feet might be sporty, using them at FL 350 is imho insane.


Important point assertively mentioned!

And prior to any other "pitch stimuli"

Showing a completely inadequate handling technique.

With the enormous responsibility yet in the "correction loop" as one crucial "element".

Other than possible wrong indications (due AS anomalies) the displayed bank angle were reliable (and redundant)

Last edited by RR_NDB; 12th Mar 2012 at 00:36. Reason: gramatics correction
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Old 11th Mar 2012, 20:51
  #146 (permalink)  
 
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GIGO

Hi,

Garbage in is not allowed by IT personnel wisely because will generate Garbage out.

Question:

Considering PF is "inserted in the loop" when A/P (and A/THR) drops why PF of AF447 told about "crazy speeds"?

The System presents to the crew, Garbage (AS)?

If IT system is not fed with garbage, why erratic and conflicting data could be fed to "organic processors"?

This is safe during the transients? For example just after Law degraded.

This (garbage to the crew) promotes "graceful degradation" of the "Effective System" (system + PF) or could promote (briefly) accelerated degradation?
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Old 11th Mar 2012, 20:57
  #147 (permalink)  
 
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No redundance?

Hi,

A33Zab

Why in series?
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Old 11th Mar 2012, 21:00
  #148 (permalink)  
 
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Look, even at high level it's not that difficult, controls are soggy not firm but hey they still work.

Straight and Level Two as I taught it for years = Power plus Attitude plus Trim = Trimmed Performance.

Never mind complicating the issue by programming in benign failure, all the crew needed to do, even if the autopilot dumped the problem in their laps, was fly the S&L attitude and leave the ****ing power where it was.

That they weren't trained to do so, or that Airbus/AF encouraged a mindset that the software will save you, is the real problem.
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Old 11th Mar 2012, 21:02
  #149 (permalink)  
 
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Considering PF is "inserted in the loop" when A/P (and A/THR) drops why PF of AF447 told about "crazy speeds"?
Mac, If you will recall, the statement about crazy speeds was likely not the result of the instrument displays, but from the noise of the turbulent flow around the aircraft (due to extremely high AOA). Actual airspeed indications were largely Invalid due to the extremely high AOA, or extremely low-for the same reason.
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Old 11th Mar 2012, 21:11
  #150 (permalink)  
 
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New thread

Hi,

gums

As i understand, when PF is "inserted in the loop" due A/C anomalies, "crew coord, warning systems and training" becomes much more critical. Man machine interface must be very good (and simple up to a certain limit).

THS silently moving, SS of other pilot not viewable, etc. sounds like a threat to the "CRM involving the automatism features of the plane"

Mac.

PS

"CRM" in the sense of Management of all resources (including the auto ones) like THS.
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Old 11th Mar 2012, 21:11
  #151 (permalink)  
 
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Was it not the sound of the crystalline ice shower? Was it sound at all? Didn't he just "feel like we have some crazy speeds". We are at a linguistic disadvantage,
French is a challenge for me.

EG. If climbing and airmass is supplying some of the energy, rate of climb can be inconsistently sensed? Climbing "too quickly" for the expected g?
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Old 11th Mar 2012, 21:12
  #152 (permalink)  
 
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A33Zab can follow up if he wishes, but I think I can answer this.

First, there are two heaters in the pitot tube, one for the pickup barrel of the tube, the other for the watertrap area of the tube. The reliability of the pitot tube heater elements is very high. The current is monitored by the control computer. You want to know if there is a heater malfunction in either heating element. When in series, if either fails open, you know about it in a timely manner with a single current sensor. Since you have redundant pitot tubes, a single failure is no big deal by itself.
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Old 11th Mar 2012, 21:27
  #153 (permalink)  
 
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Pitot heater

Hi,

Machinbird:

I would design like that. it is correct.

Thank you

Mac

PS

A33Zab could help us in more important questions

i am scanning fast previous posts after a "difficult mission" (trip) and now preparing to post a continuation of the "PF in the loop, transient" issue. Part B will cover from 350 to apogee. When like you precisely said, they had the beginning of the end. by completely inadequate handling at this FL. And Why? Very interesting issue.
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Old 11th Mar 2012, 21:41
  #154 (permalink)  
 
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Crazy speedS

Hi,

Machinbird:

My rationale was based in the speeds (in plural). And also because "crystalline ice shower" IIRC started before.

And,

the noise of the turbulent flow around the aircraft (due to extremely high AOA
Occurred IIRC later when A/C was stalled. "turbulent flow around the aircraft (due to extremely high AOA"

The timing must be reviewed to verify. My feeling is of crazy speeds saw in his side and ISIS.


Plz, not consider:


Argument for my rationale:

Actual airspeed indications were largely Invalid due to the extremely high AOA, or extremely low-for the same reason.
So erratic, "viewed" as crazy.


Error!

Last edited by RR_NDB; 12th Mar 2012 at 03:12. Reason: text impvmt, argument and finally, removal of argument
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Old 12th Mar 2012, 00:31
  #155 (permalink)  
 
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Crazy speedS

Hi,

Bear,

Was it not the sound of the crystalline ice shower?


Based in a "pattern" memorized when read pertinent data (essentially BEA) my feeling was PF phrase was due what he was seeing.

This feeling could be verified looking the timing since start of ice crystals noise to the "crazy speedS" phrase.

Mac

PS

I posted before this analysis. Decision making, risk taking.
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Old 12th Mar 2012, 01:31
  #156 (permalink)  
 
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RR NDB

I think it is very hard to be accurate with this conversation. Firstly, it was hardly "discourse". I think also it was not CRM. If the CVR releases are complete, I would be astonished. I believe much is witheld, and, again, the translation is questionable.

If memory serves, Bonin mentions only "speed". Crazy or otherwise, crazy is not cockpitspeak for any condition I am aware of. PNF is closer to the ideal, but it is not fair to make any finding: conversation.

Entirely lacking context and continuity, until the final is in, this banter is confusing at best!

May your beacon find a direction, bear.
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Old 12th Mar 2012, 03:28
  #157 (permalink)  
 
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Glitch or intermittent failure

Hi,

Bear,

Probably facing a glitch,

I believe much is witheld, and, again, the translation is questionable.
Certainly.

but it is not fair to make any finding: conversation.
I was looking to "garbage in" fed to PF. So, "crazy speeds" could be a confirmation for that.

Again very limited factual information (necessary) and others factors like you mentioned.

I will investigate closer this point.

May your beacon find a direction, bear.
Sometimes our beacon could present "crazy headings".

Intermittent failures were one of my nightmares. I had one in RR (375 KHz) NDB many years ago. And in the return flight to my base it failed again,

Nothing compared to intermittent failures in "feedback Systems" where also the "failure" is feedback to the inputs of the System.

Last edited by RR_NDB; 12th Mar 2012 at 04:01.
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Old 12th Mar 2012, 04:00
  #158 (permalink)  
 
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Failures in Feedback Systems

Hi,

I learned from CJ, on the Concorde YD was slightly disturbed when HF radio was transmitting. Yaw Damper is a good example of a "closed loop" feedback System.

EMI/EMC aspects caused this problems later solved, i guess through shielding, etc.

PF was inside the loop after A/P and A/THR dropped.

As i understand, his "inputs" came from the displays ahead of him and from other "inputs" like noise, G, etc.

His actions with SS were clearly inadequate specially near the "corner". For example, roll.

Question:

His initial "pitch up", the ones that put the A/C in the zoom climb could be justified by a set of erratic "inputs" he saw?

The change of speed to alt could be a "based" decision (acting thinking to be under imminent risk) and putting the plane above REC MAX?
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Old 12th Mar 2012, 08:00
  #159 (permalink)  
 
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Cool

Hi,

Was it not the sound of the crystalline ice shower? Was it sound at all? Didn't he just "feel like we have some crazy speeds". We are at a linguistic disadvantage,
French is a challenge for me.
About "Crazy speed"
This is the exact transcript of the BEA in report N°3 in french language

J’ai l’impression qu’on
a une vitesse de fou
non qu’est-ce que vous
en pensez ?

I translate this as:
I have the "feeling" (impression) we have a crazy speed ... what do you think ?
So it's an evidence that this remark is not the consequence of instruments reading .. as he use the word "feeling"
what do you think ?
Add to the fact of "feeling" as he ask the other for infirm or confirm his "feeling"
This feeling may be the result of what he hears .. or an internal message of his body

Last edited by jcjeant; 12th Mar 2012 at 08:16.
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Old 12th Mar 2012, 11:41
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QUOTE JCJEANT
J’ai l’impression qu’on
a une vitesse de fou
non qu’est-ce que vous
en pensez ?

I translate this as:
I have the "feeling" (impression) we have a crazy speed ... what do you think ?

You are perfectly accurate in your translation. I would add that in French," une vitesse de fou" applies to very high, excessive speed. A speed very much above what you would expect, and completely abnormal.
We cannot be sure we have the whole exchange from the CVR...The sentence translated is not technical, factual language normally used in cockpit conversations. It is certainly expressing high stress, and the anxiety of not understanding the situation as far as speed is concerned.
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