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AF 447 Thread No. 5

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AF 447 Thread No. 5

Old 29th Jul 2011, 21:05
  #961 (permalink)  
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Lonewolf_50;
IIRC from our discussions a few threads ago, AoA can be called up already on one of the pages (maintenance?).
The AoA parameter, along with thousands of other parameters, may be brought up on the 3rd ACARS unit on the pedestal, using the ACMS > Alpha LBL settings. I used to watch the AoA, FPA, VRTG, LATG, CAS, TAS all the time. It takes about 3 minutes to go through the menu call-up process so it wouldn't have been available here.

Further, regarding the safety recommendations, I doubt if the recommendation to include the AoA in the available displays for crews is a realistic, or even helpful idea. Airline pilots don't fly "AoA" and it would be a significant transition from pitch, power and speed to train crews to fly primarily AoA. I don't think it would have helped or saved this situation because AoA wasn't being taught/trained. Besides, this is the only accident we know of which could have made use of an AoA display to save the aircraft. The Turkish B737 could not have been saved as there wasn't sufficent altitude by the time the aircraft stalled, and they weren't paying attention to the airspeed, so an AoA indication may not have helped.

airtren, thanks for your very kind response.
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Old 29th Jul 2011, 21:05
  #962 (permalink)  
 
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Going over this twice, the following passage looks somewhat like the PF has an attitude indication that's gone wrong.

Yes, I know there's no ACARS hit, but he does not seem to be seeing what the PNF is seeing.

I am not sure what he was looking at, but I have a suspicion that he was on a performance instrument scan rather than an attitude scan during part of this, and it may have been due to his attitude not matching what he was seeing ... but I think that if PNF had seen PF's display as being different from his, he might have done something ... what was "putting you on ATT" mean?
Was he switching attitude indicator reference?
2 h 10 min 27 to 2 h 10 min 31
PNF: Fais attention à ta vitesse Fais attention à ta vitesse
Watch your speed Watch your speed

PF: Okay, okay okay je redescends
ok ok ok I'm going back down

PNF: Tu stabilises
stabilize (“stay there”)

PF: Ouais
Yeah

PNF: Tu redescends
You're going back down

2 h 10 min 33
PNF: Selon les trois tu montes donc tu redescends
According to the three you're going up, so you go back down (meaning the three vertical speed indicators... )

2 h 10 min 35
PF: D’accord
Agreed

2 h 10 min 36
PNF: T’es à ... Redescends
You're at ... go back down !

PF: C’est parti on (re)descend
On our way we're going (back) down

2 h 10 min 39 to 2 h 10 min 46
PNF: Je te mets en en A T T
I'm putting you in in A T T

2 h 10 min 42
PF: On est en ouais on est en climb
We're in yeah we're in climb
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Old 29th Jul 2011, 21:09
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spagiola,
Great job!
I might disagree with a couple of translations, but they would depend on intonation, etc. so I've no intention to argue about them.
Yours is probably better than the "official" BEA English translation, which I haven't bothered to read yet.
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Old 29th Jul 2011, 21:12
  #964 (permalink)  
 
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PJ, what I was getting to is that the AoA data is already fed into the system anyway, as you describe: it's there for the taking. My thought was to allow it to be direct fed to a different page rather than having to page down to dig it out.

If I am reading correctly, the F/CTL page comes up with one or two movements or touches, or comes up on its own if a given malfunction circuit completes. (If I misunderstand, sorry).

Put another way, have it on the first floor rather or the lobby of the hotel, not the seventh level of the underground parking garage.

No need to change anything else.

Buuuuuuuuuuut,

that means you'd need to believe you needed to look at AoA to summon F/CTL and see what it is. Different scan and Cockpit coordination drill, certainly.

I also appreciate your point on the AoA in the scan: what scans do you teach for which aggregate tasks or task sequences? It's a cross check, not a primary, as I see it.
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Old 29th Jul 2011, 21:14
  #965 (permalink)  
 
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French translation...

"J'ai plus du tout controle de l'avion" means "I have no control at all of the plane".
Good French would read: "Je n'ai plus du tout controle de l'avion", but of course most people in France and elsewhere do not speak their own language properly, creating ambiguities and confusion for any kind of automated software translation.
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Old 29th Jul 2011, 21:15
  #966 (permalink)  
 
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Originally Posted by Lonewolf_50
Going over this twice, the following passage looks somewhat like the PF has an attitude indication that's gone wrong.
I'm not sure - to me it seems like he thinks he knows exactly what he's doing and does not understand why despite full back stick and full power he is still losing altitude (this despite the stall warning going off - possibly "tuned out" by the stress of the situation)...

Originally Posted by spagiola
2 h 13 min 25
PF: Qu’est-ce qu’y… comment ça se fait qu’on continue à descendre à fond là?
What is... how come we're continuing to descend so fast?

2 h 13 min 28
PNF: Essaye de trouver ce que tu peux faire avec tes commandes là-haut Les primaires et cetera
Try to see what you can do with your controls up there. The primaries etc

2 h 13 min 32
PF: au niveau cent
At level 100

2 h 13 min 36
PF: Neuf mille pieds
9000 feet

2 h 13 min 38
CAP: Doucement avec le palonnier là
Easy with the rudder

2 h 13 min 39
PNF: Remonte remonte remonte remonte
Climb climb climb climb (literally, "remonte" is "climb back up")

2 h 13 min 40
PF: Mais je suis à fond à cabrer depuis tout à l’heure
But I'm nose up to the limit since earlier
Followed by the Captain realising what's happened and telling him to get the nose down

CAP: Non non non ne remonte pas
No no no don't climb back up

PNF: Alors descends
Go down, then
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Old 29th Jul 2011, 21:16
  #967 (permalink)  
 
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Originally Posted by Dozy
CAP: Là je sais pas
That one I have no idea of


Could be airspeed.
Not at all. The Captain is answering the previous question from the PNF addressed to him:
PNF: what do we have to do?
CAP: No idea (basically, it is the meaning = here, I don't know.), we are going down (constat ; statement).

See:
2 h 12 min 13
PNF: Qu’est-ce que tu en penses qu’est-ce que tu en penses, qu’est-ce qu’il faut faire ?
What do you think ?what do you think ? what do we have to do?

2 h 12 min 15 to 2 h 12 min 19
CAP: Là je sais pas là ça descend
I don't know we're going down
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Old 29th Jul 2011, 21:20
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@JCJEANT:

You mean this period? I did draw some lines and added text.

Indeed most peculiar, TOGA?
sorry no answer yet, I have to wait for full translation.

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Old 29th Jul 2011, 21:24
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Originally Posted by takata
Not at all. The Captain is answering the previous question from the PNF addressed to him:
OK, I got you - so you're disagreeing with vanHorck's theory (which in retrospect, having reread I'm inclined to agree with you).

That doesn't change my reading of what the captain was getting at though, which must have been an awful realisation when it hit him.
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Old 29th Jul 2011, 21:34
  #970 (permalink)  
 
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Dozy, you and I are quoting different parts of the discussion.

Can we try and discuss the same parts?

Early on, we seem to have a disagreement in what the two of them are seeing, as the PNF keeps telling him about what he's doing and what's going on. It may be that they were seeing something different. It is also possible they were seeing the same thing and interpreting it differently. It is also possible that PF's scan began to break down about the time he took controls in Alt 2 ...
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Old 29th Jul 2011, 21:40
  #971 (permalink)  
 
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Good points!

A further departure from the original recorded voices seems to be also the French notation, which is not capturing the use of the "imperative", as in to giving directions of what to do: do that !, don't do that!, sort of giving orders...

Like the first instances of "redescend", should have been "redescend ! "., as an imperative, as an order - the PNF tells PF what he should do to correct the altitude gain.

airtren

Originally Posted by takata
Hi Lonewolf,

Be carefull (everybody) about the transcript meaning. It is better to wait for the English translation which will be painful to do (I guess it is the reason why they are late on it).
French talk (especially in high stress context) is using a lot of undefined terms; here, "il est où" could mean "where it is?" or "where he is?". In context, I understand that something is missing on his pannel (like Flight Director, or another indication he was looking at that disapeared) rather than "someone" -the captain.
A lot of these sentences are completely meaningless without the tone -might be interrogative, or talking to one or to the other or to himself or even to the aircraft.
....
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Old 29th Jul 2011, 22:06
  #972 (permalink)  
 
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A first post from a non aviation-professional who has lurked here for 3 years:

Is there a detailed time-stamped control input graphic available somewhere? If already posted, would appreciate the post #.

Specifically, I am interested in the seconds after the nose down input at around 2:17:17. Was the limited amplitude of this input the reason why the TLS stayed fully up? Or was the limited duration of this input the reason why the THS did not change position from fully up? Bear with me please, I appreciate I have no understanding of the autotrim algorithms in any mode.

Also, how many seconds elapsed between the stall warning following the nose-down input around 2:12:17, and the subsequent nose-up input? Did the PF immediately move the stick nose-down after the stall warning sounded?

What I am trying to get an estimate for is, how much time would have been needed before the aircraft regained enough speed to turn off the stall warning (i.e. because of adequate airspeed and not because of the warning being disabled by illegal angle of attack), in 2 hypothetical situations:
  1. the nose-down input at around 2:12:17 had been maintained?
  2. the nose-down input at around 2:12:17 had been maintained and the THS had been at 0
and then compare the estimated times in with the time between the stall warning a few seconds after 2:17:17 and the PF's subsequent nose-up input (reaction?)?

Informed estimates, anyone?
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Old 29th Jul 2011, 22:11
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Dumb non-pilot SLF question here, and I apologise for posting in the Tech forum - but this has been nagging at me.

The a/c described almost a complete circle, anti-clockwise, before it hit the sea. Is this typical of what happens in a stall, or does it suggest the plane was wing-down all the way?

The Captain sounded concerned about getting the wings level before anything else, and the whole mess kicked off with the PF trying to correct a roll to the right. Is there something in this that might have confused / distracted them? Would a persistent tilt to the right, or a roll from one side to the other, have confused the sensation of being light in the seat, or made it harder to distinguish dive from stall?

Apologies again. Please ignore if stupid.
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Old 29th Jul 2011, 22:12
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Hi A33Zab, jcjeant, (post #966)

I think the portion to the right which is cut out from your chart, which shows that the elevators positions corresponding to the ND stick commands, go from -30 to -15, which is still on the same side of the Y-axle as the HTS, which is steady at -13.

Originally Posted by A33Zab
You mean this period? I did draw some lines and added text.

Indeed most peculiar, TOGA?
sorry no answer yet, I have to wait for full translation.
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Old 29th Jul 2011, 22:31
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Hi Lonewoolf_50 (post #918)

The Tarom pilots were on "the top of it", from the start of the ascent, before the stall, and during the undesired ascent, trying to bring the nose down. The A/THR pushed the HTS all the way UP. According to the BEA report, at some point the HTS was full UP, the Elevators full DOWN. Remember this guys were at 60 degree pitch up, and 30knots, at stall, and they still managed to turn the nose downwards, get enough speed and lift, to level at 800ft (within 3300ft)....

Now the AF 447's 10000ft/min could have worked to their advantage, of having an initial speed, had they been able to just pitch it down enough, from the nose up pitch, so that the falling speed would have started putting lift into the wings.
airtren

Originally Posted by Lonewolf_50
I doubt that aircraft developed a 10,000 fpm rate of descent. (And good thing, the pilots reacted promptly! Overcoming that 10,000 fpm from first unstalling, then getting knots on, then recovering with a nice firm pull without heading toward accelerated stall, since you are not in Normal Law ... how much altitude that takes is a question worth thinking through.
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Old 29th Jul 2011, 22:34
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Cool

Hi,

Is there a detailed time-stamped control input graphic available somewhere? If already posted, would appreciate the post #.
Page 111 of the french report it's a graphic ... and some other below ...
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Old 29th Jul 2011, 22:37
  #977 (permalink)  
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Lonewolf_50
"PJ, what I was getting to is that the AoA data is already fed into the system anyway, as you describe: it's there for the taking. My thought was to allow it to be direct fed to a different page rather than having to page down to dig it out."

If you are going down at 10,000 f/min in a more-or-less horizontal attitude you must have a very large AOA. You are either stalled or the fuselage has come off.
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Old 29th Jul 2011, 22:45
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p110 - the 'TEMPERATURE STATIQUE' is also clearly affected by ice at same time as the speeds - temp rises to 0 as ice melting - so what about the super-cooled ice theory again - and could it have also frozen the PF's static pressure and altitude readings?
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Old 29th Jul 2011, 23:03
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Originally Posted by Lonewolf_50
Dozy, you and I are quoting different parts of the discussion.

Can we try and discuss the same parts?
Sure, although the truth is that I haven't a clue what that exchange signifies and this is probably key to the BEA's recommendation to get more parameters onto the DFDR (like the instrument displays on both sides). If the PF's attitude display was faulty (or not making sense), then logically the first thing to do would be to hand control to the PNF, who seemed to have a better handle on things.

Unfortunately because we can't know that, there will always be a question mark about what caused the PF to make those inputs. Sadly this is a thread that has run through accident investigation for some time, examples being BEA548 - where the FDR explained what happened but there was no CVR to give definitive clues as to why, UA535 - where the FDR was a primitive model that didn't record enough parameters to give a full picture, and Tenerife, where full CVR, FDR and ATC recordings were available but the error was so basic and yet so gargantuan that one of the investigating teams had a tough time believing what they were hearing and seeing. "If we only had that parameter recorded" is a sad lament in an age where we can store hours of nonvolatile audio-visual information on a sliver of metal about the size of a child's little fingernail.

I think ultimately what needs to come out of this is an understanding of the psychology of pressure situations - how one pilot can lose both engines and yet rely on his training to ditch the aircraft in a river and save everyone on board, yet at least two others have lost airspeed indications and been so confused by what their instruments were presenting them with that they stalled an otherwise serviceable airliner into the sea. It's not really a fair comparison, because in the former case all the instruments were working - but it's the level of pressure and knowing that this situation is for real that really interests me. China 006 (The 747SP that went aerobatic over northern California) is another example of instrument perception being clouded by pressure and stress. All three of the flight crew swore that their horizons had tumbled when in fact they had not.
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Old 29th Jul 2011, 23:16
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Cool

Hi,

then logically the first thing to do would be to hand control to the PNF, who seemed to have a better handle on things.
You make me remember that "Der Spiegel" had used "baby pilot" for the PF
Seem's they had good informants as the BEA report show now that it was the youngest pilot as PF during the event
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