PPRuNe Forums - AF447 Thread No. 3

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AF447 Thread No. 3

This is what I do not understand. Why would the PF pitch up whilst reacting to the stall warning? Or have I missed something?

It s also time for a new server for the bea website. :bored: The current one is smoking.

It would be preferable for you to read the (very small) report before making such silly statements. JT

Like Colgan Air 3407, perhaps?

The French-language version (which is the official one) has some differences from the English one:

http://www.bea.aero/fr/enquetes/vol....mai2011.fr.pdf

Dozy, I would not dare to say that yet, the report is very unclear. It feels as if we are presented only half the information.

AGB, could you elaborate on those differences, my French is very rusty.

@ Penko

The differences are fairly slight, and look to me to be the result of rushing the job of translation and even missing a couple of sentences altogether (not helping the flow of sense at all - the initial English copy, for example, missed the sentence about the first stall warning, with the second warning being the first one detailed.....). BEA have already slightly corrected the English version (as usual) - so, when things have calmed down a bit, I'll take a close look at both and see what, if any, substantive differences remain.

[BTW, I'm no aviator, so my only contribution will be a language-thing, as best I can.]

Thanks AGB, I'll check again tonight.

Hi Takata,

Thanks for your reply. Yes, you're right, the BEA have to keep it factual and proper. I just thought we might learn some more about communication between the pilots, which I'm sure was a bit more colourful than what has been released, and may also shed some more light on what was happening.

All in due course, I'm sure.

Agreed with, the differences noted so far don't change much of the facts.

Anyway, as per the disclaimer, french version is "the good one".
Let's see : (french/english bad[/COLOR]/english corrected)

"L’assiette de l’avion augmente progressivement au-delà de 10 degrés et il prend une trajectoire ascendante."
"The airplane’s angle of attack increased progressively beyond 10 degrees and the plane started to climb."
"The airplane’s pitch attitude increased progressively beyond 10 degrees and the plane started to climb."

"Il y a eu une incohérence entre les vitesses affichées côté gauche et sur l’instrument de secours (ISIS). Elle a duré un peu moins d’une minute."
"There was an inconsistency between the speeds displayed on the left side and the integrated standby instrument system (ISIS). This lasted for less than one minute."
"There was an inconsistency between the speeds displayed on the left side and the integrated standby instrument system (ISIS). This lasted for a little less than one minute."

That's all I found after a quick reading.

Hi,

Air France communication in reaction of the BEA communication 27 May 2011

Communiqués de presse

takata: thanks for the diagram you posted, I am unable to access the BEA report. (Will wait until this weekend when traffic slows down).

Dozy:

I think that it would be a mistake to try too hard to compare this to Colgan Air mishap near Buffalo, on the human side (significantly greater and depth of experience), and because the flight was in the cruise rather than terminal phase of flight.

I appreciate the "why the nose pitch up?" question.

Until after the weekend, I'll be scarce. I wish you all a pleasant weekend.

Type of Weather Radar used?

Would anyone be so kind to indicate what type and brand of weather radar was installed in AF447?Don`t forget that even though it might have been incorrect stall recovery by the pilots,how they ended up in a CB IN THE FIRST PLACE,would most likely be ,the blame of the weather radar.To me 10 000 fpm descent, might have been aided with the CB downdraft.

A few posters have commented on the THS movement, and how one idea was the pilots not moving the THS following recovery of the stall.

From my knowledge this is an auto-trim aircraft. Aside from movement of the trim wheel is there any other action that could have been done to manually reset the THS. Unlike a 737 for instance where there is a separate trim switch.

can someone explain

Can some professional pilot on this board please explain why any pilot would rationally want to have a nose-up attitude in a stall situation? The report said the pilots were nose-up and with a angle of attack of 35 degrees on descent (double what would cause a stall in my admittedly amateurish C152). I am 29hrs into my PPL, and have always believed/taught/executed that the first thing you do to break a stall is a nose-down (and level wing) attitude. I am a complete novice and really do not understand why/how this happened. It is a real tragedy but as a green trainee I want to learn from this.

can anyone help explain what i'm missing here?

Hi,

Quote:

A few posters have commented on the THS movement, and how one idea was the pilots not moving the THS following recovery of the stall.

Quote:

A 2 h 10 min 51 , l’alarme de décrochage se déclenche à nouveau. Les manettes de commande de poussée sont placées sur le cran TO/GA et le PF maintient son ordre à cabrer. L’incidence enregistrée, de l’ordre de 6 degrés au déclenchement de l’alarme de décrochage, continue à augmenter. Le plan horizontal réglable (PHR) passe de 3 à 13 degrés à cabrer en 1 minute environ ; il restera dans cette dernière position jusqu'à la fin du vol.

At 2H10.51 this is again a stall alarm.the power levers are put on the position TO/GA and the PF keep the command to climb.
Incidence angle of 6° when sounded the stall alarm continue to rise.
The adjustable horizontal stabilizer go from 3° to 13° (climb position) in about 1 minute.
He will stay in this position to the end of the flight.

Quote:

A 2 h 12 min 02, le PF dit « je n’ai plus aucune indication », et le PNF « on n’a aucune indication qui soit valable ». A cet instant, les manettes de commande de poussée se trouvent sur le cran IDLE, les N1 des moteurs sont à 55 %. Une quinzaine de secondes plus tard, le PF fait des actions à piquer

At 2H12.02 the PF tell "I have no more indication" and the PNF "we don't have any accurate indication"
At this moment the power levers are on position IDLE and N1 engines indicate 35%
15 seconds after the PF perform a command to dive

How it's possible that the horizontal stabilizer stay in climb position when the PF perform a dive command ?

Quote:

Originally Posted by ask26 (Post 6476521)

From my knowledge this is an auto-trim aircraft. Aside from movement of the trim wheel is there any other action that could have been done to manually reset the THS. Unlike a 737 for instance where there is a separate trim switch.

It's auto-trim until it's not - that function/law can drop out automatically (when HAL/George gives up) and it did at Perpignan.

737 has auto-trim too - again, it can drop out automatically, after putting the trim full up - see Schipol (and at least one other incident).

he thinks he's diving

Maybe the reason the PF persists with a nose-up command and then resets throttles to idle is that his instruments tell him he is diving and overspeeding????

Quote:

At 2H12.02 the PF tell "I have no more indication" and the PNF "we don't have any accurate indication" At this moment the power levers are on position IDLE and N1 engines indicate 55% {per the French original} 15 seconds after the PF perform a command to dive

Don't have any accurate indication of what parameter, what gage on the instrument panel? :confused:

I'm posting here as the old thread disapeared.

Hi Svarin,

Quote:

Originally Posted by Svarin

BEA wrote :

Quote:

The airplane’s angle of attack increased progressively beyond 10 degrees and the plane started to climb. The PF made nose-down control inputs and alternately left and right roll inputs.

Feels strange to me...

Quote:

The trimmable horizontal stabilizer (THS) passed from 3 to 13 degrees nose-up in about 1 minute and remained in the latter position until the end of the flight.

Suspiciously similar to Perpignan.

Well... suspiciously not surprising from you by the way you are quoting the report by removing the parts between both "nose down" orders and what happened when this THS trimming changed from +3 to +13 deg. Read it between 0210:51 and 0212:17.

For this part, the report says:

Quote:

A 2 h 10 min 51 (5), l’alarme de décrochage se déclenche à nouveau. Les manettes de commande de poussée sont placées sur le cran TO/GA et le PF maintient son ordre à cabrer. L’incidence enregistrée, de l’ordre de 6 degrés au déclenchement de l’alarme de décrochage, continue à augmenter. Le plan horizontal réglable (PHR) passe de 3 à 13 degrés à cabrer en 1 minute environ ; il restera dans cette dernière position jusqu'à la fin du vol.L’altitude est alors d’environ 35 000 ft, l'incidence dépasse 40 degrés et la vitesse verticale est d’environ - 10 000 ft/min. L’assiette de l’avion ne dépasse pas 15 degrés et les N1 des moteurs sont proches de 100 %. L’avion subit des oscillations en roulis atteignant parfois 40 degrés. Le PF exerce une action sur le manche en butée à gauche et à cabrer, qui dure environ 30 secondes.

0) Stall Warning
1) TOGA applied (pitch up reaction)
2) PF maintaining pitch up during 30 seconds
3) THS moving from +3 to +13 deg.
4) Pitch increase to about +30 deg (from +10 to +40).

Quote:

A 2 h 12 min 02, le PF dit « je n’ai plus aucune indication », et le PNF « on n’a aucune indication qui soit valable ». A cet instant, les manettes de commande de poussée se trouvent sur le cran IDLE, les N1 des moteurs sont à 55 %. Une quinzaine de secondes plus tard, le PF fait des actions à piquer. Dans les instants qui suivent, on constate une diminution d’incidence,les vitesses redeviennent valides et l’alarme de décrochage se réactive.

It looks like the PF did not order a nose down command until 0212:17 -- hence, 1 mn 26 sec without any nose down orders... no indication that he tried to override manually the THS either). The only corrective action against the positivie attitude was to select IDLE thrust. Those late nose down action started to reduce the pitch despite this +13 deg THS. (Now, why it stayed frozen here is nonetheless a disturbing issue when those nose down orders were finally applied, but it is the reason why I'm waiting for more info about any use of the manual trim wheel during the previous upset).

But, a VERY selective reading could always make one quite happy with his very "suspicious" findings!