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AF447 wreckage found

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AF447 wreckage found

Old 31st May 2011, 14:24
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The manufacturer Thales was well aware of the catastrophic consequences of a failure of the speed sensors as early as 2005. At the time, the French company concluded that such a failure could "cause plane crashes."

A total of 32 cases are known in which A330 crews got into difficulties because the speed sensors failed. In all the cases, the planes had pitot sensors from Thales, which were significantly more prone to failure than a rival model from an American manufacturer.

But none of the responsible parties intervened. In 2007, Airbus merely "recommended" that the sensors be replaced. Air France took that as a reason not to carry out the costly work -- and it even got official blessing for doing so. The European Aviation Safety Agency wrote that it currently saw "no unsafe condition that warrants a mandatory modification of the Thales pitot tubes."
Money is in play here, I'm sure. Typically, if the component maker or airframe builder make a Service Bulletin mandatory, they pay for it. If the SB is optional, the airline pays. I've known airlines who refuse to pay for SB that are to correct defects, regardless.
More rubbish from Der Spiegel. Air France was in the process of changing out the pitot tubes. They received their first shipment of replacement parts a week before the accident, but had not applied them to that particular aircraft.

As to why they did nothing for two years, consider that they were told that there was no safety problem by both the manufacturer and the regulator, and they must have agreed, so why do anything? It's not as though pitot tubes are that expensive when compared to other costs. It was only after a few other incidents that they took action on their own to start the replacements.
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Old 31st May 2011, 14:24
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On a Dutch news site here ( Inmiddels 77 lichamen uit ) the following claim is made (translated into English):
Quote:
The pilots wanted, thus becomes clear from the 'current conclusions' from the investigation into the two black boxes of the plane, to fly over a lightning storm, but were prevented from this because it wasn't possible due to the temperature to fly to that height.
Reading this kind of surprised me, as I didn't have the impression that they wanted to fly over the storm, but it would explain why they suddenly went into this steep climb.
31st May 2011 07:50
Elledan, the Dutch news site is wrong. To be sure of climbing over an ITCZ "lightning storm," the AF flight crew would have to have assumed they might well have to climb as high as 55,000 feet or so, and to do that, they'd have needed the Space Shuttle, not an Airbus. Their sudden climb to 380 had nothing to do with any attempt to top a thunderstorm.
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Old 31st May 2011, 14:32
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ST27

"The PF knew he was pulling up, but are you sure the PNF knew it? It's not quite as obvious what the other guy is doing with sidesticks, particularly if you are concentrating on a checklist."

It took me three pages to catch up and catch this statement, the rest mostly rehash, argument, etc.

Inferred in this statement are some very basic questions as to where cockpit management and aviating clash. If it turns out that PF was handling the situation poorly (and we have no idea if that is the case), then we have single pilot crew. Not trashing that concept, but ST27 points to a fundamental flaw (perhaps?) in allowing (mandating) a review of procedures developed by folks who were clueless re: the situation to hand. A fully qualified Pilot, rather than assisting in the aviating, is doing a checklist that arguably has no bearing on the current problem(s). Additionally, the procedure requires to distract the PF from his focus?

Here is an identified evidence of the Airline, the Manufacturer, the a/c, and the F/O distracting the recovery. At all times by the book, or memory of the book. PF and F/O were writing a new book, and the old book was horning in, inexcusably.

So in preventing the popular conclusion that all responsible parties were remotely engaged in sabotage by reflex, perhaps the authority will give it up?

Secrecy is Power, make no mistake, and at some time, even the apologists for the archaic dance of power will have to become vocal. Other than to say, "it is complicated".

Thanks to ST27
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Old 31st May 2011, 14:35
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Some people are better than others at maintaining good situational awareness. I would not belittle training and experience. But even very experienced pilots can become disorientated, as indicated by many sad examples among the accident investigation reports I have studied over the years.

Therefore, IMHO, any instrument which might work counter-intuitively in unusual circumstances, significantly increases the risk of disorientation and its associated consequences if those unusual circumstances should arise.

It remains my tentative view that the stall warning (the one at 2h10min51, perhaps; but mainly the one at 2h1202-17) could well have seemed to indicate that the nose-down inputs were for some reason causing the aeroplane to enter a stall, so discouraging the PF from developing the very inputs which might have led to an exit from the stall.

According to the preliminary report the angle of attack "n’est pas présentée aux pilotes": ie, the instruments did not include an AoA indicator. No longer trusting the airspeed or other indicators ("je n’ai plus aucune indication", and "on n’a aucune indication qui soit valable") it may have seemed to the PF that he faced two risks: going too fast for the airframe, or going too slow for the AoA. He seems to have discounted the second of those risks despite the stall warnings. So stated, this was an irrational response. Therefore, it is probable that something made it appear rational at the time. I suggest that he discounted it partly because of the stall warnings or, rather, because of the timing of the stall warnings and their seeming linkage to his nose-down commands.
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Old 31st May 2011, 14:41
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As to why they did nothing for two years, consider that they were told that there was no safety problem by both the manufacturer and the regulator, and they must have agreed, so why do anything? It's not as though pitot tubes are that expensive when compared to other costs. It was only after a few other incidents that they took action on their own to start the replacements.
Not so fast....Air France was well aware that the pitot tubes where a problem and sat on there hands. Yes, they had ordered them, but in hindsight too late. The fact that AF pilots refused to fly with the Thales pitot tubes after the accident because they were "aware of the problem" suggests that AF was not listening to there own pilots, or the pilots kept quiet...
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Old 31st May 2011, 14:44
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000tfm000

For the present, the times are merely landmarks, suggestive only of snapshots of aspect, response, input, etc. Just prior the Stall Warning that the pilot is rumored to have disobeyed, he is trending out of a high deck angle, and accelerating. This is the result of a Stall, and he will have known that he is in a Stall. Now you may argue that the alert (only an alert) has dissuaded him from continuing the recovery. Given the sparse frame work of such an argument, I will say that to be 'dissuaded from continued recovery' in the midst of physical cues that affirm it, defames our PF further.

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Old 31st May 2011, 14:46
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It remains my tentative view that the stall warning (the one at 2h10min51, perhaps; but mainly the one at 2h1202-17) could well have seemed to indicate that the nose-down inputs were for some reason causing the aeroplane to enter a stall, so discouraging the PF from developing the very inputs which might have led to an exit from the stall.
The one at 2h10min51 happened well over 60 kt, so there it wasn't switching back on from a deactivated state.
The second one was, but here no further information about what happened in the next 1m30s is given at all. Maybe he was discouraged, but maybe he kept pushing ND to no avail. We simply don't know because the report doesn't say.
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Old 31st May 2011, 14:50
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From ST27:
Once descending, the rate of descent didn't change, so passengers would have only sensed that the nose was pointed up, somewhat like an initial climbout on takeoff on say a DC-10 or 757. There also would have been heavy buffeting. Given that they were flying at night in a storm, the passengers would have had no outside references to know what was happening, and would not have known they were falling. A clue would have been the change in cabin pressure, but how many passengers would connect that with rapid descent?
If like me you click on the flight map when woken by turbulence, you might notice a drop in altitude/airspeed...

From ST27:
More rubbish from Der Spiegel. Air France was in the process of changing out the pitot tubes. They received their first shipment of replacement parts a week before the accident, but had not applied them to that particular aircraft.
Yes, but as you yourself point out they waited two years to do so because EASA told them, quote: "...[that it saw] no unsafe condition that warrants a mandatory modification of the Thales pitot tubes." So whether you blame AF for ignoring the soft Airbus recommendation, or AB for its soft recommendation, or EASA for its hard statement, clearly when even the manufacturer of a part says its a problem these things should not happen. EASA should be focused on one thing only - SAFETY. At least EASA - unlike the FAA - is not operator funded, so it has no excuse.
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Old 31st May 2011, 14:55
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Who was PF?

A number of news articles have stated that the PF was the relief pilot, who was the youngest of the crew, had the least amount of experience on type (800 hrs), and the least total flying time. If that is true, and with the captain going for rest, that would leave the FO as PNF. The FO had the most time on type of all the crew (4500 hrs).

None of the BEA reports have stated who was flying at the time of the upset. Perhaps the media obtained the information as a result of a leak. However, this arrangement seems odd to me.

Can anyone familiar with how work would be assigned on trans-ocean flights comment on whether this would be a typical assignment, given that they were about to fly into the ITCZ?
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Old 31st May 2011, 15:00
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For example, there is not enough informations to understand why the A330 climbed and stalled at 38 000 ft :

> the pilot gives «ordres à cabrer» (pitch-up orders)

> then the PF gives «ordres à piquer» (pitch-down orders)
Actually, I believe there is enough information to determine why the aircraft entered an initial climb after the disconnects - the pilot commanded it to.

Now, I also think that the report is missing some information but the BEA has shared when power settings changed. After the initial AP/THR discconect, no mention of a power change is made - so it is probably at the setting for FL350 and M0.8. The first input is a pilot commanded climb with a max recorded rate of 7,000ft/min. By the time they reached FL375 nose down had reduced that rate of ascent to 700ft/min (I believe that the plane was still climbing at that point albeit much slower than initially).

Without an increase in thrust, there is a trade of speed for altitude. Most likely pilot commanded but turbulence/updrafts may have played a part too. I think if there was an intent to climb over any weather then a thrust setting change would have been made by the PF and none is noted by the BEA.

At 2h10m51s the stall warn sounded. It probably hasn't stalled at this point - the BEA indicates the last 3m30s were stalled and the recording finished at 2h14m28s. That makes the stall a 'fact' at 2h10m58.

John.
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Old 31st May 2011, 15:01
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Who was PF?

According to this article, Bonin was the PF. As you suggest this could very well be pure speculation on the part of the journalist - or possibly based on a leak? 'Baby' pilot at controls of doomed Air France Airbus | The Australian
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Old 31st May 2011, 15:04
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Deliberate climb to get out of icing but with no reliable speed mismanaged thrust ?
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Old 31st May 2011, 15:07
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Elledan, the Dutch news site is wrong. To be sure of climbing over an ITCZ "lightning storm," the AF flight crew would have to have assumed they might well have to climb as high as 55,000 feet or so, and to do that, they'd have needed the Space Shuttle, not an Airbus. Their sudden climb to 380 had nothing to do with any attempt to top a thunderstorm.
Yeah, that's what I figured. Pilots can fly around a storm, but they can't fly over one. No idea why this news site (usually very reputable) made such a big blunder. Their claim struck me as odd as it was never coined as a possibility elsewhere, especially not on this site

The current conclusion seems to draw towards pilot error with equipment failures and gaps in training as likely contributions. The nose-up inputs especially seem beyond merely curious. I really wonder whether there might be anything about that on the CVR.
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Old 31st May 2011, 15:15
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Can anyone familiar with how work would be assigned on trans-ocean flights comment on whether this would be a typical assignment, given that they were about to fly into the ITCZ?
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The trouble is when a pilot is given "a leg" which is more or less what happened when the second officer was PF after the captain had gone down to have some shut-eye, there seems to be a attitude that as PF he hangs on to the decision making and controls even though the real first officer is more qualified and senior in succession. "My leg" is not carte blanche to be in command unless of course the captain is PF.

Clearly in the Air France case the experienced first officer as PNF should have taken control immediately things went wrong. Of course there was no guarantee the F/O could have saved the aircraft either but the political correctness of "my leg" needs to be examined. In my era the captain would at his discretion offer the F/O a take off and/ or a landing. It was never a case of "your leg" with all that implies. It was always the captain's "leg". Every sector was under the command of the captain and supported by his F/O.

Now it is almost seen as an insult to the first officer if the captain decides to take over control of the F/O's "leg". In the case of the Air France accident it is this politically correct mind-set that may have caused the real first officer to assume the subordinate role as PNF while the second officer lost control of the situation.
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Old 31st May 2011, 15:28
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This is indeed an interesting observation, worthy of a study in itself. Where I work, we have a general inkling that CRM has gone 'bonkers'. It certainly was baffling to me why the Captain did not jump back into the seat and 'take over', until explained this way...
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Old 31st May 2011, 15:49
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Yeah, that's what I figured. Pilots can fly around a storm, but they can't fly over one.
Some unfortunatelty try to do it , it ends up badly most of the time.

In my years as ATC the one I remember best was a transatlantic bound 747 from a major European airline (now defunct) who decided against the 60-80NM dogleg that everyone else was doing to avoid a line of CBs above Belgium. He asked to climb to FL390 to keep its route , then when above dropped down 5 or 6 thousanfds feet right inside. His voice was shaken afterwards. The incident report must still be out somewhere.

2 weeks a go an A320 tried the same thing above Germany, with same results. 3xmayday, dropped 4000ft etc..
Rare events , sure ,but not unheard of.
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Old 31st May 2011, 17:19
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Allocation of (PF) flight legs to crew.

A37575:

It is not a right that every other leg belongs to the F / O or 2nd Captain.

It is the Commander's decision to allocate the legs, if he wants to.

The decision of the Captain, to go to the "bunk" so early in the flight seems strange to me, however he must have had a reason.
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Old 31st May 2011, 17:36
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The decision of the Captain, to go to the "bunk" so early in the flight seems strange to me, however he must have had a reason.
Not really, as I think has been mentioned earlier in the thread if it's pure timing we're questioning here then if the Captain had "second break" the timing makes sense.

On the broader issue of him being "off watch" during the ITCZ crossing, personally, I think you have to take into account the fact that he left two fully rated pilots up front - not cruise only copilots. If we're saying a Captain shouldn't ever leave the Flight Deck because inclement weather is forecast in the cruise how do we suggest handling say, traversing Asia or Indonesia during the monsoon season or the North Atlantic if there's forecast of occasional severe CAT all the way across the pond......two Captain ops/no in flight rest ????

(BTW am I alone in often not being able to see the last page of the thread?)

Last edited by wiggy; 31st May 2011 at 18:07.
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Old 31st May 2011, 17:43
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Dumb question

Maybe a dumb question from a dumb SLF - wouldn't it make sense to have a mechanism that blows into the Pitot tube from the inside to test if it is clogged? If there is higher resistance than its clogged and disregard readings. Maybe it can also be cleaned that way...?
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Old 31st May 2011, 18:24
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Originally Posted by 000tfm000
Some people are better than others at maintaining good situational awareness. I would not belittle training and experience. But even very experienced pilots can become disorientated, as indicated by many sad examples among the accident investigation reports I have studied over the years.

Therefore, IMHO, any instrument which might work counter-intuitively in unusual circumstances, significantly increases the risk of disorientation and its associated consequences if those unusual circumstances should arise.

It remains my tentative view that the stall warning (the one at 2h10min51, perhaps; but mainly the one at 2h1202-17) could well have seemed to indicate that the nose-down inputs were for some reason causing the aeroplane to enter a stall, so discouraging the PF from developing the very inputs which might have led to an exit from the stall.
I too shall declare my interest: A320 Captain.

I really don't know where to start with this thread. So much noise, so little signal. The number of red herrings and long irrelevant side tracks is so great that no one can even start to address them.

The PF quickly and correctly diagnosed the situation. Loss of airspeed indication, resulting in AP/AT off and Alternate Law. He then incorrectly pitched up to 10° until the AoA was just 2° from the stall.

In this perilous position, the AoA increased again to 6° and the aircraft stalled. The response was incorrect with TOGA + pitch up.

So, two apparent errors. So much has been said about the wrong procedure being used (TOGA + pitch up is used in many other procedures) and a lack of training that I won't bother. But here is something frightening:

Most older Airbus pilots have done their time in cranky old jets and turboprops, where you fly by pitch. Everything is done by pitch settings - choosing, setting, adjusting, waiting and so on. However, in the world of the safety committee it is fine to pluck young lads straight from a Seneca and place them into an Airbus. To mitigate the risk, the flight director must be on at all times. Now all the cadet has to do is put the square in the centre of the cross. Never has a pitch been noticed nor noted.

I asked 5 first officers in the cruise to look me in the eye and tell me what pitch we were at (2.5°). 4 cadets answered between 5° and 10° , and one ex TP guy answered correctly at 3°. Not much of a sample, but indicative I suspect.

The Airbus is a fine aircraft. It is conventional, and simple. On top is a thick layer of cotton wool, that should protect us from our silly mistakes.

Once the cotton wool is removed, we are back into a simple jet. The snag is that with the current drive to train/recruit people as quickly and cheaply as possible, not one of the recent arrivals has ever flown in "simple jet mode" (by pitch and thrust). Incredibly in our airline it is now even prohibited to take off with the flight directors off.

I feel sorry for the two FOs on the flight deck. Without the FD they will have been in new territory. Without the airspeed, it is no time to have to guess pitch settings and develop a strategy to keep the thing in the air.

I hope the airlines have a good think about this. I imagine the safety departments will, but nothing will happen due to the cost of recruiting people with experience on conventional types.

PS: Below 60 knots I imagine the stall warning is inhibited because there is not enough airflow over the AoA vane to make it accurate and trustworthy.

PPS: Has any Airbus pilot here ever actually heard the stall warning in the sim?
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