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Why did Air France 447 go down?


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This author has some interesting opinions about thunder storms.

http://www.nationalpost.com/opinion/columnists/France+down/4722139/story.html

Indeed he does... quite well written article, except for the fact that on most airliners, such as the A330, pitot heat is always ON, so pilots won't forget to turn them on in "precipitation".

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I don't find his opinion about TSMs interesting. Basically what he said is true....most drivers never go near them and those that do learn that Mother Nature wins. Seldom do TSMs bring down an airliner, certainly Micro bursts can, at low altitude when the aircraft is in a "low/slow and possible "dirty" config.

Hopefully the black boxes hold the answers cause as it stands now, based on what we, the public, know the aircraft stalled in from a very high altitude....how did that happen?..too much reliance on technology or ??????

It will very interesting to see what washes out and hopefully the Black Boxes have the info the investigators need.

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When you consider the scope of that result, in it's entirety, it is truly remarkable! Those devices, and their memory modules, having been violently wrenched from their perches, were sitting in 5000psi salt water for 2 years!

I anxiously await publication of their contents!

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If the initial evidence had shown that a problem with the aircraft was likely the cause and that the crew had been helpless to do anything about it, what are the chances that Air France would have sat on that bit of news for over a year while the final report was still pending? :scratchchin:

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PARIS—Air France Flight 447’s flight recordings show the aircraft lost speed and stalled after its airspeed sensors failed while the two co-pilots were at the controls, two people with knowledge of the investigation said.

The chief pilot, Captain Marc Dubois, was not in the cockpit when the Airbus A330’s airspeed sensors malfunctioned, causing the autopilot to disengage over the Atlantic Ocean, the sources said.

A low-speed stall occurs when an aircraft slows to the point where its wings suddenly lose lift, an incident pilots learn to overcome in basic training. Flight 447’s last automated transmissions logged faulty readings from airspeed sensors that caused the autopilot to shut down in bad weather, minutes before the accident in which all 228 passengers and crew perished.

“To get out of a stall, you stick the nose down and wait for gravity to speed up the aircraft,” said David Learmount, a former U.K. Royal Air Force pilot and safety editor at Flight International.

Pulling out can be straightforward, “providing you realize you’re in one,” he said.

Air France spokesman Jean-Charles Trehan said the company had no comment on the investigation’s early findings. France’s air-accident investigation bureau also declined to comment on the circumstances of the June 1, 2009, crash.

Investigators say they are making progress after maritime search and salvage experts retrieved the flight data and cockpit voice recorders this month from a depth of 3,900 metres. Dubois was among the victims recovered from the sea surface in the weeks after the crash.

The failure of the Thales airspeeds sensors, or Pitot tubes, occurred while the plane was cruising at about 10,000 metres, four hours after take-off from Rio de Janeiro. At that stage in the Paris-bound flight, it is routine practice for the captain to take a rest break and leave the co-pilots at the controls, Air France has said.

Two months after the crash, Airbus advised A330 and A340 operators to replace the Thales sensors with a model from Goodrich Corp.

A stall is typically preceded by shaking and vibrating of the aircraft, and modern jets are equipped with a steering-stick shaker and audio warning to alert the pilot. Stall recovery requires pilots to coordinate the aircraft’s angle and power to the engines to avoid aggravating the situation.

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The 'blame game' has begun.

Perhaps the crew was at fault? Was experience and or training a problem?

Or...is the design of modern ac so complex that the warnings from multiple system failures would overwhelm even the best of pilots?

IMHO and even though it's a little early; there should always be someone 'flying' the ac. That is, someone that's focus is devoted to flying and not managing the 'checklist' and the associated actions. If all three crew members had been on the flight deck managing this emergency, the outcome may have been entirely different? Therefore, this accident may ultimately be properly attributed to a failure of 'design / regulation'?

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"encountered some turbulence and unexpectedly high icing at 35,000 feet"

- thunderstorm? whistling.gif

What came first, the chicken or the egg? I'm curious to know, was there any evidence of a hail encounter from the wreckage they found?064.gif

I still think they first flew into a thunderstorm, then instruments failed. Sounds like the pilots screwed up first, then the aircraft screwed up second, finishing with a fatal screw up from the pilots. glare.gif

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I love the "PILOT ERROR..."

The ROOT cause was mechanical failure not pilot error. It's a twist of words. The pilots may have reacted inappropriately (yet to be determined) but had the malfunctions never have happened then they would not need to respond.

Mechanical failure is the cause.

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Is there a licencing authority anywhere that requires pilots to train for and demonstrate an ability to respond to 'multiple unrelated system failures'? It's likely the AF investigation will provide solid evidence that the modern 'all-knowing' airliner is in fact capable of finding it's way into difficult & complex scenarios. That being the case; will this crash provide the seed for what may become, a new training standard? Alternatively, does complexity demand or necessitate three people on the flight decks of these large machines?

I think the investigators should ultimately employ the recovered data in a 'simulator program' and then use the two best 330 pilots they can find to fly the doomed profile, and without the benefit of an advanced understanding of the event. If they can't make it, should the ac be flying with two crew, or is this class of ac just too complex to operate safely?

I believe the recent A-380 engine failure event also provided a demonstration in multiple unrelated systems failures. Fortunately, the outcome was much better!

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I think it is regrettable that the failure of one component can cause so many problems, and that there is seemingly no way to hand fly the aircraft in the event of this loss. Shouldn't there be an alternate to the pitot speed if it proves to be this catastrophic. How about a GPS speed indicator.

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I think it is regrettable that the failure of one component can cause so many problems, and that there is seemingly no way to hand fly the aircraft in the event of this loss. Shouldn't there be an alternate to the pitot speed if it proves to be this catastrophic. How about a GPS speed indicator.

There are standby instruments that I would assume were working. The plane could be hand flown. No matter what else is going on, job one is to keep the aircraft flying and not allow yourself to be so distracted by everything else that is going on that you don't look after job one.

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So then we come down to pilot error.

You should have onboard a list of power settings for a given altitude and weight that would keep the aircraft flying in the absence of computer driven information.

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Once any pilot finds him/herself in a situation beyond their standard training, it is hard to judge right and wrong. After this flight seemingly entered the cell or cells that produced calamitous results, the rest of the "flight" could possibly become unmanageable. Yes, there are procedures for Flight With Unreliable Airspeed, memory procedures at that.

Still, the bigger question is why did they penetrate weather that is generally known to be severely hazardous to any flight?

The ultimate failure(s) here occurred long before any pitot tube might have been sheared off.

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I love the "PILOT ERROR..."

The ROOT cause was mechanical failure not pilot error. It's a twist of words. The pilots may have reacted inappropriately (yet to be determined) but had the malfunctions never have happened then they would not need to respond.

Mechanical failure is the cause.

I'll have to do some more reading on the facts, but as I currently understand it, there was no failure that caused the plane to become unable to fly. Was it a tough situation to be in? Absolutely. Was it a guaranteed hull loss? From what I read, absolutely not.

It's now up to the rest of us to learn from it and hope it never happens again.

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Airbus does offer a "Back Up Speed System" (BUSS) which uses AOA information to determine an appropriate speed, and GPS information for altitude. The BUSS is activated when all three ADRs are turned off. Then, the normal speed information on the PFD is replaced with a green band (with red areas above and below). .....

post-2422-0-58971100-1306434411_thumb.jp

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Airbus does offer a "Back Up Speed System" (BUSS) which uses AOA information to determine an appropriate speed, and GPS information for altitude. The BUSS is activated when all three ADRs are turned off. Then, the normal speed information on the PFD is replaced with a green band (with red areas above and below). The concept is simple; keep the speed bug in the green. When ready to configure the aircraft, let the speed drop to the low end of the green band, select flaps, and repeat until landing configuration is achieved. The last two digits of the altitude display are replaced with amber crosses to indicate the use of GPS data.

They are in the QRH. However, when using the BUSS, none are required.

Too bad not all the "safety is number one" airlines are willing to afford the BUSS.

Thanks for the info Rich.

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They may have very recently changed the policy on it'a application as well.

Once it's engaged, you're stuck with it and since most unreliable speeds indications above FL250 are temporary (ice related)they advise using pitch and thrust while up there and wait to see what happens below FL250.

If below or descending through FL250 with unreliable speed, it's likely a permanent condition so they advise selecting the ADRs OFF and use BUSS to ground.

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I'll have to do some more reading on the facts, but as I currently understand it, there was no failure that caused the plane to become unable to fly. Was it a tough situation to be in? Absolutely. Was it a guaranteed hull loss? From what I read, absolutely not.

It's now up to the rest of us to learn from it and hope it never happens again.

While the original failure may not have brought he aircraft down, it was the ROOT cause of the accident. All subsequent issues that arose from that would never have occurred if the root failure did not occur. While the ultimate cause of the crash could well have been due to actions performed by the crew, those actions were being performed while dealing with the original issue.

We have seen this in the past where crews become entangled in troubleshooting the issue and diverting their attention from flying the aircraft. It was mentioned earlier that perhaps adding the third crew mewmber back into the flight deck may be a solution. This is not necessarily true as we have seen the same distractions happen in a 3 man cockpit as well (Flight 401 in FLA). Simply the basics of airmanship need to take the forfront when anything happens and sometimes we forget this. AVIATE, NAVIGATE, COMMUNICATE. Fly the plane is always #1 the rest can wait until you have your s#$% together.

Having said all that we can wait for the preliminary report where they will undoubtedly blame the pilots.:angry_smile:

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I have to wonder if there would have been a different out come if the Captain was up front.

If so, then there seems to be a lack of training for these 'cruise' pilots or do we need to always have a qualified

Captain up front at all times ??

I agree that there seems there was machine problems before pilot problems.

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While the original failure may not have brought he aircraft down, it was the ROOT cause of the accident. All subsequent issues that arose from that would never have occurred if the root failure did not occur. While the ultimate cause of the crash could well have been due to actions performed by the crew, those actions were being performed while dealing with the original issue.

We have seen this in the past where crews become entangled in troubleshooting the issue and diverting their attention from flying the aircraft. It was mentioned earlier that perhaps adding the third crew mewmber back into the flight deck may be a solution. This is not necessarily true as we have seen the same distractions happen in a 3 man cockpit as well (Flight 401 in FLA). Simply the basics of airmanship need to take the forfront when anything happens and sometimes we forget this. AVIATE, NAVIGATE, COMMUNICATE. Fly the plane is always #1 the rest can wait until you have your s#$% together.

Having said all that we can wait for the preliminary report where they will undoubtedly blame the pilots.:angry_smile:

It is far too early and there's not nearly enough concrete evidence available in the public domain to say what caused this accident.

As for root cause and aviation accidents, the term would never be used again if it were up to me. I could argue that the root cause of every aviation accident was Orville and Wilbur deciding to invent the airplane. Had they never done that, no aviation accident could have happened. Does that do anything to fix today's issues relating to AF447? Of course it doesn't. Looking for "root" cause has led to investigations where key elements of the system that contributed to the accident were not adequately addressed. Most aviation accident reports will not include the term "root cause". They use terms such as "findings as to cause", "findings as to risk", "contributing factors" and "other findings". There is always more than one finding as to cause when a fatal accident occurs. That's because the elimination of just one of the many causes would change the sequence of events, and could potentially prevent the accident from occurring.

With what we know so far, I can think of several elements of the system which could be looked at in this accident investigation:

  • As there was a known issue with the Thales pitot tubes, it could be argued that the aircraft certification and regulatory system let them down because it wasn't made an emergency AD. But are we prepared to make the call that every airworthiness concern leads to the grounding of a worldwide fleet? Hundreds of thousands of safe flights would seem to belie that as a reasonable strategy.
  • A330 operators were told that the Thales pitot tubes should be replaced. Air France had not yet done so with this aircraft. Does the airline have a risk acceptance policy and process for making decisions in such situations, or is it left up to one person who's decisions are expected to include financial implications?
  • The area where the accident occurred (the ITCZ) is well known for severe weather. Yet we continue to operate through that airspace without the benefit of radar-styled flight tracking. Therefore, flights in this airspace must be planned for non-radar separation limits. This makes getting a clearance for a weather deviation quite difficult.
  • HF radio communications in the area can be next to impossible at times. Therefore, crews are sometimes faced with having to use emergency authority to break separation just to avoid severe weather. Are we prepared to invest in an infrastructure that would make this airspace easier to navigate?
  • Emergency authority is normally a decision made by a captain, but since the captain was apparently not on the flight deck at the time, were the F/Os prepared to make that call? Did the SOPs and training at the airline empower them to do so?
  • Did the airline mandate certain situations where a captain was required to be in the flight deck? That's not to say that the captain may have done any better in these circumstances, but I honestly cannot envision a scenario where, as a captain, I would want to be sleeping while the flight I was commanding was flying through the ITCZ. But do we need rules and SOPs to cover that, or do we leave it down to airmanship?

I'm sure there are more. But to summarize, I do not believe that the pitot tubes themselves "caused" this accident. They were simply a link in the safety chain.

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