AF447

[JD-EE]

Machinbird, you commented, " Keep in mind that the boiling point of water at FL350 isn't that high. Much less than 100 degrees C/ 212 degrees F."

Is this the right observation. What is the pressure IN the pitot-tube and the tubing up to the ADIRU? (And, for that matter, what is the temperature of the probe and of the tubing up to the ADIRU?)

JD-EE

[Graybeard]

Sorry, couldn't resist. :hmm:

There are Air Data Modules between the pitot and the ADIRU, presumably very close to the pitot. Sorry, don't remember their exact names, and it's a long ways back to find the block diagram.

Still, you point is taken that the boiling point would vary with impact pressure, i.e., airspeed, but only by an inch or so of Hg.

GB

[Machinbird]

JD-EE, The point was made to show there is more than one type of potentially erroneous output from a pitot tube. If the interior of the pitot tube is hot enough to flash fresh moisture to steam (and it doesn't need to be that hot) then you could see your airspeed indications going up instead of down after the first hail stone plugs up your pitot tube inlet.
Perhaps this type of thing accounts for the apparent difference between Thales and Goodrich probes.
How should you react to an initial mach alarm after flying into the top of a storm?
Would you just say its bogus, or begin reducing power? And then if all your airspeed indications packed up and everything associated with it downstream (like ADIRUs) began quitting, would you even remember you had just pulled a bit of power? Would you even be able to read your power setting in the turbulence?

[PBL]

I don't generally contribute any more, but I think this is important information.

There is a superb piece by Jens Flottau in Aviation Week for August 10, 2009 detailing what was known about high-altitude (e.g., FL 350) extra-cold (-50°C and below) pitot icing on A330/340 aircraft before June 1, 2009. The answer is: lots.

In my opinion this is prize-winning research and writing. It hasn't been mentioned here up to now, AFAIK.

Response to Airbus Pitot Tube Incidents Under Scrutiny | AVIATION WEEK (http://www.aviationweek.com/aw/generic/story_channel.jsp?channel=comm&id=news/aw081009p1.xml)

PBL

[cwatters]

Are any companies leaving one Thales probe on or are they replacing all three? Leaving one might allow useful data to be collected?

[lomapaseo]

cwatters

Are any companies leaving one Thales probe on or are they replacing all three? Leaving one might allow useful data to be collected?

from the link in the post above yours

EASA stopped short of banning the Thales probes outright, allowing operators to continue to use the so-called -BA standard as a third sensor on Airbus widebodies. A regulatory official says continued use of one Thales -BA probe is "probably acceptable."

[lomapaseo]

The safety related response to all this is discussed briefly in the "piece by Jens Flottau in Aviation Week for August 10, 2009. "

A speed sensing malfunction for any reason was probably judged during initial certification as a minor malfunction due to its low expected rate of occurrence as well as the barriers (crew actions and availability of other instruments) available to make it unlikely that it would progress to a more serious outcome.

The article mentioned above indicates that the additional in-service experience reveals that the frequency of the malfunctions coupled together with the likelihood of significantly increasing pilot workload now creates a more hazardous outcome which needs to be addressed. Somewhat akin to the engine grapple (ice Crystals) problems discussed in the past when aircraft flew over storms.

The challenges to addressing problems like are also similar. If you go for a simple product change like a different manufactured probe the question is immediately how much is good enough and how do you know? Since the original product meets the certification standards.

Other means of addressing the safety risk are avoidance as well as means for reducing the pilot workload (simplified tasks by memory). Again the issue is a practical way for doing this (retraining all pilots takes time).

Right now it looks like a combination will be tried in a subjective manner to at least add more data to the knowledge base. I'm not sure if this gets mandated by EASA or not or even if the FAA will follow.

[Mr Optimistic]

..however I am not sure what to make of this text:

'Since the crash of Flight 447, EASA and Airbus have reminded operators of the need to ensure that pilots are skilled in techniques to maintain level flight.'

Any insight of what this statement really means and how operators have reacted to it ?

[robertbartsch]

...interesting article from Aviation Week

What manufacturer does Boeing use for its pitot tubes?

[stepwilk]

Mr. Optimistic, I assume they're in so many words stressing the basic, classic, age-old extreme-turbulence technique: wings level, maintain attitude, disregard altitude, maintain the power you had going in (assuming you were at least intelligent enough to slow to maneuvering speed if you knew you were flying into turbulence).

Don't know what the equivalent of "maneuvering speed" would be for a swept-wing aircraft flying at, essentially, its weight-determined service ceiling...

[Will Fraser]

Scolding the pilot group about their level of skill is a political parry to shift exposure and responsibilty away from the cause of the issue. An attempt to shift the focus away from equipment to another key area of flight, training, for which EASA and AF are ultimately responsible as well. It is shameful the attempt was made, and may have backfired on the Manufacturer and Airline in any case. The pilot group doesn't train itself, it is the responsibility of the Airline to do it, and the regulator to oversee it. Bad form.

[vapilot2004]

^ Will, this is par for the course in my experience with accident investigations. The practice has led to more than a few botched/unsatisfactory final reports. It can be summed up in a six word sentence:

When in doubt, blame the crew.

[sb_sfo]

Can't lay a finger on it, but I recall seeing something about them being basically a knock-off of the Goodrich design- hence the similar part number. That they got certified a couple weeks ago seems like a lucky break for them, however.

Edit- the Boeing probes I'm familiar with at my outfit are Rosemount for the classic 74, the 744, and the 777-300ER. Rosemount was bought by Goodrich.

[PBL]

Mr. Optimistic,

in answer to your query, I imagine the quote is referring to an Airbus Telex, which I do not have, and to EASA SIB 2009-17:
EASA Airworthiness Directives Publishing Tool (http://ad.easa.europa.eu/ad/2009-17)

PBL

[Mr Optimistic]

Thanks for the response. I assumed the link meant to address skills either in turbulence or with unreliable air speed data but it didn't say so directly. It reads as if basic skills need re-addressing but I presume that wasn't the intent, just careless wording. Would guess (as I am not a pilot) that there is a problem training for severe off-nominals (unexpected dynamics/attitude) as simulator software probably isn't validated for that sort of scenario. No point learning rubbish.

[glhcarl]

The bigger picture is the investigation needs to account for ALL the data available, and to date that is somewhat thin, but surely does need to include the autopsy findings (grim as that indeed is).


I just heard on Fox Raido News the the search for the "black boxes" has been called canceled. So the information we and the investigators currently have is likely all we will ever get.

[Dutch Bru]

That is presumably the end of what BEA calls the "second phase", which was indeed forecast to end around these days. Previously released info includes the mention of a consecutive "third phase", the one to which Airbus would contribute financially. So, not all hope (and with that expectation) is gone. It is just a matter of time.

[SaturnV]

La deuxième phase des opérations de recherches sous-marines des enregistreurs de l’Airbus A330 d'Air France accidenté le 1er juin entre Rio et Paris vient de s’achever, a annoncé aujourd'hui le Bureau d'Enquêtes et d'Analyses (BEA), chargé de l'enquête technique.

"Les recherches n’ayant pas permis de localiser l’épave de l’avion, le BEA réunira au cours des prochaines semaines une équipe internationale d’enquêteurs et de spécialistes pour exploiter les données rassemblées dans la perspective d’une troisième phase de recherches et déterminer les modalités et les moyens de celle-ci", écrivent les enquêteurs.

Une première phase de recherches acoustiques avait cessé le 10 juillet, lorsque les balises des boîtes noires avaient a priori cessé d'émettre.
AFP 20/08/2009 | Mise à jour : 15:07

The second phase was the side-scan sonar sweep, which looks to have yielded nothing. The second phase was to take four to six weeks, and took about four. Not sure what they can do now.

[SaturnV]

pax2908, the BEA did earlier lay out the grids for the sonar search, with a search radius based on last position, and which extended beyond the radius to cover areas north and west of the presumed track. Apparently, the sonar found nothing. This may be a consequence of the subsurface terrain which is very mountainous, and I suppose it is possible the wreckage fell into a crevasse, or is undetectable by sonar because rock features are blocking the signal.

[SaturnV]

pax2908, BEA has now posted on its website:

Communiqué de presse diffusé le 20 août 2009 :

La deuxième phase des opérations de recherches sous-marines des enregistreurs de l’Airbus A 330 accidenté le 1er juin 2009 vient de s’achever. Le Pourquoi pas ? est attendu aujourd’hui à Dakar.

Les travaux, effectués avec l’assistance de l’IFREMER et du SHOM, ont permis de compléter l’exploration de la zone de recherche qui avait été déterminée après l’accident, un cercle d’un rayon de 75 km centré sur le dernier message de position transmis à 2h10 par l’avion. Une bathymétrie des fonds a aussi été effectuée dans un périmètre élargi.

Les recherches n’ayant pas permis de localiser l’épave de l’avion, le BEA réunira au cours des prochaines semaines une équipe internationale d’enquêteurs et de spécialistes pour exploiter les données rassemblées dans la perspective d’une troisième phase de recherches et déterminer les modalités et les moyens de celle-ci.

The bold is mine.

See pdf p. 47 for search grids as planned in July.
http://www.bea.aero/docspa/2009/f-cp090601e1/pdf/f-cp090601e1.pdf

See pdf p. 12 of this document for subsurface terrain. The further west of the track, the more mountainous.
http://www.bea.aero/fr/enquetes/vol.af.447/recherches.en.mer.pdf

IMO, there is little hope now of recovering either of the boxes. The main wreckage possibly can only be located by having a submersible search the contours of the ocean floor looking for it. I have no idea how long that would take, given the terrain, nor do I know the practicality of doing such a search over a lengthy period.

[Machinbird]

Back during the height of the cold war, there were extensive listening networks in the oceans owned by the US and Soviets that were capable of localizing unique sound signatures with a pretty high degree of accuracy. As I recall, the wreckage of the USS Scorpion was found in this manner.
In the post cold war era, I have no guess if any of these networks are still operating and able to yield usable data. I would hope that the French government has at least asked for a tip off where to look. This kind of information would not be disclosed without approvals at very high levels, and it may no longer be available due to cost cutting measures.

[JD-EE]

petemcleland, it seems the BEA already paid attention to the pre-preliminary reports they had from their own people who collected bodies. They were in good shape, in the sense of not chopped up or otherwise visibly externally injured beyond being obviously dead. A high altitude breakup would leave at least some of the recovered bodies rather cut and injured by flying debris.

Furthermore the BEA is not obligated to share its data, particularly medical data, with the public nor, according to my understanding, provide daily reports for the edification of impatient members of the public. They have a job to do that is best done without needless distractions.

JD-EE

[Squawk_ident]

From the BEA site (English section) :


Press release 20 August 2009

Flight AF 447 on 1st June 2009

A 330 – 200, registered F-GZCP
The second phase of the undersea search operations for the flight recorders from the Airbus A 330 that disappeared on 1st June 2009 has just been completed. The Pourquoi pas? is expected at Dakar today.

The work, undertaken with the assistance of IFREMER and SHOM, allowed completion of the exploration of the search area that had been defined after the accident, a circle with a radius of 75 km centred on the last position message transmitted by the airplane at 2h10. Bathymetry of the ocean floor was also performed over a wider perimeter.

As the searches did not make it possible to locate the airplane wreckage, the BEA will gather together a team of international investigators in the next few weeks to analyze the data collected with a view to a third search phase and to determine the requirements and means to undertake this.

From the AP site:

News from The Associated Press (http://hosted.ap.org/dynamic/stories/E/EU_FRANCE_BRAZIL_PLANE?SITE=AP&SECTION=HOME&TEMPLATE=DEFAULT)

[awblain]

I understand that fixed sonar networks were concentrated through the Greenland-Iceland-UK gap in the North Atlantic. It's a long way from there to the ITCZ. Moreover, the networks were operated to pick out and track long-duration machinery noise. The detection of the single, uncertain sound of an impact on the surface of the sea, in a noisy stormy region, even before considering the complex propagation of the sound far through the ocean, looks like a tough problem.

I hope that such avenues have been tried, but I am very pessimistic.

I guess the lack of volunteered information also means that no ship-borne sonars or radars detected AF447 either.

Maybe radar or radio signals from the descending AF447 could be lurking in someone's signals intelligence data, or a space-borne radar might have caught its descent, but I'm not sure that any cognizant agencies would be looking at the tropical Atlantic.

[Wannabe Flyer]

CNN reported that the search for the data recorders has been called off. So what will be the next course of action to determine what happened?

[Hunter58]

In response to replies 4291 and 4292.

Even in the aircraft (or at least it's mayor components) was intact at impact as the preliminary analysis of the BEA let to believe, it will most likely have broken into pieces at impact. Even if such a piece could be some 20 m long, it is still very difficult to find.

Immagine a surface of the size and shape of the 'Haute Savoie' (that's where the Mont Blanc is) with every mountain being quite similarly high like the Mont Blanc, some 2 km of water on top of that and the necessity to sweep through every single valley to find something, provided the something is not hidden by an obstruction like an overhang or similar.

In an unpopulated region such a search over normal land can already yield into the complete loss of an aircraft only to be found by very lucky circumstances. Water just maked the whole thing 100 times more difficult.

[stepwilk]

"CNN reported that the search for the data recorders has been called off. So what will be the next course of action to determine what happened?"

It's my impression that that's a MSM oversimplification. An article I read a couple of days ago in either the NYTimes or the WSJ said that the investigation board is pulling together a variety of information to determine where to now begin looking further, though yes, they have decided that the area already searched is finished, and that Airbus Industrie have pledged further cooperation with such a search.

[SaturnV]

stepwilk, the search had three phases. The first was the attempt to locate the black boxes using the pingers to find them. That phase ended after the expected 30 day battery life of the pingers expired (actually I think they searched a short period beyond the 30 day life).

The second phase, now completed, was to survey the sea floor using side- scan sonar in the hope of detecting larger sections of the wreckage. If the sonar had detected such, then a submersible would photograph the area. This survey failed to detect any wreckage.

The third phase was originally to conduct submersible operations to photograph and potentially retrieve parts of the wreckage, most specifically, the black boxes if these were located.

With phases one and two yielding nothing, the original purpose for phase three is annulled. The BEA will now assess what steps might be feasibly taken to locate the wreckage on the sea floor. Any further survey effort will likely cover much of the area previously surveyed in phase two. In effect, phase three now becomes yet another search.

[John47]

From
The Associated Press: French end search for Flight 447 black boxes (http://www.google.com/hostednews/ap/article/ALeqM5h7Syoehl5qyNCZBsEoP8fnqGHthQD9A6LMRO1)

The French accident investigation agency, known as the BEA, said in a statement that the research ship leading the hunt for the plane's flight recorders had left the site, more than 900 miles (1,450 kilometers) off Brazil's northeastern coast. The ship, the Pourquoi Pas, was to arrive Thursday in Dakar, Senegal.
The statement said the second phase of search efforts, focusing on the underwater hunt for debris and the black boxes, "has finished." Investigators and experts will gather in the coming weeks to determine whether to launch a third phase.
"We have not found the wreckage, we have not found the recorders," said BEA spokeswoman Martine del Bono.
She said the BEA will gather a team of about 10 specialists from several countries including Brazil, France, the United States and Germany, to study the data gathered from the second phase and decide what a third search phase would cost and require.
She gave no estimate on when an eventual third mission might begin.
The investigation "is far from finished," she said. "We must find" the black boxes, she added.

[wes_wall]

From AVnews

The family of a flight attendant who died in the Air France crash of June 1 off the coast of Brazil is seeking legal action against the carrier, its lawyer said on Friday.
Details: Family Of Crash Victim Seeks To Sue Air France (http://news.airwise.com/story/view/1250893858.html)

[broadreach]

Phase One was what we were expecting in the first weeks after the crash: immediate evidence, rapidly recoverable.

Phase Two would have brought huzzas for the technology that found the aircraft so soon. Its lack of success has messed us about a little.

Phase Three is what we’re hoping BEA, AF and AI have the bottle for, a long dreary process with some sort of find that encourages more searching, because not all the pieces may have settled in one place on the ocean floor.

I’m still hopeful that a serious search will continue, as opposed to one just for show. But one can only wonder at all the pros and cons going through the deciding minds at BEA, Airbus Industrie and Air France: consign the accident to history and move on based on assumptions, hoping that people will forget, or some right out and say how far they’re willing to go to establish what actually happened.

[mmciau]

I believe that there so many unanswered questions about this accident that the authorities will endeavour to find and retrieve the Recorders if it is at all possible.


Mike McInerney

[Mr Optimistic]

Suppose the area to be searched will be discussed by the called together forum but are there any indications, in any reports from BEA, that the negative results so far mean that the area to be searched should be changed ?

[Chu Chu]

Does anyone know how much real-time analysis would have been done on the side-scan sonar data? I've got a mental picture of the ship crew watching the screen for an outline with two wings, two engines, and a tail. Which, of course, they weren't likely to see. Maybe experts are poring over the data now, looking for more subtle targets.

[SaturnV]

There is no public info on the technical aspects of the side-scan sonar search, e,g., at what depth was the sonar operating. There are military side-scan sonars that can operate at pressures up to 3000 meters deep, so perhaps if one of those were made available, they might re-do the search grids if the sonar during the second phase search was operated at a much higher depth..

Another side-scan search might find the main wreckage. Even if the main wreckage is found, the odds of finding the boxes are pretty low. If the fuselage slid down the side of a seamount, bringing down a seaslide of sediment and rocks with it, the boxes might be buried.

[ALPHA FLOOR]

It is my opinion that neither Airfrance nor Airbus "really" want those recorders found - the lack of communication from our fleet office wrt this accident (the largest 330 operator in the world) just goes to reinforce what I and many of my colleagues consider somewhat of a conspiracy.

AFL

[RatherBeFlying]

Find a twin with similar planform parked in desert storage facility. Fit up as a drone Add robust long lived pinger Stall it over the ocean in the general accident area Run sonar over wreckage at various track angles to get signatures against the bottom Apply signature to area scans

[vapilot2004]

It is my opinion that neither Airfrance nor Airbus "really" want those recorders found - the lack of communication from our fleet office wrt this accident (the largest 330 operator in the world) just goes to reinforce what I and many of my colleagues consider somewhat of a conspiracy.

Surprising suppositions. Well almost.

Airbus should be keen on retrieving the things. The only way the manufacturer would not want the boxes to be found is if they already knew what the problem was and it has not so much to do with proboscii.

Air France on the other hand might benefit from the benefit of the doubt according to the legal guys. Doubt = minimum mea culpa.

[SaturnV]

alphafloor, you ought to include the Brazilian government as a co-conspirator. If the Brazilians had searched the area west of the track, instead of concentrating on the area east of the track, the debris field might have been discovered by June 2nd, and more proximate to the actual crash location.

ratherbeflying, the signature that the fuselage may present to sonar may be a lot smaller than you apparently expect. If the fuselage is still largely intact and on a slope, the profile presented might be more the cross-section of an 18 foot hollow tube, rather than a nice horizontal presentation of 150 feet or so of metal.

[RatherBeFlying]

If the fuselage is still largely intact and on a slope, the profile presented might be more the cross-section of an 18 foot hollow tube, rather than a nice horizontal presentation of 150 feet or so of metal.Can't say how many segments the fuselage is in now. The sea surface and bottom impacts can each make a contribution. I venture the best candidates for large components would be the wings and centre section. Then there's how they will array themselves on a slope or collect in a hollow possibly with avalanched slope debris on top:confused:

A nice long cylindrical section could roll down a slope or could hang up on a bench or projection or end up on the bottom of a slope.

It would take a lot of cheap airframes to work out the many ways the pieces might come to rest on a contoured bottom.

There have been sonar searches for historic wrecks on reasonably flat bottoms that have taken years.

[Backoffice]

As has been mentioned in earlier posts, if the majority of the aircraft sank in large sections they may have retained some buoyancy and not have gone straight to the bottom, especially with the large amount of composites and possibility of fuel trapped in tanks it may well have travelled miles outside the search area.
I would have thought the engines are more likely to be detected by their magnetic anomaly, assuming the searchers have access to and can use that detection method at that depth.

[Dysag]

"especially with the large amount of composites...."

Apart from the fin, which detached, and possibly some cabin furnishings, there is only a small amount of composite material in an A330.

[Chu Chu]

The more I think about this, the more I wonder if it's as simple as this:

Phase 2 = side-scan sonar survey
Phase 3 = identify and further investigate targets based on Phase 2 survey.

They were discussing Phase 3 not long after Phase 2 started; perhaps Phase 2 was never expected to result in locating the aircraft without more work. Given all the false sightings of floating debris, I couldn't blame them for keeping mum now even if they had a good idea that they could see the airplane in the sonar image.

[Will Fraser]

I doubt any one would fault them for giving it a rest. I wouldn't. It may be this century's Titanic, left for a better technology in future. Rest them.

[cessnapuppy]

I agree. In reflection, we either already know what happened or have enough data to make a reasonable assumption and start to take corrective action. Including but not limited to:
Better dissemination of weather information
Better training, SOP clarification and use of WX radar
Be more proactive/aggressive in diverting around bad weather
(my favorite: hand fly the AC through the ITCZ vs using the autopilot, so if you run into unseen weather, the crew isnt tossed an unstable aircraft into their laps when the AP runs for the hills )
More active collaboration between 'hand off zones' (like Dakar)
Faster response when the plane goes missingAll these things we know now, what else is the CVR FDR going to tell us? Useful? perhaps, but not particularly earthshattering - though I guess hearing and seeing their final moments trying to correct the plane may offer some training suggestions

[SaturnV]

chu chu, the general sequence for searches of wreckage where one doesn't know the precise location, is to use side-scan sonar to sweep where one thinks the wreckage might be. If there is a hit, i.e., an area worth investigating further, then a submersible is sent down to photograph. If the visuals confirm that's the object one's searching for, then more extensive photography is done to see whether objects that one wants to retrieve can be located. The ultimate phase would be retrieving any located objects.

A straightforward and laymen's description of the technology and the challenges can be read here, on the search for HMS Hood (and the Bismarck as well). Of course, this involved large ships resting at great depths on a relatively flat bottom, with a fairly good notion of where they were.

Channel 4 - Hood v Bismarck - The Search - Method (http://www.pbs.org/hood/search/method.html)

Channel 4 - Hood v Bismarck - The Search - Equipment (http://www.pbs.org/hood/search/equipment.html)

[cessnapuppy]

what would be good is if the sonar scan imagery and data could be placed in the public domain so that it could be reanalyzed, in the same way that crime scene photographs can be reexamined years later and new clues discerned from otherwise overlooked data

[FlexibleResponse]

If I was a betting man, I would say that the wreckage will be found, and it will be found by the USN.

We just need an appropriate amount of time for face-saving and the right deep-sea salvage contractor to be funded.

No manufacturer wants questions of safety hanging over his products. Regardless of the cause of the crash, there is an engineering solution for everything.

[cribbagepeg]

It may be that the USN and other nations' forces may be reluctant to deploy their best technologies in an area where they are KNOWN to be operating lest they reveal something they'd rather not. I know that echolocation frequencies in the ocean are much more restricted than in the ether, where spread spectrum stuff can be used to advantage in avoiding detection, but one could speculate a bit...

[Machinbird]

The more I read about the USN SOSUS system and about the nature of the SOFAR channel for transmitting sound long distances without loss, the more convinced I am that positioning data on the AF447 accident can be recovered if someone can be convinced to make the effort.
To understand what the SOFAR channel is about, look at this link: DOSITS: History of the SOFAR Channel (http://www.dosits.org/science/soundmovement/sofar/sofarhistory/) and then follow the internal links for more information.
The SOSUS system has been simplified over the years to reduce manpower requirements and has apparently lost some functionality, but appears to be still in existence.
Remember that the AF447 accident is a multi depth event. Even if surface noise may not carry well, it may reflect from an undersea mountain that is in the vicinity and then be carried to a hydrophone in the SOSUS array. Maybe the sounds of the engines hitting the bottom will carry.
We have the advantage of knowing within relatively small windows the time of the crash and the location of the crash. This permits writing algorithms for summing up the sounds within a particular directional hydrophone array to achieve higher gain from a particular direction, and for predicting the arrival time of potential signals at individual hydrophone arrays thus permitting more detailed analysis. Once the accident sound signature is identified on one array, it can be more easily found on the signals recorded on another array in a distant location. Once you have signals on a second array nailed down, you can use that information to predict with loran type precision the coordinates of the events detected.
It is probably worth a shot. It would take some analysis to come up with results and it won't happen unless someone tasks the Navy for results. An inter-governmental request by the French government would be probably all that is required. I hope they are working on it.

[mickjoebill]

There are images of the flight data recorder located in the tail of the airbus that dragged its tail in Melbourne this year.

Surprisingly the recorder was completely dislodged by the impact of the tail hitting the ground.

Would a better solution be to have it secured into a beefy bit of airframe, noting that there are not always "big bits" remaining after a crash.

Also, perhaps it needs its own "Rescue Streamer"?
"Rescue streamer" is in use with the US Navy, when stored it is an inch in diameter and 4 inches long, but deployed and unrolled it becomes a 40ft long 4 inch wide hi vis streamer that floats on the surface or can be deployed on land.
Would half a dozen streamers made with a metallic layer attached to the recorder aid the search? Even if they disintegrate on impact they would leave a trial in the direction of the the recorder?

Mickjoebill

[Gretchenfrage]

by cessnapuppy

I agree. In reflection, we either already know what happened or have enough data to make a reasonable assumption and start to take corrective action. Including but not limited to:
•Better dissemination of weather information
•Better training, SOP clarification and use of WX radar
•Be more proactive/aggressive in diverting around bad weather
•(my favorite: hand fly the AC through the ITCZ vs using the autopilot, so if you run into unseen weather, the crew isnt tossed an unstable aircraft into their laps when the AP runs for the hills )
•More active collaboration between 'hand off zones' (like Dakar)
•Faster response when the plane goes missing

Two reflections:

What about reprogramming the system as to allow the pilots to keep authority throughout all attempted protections? To me this should be added to your list.

You mention better training. A big AB operator wanted to do just this, but had to postpone it, because the sims were not able to simulate the presumed all pitot failures. Let me repeat that: The sims were not able to accurately simulate such a "unreliable airspeed indication" situation!!!!!

How on earth were Airbus crews trained for such a situation up to today?

[barrymah]

From todays Irish Times -

France wants to launch an expanded international effort to find the missing wreckage and flight recorders of the Air France jet which crashed in the Atlantic in June, the country's top crash investigator said today.

About a thousand fragments of the Airbus A330 which crashed on June 1st, killing 228 people, have been examined but most of the aircraft is still missing and it is still too early to say definitely what caused the crash, he said.

"We are going to see how we can optimise our search. We are going to expand it to other countries to bring in the maximum international dimension and seize every chance we can to avoid missing new clues," Paul-Louis Arslanian, director of France's BEA air crash investigation board, told journalists......

France seeks help with Airbus A330 search - The Irish Times - Mon, Aug 31, 2009 (http://www.irishtimes.com/newspaper/breaking/2009/0831/breaking23.htm)

Bye, Barry

[wes_wall]

"We are going to see how we can optimise our search. We are going to expand it to other countries to bring in the maximum international dimension and seize every chance we can to avoid missing new clues," Paul-Louis Arslanian, director of France's BEA air crash investigation board, told journalists......



Closing the barn door after the horses have long since been gone. :ugh: Pray tell where he would like to begin this search. Pitty.

[aguadalte]

How on earth were Airbus crews trained for such a situation up to today?
I had my SIM Training today.
One of the things we had to deal with was, en-route ADR2 failure, followed by ADR disagreement due to Volcanic Ashes...and Double Engine Failure (A330), due to the same reason. Attitude, Attitude, Attitude (all Pitots blocked by ashes).
It seems an improbable situation. (yeah, sometimes a guy has to think twice before leaving home:hmm:) But, when the "Gods" are against us, s**t happens...and it ended up with the Ditching Paper Check-List...
We also had the opportunity for a Double Hydraulic (G and B) Failure, Emergency Descent, Double FM Failure during SID at SBGR, Side Step Landing from Rwy 22R to Rwy 29 on a Direct Law and overweight status in KEWR, (just for the fun and for the handling training), abnormal attitude recovering and All Engine Out (forced) Landings.
There is a lot to do and to train. Always aiming for the benefice of experiencing without the "fear of failure", that most of us may feel during Check-Ride Sessions.
I have learned a lot during my four hour training sessions. I usually do.
And I thank my company for understanding the importance of those "training sessions".

[BreezyDC]

Pray tell where he would like to begin this search. Pitty.They will start with the wreckage patterns and mathematically work probable search areas. For a good summary on the location of the wreckage from South African Air Flight 295 that went down in over 5 km of water in the Indian Ocean, see HelderbergSearch Paper (http://www.strumpfer.com/Papers/HelderbergSearch.htm). More difficult for Air France though, in the topography of the ocean floor and the greater uncertainty in the flight path.

[cessnapuppy]

They will start with the wreckage patterns and mathematically work probable search areas. ??? Confused...
Wouldnt they have been doing this since June? Or were the pesky Brazilians in the way? @aguadalte I had my SIM Training today. One of the things we had to deal with was, en-route ADR2 failure, followed by ADR disagreement due to Volcanic Ashes...and Double Engine Failure (A330), due to the same reason. Attitude, Attitude, Attitude (all Pitots blocked by ashes).
It seems an improbable situation. (yeah, sometimes a guy has to think twice before leaving home) But, when the "Gods" are against us, s**t happens...and it ended up with the Ditching Paper Check-List... Fascinating... of course with 'only' 4 hours sim time, there isnt enough time to duplicate the 3 hours of complete relative boredom with the plain on autopilot before S**T happens! :)
Question: Is the list of events known to you in advance? or are they 'sprung' on you by surprise? -regards
p.s. Hope you 'passed' lol :D

[BJ-ENG]

The SA 747 was found at 4.4 KM in similar topography, and one year after the accident. The CVR was recovered and data extracted.

In 1980, Aerolinee Itavia Flight 870 suffered an in-flight explosion, thought to be a missile, while on route from Bologna, Italy to Palermo. Eleven years later in 1991, the company Winpol successfully located the wreckage at 3.5Km on the Tyrrhenian seabed. The FDR was recovered and data extracted, showing that just prior to the explosion the plane was in level flight and all the onboard systems were fully functional.

[ArthurBorges]

Investigators were still unable to explain the accident, Paul-Louis Arslanian, head of the French air accident investigation agency BEA, told reporters, adding that the third round of the search for the aircraft's black boxes would resume in the autumn.

More time was needed to analyze what happened in the four minutes before the crash of the plane, Arslanian said, adding that investigators would set priority targets and improve efficiency before conducting the new hunt for the black box

Pasted from <Cause of Air France crash still unknown - People's Daily Online (http://english.peopledaily.com.cn/90001/90777/90853/6744440.html)>

[Blacksheep]

cwatters


Quote:
Are any companies leaving one Thales probe on or are they replacing all three? Leaving one might allow useful data to be collected?
from the link in the post above yours


Quote:
EASA stopped short of banning the Thales probes outright, allowing operators to continue to use the so-called -BA standard as a third sensor on Airbus widebodies. A regulatory official says continued use of one Thales -BA probe is "probably acceptable."

EASA Airworthiness Directives Publishing Tool (http://ad.easa.europa.eu/ad/2009-0195) issued today and effective 07 September for compliance within four months. Most airlines already did this after we saw the contents of that ACARS report. Notice that EASA consider this to be an interim measure and further AD action cannot be excluded.
It is important to act on known problems even though the full story may not be available.

[aguadalte]

Question: Is the list of events known to you in advance? or are they 'sprung' on you by surprise? -regards
p.s. Hope you 'passed' lol :D

CessnaP: I don't have to pass...it's a training session, not a check-ride, and that's why it is so important! And yes, some of the events are known to us, others aren't. Part of it, is up to the TRI or to the training pilots. A briefing is done before the session and a debriefing after it. Its not a joke. Its a professional work, from which we all take lessons and above all, are offered the opportunity to know our aircraft better.
It represents an investment in flight safety, as I'm sure you will understand.

[Dutch Bru]

.....just relaying what the Times online reports today:


"Air France pilots yesterday accused accident investigators of trying to cover up the cause of the Airbus crash off the coast of Brazil in June that killed 228 people after officials appeared to blame the crew for the disaster.

The airline also provoked anger after it emerged yesterday it has ordered special training for all flight crew that operate Airbus aircraft, to teach them to manage a high-altitude system failure of the kind experienced by the crew of flight AF447.

Families of the victims as well as pilots’ unions are upset at what they see as obfuscation by the state Bureau of Investigation and Analysis (BEA) and Air France over what caused the crash.

On June 1 the Airbus 330 plunged from altitude as it passed an area of storms on a flight from Rio de Janeiro to Paris. The flight recorders have not been found. Fifty bodies and about a thousand pieces of wreckage have been retrieved.

"They are trying to blame the pilots. They do not want the truth,” Gerard Arnoux, a spokesman for the Union of Air France Pilots, told The Times.

Mr Arnoux, an Airbus captain, said that the BEA was trying to overcome its previous failure to act on known faults with speed sensors, known as pitot tubes, on Airbus aircraft. “The architecture of the Airbus systems is in question,” he said.

The families have accused Air France and the BEA of dishonesty. Christophe Guillot-Noël, who heads an association of victims’ families, said that Pierre-Henri Gourgeon, the airline boss, was privately blaming the pilots. The BEA report was shaped by politics, he said.

A new deep-sea search is to start this month for the flight recorders, but data sent in the moments before the aircraft disappeared has offered an outline of the chain of events. Faulty speed readings, apparently caused by ice, prompted erratic behaviour by the automated flight system. Flying by hand, and without key data, the two pilots were unable to keep control.

In a preliminary report in July, the BEA said that the speed sensors were “a factor, but not the cause” of the crash.

In late July, the European Aviation Safety Agency ordered replacement of the French-made pitots with American ones on all long-range Airbuses.
On Monday, Paul-Louis Arslanian, the head of the BEA, blamed the crew. He said that flight crew had for decades been taught to manage faulty airspeed readings. In the case of the Air France aircraft, “certain of these fluctuations in speed [data] were perhaps not sufficiently taken into account in the training of the pilots”, he said. The BEA does not expect to reach a conclusion for 18 months.

Argument over the crash has focused on whether the crew — probably the two juniors of the three pilots on board — made errors or, as the pilots’ unions maintains, were dealing with an unflyable aircraft. “There is no doubt there was a loss of control, but the Airbus system is not supposed to let this happen,” said Mr Arnoux. “There would have been no accident without the failure of the pitot probes.” Air France’s pilots had not previously been given simulator training in speed problems at cruising altitude, where the aircraft is more prone to stall. This is now being done, at the request of all airlines’ unions. Suspicion has fallen on the highly automated design of the Airbus flight systems.

Stewarts Law, a London firm representing more than 30 of the victims’ families, said that Air France is likely to face a compensation claim of about $450 million (£278 million). “It was a prevent- able accident,” said James Healy-Pratt, a lawyer with Stewarts who is also a pilot. “It was a mix of Airbus and Air France.” "'

Until so far, DB

[Gretchenfrage]

“The architecture of the Airbus systems is in question”

Very interesting article DB.

At least I feel less alone now in my pointing fingers at Airbus (design) and some AB operators (training).

I would not exclude other manufacturors and other operators of such criticism. I wrote on another thread what I think about managers, regulators and for that matter put in the manufacturors as well.
I simply think that the Airbus environement has pushed it over the limits.

As lots of us are suspecting a cover up, I truly hope that more risen voices will finally put some pressure on the industry to go for the truth, the whole truth and nothing but the truth ......:cool:

[cessnapuppy]

It almost sounds like those guys dont fly the Airbus? “There is no doubt there was a loss of control, but the Airbus system is not supposed to let this happen,” said Mr Arnoux. What part of dropping out of Autopilot, entering Alternate /Direct Law and saying' si longtemps, suckers! vous êtes sur votre propre!' did they NOT read in the manual? http://www.a330jam.com/documents/fltlaws.pdf

Obviously it was pilot error, since, if they had called in sick it wouldnt have happened (said with mostly a straight face)

p.s. @ aguadalte: I know! by 'pass' I meant, I hope you handled it well and didnt prang the sim, or if you did, not as much as the others :)

[VicMel]

Reply to SaturnV #4296 & cessnapuppy #4297
The time and effort needed to analyse the sonar data is an interesting point as there should be a vast amount of data. I presume that the raw sonar data is first processed by computer to produce a 2D (or 3D?) image of the ocean floor, which then has to be carefully inspected by a human in order to identify a possibly significant shape. I would guess that the scale used on such an image would need to be about 1cm to 2.5m in order for a distinctive shape such as an engine cowling, section of fuselage etc. to be recognised. In which case, a 30cm by 20cm image would represent about 0.004 sq km of the ocean floor; a sonar search over a radius of 75km would require 4.5 million such images to provide coverage of the area with a view in just one direction. Obviously a sonar scan of the front of the engine is going to stand a better chance of being recognised than one from the back. Assuming a human could process 200 images per day, and could continue to carry out this task every day for a month or so this would require 50 man years of effort or more!! Perhaps a team of 200 spending a day per week for 2 years.


An alternative approach was used on a similar data analysis task for an internet project called 'Galaxy Zoo'. The task was to analyse images of galaxies ( a million of them). The instigators of the project set up a web site where interested members of the public could download a set of images, analyse them and send the results back. They were amazed at the response they received; more than 50 million classifications were received by the project during its first year, from almost 150,000 people. The loss of AF447 has generated a lot of public interest, perhaps the 'Galaxy Zoo' approach could work here on the sonar data and complete the analysis in months rather than years? Could the Pprune network be a good starting point to get the ball rolling?

[wes_wall]

“They are trying to blame the pilots. They do not want the truth,”

All the more reason NOT to locate the airplane, or any critical parts. As long as a finger can be pointed at someone else, or the avenue created that cause is undeterminable, no harm, no foul. Typical catch 22. Seems like we have seen this coy before, or am I dreaming?

[noelbaba]

eTurboNews | Travel and Tourism Industry News (http://www.eturbonews.com/?page=1)

BY UNAL BASUSTA AND WIRES, ETN STAFF WRITER

BEA director Paul-Louis Arslanian, The director of the French agency investigating the crash of Air France Flight 447 said Monday that investigators could take at least a year-and-a-half to reach a conclusion.
Arslanian said he still doesn't know exactly where the plane went down nor what caused the accident, three months after the Rio to Paris flight crashed into the Atlantic, killing all 228 people aboard.
Speaking before a gathering of aviation journalists in Paris, Arslanian said the agency has not issued a recommendation to airlines over speed measuring equipment (pitot tubes) because he didn't have evidence to justify it.
Nevertheless, since the crash both the European air safety agency and planemaker Airbus advised airlines to replace the Pitot probes used on the doomed jet with a later and more reliable model made by a US firm.
A series of automatic messages sent by the plane point to a malfunction of the speed monitors, known as Pitot tubes, which some experts think may have iced over and given false speed readings to the Air France plane's computers as it ran into a turbulent thunderstorm.
Just before Air France 447 went down, it transmitted a four-minute data reporting 5 failures and 19 warnings via its radios (ACARS). The data already gives a hint what went wrong on the airplane but the true story will come out if searchers find the black boxes.
According to messages we know the autopilot disengaged, the flight control computer failed, warning flags appeared over the primary flight data screens used by the captain and first officer and the rudder moved beyond its limits. All of it is consistent with a flight control system that was getting some bad information about how fast the airplane was moving through the air. The device that performs this task is called a pitot tube.
Emergency messages emitted shortly before the crash showed that the pilot had had to revert to manual controls and that the plane’s speed was "inconsistent".
If true airspeed is not known it is so easy to stall or overspeed the plane. That’s why the A-330 has three pitot tubes. If they all iced up, or get clogged with crystals, they won’t work – To prevent icing they are heated. There were many instances that A-330 pitot tubes were icing and failing in flight so Airbus issued a “service bulletin” recommending airlines replace them with a newer model that has a more powerful heater. It was not considered urgent – and so the pitot tubes on the doomed plane had not been replaced yet. .
After all these Mr. Arslanian still saying "If I had thought it was important to make a recommendation, I would have done it,"
The epic thunderstorm system that Air France 447 flew into would have created icing that could have overwhelmed the factory installed original pitot tubes.
These type of failures chronicled in the ACARS text messages were identical a 2008 event when an Air Caraibes A-330 flying the same route encountered same pitot tube icing. That plane was not in such severe circumstances so the crew was able to get things back under control – and lived to report it to their company and the Airbus.
As auto flight control systems fail in an Airbus, the rules that the computers live by change from “normal”, to “alternate”, to “direct” law. At each stage the computers surrender more authority to the humans – until finally all computers gives up and control no more and all outhority and controls are handed to pilots – with darkness and thunderstorm with no help at all from computers – at just the point they need them most.
Here in this event, while everything is calm and quiet aircraft getting blown around by turbulence, all major instruments become useless and hundreds of alarms some with very high pitch sounds and blinking lights all vie for pilots attention. And the need to fly with absolute minimum equipment and control.
A plane that was designed and built to be controlled by computers – with a deceptively simple cockpit becomes so complex and confusing it is almost impossible to pick the most urgent action.
In this event AF447 appeared to crossed through three key thunderstorm clusters: a small one, a new rapidly growing one, and finally a large multicell convective system. (MCS) according to AF aircraft transmission, entered a "thunderous zone with strong turbulence."
While 3 different flights deviated from the route and flew their destination safely why this crew decided to stick with the original route while they have the state of the art radar showing the thunderstorms ahead. The remains of Mr Dubois, 58, and those of one of the stewards, were among a dozen bodies identified from 50 that were found in the Atlantic off Brazil and taken to the coastal city of Recife.
The discovery of Mr Dubois’ body was seen as a possible confirmation that, in keeping with standard practice, he was resting during the cruise phase of the flight. The first and second officers would have been at the controls. It is thought that seat-belted pilots were unlikely to have been thrown clear of the tightly enclosed flight deck.
The captain should be present in the cockpit while cruising thru this very strong thunderstorm passage.

At 0210Z, one of the first ACARS transmission involved the rudder limiter. One Air France official, said the error message pertaining to the rudder limiter did not indicate it malfunctioned, but rather that it had locked itself in place because of conflicting speed readings. But, some experts theorized that based on the previous Airbus rudder separating incidents the vertical stabiliser may have been damaged. If the rudder were to move too far while travelling fast, it could shear off and take the vertical stabiliser with it. (Brazilian recovery photos do show these two pieces still joined together, when the vertical stabilizer and rudder were recovered at sea ). The recovery of these items intact would lend much support that the turbulent air may have produced a force striking the vertical stabilizer broadside on the Airbus 330 and sheered it off!!!
Arslanian said around 1,000 parts of the plane have been recovered from the Atlantic Ocean - including a nearly intact vertical stabilizer-rudder, an engine cover, uninflated life jackets, seats and kitchen items.
The Brazilian authorities have yet to send detailed information on the results of the autopsies, although the BEA is working with general information obtained from French authorities, he said.
Arslanian says investigators are gearing up for a third phase of searching, over a wider area, which could cost tens of millions of euros and start before the end of the year. Airbus has offered to help fund the search.
A preliminary report into the crash said the plane hit the ocean intact and belly first at a high rate of speed. But without the flight recorders, investigators may never know fully what happened..
Relatives of the dead have angrily demanded that Air France and Airbus take responsibility for the crash and French prosecutors have opened a preliminary manslaughter investigation that could lead to negligence charges.

Hopes of finding the two flight recorders were almost finished because the locator beacons are already lost power by June 30.
Leaks from Air France and pilots’ unions indicated that the airline was aware earlier than it has publicly admitted that there was a problem with the speed instruments on the fleet of long-range A330 and A340 aircraft. At accident time Air France was already in the process of replacing the pitot tubes.
Air France 447 was the 36th flight in which there had been known faulty speed readings on the A330 and A340 series operated by various airlines, said Eurocockpit, a French-language website run by pilots, including Air France crew.
The previous incidents followed the same pattern as those reported by AF447, except that the pilots were able to recover control and return to normal flight.
Because of the storm conditions maintaining control in AF447 would have been a monumental task, the website said. We have consulted the [Air France] pilots who had these pitot problems. All told us that it took a big immediate dose of lucidity to avoid distraction by the stall warnings which came with the incident and face up to the deluge of alarms.”

[rgbrock1]

@noelbaba,

The rudder moved beyond its limits? I've not seen that before, has anyone else?
What would have been the source of such a statement? Is this something contained in the ACARS messages? I consider the entire report, in eTurboNews, complete conjecture, no?

[Will Fraser]

The Benefit of the doubt is generally reserved for those who deserve it.
A known a/s sensing problem, a dangerous reliance on autoflight, an "untrained" (sic) aircrew with one (senior) member missing, Radar left to 'bon chance' (Gourgeon). I have slammed each of these for eight weeks, only now does Arslanian muster the troops (other people's money) to 'leave no stone unturned'. ?? The initial release of 'official' information was a laughingstock; from the git go the crew were being set up, the a/c 'protected' (politically as well as technologically), and the line was deflecting everything that smelled like responsibility toward the 'unlucky' flight deck. This is 'news' ?

rgbrock1- Of course the Fin moved beyond limits. The question is 'when'. It is an open question for those who are not an easy sell.

[Gary Brown]

I had my SIM Training today.
One of the things we had to deal with was, en-route ADR2 failure, followed by ADR disagreement due to Volcanic Ashes...and Double Engine Failure (A330), due to the same reason. Attitude, Attitude, Attitude (all Pitots blocked by ashes).
It seems an improbable situation. (yeah, sometimes a guy has to think twice before leaving home:hmm:) But, when the "Gods" are against us, s**t happens...and it ended up with the Ditching Paper Check-List...
.........

Thinking back to that very interesting Air Caraibe incident report (see my post at http://www.pprune.org/rumours-news/376433-af447-now-added-preliminary-report-193.html#post5079036 and the several discussion posts either side of it), what in the training / experience of those guys led them to reject the STALL warning, and what might have been the consequences of their not rejecting it?

AGB

[JD-EE]

noelbaba, your screed rushing to judgement on virtually no evidence at all is a fascinating read into the pathology of lawyers and conspiracy theorist minds. Thank you.

There is no bottom line here to work with. There are hints that too little of the right kind of training took place leading to pilot error. There are hints that there was a pitot fault. There are hints that there is a pathological (likely lawyer inspired) fault in the flight controls themselves. There are hints that too little training in the use of wx radar (or none at all) took place leading to pilot error. There are hints upon hints upon hints. There are no solid facts. Then you conflate the rudder coming off on impact with the ocean with rudder over travel. The visible indications present on the rudder itself did not suggest it was twisted off sideways as with rudder over travel. But you insist it happened.

You seem to be slavering to see some likely innocent party convicted of malfeasance and soundly financially punished for most likely bad reasons just to satisfy your emotions. This is unseemly, sir.

JD-EE

[wes_wall]

The US FAA is now flexing some might.


September 2, 2009
US airlines must replace speed sensors on some of their Airbus planes, parts that have come under scrutiny since the crash of an Air France jet three months ago.

The Federal Aviation Administration (FAA) on Wednesday ordered carriers operating A330 and A340s -- Delta Air Lines and US Airways -- to swap probes manufactured by Thales with components made by Goodrich.

The FAA order, which takes effect from September 8, affects about 40 planes, and follows similar action by European authorities in response to the crash of Flight 447 that killed 228 people. The A330 crashed into the Atlantic Ocean on a flight from Rio de Janeiro to Paris on June 1.

Investigators said they do not yet know what caused the crash but are interested in what role, if any, unreliable speed readings from the plane may have played in events leading up to the disaster.

The investigation is expected to take another year.

European safety officials have reported speed indicator discrepancies on some A330 and A340 planes at high altitudes in bad weather. Investigators indicate that planes equipped with Thales probes appear more susceptible in rough conditions.

Regulators are especially concerned about ice crystals forming on sensors and throwing off readings. Inaccurate readings can disengage the autopilot or other automatic functions and cause the pilots to lose control of the aircraft.

There have been several reports of problems with Thales sensors.

Airbus in July urged airlines to switch to Goodrich, which already supplies sensors on most of the world's A330/A340 fleet. About 200 planes are equipped with sensors made by Thales, Airbus has said.

Separately, US transportation investigators are looking into possible anomalies with speed and altitude indicators on two A330 planes in May and June.

Privately held Thales is Europe's largest defense electronics company, which has so far declined to comment on the sensor matter.

(Reuters)

[JD-EE]

Will, unless somebody has proof the pilots were playing canasta on the flight desk as the plane flew into the storm there is no way the pilots can be blamed for the AF447 mess without leading to a conclusion that their training had astounding gaps.

One does not convict on "slightly more likely". One convicts on "beyond reasonable doubt" in polite societies.

Too little evidence exists for a conviction of anybody.

Plenty of evidence exists that various elements of pilot training, the instrumentation, and the flight data computers could be improved.

With all that evidence of "not quite good enough and MIGHT cause problems" there is cause to work for improvement. There is not sufficient evidence to prove the disaster was not caused by a mouse that got on board and chewed through some critical control cables. So apportioning blame and crying for revenge is stupid. It also, if you cannot tell, offends my sense of justice.

JD-EE

[vapilot2004]

What I would like to know is when the pitots are replaced, do the ADIRU/FBW software boxes get 'updated code' ?

[Graybeard]

The Air Data Modules are the interface with the pitot probes. They convert dynamic pressure to a data bus. I don't know, but there would be the logical location for correction calculations. It's done in the Air Data Computer in planes without ADMs.

Thinking about the amount of fright testing needed, it's kind of surprising there would be more than one maker of pitot probe certified. Is there more than one on Boeings? The 737 doesn't even have a choice of engines..

GB

[broadreach]

JD, are you not shooting the messenger? Unless Noelbaba has removed one or more posts stating his own opinions, all I've seen is his posting of something from eTurbonews.

[ArthurBorges]

Anecdotally, Airbus CEO Thomas Enders told the Paris tabloid "Le Parisien" that "We are studying other ways of collecting flight data... For example, the most important data could be sent out over a satellite link in real time, as is already the case with maintenance data. We're working on this with our partners and suppliers."

Le Parisien also quotes blackbox inventor Pierre Jeanniot as saying the recorders were "obsolete" and "new technologies are available."


Source:
Airbus envisage la fin des boîtes noires - Yahoo! Actualités (http://fr.news.yahoo.com/3/20090904/tfr-aviation-securite-boites-noires-airb-d0963a8.html) (in French)

[GMDS]

[/URL][URL="http://www.eturbonews.com/?page=1"]eTurboNews | Travel and Tourism Industry News (http://www.eturbonews.com/?page=1)

BY UNAL BASUSTA AND WIRES, ETN STAFF WRITER

BEA director Paul-Louis Arslanian, The director of the French agency investigating the crash of Air France Flight 447 said Monday that investigators could take at least a year-and-a-half to reach a conclusion.
...

The captain should be present in the cockpit while cruising thru this very strong thunderstorm passage.



Reading this article I could not clearly determine who of the two (Basusta or Arseline) did the last statement. Either way, it is sustaining one of my main concerns about inflight rest facilities and policies of many airlines.
If the captain, and this is meaning the most experienced or sometimes the only experienced on certain routes or the only aera-qualified, is to be on deck in certain difficult situations, then I agree 100%. But if they are confined into rest facilities in the back or the cargo cptmt of the aircraft, then they clearly cannot cope with such common sense requirement. The same applies to certain procedures that basically only allow the skipper to rest in the middle of a flight (t/o and ldg presence) and on most such routes the critical phase is mainly at this time (Himalaya, Ocean etc.).

The authors of such claims should really help us by building up pressure on airlines to review some rest policies and locations. Simply because most of such decisions are made for the profit or like EK having rest facilities adjacent to the cockpit REMOVED and replaced in the very rear of a long aircraft for passenger comfort reasons. I'd rather be safe than a little more confy!

[Me Myself]

The authors of such claims should really help us by building up pressure on airlines to review some rest policies and locations. Simply because most of such decisions are made for the profit or like EK having rest facilities adjacent to the cockpit REMOVED and replaced in the very rear of a long aircraft for passenger comfort reasons. I'd rather be safe than a little more confy!

There isn t any rest policy and as a captain, I really do not need one. I ve got my own swiss pocket knife called common sense and experience to help me DECIDE what and when I am going to do it. Period.
Experience is to have ploughed those tropical routes years in and years out as a F/O watching how " the old man " does it..............or screws the pooch. That s also experience.
As to common sense, I don t think I need to give a specific definition but let s say that along with experience, it is what brings you home alive.

I too, have made errors of judgement, and trust me when I say I am a sorry, prudent, scared wooss when it comes to CB s. Luckily, I came out ok without sending any pax through the roof. But still, this memory humbles me when I am wicked enough to think about it.

The answer to that isn t in writing the 10 000 s rule in the rule book which will go forgotten in less than a week, but putting emphasis on training.

One thing that has always rocked me off my saddle at AF is that when you upgrade to command, your training captain is likely to be a guy who was upgraded just a year before you. What kind of experience can a guy like that bring you ???? Just about zilch. Sure thing, he ll stuff your head with " ze book of rrrrrrrules " like a turkey on Thanksgiving, but as far as experience is concerned he is just as virgin as you are.
Safety culture comes from Flight Safety department but is relayed, or should be , down the ranks by old hands and it should be something one should be enthousiastic about and not have 4000 different pig headed minds about.
This culture, just like geraniums on spring time, has to be " nourrished " on a regular basis otherwise it goes into oblivion within months.
The Jo burg incident in 1998 could have had the same ending had Mr Boeing not built his 744 like a tank. For a few weeks / months, all of what people could talk of were " hu dangerrrrrrrrrrrous cee bee werrrrrrrrre " veer this 40 deg, veer that 50, AF planes all over the bloody place. Superb ( and I m not jesting here because when AF puts its mind to it, they really come up with some fantastic material ) publications, rehash on line check, you name it. What happens then ???................zzzzzzzzzzzzzzzzzzzz !! The matter is considered as " solved " as Inspector Clouzeaux would put it, forgetting that people leave and new one join. This is a never ending task and no zzzzzzzz is allowed.
Nor can it be left solely to the goodwill of some fantastic fleet heads of training, who too, won t be around forever.

The Colin report adressed all this and strongly advised to go back to basic which was done in part but not the whole way. In order to judge this report, one should have implemented it in full. Instead, some people started winging about " Whot ??? you want me to go and get a command on short haul when I had .......PLANNED on a forever Daiquiri splash on the beach. Nope !!! " and the implementation of this rule was postponed ...........yes !!!............10 years. Do I need to translate into NEVER or NEVER NEVER land, cuz sometimes I feel this is where we live ??? .

I see nothing shocking in the fact it is going to take that much time to come up with conclusions. If memory serves, Swissair 111 took just as long as that, and they had a lot more evidence to work with.
I can already hear the rant about " The BEA, the french state, AF, not to mention Airbus" will see to it that the books are cooked " well done ".
Hoy !!!! smell the coffee !!! So many states are involved that this will never be possible even if the french wanted it that way and for all their flaws, I don t think they do.
Something will come out of this and I am confident the ventilator will have enough dung for everyone to stay occupied cleaning himself for the next 10 years.

[SaturnV]

GMDS, noelbaba's quotation of the eTurbo news article by Unal Basusta is laced with what appears to be noelbaba's opinions. Basusta's reporting, while itself containing some conjecture and opinion, has no sentence about the captain needing to be present in the cockpit during severe thunderstorms.

The French press (Figaro, Le Monde, France Soir) in reporting on Arslanian's conversation with aviation reporters on August 31 makes no mention of Arslanian saying anything at all about where the captain was during the final minutes of AF 447.

[Me Myself]

The French press (Figaro, Le Monde, France Soir) in reporting on Arslanian's conversation with aviation reporters on August 31 makes no mention of Arslanian saying anything at all about where the captain was during the final minutes of AF 447.

...................and for one very good reason.............nobody has a clue. The fact his body was the only recovered of the 3 techies doesn t prove a thing as to where he was seating. One can only speculate.
All the BEA will ever be able to conclude, be it tommorrow morning or in 18 months, will only be the most likely scenario..........unless the flight recorders are retrieved. I ve stopped holding my breath on that one.

Look folks, the french press has got to sell paper. Last week it was real estate in Paris supposidly .........affordable ( tons of laugh ), this week it s 447. In summer they come up with the usual " The wisdom of greek philosophers " when everyone is trying to get laid on a sunny beach. I think they call that " Les maronniers " in journalistic terms. Topics they pop out of the hat when they have nothing else to say. Next week it will be the famously dreaded french " La rentree " where doomsday and social Armagedon are the journo s prediction and politicians run for cover. We then quietly move on to Xmas where family turns to be a jolly good thing ( highest rate of divorce claims comes boxing day ) and so on.........
Do yourself a favour, stop reading the french press.

[broadreach]

JD, my apologies; noelbaba's post is a mixture of the original article and what appear to be his own opinions. You had obviously done a better job of checking than I.

[JD-EE]

No problem, broadreach, I have done that very thing before. So I had to go back and double check.

[promani]

I recall that the F/O had more experience flying the A330 and more rotations on the South American sector than the captain, although the captain had more flying hours overall. So I just wonder if the captain's presence, if it was missing, on the FD would have made a difference. Unless the CVR is recovered, we can only guess what transpired after TO up to the end. My humble opinion is that in the case of F-GZCP, what could go wrong, did go wrong.....throughout the short flight. The finger of blame points in many directions.

[mm43]

This is a revisit of the data I originally presented on page 210, and something between the original and that presented below may be close to the truth.

After analysing OSCAR/NOAA surface current data for the period 01 June - 15 June 2009, and the Quikscat satellite surface (+10m) winds for the same period for the area encompassed by 5°30'N 32°30'W, 5°30'N 29°30'W, 2°30'N 29°30'W and 2°30'N 32°30'W, I have come to the conclusion some of the "observed data" bears no relation to the "actual data" resulting from the location of bodies and other debris from AF447.

The basic problem is that the North Atlantic Equatorial Current had developed a "blip" in the area of the suspected crash location. This area was in fact the location of the Doldrums at the time of the accident and the current was attempting to flow Northeast to become the Equatorial Counter Current. However, at 3°30'N 30°30'W a very strong pull to the West was developing and the surface current velocities over the period from 07 June to 17 June increased to average 9.35NM per day or 20cm/sec along the general line in which the bodies were recovered. This is nearly twice the rate provided by the satellite data. In the meantime part of the current continued from 3°30'N 30°30'W in a Northeast direction at velocities approaching 1.5 times the published figures.

The anomolies associated with the OSCAR data are probably due to a slightly lower than expected Mean Sea Level barometric pressure in the pivotal area to the West of 3°30'N and 30°30'W, resulting in the actual MSL being slightly higher than the one used in the OSCAR/NOAA calculation of the current vectors and velocities.

The Northeasterly branch of the current from 3°30'N 30°30'W carried very little debris with it - the most notable (that we know of) being the Starboard Outer Spoiler which was recovered on 13 June NNE of TASIL. Looking closely at the photos of the recovered spoiler, I sense that the damage which resulted in its separation was caused by the high velocity vertical impact of the underside of the wing with the sea surface as the wing was rotating clockwise (backwards) horizontally. The clockwise vertical rotating force exerted by the Vertical Stabilizer as the tail entered only added to the forces experienced by the spoiler.

The heading of the a/c at the time of impact was probably at some point in the East quadrant, which resulted in the spoiler departing "explosively" in the same general direction. Once the general disturbance caused to the sea by the impact had subsided, the spoiler was likely located some distance east of the remaining debris. Hence it later missed the anti-clockwise turn near 3°30'N 30°30'W and continued with the NE branch of the surface current, and was also unaffected by the surface wind due to its very low surface profile as noted in recovery photos.

In the graphic below, overlay of data is on the 06 - 18 June 2009 composite showing "positions of bodies and debris recovered" produced on page 37 of the BEA's Preliminary Report (French version) into the accident. You should note that this graphic in the body of the report differs from that shown in the Appendix, and when comparing data attributed to specific days, positions do not always match up. The pressure on the BEA to complete their initial analysis and compile the data in a limited time may well be behind these discrepancies.

http://i846.photobucket.com/albums/ab27/mm43_af447/af447-location-1.gif

Knowing the approximate position of the Vertical Stabilizer when it was recovered on 07 June, and that of debris and bodies recovered on 06 and 07 June were fairly well grouped, has helped tighten down the analysis required to back-track to the possible impact point. South of 3°30'N the current vectors and velocities provided by OSCAR seem to be fairly constant, and provided those velocities are reasonably accurate a recalculated position of the impact point is shown.

The back-track involved equating the distance and bearing that the Vertical Stabilizer was from the general track line of bodies (dashed magenta line) with the mean surface current along with wind vectors and velocities from 0300z on 01 June to 1500z on 07 June 2009 (6.5 days). A light blue (cyan) line marks the general line along which debris with a low profile to windage has been recovered. The total leeway vector and distance of the v/s is 255.3°T x 9.38NM from the mean bodies track line, and the daily factor derived from Quikscat data (modified to 2m above sea level [velocity x 0.75]) has been used along with the appropriate current vector and distance in the back-track exercise. The data used is replicated below.

http://i846.photobucket.com/albums/ab27/mm43_af447/set-leeway.jpg

Referring back to the top graphic, the green (lime) line represents the NE'ly branch of the current, and the area between the light blue (cyan) and red lines is the area in which the majority of bodies and debris were located and recovered. Debris to the West of the red line has been subject to significant windage and consequent leeway. One body was located close to the red line, and the assumption is that it was caught up in other debris. Three debris items near 3°15'N 29°45'W do not appear in the Appendix version and possibly are unrelated to AF447. An item marked "07" near the "last known position", has probably broken lose at depth from the wreckage and made its way to the surface, but how long it was there before being recovered on 07 June is another matter. Water spouts are common in the ITCZ, and odd items of debris may have been moved about through being lifted and later dumped some distance away. The current vectors shown are overlaid from the OSCAR data, and it is fairly obvious that the general drift of the bodies and debris hasn't always followed the expected line.

The accuracy of the information presented is of course reliant on data from a number of sources, but is the best that could be obtained.

mm43

[JD-EE]

mm43, I really like your analysis. It fits with other known data very nicely. The impact point, for example, is within the annular ring I'd expect for minimum distance from last known position and maximum distance from last known position for a plane that was not spiraling down completely out of control.

No hand of God reached out to stop them cold in their tracks. And they may not have been entirely in control. The distance of your calculated point of impact is near a point I'd expect for a plane that had been going at 4 to 5 nm a minute and was turning to the left and downwards.

Now, as to why it might be turning to the left I can only guess from an ignorant bystanders standpoint. I understand that normal deviations are to the right for traffic control reasons. I have further gained the impression that the planes fly slightly to the right of the nominal track under normal circumstances, although this is not critical to my thinking. The pilot in charge may have deviated to the left planning to go down to an appropriate flight level for a quick return to Brazil for some reason. And then he lost it. Or the entire trip to the ocean may have been in only partial control leading to the deviation to the left.

Maybe he'd executed a partial turn, the engines quit, and he dove to try to restart them. He got too low, tried to pull up into a proper ditching, and didn't made it.

Those are raw almost fantasy reconstructions to fit this additional data consistency. So please don't make a big deal of them.

There are still so many possibilities that it'll be really hard to place solid "blame" on any one thing. But, we may know enough to call for some changed procedures and MAYBE some changed equipment to prevent this happening again. (Personally I'd like to hear that the flight control computer was modified to "very strongly recommend the pilot take over but retain control until the pilot is firmly at the controls" rather than throw up its hands and say "The pilot's got the plane" when the pilot is having trouble due to buffeting getting his arm into position to take control.

JD-EE

[SaturnV]

mm43, thank you for extensive and excellent analysis.

Two questions, and perhaps you don't have the answer.

1.) Does your calculated point of impact lie to the west of the westernmost vector of the search grid flown by the Brazilian Air Force on June 1? (That search basically overflew the projected enroute track between INTOL and TASIL with a bit of coverage on either side of the track. On June 2, the search boxes were expanded to the east and not to the west of the track. I realize you may not have the coordinates for the area searched by Brazil on the 1st. Although I understand why the grids were expanded to the east, and then south, if the grids had also been expanded to the west in the immediate days after the crash, the wreckage likely would have been found sooner and closer to the actual impact.

2.) Arslanian in his August 31 conversation with reporters said that the wreckage was in waters 3,000 to 3,500 meters deep. Here is a Wiki profile graph of the area. Eyeballing, 30.5 W is roughly near the vertical bar for the Mirante do Vale building. However, the profile is for 3.5N, not 3.1N, and this is basically an east west profile, with no north-south component. Do you have any bathymetric profile for the bottom near 3.12N, 30.54W?

http://upload.wikimedia.org/wikipedia/commons/thumb/9/9e/AF447Cross-Section.jpg/606px-AF447Cross-Section.jpg

Notes on the profile here:
File:AF447Cross-Section.jpg - Wikimedia Commons (http://commons.wikimedia.org/wiki/File:AF447Cross-Section.jpg)

Added:
Also, the vertical scale of the bathymetric profile is greatly distorted, so the slope between peak and valley may not be so much off-the-cliff as depicted.

[mm43]

JD-EE, Thanks for your comments.

SaturnV, I have managed to dig out a video monitor shot taken in the FAB SAR control center at Recife. It shows that a grid search was undertaken in 2NM lanes 10NM either side of the track and for 55NM past the Last Known Position. With lanes 2NM apart, I expect the altitude flown was 1500 feet. However, it seems from other data in the pic that they finished up concentrating on unrelated debris found well to the SE of the track

The screen shot below has had some Lat / Long points marked, along with TASIL and the possible crash location.

http://i846.photobucket.com/albums/ab27/mm43_af447/af447-fab.gif

Arslanian in his August 31 conversation with reporters said that the wreckage was in waters 3,000 to 3,500 meters deep.I thought "they" hadn't been able to find any wreckage, so I think he is just making something up for the media - or maybe the media padded out the story.

The Wikipedia bathymetric profile gives a reasonable idea of the topography in this area, and your reference to the distorted height is good. Put it another way, the deepest valley is about 1.6km and the horizontal distance from top to bottom is 14km, giving a 6.57° average gradient. Bit much for most railways/railroads (1.5°), but not mountainous by any stretch of the imagination.

I will try and dig out a bathymetric profile for 3.2°N 30.9°W, I think something is available.

mm43

[Dutch Bru]

.....however the SAR grid you posted doesn't say much without a date and legenda.

Here is for instance a map with grid west-northwest of the last known poisition, flown by one of FABs C130 on 6 June, which does seem to cover the area you're pinpointing in your highly interesting earlier post on the possible crash site:

http://www.fab.mil.br/portal/voo447/FOTOS/dia0606/carta_da_operacao_assinada.jpg

But perhaps that is the point you and others try to make: it was six days after.

Having said that, interestingly enough your presumed impact point is within the northen part of the grid of 10000 sqkm of search area along the flight path on the same map, flown by FAB's EMB RJ 99's and fully completed by them on 2 June (re FAB note nr 6 of that date)

[mm43]

Dutch Bru,
Your point about no date on the grid I posted is of course valid. It was obviously before 6 June on account of where the FAB seemed to be concentrating its search. The difference is that on 6 June the FAB were finding debris in the area SW of TASIL, whereas on 2 June I believe the visibility was variable in rain/showers, and even though they may have flown near to, or over the 3°18'N 30°48'W position the v/s is assumed to have been at 1500z on that day, they obviously sighted nothing.

One and a half days after the impact the floating debris pattern would still have been relatively compact - say a radius of 0.5NM, as I construe the BEA's description of the impact as having little or no horizontal momentum - more a tail heavy "flat spin".

In the cruise, I assume the trim tank was in use - not helpful later on.

Still, it puzzles me as to why the FAB had no radar contacts, e.g. a number of metalic objects were in the debris. The spoiler unfortunately would have been a rather poor target - floating flush with the surface and effectively sea clutter.

mm43

[HarryMann]

In the cruise, I assume the trim tank was in use - not helpful later on.

Indeed, I also highlighted this point a couple of times back in the thread... unfortunately there doesn't seem to be much acceptance that it could have played a significant role as the systems degraded and heavy turb might have had to be flown manually - something I would have thought would be extremely significant when speed stability was paramount.

[SaturnV]

mm43, WOW!

On the chart with the search grids, the boxes lined in red near TASIL were the grids flown on June 2nd, if I recall correctly.

The most extensive article in French that I found on Arslanian's conversation with aviation reporters on August 31 was in France Soir,

Ce sera la troisième phase de recherches. Lundi, Paul-Louis Arslanian, le directeur du Bureau d’enquêtes et d’analyses (BEA), a déclaré que les investigations pour retrouver les boîtes noires de l’Airbus A330 devaient « reprendre à l’automne ». Peut-être la dernière chance de comprendre les circonstances du crash du vol AF447 qui devait relier Rio à Paris dans la nuit du 31 mai au 1er juin 2009. Car « pour l’instant, nous n’avons toujours pas compris la cause de l’accident » a concédé, lundi, le responsable des investigations techniques. Pour cette troisième phase, l’enquête « va être élargie à d’autres pays, de façon à mettre le maximum de vision internationale » a-t-il précisé. Le coût ? « Plus de dix millions d’euros et peut-être plus » selon cette même source. Fin juillet, l’avionneur européen Airbus s’était dit prêt à débloquer entre 12 et 20 millions d’euros, sur une durée de trois mois, au moins, pour les recherches du BEA.

Nouveau rapport d’étape

Le 20 août, les opérations sous-marines engagées pour retrouver les boîtes noires de l’Airbus A330 d’Air France, au large de l’Atlantique, entre 3.000 et 3.500 mètres de profondeur, se sont terminées sans succès. Cette seconde phase succédait à une première étape de recherches acoustiques, achevées le 10 juillet au terme de quarante jours d’investigations. Ce jour-là, les balises, auxquelles sont reliées les boîtes noires, avaient a priori cessé d’émettre. Le 2 juillet dernier, le BEA avait estimé qu’une défaillance des sondes Pitot qui mesurent la vitesse de l’appareil, était « un élément, mais pas la cause » de l’accident. L’hypothèse de la dislocation de l’avion en plein vol avait également été écartée.

Paul-Louis Arslanian a annoncé la présentation d’un nouveau rapport d’étape « dans quelques semaines ». Le responsable de l’enquête espère pouvoir être en mesure de fournir les explications du crash, dans un an, un an et demi.

Perhaps, Arslanian was describing the general area of the search (see Switzerland quote below), or the reporter simply added that. I agree that Arslanian did not say they had found any subsurface wreckage

Reuters has this quote from Arslanian (I assume translated from the French):
"The work is a bit like crossing Switzerland by foot, trying firstly to listen out for the noise of a cricket and now looking for debris with a pocket torch in the dark," Arslanian said.

Bloomberg
The accident occurred in the middle of the Atlantic, near where the earth’s tectonic plates meet one another, Arslanian said. No one knows exactly where the plane went down, he added.

And AFP reported that Arslanian said the BEA had still not received the final autopsy reports from Brazilian authorities. He sounds a bit frustrated

"Our Brazilian counterparts have provided us with a large quantity of information. I am still waiting for the detailed results of the autopsies. I still don't have them," he said.

[PJ2]

HarryMann;

If I may offer some thoughts on why there wasn't much acceptance of a "tail-heavy due to the trim tank" theory and why, in comparison with other theories, it is far less plausible to theorize loss-of-control due to a trim-tank/CofG issue.

The trim tank will carry approximately 4800kg when full. Aft fuel transfer begins at FL255 (if the trim tank wasn't full at takeoff), and forward transfer occurs during flight as fuel is burnt. The fuel load for AF447 was 70.4k kg. I can't recall directly from my own experience with similar fuel loads but am almost certain that the trim tank would have been full at takeoff - I don't have the distribution tables for an A330 with center tanks.

First, the CofG for takeoff was well within limits and the calculated CofG 3:41 into the flight was approximately 37%. My numbers show the aft limit is 39%. The QRH Trim Tank Fuel Unusable Abnormal Procedure states that if the Trim Tank fuel is unusable the maximum flight time, depending upon fuel distribution, is 4hours at which time the aft CofG would be reached.

Since the flight was only 3:41hrs long (BEA Report), the trim tank would have had about 4500kg of fuel which begins transferring forward at cruise altitude. The crew would have to have known about any trim tank problem resulting in unusable fuel at least upon reaching cruise altitude if not slightly after. The flight would require this fuel for the arrival at Paris. Unusable fuel, especially given the weather enroute (diversions), would present a significant operational decision to turn back or continue which would have had to have been made in these first 3hrs.

There is no evidence either by communication or in any ACARS messages received that there were trim tank issues.

Second, the QRH drill then states that "For Landing", *if CG > 39% - Approach Speed Vls+10kt with the landing distance procedure to be applied, (landing distance increase by 1.25).

So a CG > 39% is catered for by a 10kt increase in Vls, meaning that the aircraft can be flown without issue. There are no cautions, no imbalance limits stated between trim tank and wing tanks and no warnings associated with this condition to which the attention of an A330 pilot is drawn in the AOM.

That doesn't mean that handling characteristics in abnormal flight such as approach to, or full stall would not be affected. What it means, as I interpret this as an experienced A330 pilot is, (and what I would expect from my aircraft is), a fully controllable airplane with no squirrely habits or handling characteristics in all flight regimes with a CG > 39%. That is, I expect as a pilot of the airplane, what the certification of the aircraft means - it is controllable even with maximum fuel in the trim tank at the expected landing weight, on approach.

That is why I would consider the CG and Trim Tank theory highly implausible at least as an initiating cause when in heavy turbulence etc.

All bets are off in any severe loss of control/jet upset.

[HarryMann]

Many Thanks

I take it c.g. > ## implies forward of :)

All bets are off in any severe loss of control/jet upset.Yes, that's what I meant - I don't think either of us had conceived the idea that an event was likley initiated by a trim-tank or c.g. problem.

I am surprised (a bit) that no cautions for severe turbulence, maneouvring or flight near Mmo with full aft c.g. are made, but on reflection, this might logically I suppose be a certification requirement.

Regardless, the fact is, aerodynamically, the a/c must be less stable in pitch anywhere near the aft c.g. than further fwd?
Asking for early or temporary fwd fuel transfer when entering turbulence, would of course, be both impractical as well as somewhat 'worrying'

[PJ2]

HarryMann;

My pleasure as always.

"> ##" is to me a higher CG, so aft is what I meant...BUT, I see what you mean wrt the QRH and therefore it is open to interpretation and it shouldnt' be - may take it up. To me, ">39%" means further aft. If it means further forward, as a pilot I have to assume still, that there is "no risk, no danger" as there are no cautions/warnings.

I'm unsure of what the meaning of "unstable" is in a fbw design. As we both know, fighters are inherently unstable without fbw to reduce drag and increase maneuverability. The 330 is not nearly in that category of course but still, any instability, or flight control problem, (floating spoiler) or CG issue would be masked by the fbw response until the autoflight gave up due to being beyond it's design certification limits.

So "unstable" isn't something an Airbus pilot would be expected to handle/deal with except again, in jet upset conditions, then all bets...etc.

Re "not initiating", oh, ok - I had mis-understood, believing that some were considering an aft CG could have been an initiating item in heavy turbulence - sorry. In heavy turbulence the only caution is to slow down - Mach 0.78 to 0.80 or 280kts if I recall. Also, it is recommended to disconnect the autothrust to keep it from hunting the airspeed.

best,
PJ2

[HarryMann]

That's interesting, my first response to >39% was the correct one, then by context misjudged it to mean fwd of . Mr Semantic-Pragmatic here, maybe it should be looked at - aft/fwd of are not big words, and then it's totally clear!

At the risk of extending a somewhat off-topic discussion, the fbw, however smart, is still working with a less stable machine, so presumably working harder, letting go sooner...

A secondary effect, of such a mass at such a distance, regardless of c.g. position, is an increased pitch and slightly increased yaw inertia. This likely has some +ve and some -ve aspects. One -ve would be higher rear fuse bending moments, which may well be small or insignificant in the whole scheme of things.

[PJ2]

Re bending moments, I know the DC8-61 & 63 series would bend - suspect same with all types, save perhaps the 747 simply due mass and oblong cross-section.

If I may be permitted to wander a bit with some off-the-cuff thoughts...

Agree on the fbw notion - once it "gets there" it springs loose, so to speak? In assessing all this and as a pilot of these things I place a huge amount of faith/trust in the design/certification/manufacture process in the sense that I ask no questions of the airframe or systems. I take "what is" from where I sit and if it disappoints, that is the designer's/regulator's problem. Essentially, none of us are trained test pilots, having no business outside the normal flight regime, (save circumstance, obviously), and so that is the only approach open to professional airline pilots today. We used to do nuts-and-bolts courses, drawing systems, sometimes playing "what-if" across the Atlantic; no longer. Second-guessing the airplane and it's designers is not possible from our cockpits and we have to accept that both the manufacturer and the regulator have done their work correctly. In my experience, I have yet to be surprised, have yet to find an ECAM drill poorly thought out, so I guess they've done okay.

That's why this accident is truly an enigma. I suspect there are many A330 pilots here, silent or otherwise, who have been in the very same circumstances as this crew and are really, really wondering what unfolded so swiftly as to bring the aircraft down. We can all imagine different scenarios, (and have posited them here) but in the end all we know is it took off and it crashed just about 4hrs later.

[pax2908]

You may be aware of claims (on the French forum) that the particular configuration (weight + flight level + assumed full aft CG) was allegedly very hard or impossible to fly with A/P off in the simulator.

[HarryMann]

You may be aware of claims (on the French forum) that the particular configuration (weight + flight level + assumed full aft CG) was allegedly very hard or impossible to fly with A/P off in the simulator.No, not aware, thanks.

Which (degraded) control law were they assuming?

Was this in still air or simulated turbulence?

PJ2 and others estimate c.of g. @ 37% ~ 2% fwd of aft limit at the time of the accident

[pax2908]

Sorry for the lack of precision. I had in mind a message posted on August 9th on that forum. I try to translate a small part of that message:

"We are currently trying to estimate the CoG after 3h25 flight time. Roughly the aft limit is 38% MAC and the a/c would have been at 37.7%, yet to be confirmed.

In ALT2 or worse in direct law (we don't know yet) nobody managed to fly this at FL350. Try it in the simulator, it feels very odd, dont forget you don't have airspeed information, you are in night IMC, and with turbulence".

So indeed this scenario is more degraded than what one would understand from my previous message.

[ArthurBorges]

Distilling the content from this, we get Arslanian saying the third phase "should start in autumn" and "right now, we haven't understood what caused the accident." The third phase "will be expanded to include other countries for optimal international vision" and will cost "Over € 10 million, maybe more." In August, Airbus said it would allocate €12 to 20 million for at least three months of searching. The second phase sideswept from 3,000 to 3,500 metres and ended Aug 20 in failure.

Finally, Arslanian promised a new status report "in a few weeks" and said he hoped to explain the crash in a year or year and a half from now.


Your original pickup, SaturnV:

Ce sera la troisième phase de recherches. Lundi, Paul-Louis Arslanian, le directeur du Bureau d’enquêtes et d’analyses (BEA), a déclaré que les investigations pour retrouver les boîtes noires de l’Airbus A330 devaient « reprendre à l’automne ». Peut-être la dernière chance de comprendre les circonstances du crash du vol AF447 qui devait relier Rio à Paris dans la nuit du 31 mai au 1er juin 2009. Car « pour l’instant, nous n’avons toujours pas compris la cause de l’accident » a concédé, lundi, le responsable des investigations techniques. Pour cette troisième phase, l’enquête « va être élargie à d’autres pays, de façon à mettre le maximum de vision internationale » a-t-il précisé. Le coût ? « Plus de dix millions d’euros et peut-être plus » selon cette même source. Fin juillet, l’avionneur européen Airbus s’était dit prêt à débloquer entre 12 et 20 millions d’euros, sur une durée de trois mois, au moins, pour les recherches du BEA.

Nouveau rapport d’étape

Le 20 août, les opérations sous-marines engagées pour retrouver les boîtes noires de l’Airbus A330 d’Air France, au large de l’Atlantique, entre 3.000 et 3.500 mètres de profondeur, se sont terminées sans succès. Cette seconde phase succédait à une première étape de recherches acoustiques, achevées le 10 juillet au terme de quarante jours d’investigations. Ce jour-là, les balises, auxquelles sont reliées les boîtes noires, avaient a priori cessé d’émettre. Le 2 juillet dernier, le BEA avait estimé qu’une défaillance des sondes Pitot qui mesurent la vitesse de l’appareil, était « un élément, mais pas la cause » de l’accident. L’hypothèse de la dislocation de l’avion en plein vol avait également été écartée.

Paul-Louis Arslanian a annoncé la présentation d’un nouveau rapport d’étape « dans quelques semaines ». Le responsable de l’enquête espère pouvoir être en mesure de fournir les explications du crash, dans un an, un an et demi.

[SaturnV]

Arthur Borges, as I read the French, and quite possibly incorrectly, the depth of the area where the side-scan search was focused was around 3,000 to 3,500 meters, not that the sonar was being trawled (towed) at that depth.

If a second side-scan search is unproductive -- assuming there will be one -- I would think they would need both that and other survey tools to first map the contours of the bottom to high detail. With a contour profile in hand, they could deploy the proverbial torch or flashlight (a submersible with video and lights). And even then I would say -- to continue the BEA metaphor -- they would not intend searching the whole of Switzerland, but only part of one canton.

[cessnapuppy]

You may be aware of claims (on the French forum) that the particular configuration (weight + flight level + assumed full aft CG) was allegedly very hard or impossible to fly with A/P off in the simulator. They must have forgotten how to fly. I find it unthinkable that a legal configuration (and one eminently expected) can be in any way be 'unflyable' in any law state. How could the airplane be certified if that was the case?

[caiozink]

Happened to my and several other A330 drivers in my company...not a "close to zero" probability at all !!! ALL speed indicators went to ZERO...no AP / AT / Rudder travel limiter / Alt Law no protections.....turb was light, we came out of the clouds, ice was melted by probe heat....airspeed was recovered, as well as AP / AT.....alternate law remained, as expected (reset possible only on the ground, no hyd press). Beleive me....airplane is VERY tricky / sensitive to fly !!!

[jcjeant]

How could the airplane be certified if that was the case?

That's a good question.
If you allow me to make a comparison:
Some drugs tested and approved and certified by all the official health agencies .. are after some years back down from the market due to unexpected effects.
That can happend for many things.
Just a tough.

[cessnapuppy]

With respect, determining flight capabilities along the entire flight envelope in direct law is a straightforward mathematical and observational endeavor - as opposed to putting drugs or biologics in a human body that is immensely variable. Why, even the patient's mental state (happy/sad etc) may affect the outcome, whereas a happy airbus performs just as well as an unhappy one*

I think PJ2 may say however, that a 'happy airbus' will "go around again after a bounce' but the 'unhappy airbus' will just roll over and have a cigarette - not sure what that means, you may want to try it in a sim! :)

[mm43]

Moving away from what an "unhappy airbus" might do, the following graphic shows possible impact positions from pages 210/217 plus an alternative position (#3) back-tracking the current at 1.5 times the velocity provided by the OSCAR/NOAA data from near 3°30'N 30°30'W.

http://i846.photobucket.com/albums/ab27/mm43_af447/af447-3N31W.gif

For those wanting to make a profile, multiple cross sections using slices at all vectors should be possible. However the area of interest seems to lie in a broad valley between -3000m and -3500m. Beware, the isobath lines shown are smoothed and there are ridges and ravines cutting across much of the area.

Note:: The isobath levels, e.g. -3K0 etc. have been added by me following inspection of a color spectrum relief graphic of the same area. The absolute levels could be wrong by +/-100m (or more) - subject to my interpretation of the color data associated with a high spot.

mm43

[DC-ATE]

caiozink -
Happened to my and several other A330 drivers in my company...not a "close to zero" probability at all !!! ALL speed indicators went to ZERO...no AP / AT / Rudder travel limiter / Alt Law no protections.....turb was light, we came out of the clouds, ice was melted by probe heat....airspeed was recovered, as well as AP / AT.....alternate law remained, as expected (reset possible only on the ground, no hyd press). Beleive me....airplane is VERY tricky / sensitive to fly !!!

If this is indeed the case, I submit some serious modifications need to be made...NOW.

[ArthurBorges]

Arthur Borges, as I read the French, and quite possibly incorrectly, the depth of the area where the side-scan search was focused was around 3,000 to 3,500 meters, not that the sonar was being trawled (towed) at that depth.

You read the French perfectly.

Your sentence:
Le 20 août, les opérations sous-marines engagées pour retrouver les boîtes noires de l’Airbus A330 d’Air France, au large de l’Atlantique, entre 3.000 et 3.500 mètres de profondeur, se sont terminées sans succès.

Obtains:
On August 20, underwater operations undertaken at 3,000m to 3,500m off the Atlantic coast to recover the blackboxes from the Air France Airbus 330 ended without success.

The sentence doesn't specify sidescan or trawling with sonar; I inserted "sideswept" from memory of other postings here and, perhaps erroneously, took it as a perfect synonym for "sidescanned".

Happy Skies!

[PJ2]

cp;
I think PJ2 may say however, that a 'happy airbus' will "go around again after a bounce' but the 'unhappy airbus' will just roll over and have a cigarette - not sure what that means,
I wouldn't have said it as I don't know what all that means either! :)

However, I question the testimony above which claims the airplane is "unflyable". Perhaps an airplane may not as easy to fly as in Normal Law in smooth air in daytime but describing an airliner as "unflyable" is a serious statement/accusation that can't be taken at face value. In certain hydraulic system failure cases the airplane is not as easy to fly but it is emminently "flyable" all the same. An aft CG is less desireable than one that is more forward but as you point out, the airplane is certified. I discussed the reasons why I didn't think an aft CG wasn't "in the running" as a primary cause and I think those comments require addressing by those who claim the airplane is "unflyable" or even seriously compromised before any other claims can be made. Nor do I think the "drug company certification" metaphor works - it's biological vs pretty basic, well-understood physics - not even in the same arena.

My understanding of the certification process (from reading, not experience), flying an airliner in all it's normal and degraded possibilities should not require greater than "average" skill. "Average" here does not mean "mediocre" - it means the high degree of handling skills that a line pilot would be expected to possess and be able to demonstrate in normal operations vice a pilot trained and experienced in certification and test flight work in which "normal" is a long way from familiar/routine line experience and the necessary, trained skills to maintain controlled flight at the extremes.

[BOAC]

but as you point out, the airplane is certified. - perhaps relevant here, PJ, is that 'certification', being a human function, is open to errors and omissions as with the EasyJet ACBus1 electrical failure and the 'certification' of the CFM 56-3 to highlight just 2: can we be sure that all handling aspects have been fully 'certified'? Was the (possible) loss of 3 ADUs and aft CofG considered? Was it this crew who did the flight trials? I fear my trust in the 'security' of the inspectors' stamps is less than yours.

Perhaps we will never know, sadly.

[HarryMann]

Surely it is just those conditions, and the 'relative flyability' that is being investigated and quantified by BEA and Airbus as we speak. It's certainly something that from the uncertainty evinced here, seems to require re-quantifying... especially for increasing levels of turbulence and decreasing levels of instrumentation.

Some of these pages contain discussion of the existence and capabilities of Airbus simulators extending the envelope beyond normal line-training purposes.

[Mr Optimistic]

BOAC, how's the rust ?

[BOAC]

Mr O - it is best not to mention that here - PPrune Towers gets awfully excited about that sort of thing.....:)

[Donkey497]

Read an interesting comment in Flight International yesterday in one of the letters, suggesting that a [panic] button be introduced along the lines of the airbus ditching button alluded to in the Hudson river incident, but with the effect of tranmitting an automated mayday message.

The idea being to reduce pilot workload if they find themselves in a true mayday situation. The idea being to automatically provide basic details, position, airspeed, flight number etc. from data entered into the flight computer prior to take off & in-flight updates to aid in any search should the worst happen.

Forgive me for my ignorance of the ACARS system [I don't get into the "front offices" very often], but wouldn't it be easier to make the automated reports sent on ACARS include position, speed, altitude & heading, or to have separate ACARS reports of this data, say every five minutes mandated when out of range of ATC radar / radio?

[jcjeant]

Hi,

but as you point out, the airplane is certified.Certification :confused:
One can ask:
In his commercial operation life the de Havilland Comet was certified or not ? :eek:
Think about.

[HarryMann]

Yes, it was certified of course; then withdrawn for a few months while very extensive investigation was made of every possible aspect that might have brought down G-ALYP out of Ciampino. Quite a few modifications were made, including electrical and fire safety before it was re-issued.
2 weeks later G-ALYY was lost and the certificate withdrawn indefinitely whilst the largest accident investigation of its kind took place.

It was this investigation that introduced cyclic water-tank testing to establish a safe fatigue life of a/c pressure-hulls.
The original CoA was based on extensive testing of samples and sub-sections of the fuselage.

I think it is a rather trite point you make....

[grizzled]

HM,

I think you may have overreacted a tad to jcj's post. I take his point to be this: certification is not a perfect process.

Especially with the speed of change in technologies, design and construction procedures, significant issues can and will arise before, and occasionally even after, certification.

[HarryMann]

OK, just a tad :)

The point surely, is whether the Cert requirements stipulate manual handling capability to be demonstrated in such a potentially degraded aircraft at night, in turbulence, up at cruise altitude and speed.

I imagine not!

[cessnapuppy]

but if, as we suspect, they flew headlong into CB then they would be subjected to such massively differing conditions, huge updrafts, multiple lightening strikes, changes in wind direction, intensity,ice ingestion, potential for engine flame out etc. Its possible that NO aircraft would be flyable under those conditions -or even maintain structural integrity as it appears AF447 mostly did.

Tho 'handflyability' w/o machine assistance is something needed, wouldnt they be better off if they had REAL weather radar (one that did the active scanning up and down and around and with different intensity parameters..automatically), + training how to use it?

[singpilot]

and maybe even be looking at it, understanding what it means for their continued safety of flight......

[John47]

wouldnt they be better off if they had REAL weather radar (one that did the active scanning up and down and around and with different intensity parameters..automatically), + training how to use it

maybe but pure speculation just as maybe something totally different may have occurred

[jcjeant]

Hi,

Weather radar ? sure.
Anyway it was a possibilty to have a great help ..... from the weather satellite(s) ..
Air France dispatch sended (ACARS) at 00H31 (BEA report p 61)

BONJOUR AF447.METEO EN ROUTE SAILOR:PHOT SAT DE 0000Z:
CONVECTION ZCIT SALPU/TASIL .- PREVI CAT:NIL.-SLTS DISPATCH

This was a old satellite meteo report.
Nevertheless was available a other satellite imagery dated from two hours before the AF447 approach the bad zone.
This was not sended to AF447.
AF447 had only a TEMSI outdated of 24 hours.
What is the point to have old weather report for planning a flight?

[singpilot]

The use of such a report is very much like the use of the 4300+ posts here previously. Not much use if you don't pay attention.

Trust me here. Several hundred crossings of this exact route are speaking.

ANYONE that has flown this route KNOWS about the WX in the Intertropical Convergence Zone. The WX severity that particular night was actually WANING from the 5 to 7 day cycle it usually follows RELIGIOUSLY that time of year.

The Zone forecast for that region was exactly accurate. No one should have been surprised by the WX that night. This crew had traversed this route the other direction a day or so earlier; In WX that was almost at PEAK of cycle.

The other 9 flights that traversed that exact region (all with the same WX reports) within 4 hours all went thru without difficulty.

Somehow these facts keep escaping from collective consciousness every 10 pages or so.

[HarryMann]

The other 9 flights that traversed that exact region (all with the same WX reports) within 4 hours all went thru without difficulty.

Somehow these facts keep escaping from collective consciousness every 10 pages or so.
But isn't that what often creates an accident - the unexpected co-incidence of several contributory factors - or a sequence of (likely or expected) events occuring in an unexpected or rare order.

Are we really 'forgetting' the fact that an accident is an unexpected occurrence ?

[promani]

Harry, may I also add that an accident is caused by humans and should be avoidable. An 'act of God' may have brought down AF447, but as had been said many times other flights passed through the ITCZ without mishap. The flight crew were familiar with this region. Oh for the CVR.

[SPA83]

yes, but how many with AA probes ?

[augustusjeremy]

without the CVR/FDR this thread is now completely useless.

[SaturnV]

jcjeant, the satellite image referred to in the message sent at 0031 hours to AF447 was the image from 0000 hours; it was not an image from a day earlier.

The weather-related messages between AF447 and AF dispatch

à 22 h 51 l’équipage demande et reçoit les METAR des aérodromes brésiliens de Belo Horizonte, Salvador de Bahia et Recife,

à 0 h 31 le dispatch envoie le message suivant :
« BONJOUR AF447
METEO EN ROUTE SAILOR :
PHOTO SAT DE 0000Z : CONVECTION ZCIT SALPU/TASIL
PREVI CAT : NIL
SLTS DISPATCH »,

à 0 h 33 l’équipage demande et reçoit les METAR et TAF des aérodromes de
Paris Charles de Gaulle, San Salvador et Sal, Amilcar.

à 0 h 57 l’équipage se renseigne sur l’utilisation du deuxième aérodrome
d’appui ETOPS et le dispatch répond à 1 h 02,

à 1 h 13 l’équipage demande et reçoit les METAR et TAF de Dakar,
Nouakchott et Natal,

The BEA preliminary report does not include the image from 0000 hours. The earliest image in the report is for 0037 hours, which shows the presence of a mesoscale convective system along the route of flight.

A scientist at the Jet Propulsion Lab, NASA sent the following imagery to Tim Vasquez. Note the comment that several storms at 0330Z, by this NASA lab's calculations, had penetrated the troposphere.

http://www.weathergraphics.com/tim/af447/METEOSAT_AIRS_DCC.analysis_sm.jpg

Air France 447 - AFR447 - A detailed meteorological analysis - Comments from pilots and other aviation professionals (http://www.weathergraphics.com/tim/af447/comments.shtml)

[promani]

AJ, I do not think your comment is fair to the people who have taken a lot of their time gathering facts and figures relating to AF447 demise. The BEA and AF are being very economical with the facts known to date, so there are those who try to use their knowledge and skill to enlighten us as best they can. We all want the BBs to be found.

[augustusjeremy]

Promani,

I am just saying that this discussion will be fruitless at this point, with all that could be discussed effectively taken into account.

Nothing against the people who are cooperating here. It was just an advice.

[GarageYears]

Well, without further data, I think it very fair to say that any additional comment here is either conjecture (of which every possible theory under the sun have certainly already been explored), or repetition (since most new posters don't seem inclined to read the 4000 odd posts that went before them).

If new analysis of existing data reveals something unnoticed previously, then fair enough, but really there has been nothing of value added for at least 2 weeks I'd venture.

- GY

[wes_wall]

but really there has been nothing of value added for at least 2 weeks

I am sorry, but I do not completely agree. While information added may be repetitive or redundent, it still provides an ongoing understanding of what may have occured. At the least, it keeps the subject alive, under continuous review, and a thought provoker from those who fly the airplane. I fear there may be a complete likelyhood that neither recorder will be located. Perhaps additional pieces of the airplane may be recovered, but that will likly be the best one might expect. Thus, we are left with one option, to continue to develope a credible cause based on the facts as known todate. Sticking our head in the sand touting "thats been said before" is not the answer. I favor keeping the opinions flowing.

[cessnapuppy]

whats curious to me is why in heaven's name the Autopsy reports havent been released.

Pilot (or maybe aircrew specific question)

If you start to feel a tightness in the chest, and notice blurring and/or eye pain what would you think?

or if you happened to notice a vague absent mindedness perhaps coupled with a thin watery nose (like rhinitis /allergy reaction) what would think of doing? (If anything?)

[singpilot]

Oh yeah. Lets keep the opinions going.

A post like that ought to get a few going.

[BOAC]

Forgive the lack of application, but did we ever get a 'final' on the big panels washed up in W Africa?

[singpilot]

Ariane. (yes is less than 10 characters....)

[mm43]

Cessnapuppy,

whats curious to me is why in heaven's name the Autopsy reports haven't been released.That's what the BEA are asking, but then the politics and inter-government deals about what the BEA will say in its final report have yet to be sorted out. Guess who's holding the joker in their hand of cards? Yeah right! ;)

mm43

[One Outsider]

AJ is spot on.
*
200+ pages (and a lot of deleted posts) later, nothing has been uncovered that was not known already.

[lomapaseo]

200+ pages (and a lot of deleted posts) later, nothing has been uncovered that was not known already

Double negatives are hard to decipher, but this one is worth remembering for future use:ok:

[One Outsider]

Somehow I knew you would appreciate it.

[singpilot]

Guys, I apologize.

I re-read my earlier post this morning and realized it was a little harsh. We have a political mess over here in the colonies, and reading the morning papers always gets me riled up.

I did not mean that we should give up. Or even give up hope of finding the BB's. (Is that a double negative?)

I am pretty sure what I was posting was the frustration of not KNOWING yet. OK, there MAY be some politics involved, but not necessarily. I would hope that SOMEONE would spend whatever (impossible sums) of money to find my last words in a CVR, if that was all that was left to tell the story. There are large sums of money being spent to do as methodical a search as can be designed. It may not look it from here, but tougher underwater search tasks have been accomplished, eventually.

We will not know any more until the following order of retrieval is complete. CVR (I believe the answer is there), DFDR (may be some more data, but I doubt it). I am earnestly praying that the bus power lasted long enough to keep the boxes recording. The ACARS transmissions (from a relatively minor bus) lasted long enough to provide pretty much everything we know so far, so that fact that the ACARS bus was alive pretty late in the sequence gives GREAT hope of there being invaluable data in the CVR. Next would be complete autopsies, crash debris, an eyewitness or a survivor would be even spectacular. Sorry for the black humor, but I cannot think of another single thing that would tell the ending of this story.

I tell every one of my newbies that each and every word on our checklists are written in blood (even the 'Printed in China' at the very last page...). Having been involved with some of my many types from the very beginning, I could cite the incident/accident that spawned every item on the checklist.

There is an answer out there in the mid-Atlantic to learn from. It will be found. It must be found.

[jcjeant]

Hi,

saturnV do you agree with this ?

AF447 had only a TEMSI outdated of 24 hours.
What is the point to have old weather report for planning a flight?

http://i27.tinypic.com/nq5spk.jpg

[SaturnV]

jcjeant

From the English version of the BEA report:

The part B meteorological charts were printed in black and white with the route traced by computer. The following charts were handed over to the crew:
• the TEMSI chart valid on 1st June at 00 h 00 between FL 250 and FL 630,
• the wind and temperature charts valid on 1st June at 00 h 00 at FL100, FL180, FL300, FL340 and FL390,
• the CAT charts valid on 1st June at 00 h 00 at FL340 and FL390 (no clear air turbulence was forecast).

Part C of the flight dossier contained the TAF and METAR of the departure, destination and alternate airfields and relevant airfields on the route, including the ETOPS support airfields along with the SIGMET.

A dossier thus constituted meets the regulatory requirements.

The criteria for selecting a SIGMET in a flight dossier via EOLE are:
1. the FIR involved with regard to the planned route,
2. the validity at the time of printing of the set of documents.

Note: ICAO Annex 3 does not impose any requirements related to the selection of the SIGMETs

According to testimony, the request for the printing of part C of the flight dossier was made after the printing of parts A and B of the dossier and shortly before the arrival of the crew, i.e. between 19 h 00 and 20 h 00. The time of this transaction was not recorded. In this interval, the SIGMETs that satisfied the selection criteria were:
• SIGMET 5 SBRE (RECIFE) of 31 May from 18 h 00 to 22 h 00
• SIGMET 7 SBAO (ATLANTICO) of 31 May from 18 h 00 to 22 h 00
• SIGMET 7 GOOO (Oceanic DAKAR) of 31 May from 16 h 35 to 20 h 35. The route of flight AF447 did not enter into the area of this SIGMET.

The crew also had the option of using a computer application (EOLE) to consult a colour screen showing other meteorological charts (particularly the tropopause and icing chart) and satellite photos and printing them in black and white.

Note: on the crew's OCTAVE flight plan there was additional turbulence information (SHEAR RATE) calculated according to the estimated wind gradient, between 0/1/2, weak and 7/8/9, strong. Between the NTL and CVS reporting points the highest value was 2, around point INTOL. This value did not take into account turbulence of convective origin.

The SIGMETs cited above were subsequently superseded by several other SIGMETs:

SIGMET 10 was then issued for the ATLANTICO FIR for the period from 31 May at 22 h 00 to 1st June at 2 h 00, reporting a forecast of stationary storms in the layer, with tops at FL400 [I've omitted the chart that shows the coordinates for this SIGMET.]

SIGMET 1 issued on 1st June for the ATLANTICO FIR, valid between 2 h 00 and 6 h 00, reported forecast stationary storms in the layer, with tops at FL380

If your point is that there is nothing in the BEA report indicating that the crew of AF447 were aware of SIGMETs 10 and 1, and their knowledge of significant weather enroute was apparently based to a large extent on SIGMET 7 which had expired at 2200 hours on May 31, then I would agree with your point in part.

I will note that there was the alerting message from dispatch at 0031 hours of convection between SALPU and TASIL. And this BEA report does not include any communications between flights preceding or immediately following AF 447 on this route and the ATLANTICO controller from 0133 hours to 0200 hours that AF447 might have overheard while it was on that frequency. (AF447 contacts with ATLANTICO lasted all of two minutes, from 0133 to 0135 hours, and without the CVR, we will not know whether they unsuccessfully tried to contact ATLANTICO after 0135, or switched frequencies to DAKAR early.)

[VicMel]

As pointed out within the posts of 4th July (In particular Rob21, post #2964) there should have been an 'automatic' mayday response to the circumstances on the AF447 situation. An automatic response should have happened because of the number of ACARS maintenance messages received within a few minutes, describing multiple system 'failures', ending with a message that could indicate a rapid descent; the AF maintenance centre could have instigated the SAR process within minutes, rather than others taking hours to realise that there was a problem! Introducing a 'panic' button will not help if there is no-one listening. But (as you hint) the monitoring and data gathering approach would certainly seem to need a serious upgrade. A possible starting point could be to replace the on-board FDR and CVR systems with real time data transmissions. If ACARS cannot cope/is too expensive to handle the volume of data or cannot deliver the required dependability, the Iridium system (Iridium (http://www.iridium.com)) would seem to be an alternative. If such a data collection service were to be made available, automatic monitoring would be possible. For example, if an aircraft went off course or had an unscheduled change in Flight Level a low level alert could be generated; loss of a sequence of transmissions could generate a higher level alert. Replacing the FDR and CVR with a global data transmission capability should be a cost saving; as they are built to such a high spec, I'm sure that FDR do not come cheap. There should be a weight saving as well.
However, I believe such a change (plus other improvements in data gathering and analysis) is highly desirable purely from an aircraft safety perspective. It should be 'unacceptable' that aircraft may still be flying with possibly the same vulnerabilities that has already resulted in loss of aircraft, just because of the lack of adequate diagnostic data. We have the situation now that it might take a year (or never) to find the FDR; we are all living in hope that another aircraft is not lost to the same problem (or more likely combination of problems). The problem(s) could apply or not to Boeing and/or Airbus, to Goodrich and/or Thales, could be related to freak weather conditions or inadequate pilot training or something else. We just do not know, but we could, and should.

[grizzled]

VicMel's post sums up why this thread can still be useful.

The most important reason we conduct thorough, and very expensive, investigations is to reduce the likelihood of a similar accident, through "lessons learned." In this case we have had confirmation of this lesson: Recovery of the all-important recorders is a herculean task in a deep ocean environment.

Recovery may not happen, or it may be that if the recorders are recovered, the data may be irretrievable due to the integrity of the boxes being compomised over time.

So, discussion of different data storage methods, possible in-flight transmission of CVR and FDR data, different structural and signalling requirements for the "boxes" are all valid and worthwhile. Having said that, the mods may well believe that such a discussion is more appropriate under a new thread on a different forum.

Grizz

[ATC Watcher]

VicMel :A possible starting point could be to replace the on-board FDR and CVR systems with real time data transmissions. If ACARS cannot cope/is too expensive to handle the volume of data or cannot deliver the required dependability, the Iridium system (Iridium) would seem to be an alternative. If such a data collection service were to be made available, automatic monitoring would be possible

This already exists. A Canadian company (Aeromechanical services) offer real time data streaming using Iridium for operators that want to pay for it.
So far only VVIP jets are customers .
Iridium rates are not cheap, and as you rightly said someone must be at the other end listening, 24/7 and able to take decisions ( like alerting SAR ), also expensive. It is all down to money as usual.

[vovachan]

I keep referring back to the Pulkovo 612 crash. You've got a super-experienced training captain, augmented by a navigator, who flew into some nasty weather and couldn't extricate themselves. I am sure their plane would be sending some funny error messages as it was spinning out of control, if it were so equipped, and people would be still coming up with all sorts of interesting theories abt what happened...

[Dutch Bru]

Augustus is right (with exception of mm43's recent interesting contributions)

With all due respect, wx info has been discussed some 1000 posts back in the first half of July. For ease of reference: # 3428 DB, #3430 PJ2, # 3433 SaturnV, # 3479 DB, 3482 SaturnV, # 3494 PJ2

Let's put our hopes on the 3rd search phase and let's get a life in the meantime.

DB

[cessnapuppy]

A possible starting point could be to replace the on-board FDR and CVR systems with real time data transmissions. If ACARS cannot cope/is too expensive to handle the volume of data or cannot deliver the required dependability, the Iridium system (Iridium) would seem to be an alternative. If such a data collection service were to be made available, automatic monitoring would be possible

Bad idea.
Augment perhaps, enhance -sure! but replace? never!

Instead of an independent device with its encapsulated nugget of information, you have a parsed 'summarized' data stream subject to the control of....who?
The Airline? the Airbus/Boeng? or the NTSB/CAA body?

The scheme does have some attractive parts to it, a central database of all flight parameters that can be data mined and analysed....nice!
but dont forget, these tools are for POST MORTEM not protection.

"Sir, why are you wearing a LEAD LIFE JACKET?"
"why, so if I DROWN, my body is not swept away by the current!"

A more frequent pinging of flight position and altitude (with maybe more frequent updates triggered by any anomalies) AND A QUICKER RESPONSE WHEN CONTACT IS LOST should more than suffice and would be a very minor software update to the ACARS system and its ilk

[Lazerdog]

Some recent coverage....

Pilots question airspeed sensors' troubled history - Yahoo! News (http://news.yahoo.com/s/ap/20090916/ap_on_re_eu/eu_france_flying_blind)

[Machinbird]

whats curious to me is why in heaven's name the Autopsy reports havent been released.
In addition to a general summary types of injuries sustained, there is one such report that may bear strongly on this accident. It is a bit grim, but bodies can convey witness marks from objects in the vicinity. The whereabouts of the Captain on the aircraft at the time of the accident might be pinned down conclusively by paint fragments, plastic fragments, or the general shape of his injuries corresponding to items known to be in a particular location in the aircraft. I hope someone has looked at this aspect of nailing down who was in the cockpit. With an accident like this, there is no certainty of finding the Boxes within a relevant time frame.

[rgbrock1]

Hello,

I know this is all based in conjecture as to what the causal factors were which brought down AF447. Many posts ago some were entertaining the idea of a flat spin brought on by....whatever. (weather-related? Perhaps. Perhaps not.)
My question to all you pilots out there is this. What are the "normal" recovery methods used to fly an aircraft out of a flat spin? Are there any? Is this scenario something which is not simulate-able in the simulator?
These questions are asked merely out of curiosity and to obtain knowledge. In no way am I inferring anything.
Thank you.

[vovachan]

Instead of an independent device with its encapsulated nugget of information, you have a parsed 'summarized' data stream subject to the control of....who? The Airline? the Airbus/Boeng? or the NTSB/CAA body?

The whole idea is a nonstarter given the resistance by pilots and their unions to the FDRs being read/analyzed in the course of routine operations.

I am not holding my breath for the recorders. I feel that those in the know already have a pretty clear picture of what happened and why and hopefully are acting on it. For the rest of us - the investigation will drag on and on until some appropriately anodyne language is found that all parties can live with.

[ATC Watcher]

Please explain to this SLF the normal recovery from a flat spin

An A330 is not a Pitts or an Extra 300. There are recovery techniques but for Aerobatic aircraft and aerobatic (well ) trained pilots, not for airliners.

Even one of the best pilot still around , i.e. Chuck Yeager, did eject after a flat spin in the F104 prototype I my memory serves me well.

[rgbrock1]

@ATC Watcher:

Then is it correct for me to ascertain that a flat spin is an unrecoverable condition in
a commercial aircraft?

[BOAC]

If the GofG is far enough aft to generate a 'flat spin', it tends to be difficult to recover in ANY aircraft unless spin recovery devices are fitted. However, it should be remembered that we have absolutely NO proof that 447 entered any sort of spin.

[rgbrock1]

BOAC:

I never alluded to the flat spin being the cause of AF447. (My use of the word "conjecture" shows that.) My post says as much. I know this topic was broached in previous postings but I was just inquiring about recovery techniques from such a condition as I don't recall having seen anything about such techniques.
Thank you.

[Ptkay]

One well documented high altitude stall and flat spin
airliner accident was this one:

ASN Aircraft accident Tupolev 154M RA-85185 Donetsk (http://aviation-safety.net/database/record.php?id=20060822-0)

Pulkovo Tupolev 154M

The accident circumstances, weather was similar to AF447.

For them flat spin was unrecoverable.

[Tailspin Turtle]

Deploy the spin chute. Don't have one? Well, there are a few things you can try with the engines to break the spin but they've probably all flamed out or are stalling due to the inlet conditions in a flat spin. So recovery is very unlikely. However, my understanding is that they hit the water nose high and wings level with a high sink rate and minimal yaw. That suggests an upset into a high-speed spiral dive with a recovery in progress when they ran out of altitude, rather than a flat spin which would result in a completely different water entry.

[Will Fraser]

Arguably one of the very best aero pilots ever, Art Scholl, was killed while flying and filming the Movie, "Top Gun". From memory, I think he was flying an Extra 300, but I think his favorite had been the Chipmunk. He entered a flat inverted spin and went into the Ocean with his a/c. The spin entry was planned, and needless to say, all were astonished when he failed to recover. When spin testing a/c, a drag chute is fitted to recover controlled flight if the control surfaces cannot. IMO it is safe to say 447 would have had an enormous challenge to 'merely' ditch, let alone recover from upset, given flight conditions. There is NO reason to believe the crew were anything less than heroic.

Will

[Yiorgos]

Ptkay:

but Tupolev 154M is T-Tail and this makes a HUGE difference

Yiorgos

[Machinbird]

Flat Spin Recovery?
......... However, my understanding is that they hit the water nose high and wings level with a high sink rate and minimal yaw. That suggests an upset into a high-speed spiral dive with a recovery in progress when they ran out of altitude, rather than a flat spin which would result in a completely different water entry.
It appears that AF447 came down rapidly, but how did it dissipate all that energy in perhaps 5-8 minutes and then impact at relatively low airspeed and high angle of attack? To me it suggests they were locked in a stable deep stall and couldn't break it. Swept wing aircraft do pitch up in a deep stall and that can completely overpower the tail's corrective abilities. An aft CG makes it worse. With airliners, particularly FBW ones you just are not supposed to get in a deep stall in the first place.:=

[barit1]

Arguably one of the very best aero pilots ever, Art Scholl, was killed while flying and filming the Movie, "Top Gun". From memory, I think he was flying an Extra 300...

Just to set the record straight - Scholl's aircraft was a Pitts S-2A (http://www.ntsb.gov/ntsb/brief.asp?ev_id=20001214X37820&key=1)

[JD-EE]

Flat spins seem to be a nice boogey man again, with some people seeming to insist that was the mechanism behind the AF447 demise.

I cannot naysay that they're incredibly dangerous events. I can observe that in a nice flat spin the plane's not "going anywhere." (I parenthetically note that that nice big flag in the air called a vertical stabilizer isn't going away, either, given the parameters for its removal from AF447 by a forward push rather than a sideways push. That means the spin would have to be a seriously slow spin.)

What I can observe is mm43's excellent work, again. (And if needed again and again.)

Look at the last reported position. Look at the ACARS messages. How does a flat spin account for the potential impact locations as derived by mm43's many efforts including but not limited to Crash Location - A revisit using OSCAR & Quikscat data (http://www.pprune.org/rumours-news/376433-af447-217.html#post5170393) and Bathymetry - centered on 3°N 31°W (http://www.pprune.org/rumours-news/376433-af447-218.html#post5184327)?

When you can reconcile these inconvenient facts with a flat spin scenario and why the plane got to those potential impact points and THEN chose to flat spin I'll entertain that scenario for AF447. Until then it appears to be vaporous wanderings of a group of people bored out of their minds with this discussion.

Maybe another topic would be a good place to vamp on "flat spin" conditions, their dangers, recovery therefrom, and aircraft parameters that seem to foster or prevent flat spins.

JD-EE {o.o} Just sayin'

[aguadalte]

Please explain to this SLF the normal recovery from a flat spin

1 - Idle power;
2 - Hands OFF the stick/yoke;
3 - Full Rudder deflection, opposite to the rotation of the Spin, until rotation stops;
4 - Neutralize Rudder and pull out of the dive.

Now, this is the Muller/Beggs technique. Used on aerobatic (normally single-engined) aircraft.

An airliner is not supposed to be designed to be flown into a spin, nor (as far as I know) is supposed to be certified to fly-in and fly-off a spin. There is, therefore, no "technique" or training required by crews to fly-off spins on any Airbus or Boeing a/c.
Airline Pilots are supposed to prevent their aircraft to enter any stall. They are supposed to be aware at all times and to manage the energy of their aircraft to avoid them to enter any unrecoverable situation. But the issue you are rising is much more complex than that...and an A330 with at least 3 Tons of Fuel on the Trim Tank, with an aft CG is hardly "spin recoverable".

[Centaurus]

Airline Pilots are supposed to prevent their aircraft to enter any stall. They are supposed to be aware at all times and to manage the energy of their aircraft to avoid them to enter any unrecoverable situation

If you could see what I am sure hundreds of simulator instructors often see during their training career, you would be staggered at the number of experienced and not so experienced pilots that are "supposed" to be able to prevent their aircraft from entering a stall - but are unable to do so.

[stator vane]

re: the question about recovery from flat spin--

with my limited knowledge, if i find myself strapped to an aircraft that appears to have a mind of its own and everything else i have tried doesn't work, i will put the gear down.

that might put enough drag into the equation to break the stalemate.

i read that the pilot of an uncontrollable 727 at altitude had tried everything else he knew (he was an aerobatic pilot); put the gear down as a last resort. the china 747 experienced such g-forces that the uplocks failed and the gear came down and they both lived to tell the tale.

admittedly not related to the thread's title.

and will respect any feedback.

[Tailspin Turtle]

"It appears that AF447 came down rapidly, but how did it dissipate all that energy in perhaps 5-8 minutes and then impact at relatively low airspeed and high angle of attack?"

That's the problem. With enough elevator control power and no computer between you and it to restrict G, you can yank the nose up without changing the velocity vector much at first. The pitot won't read much airspeed because it's looking forward and not down, but you're still going down at almost the same rate of descent, which is consistent with a high angle of attack.

[aguadalte]

Centaurus: If you could see what I am sure hundreds of simulator instructors often see during their training career, you would be staggered at the number of experienced and not so experienced pilots that are "supposed" to be able to prevent their aircraft from entering a stall - but are unable to do so.
I do understand you, Centaurus, several actual incidents/accidents, come to mind...and that is related IMHO to the issues aired by Captain Rory Kay (ALPA's Executive Air Safety Chairman) on this conference, but that's a story for another thread: http://www.alpa.tv/DesktopModules/UltraVideoGallery/UltraVideoGallery.swf?vId=247&portalId=14
(http://www.alpa.tv/DesktopModules/UltraVideoGallery/UltraVideoGallery.swf?vId=247&portalId=14)

[Machinbird]

The Energy Wasn't Dissipated
That's the problem. With enough elevator control power and no computer between you and it to restrict G, you can yank the nose up without changing the velocity vector much at first. The pitot won't read much airspeed because it's looking forward and not down, but you're still going down at almost the same rate of descent, which is consistent with a high angle of attack.T-Turtle, I have participated in a few accident investigations including one where the pilot yanked the nose up to avoid flying into the ground (to no good effect) and I can state pretty conclusively that is not what happened with AF447. Further, although I may be going out on a limb because BEA has not made a statement in this regard, the character of the damaged components I have seen pictures of and the reported condition of the human remains indicates a low speed collision with the water below 200 knots. Believe me, that energy was dissipated. If you would like to discuss further, drop me a PM.
Further, on an A330, there is no direct connection between the side stick controller and the control surfaces. You only give the computer "hints" at what you want it to do and it processes those hints in accordance with the current control law it is operating in. And if there is no power to the computers-there is no control.

[wes_wall]

the character of the damaged components I have seen pictures of and the reported condition of the human remains indicates a low speed collision with the water below 200 knots.


Very interesting comment, particularly with regard to condition of the bodies recoverd. You seem to have a firm idea on airspeed, however, do you care to post an opinion on vertical speed?

[cessnapuppy]

however, do you care to post an opinion on vertical speed?
... I think he already did, since the aircraft was moving vertically at the time?

[Machinbird]

Hi Wes-wall. I posted the answer to your question some time ago but with the volume of posts, I can well understand that you might not have seen it. http://www.pprune.org/5085433-post3947.html. But maybe as high as 9000 fpm down.
Since the rudder was thrown forward according to the BEA preliminary report, it is probable that there was comparable forward velocity too , but at this point I'm just guessing.

[mm43]

JD-EE,
Thanks! Notwithstanding your comments, I did generate -

Someone might like to comment on how effective the rudder would be in direct law at near stall speed pulling TOGA with only one engine. Remember, the BEA stated the vertical stabilizer damage showed the tail was rotating to port on impact and I couldn't help but wonder if only No.1 was operational.and later I also remarked -

One and a half days after the impact the floating debris pattern would still have been relatively compact - say a radius of 0.5NM, as I construe the BEA's description of the impact as having little or no horizontal momentum - more a tail heavy "flat spin".

In the cruise, I assume the trim tank was in use - not helpful later on.My supposition was that the a/c had had a 2 x flame-out at around 02:13:10z (loss of supply to the SATCOM) and the subsequent re-powering of the SATCOM at 02:13:40z was either on a restart of No.1 or the APU. A deep stall and high sink rate was already established, and the attitude could have resulted in the descriptions alluded to in the above quotes.

To put it bluntly, the crew/pax that were not belted in could well have compounded the maximum aft center of gravity problem.

The BEA's preliminary report provides -

02:14:14 - .1/WRN/WN0906010214 341036006MAINTENANCE STATUS ADR 2
02:14:20 - .1/FLR/FR0906010213 22833406AFS 1,,,,,,,FMGEC1(1CA1),INTERMITTENT
02:14:26 - .1/WRN/WN0906010214 213100206ADVISORY CABIN VERTICAL SPEEDThese final 3 ACARS/ATSU/ACOM messages were probably initiated at 02:14:10z and their transmission time and sequencing provide for the reception times noted by the BEA. The Cabin Vertical Speed advisory tells me that passing through say 8,000 feet (various docs say 7350 or 9550ft) the a/c's vertical speed was in excess of 1,800 feet/min, or more succinctly that the cabin air pressure controllers ability to compensate had been exceeded, i.e. the cabin pressure was less than the external pressure. The earliest the CVS advisory could have been generated is 02:14:10z and the latest at 02:14:22z which provide descent/sink rates of 2,700 or 6,700 feet/min if impact is assumed at 02:14:30z. I have assumed a GS at impact of around 120KTS, which combined with the descent/sink rates mentioned of 2,700 feet/min (24KTS) or 6,700 feet/min (61KTS) is quite a substantial impact velocity. Put another way, the a/c's attitude was pitched up +10/15 degrees and on a glide slope (misnomer) of between 14 to 40 degrees.

The damage noted in various photos would probably support those speeds when combined with the impact square area and a/c mass, along with the resulting sequential break-up. In the case of the v/s the combination of the forward velocity and the tail yaw (to port) have obviously been used by the BEA in making their initial conclusion.

So in summary, the track flown from the Last Known Position at 0210z to the possible impact positions previously deduced could well have been direct and for about 1 minute prior to 02:14:30z the deep stall/high sink rate was established.

mm43

[TheShadow]

.
.
Part ONE (http://tinyurl.com/n4a6pr)- A little hard to follow
.
.
Part TWO (http://tinyurl.com/msbpkl) - Quite close to the mark (IMHO)
.
.

[Machinbird]

Probably as Close as We'll ever get to the Truth?
Part ONE (http://tinyurl.com/n4a6pr)- A little hard to follow.
Part TWO (http://tinyurl.com/msbpkl) - Quite close to the mark (IMHO)
Hi Shadow, Yes, there is a lot of good information in those links, but the author intimates that the resulting loss of control was in the overspeed direction. Frankly, I would expect an overspeed loss of control to end up in a pointy end down high speed water entry or an inflight breakup. It doesn't quite fit the observed data.
I like the Boeing article here: http://www.boeing.com/commercial/aeromagazine/aero_08/erroneous_textonly.html (http://www.boeing.com/commercial/aeromagazine/aero_08/erroneous_textonly.html) and believe that some of the accidents involving loss of airspeed data reported at the end of the article in the block titled, "ACCIDENT AND INCIDENT CASE STUDIES" are a better model for what happened to AF447 (IMHO).

[OVERTALK]

...the author intimates that the resulting loss of control was in the overspeed direction.

I think he's straight out saying just that. A Mach encounter due to speed sneaking up to the high side unobserved could lead to a pilot mistaking its characteristics for stall buffet and lowering the nose, further embedding in a Mach tuck pitch-down. Some of those Boeing examples demonstrate how easy it is to mistake symptoms. Disorientation after a Mach Crit encounter inducing a loss-of-control could easily lead to a nose high/stall entry type situation.

Personally not sure about the plausibility of a double flame-out (from a post-disorientation stall/spin scenario) and failure to relight - culminating in an attempted engines-off ditching (as an explanation for the assumed wings level water-entry attitude, high RoD and low speed). The 4 minutes (only) from height could be explained away by the high speed/high RoD required for relight attempts OR that those 4 minutes just represented the time from height to losing all useful electrics (to the ACARS) due to a LOC induced double flame-out.

.

[Machinbird]

I think he's straight out saying just that. A Mach encounter due to speed sneaking up to the high side unobserved could lead to a pilot mistaking its characteristics for stall buffet and lowering the nose, further embedding in a Mach tuck pitch-down. Some of those Boeing examples demonstrate how easy it is to mistake symptoms. Disorientation after a Mach Crit encounter inducing a loss-of-control could easily lead to a nose high/stall entry type situation.
Ok, lets follow that line of thought a bit further. The nose starts to tuck as trim limits are reached (because of the shifting center of pressure on the wing as you go transonic) and the nose starts to fall, altitude starts to unwind quickly and the crew reacts by reducing power and deploying speed brakes. Assuming they are successful in arresting the plunge, what is the next thing they would encounter? It would be a transonic pitch up as they decelerate (caused by the center of pressure moving back to its normal subsonic positon) as all the nose up trim makes itself felt. Say the aircraft bottomed at FL 250 while pulling maximum permitted g, and just below M Crit. In an F-4 for example, this type of transition to subsonic could cause a 50% 'g' overshoot because it happens very quickly. Can the Airbus G protection mitigate this 'g' spike quickly enough to keep the wings from breaking (while in alternate law and with an aft cg)?
Would the wings stay on? I don't know since I don't have enough aircraft data, but if the wings did stay on, then you would probably soon find the nose pretty high in the air since the crew would be unlikely to have the presence of mind to drop a wing. Then you could get into a deep stall very quickly. But, can the critical Mach recovery even be made in alternate law?:confused:
On the face of it, the foregoing scenario doesn't pass the Occam's razor test.http://en.wikipedia.org/wiki/Occam%27s_razor Why not a simple deceleration into a stall with heavy turbulence and a cockpit full of warning lights as a distraction? It seems to fit the event time line better.

[OVERTALK]

Machinbird says: (of post 4426/4427 - link (http://www.pprune.org/rumours-news/376433-af447-222.html#post5202948))
"....Why not a simple deceleration into a stall with heavy turbulence and a cockpit full of warning lights as a distraction? It seems to fit the event time line better."
.
Seems to fail the logic test for Occam's Razor. Up until the A/P disconnect, as far as the ADIRS and PRIM were concerned, everything was nominal. The auto-thrust would have been doing its job in maintaining the sched speed. ........ as the three pitots iced up internally and indicated, to a gullible system, that the aircraft was tending to slow (just as the autothrust would respond, say, if it was picking up a load of wing and fuselage ice).

That means that the speed observed on both the L&R PFD's was (misleadingly), and continued to be, exactly what the pilots expected to see, but in actuality the aircraft speed through the air was somewhat in excess of that (and increasing as the pitot blockage increased towards, but not necessarily TO, a total blockage). Then the autopilot disconnected and the TCAS dropped out - because the two different sources of static pressure were now in total disagreement. .... and parametrically unacceptable for RVSM flight. Why the TCAS? It needs the static pressure to be in agreement (and good) for a highly accurate RVSM flight level maintenance.

That's what I'm getting from those two links. Suggest you re-read them both.

So the case for it having been a Mach Crit encounter is there (IMHO - and unless some of the cognoscenti have a contrary argument).

[mm43]

OVERTALK,

Why the TCAS? It needs the static pressure to be in agreement (and good) for a highly accurate RVSM flight level maintenance.Why was the ACARS TACS FLT msg not explained by the BEA? Your logic is not in question, and the scenario you have promoted fits well with the assumed outcome.

mm43

[Machinbird]

Sorry Overtalk, I understood the point made in the two parts of the referenced article from the beginning, however I am having great difficulty in understanding how an overspeed induced departure will lead to other than a sky full of confetti.or a high speed impact with the water. The fact that AF447 arrived at the surface apparently essentially intact and apparently at low speed high angle of attack, high sink rate and perhaps in as little as 5 minutes requires an involved process if one assumes an initial overspeed departure from controlled flight. Until such time as additional information arrives supporting that view, IMHO it might be more productive to consider how a low speed departure from controlled flight might have happened.

[Belgique]

OVERTALK,

Why the TCAS? It needs the static pressure to be in agreement (and good) for a highly accurate RVSM flight level maintenance.
Why was the ACARS TCAS FLT msg not explained by the BEA? Your logic is not in question, and the scenario you have promoted fits well with the assumed outcome.

mm43
TCAS derives its altitude information from the aircraft altimeter (i.e. its mode Charlie squawk that's continually being punched out in response to ATC and TCAS interrogation via the transponder). If the ADIRS is suddenly in WTF? rejection mode for increasingly divergent derived static pressures (due to the pitot blockage rate increasing), then two things must happen:

a. Autopilot baro hold will be corrupted and so the autopilot will kick out and....

b. TCAS will throw in the towel (and ACARS will be stimulated to tattle-tale that info also)

Same thing (essentially) happened when the BIZJet copilot placed the laptop on the center console over the Amazon jungle and its lid cancelled their transponder - effectively crippling their TCAS (which then showed a non-flashing and bland TCAS message on-screen)- for quite a while before their connecting with the GOL 737....
But then again, ACARS wasn't part of their bizjet repertoire. In their case their baro hold was good, but it was still the TCAS that had been fatally disabled. In Af447's case their TCAS merely lost that valid mode C input. ...and quit.
.
and then Machinbird said:
The fact that AF447 arrived at the surface apparently essentially intact and apparently at low speed, high angle of attack, high sink rate and perhaps in as little as 5 minutes requires an involved process if one assumes an initial overspeed departure from controlled flight.
.
Hmmm
.
For a non T-tail, a sustained deep stall is not really on the cards. A flat spin maybe? Not really. The A330 aerodynamics don't support either proposition. A double flame-out due to a nose-high departure and auto-rotation following a Mach Crit encounter and loss of control? YES, most affirmatively. WHY?
.
Well Airbus test-pilots don't test for any flame-out proclivities during stall or coffin corner auto-rotation, however the A330's engines would be quite vulnerable to that at cruise height (see recent Pinnacle Airline's example). My guess is that the AF447 crew were burning off height at a great rate attempting relights all the way down and then, logically, were eventually forced to give up on the relight attempts for an engine-off, best configured/best attitude/best speed arrival at ditching station "terra oceana". That's what could have happened to Air Transat's A330 - if the Azores hadn't been in their sights all the way down.

That explains it all via Occam's Razor first principles - as modified by arody logic (IMHO).

The links at:
.
Part ONE: Air France Flt 447 (http://tinyurl.com/n4a6pr)

Part TWO: The AF447, QF72 and 9M-MRG comparison (http://tinyurl.com/msbpkl)

contain a quite convincing version of the likely AF447 event.
.

[Graybeard]

The TCAS gets its altitude from the selected transponder. The transponder gets its altitude from its selected ADC. ADC altitude is separate from ADC airspeed, whose source was apparently flawed. There is no reason for the ADC to fail its altitude output if its airspeed input has failed.

Hence, the TCAS Fail is unrelated to pitot problems, and still a mystery, in my alleged mind. The BEA report said the same.

GB

[Belgique]

GrayBeard says
The TCAS gets its altitude from the selected transponder. The transponder gets its altitude from its selected ADC. ADC altitude is separate from ADC airspeed, whose source was apparently flawed. There is no reason for the ADC to fail its altitude output if its airspeed input has failed. Hence, the TCAS Fail is unrelated to pitot problems..

Perhaps drop to another earlier level of air data processing (i.e. the ADM) and reflect that the pitot takes in BOTH RAM (dynamic) and static pressure (the latter being deducted by static port sourced static pressure to derive the CAS). It's the fact that the two sources of static received by their respective ADM's slip outside allowable minor differences that creates the "reject".
.
per.....
.
Each ADIRU comprises an Air Data Reference (ADR) and an Inertial Reference (IR) component.
An ADR (Air Data Reference) fault will cause the loss of airspeed and altitude information on the affected display.
Air Data Reference

The ADR component of an ADIRU provides airspeed, Mach, angle of attack, temperature and barometric altitude data. Ram air pressure and static pressures used in calculating airspeed are measured by small Air data modules (ADM) located as close as possible to the respective pitot and static pressure sensors. The ADMs transmit their pressures to the ADIRUs through ARINC 429 data buses.
Complexity in redundancy
Analysis of complex systems is itself so difficult as to be subject to errors in the certification process. Complex interactions between flight computers and ADIRU's can lead to counter-intuitive behaviour for the crew in the event of a failure. In the case of Qantas Flight 72, the captain switched the source of IR data from ADIRU1 to ADIRU3 following a failure of ADIRU1; however ADIRU1 continued to supply ADR data to the captain's primary flight display. In addition, the master flight control computer (PRIM1) was switched from PRIM1 to PRIM2, then PRIM2 back to PRIM1, thereby creating a situation of uncertainty for the crew who did not know which redundant systems they were relying upon.
.
Reliance on redundancy of aircraft systems can also lead to delays in executing needed repairs as airline operators rely on the redundancy to keep the aircraft system working without having to repair faults immediately (the MAS 777 case - 9M-MRG had graceful degradation failures dating back many years that were intentionally "hidden". A further failure brought that failed accelerometer back into play - and precipitated QF72's wild ride).
.
Precedents:
a. This pre QF72 incident to a QANTAS A330 (QF68 on 12 Sep 06) (see: this link (http://tinyurl.com/l9fwpp) ) was quite probably an incipient AF447 scenario. No fault was ever found. Why? The pitot ice had melted well prior to landing and the CirroStratus encounter/exposure was likely to have been a mild one (AND the crew took prompt and luckily, correct action).

b. On 07 Feb 08 another QANTAS aircraft (VH-EBC) suffered an identical event while conducting the JQ7 service from Sydney to Ho Chi Minh City, Vietnam.

c. 27 December 2008, Qantas Flight 71 from Perth to Singapore, the same A330-300 registration VH-QPA and the same ADIRU as involved in the Qantas Flight 68 incident, was involved in an incident at 36,000 feet approximately 260*nautical miles (480*km) north-west of Perth and 350*nautical miles (650*km) south of Learmonth Airport at 1729 WST.

d. While examining possibly related events of weather-related loss of ADIRS, the NTSB decided to investigate two similar cases on cruising A330s. On a 21 May 2009 Miami-Sao Paulo TAM Flight 8091 registered as PT-MVB, and on a 23 June 2009 Hong Kong-Tokyo Northwest Airlines Flight 8 registered as N805NW each saw sudden loss of airspeed data at cruise altitude and consequent loss of ADIRS control.

Whether or not the Autopilot and TCAS drop out probably depends upon how fast the situation onsets - and to what extent the differently derived static pressures eventually disagree.... prior to crew intervention.

[Graybeard]

Belgique:
Perhaps drop to another earlier level of air data processing (i.e. the ADM) and reflect that the pitot takes in BOTH RAM (dynamic) and static pressure (the latter being deducted by static port sourced static pressure to derive the CAS). It's the fact that the two sources of static received by their respective ADM's slip outside allowable minor differences that creates the "reject".


From the ISIS block diagram I copied from a much earlier post, each pitot ADM is a separate module from each static ADM. The static ports are a good distance from the pitot probes, of course. Are you saying each pitot probe has its own static port in addition to the primary static ports? Otherwise, CAS is calculated inside the ADR, whereas altitude at flight levels is more or less raw data, unaffected by airspeed or lack of.

Thanks for the info on the QF anomalies being related to the pitot problems.

GB

[Belgique]

Are you saying each pitot probe has its own static port in addition to the primary static ports?

No, of course not. Forget ADIRS. Think Cessna GA. What comes down the pitot tube is not just the dynamic pressure of airspeed. Yes it's a dynamic pressure, but comprising BOTH airspeed(A) + static(x). That's why a static line delivers static port pressure to an ASI, now isn't it?...... to offset the pitot-derived static pressure.

To deduce the airspeed (A), the (baro)static pressure(y) from the static ports is deducted from x - in any conventional analogue Airspeed indicator. It's just that, in an ADIRS, it's done using digitized data.

A more confusing way of putting it is: "Airspeed indicators work by measuring the difference between static pressure, captured through one or more static ports; and stagnation pressure due to "ram air", captured through a pitot tube. This difference in pressure due to ram air is called impact pressure."

But in an ADIRU, when the pitot ADM's (measuring x) start showing a significant difference from the static ADM's (measuring y), then there's the increasing possibility of a rejection by various systems (baro hold and TCAS being two of them and the more sensitive).

A case study perhaps? Take the case of a static line containing water. You climb through freezing level and it turns to ice. You continue to climb. What happens to the airspeed? Because the static port derived (baro)static pressure is then trapped at the higher value of a lower altitude, the IAS winds back towards zero. In fact at 220kts it's back to zero within a further 2400ft of climb (been there, done that, got the guernsey). Downward sloped static port with a bung inserted upwards into it. You'd swear it'd never allow water into the lines while parked?

Wrong! Bung had hole in its centre to allow pressures to equalize. Rainwater dripped down over hole and got drawn through bung into static lines as local atmospheric pressure increased with the passage of a front. Airborne passing FZLVL in the climb, you have now lost the altimeter, the VSI zeroes out and your airspeed winds back to zero. Quite frightening when you're in the thick gloop.

In a descent of course the ASI increases as the pitot tube's contribution of static pressure eventually equalizes (and exceeds) at the same height that the static lines froze..... at which point it's over-reading in that descent (until the ice melts of course).

I was quite young when it happened to me and didn't know that the solution was to depressurize and get another cockpit source of static by smashing the face of the VSI. It was the reason why DC4's and Neptunes etc had an ALTERNATE static source switch to tap cockpit air pressure as a fallback static source.

http://upload.wikimedia.org/wikipedia/commons/f/ff/Airspeed_indication_system_-_fly_by_wire.png
http://upload.wikimedia.org/wikipedia/commons/c/c8/ASI-operation-FAA.png
There's a much higher resolution different cutaway diagram of an ASI/machmeter at this link (http://upload.wikimedia.org/wikipedia/commons/4/49/Airspeed_Mech.PNG)
.
Rudimentary but hopefully helpful in understanding why clogged pitots can subvert system resolution of static pressures.
.
For a description of operation of an ASI (see this link (http://en.wikipedia.org/wiki/Airspeed_indicator#Operation))
.

[RetiredF4]

I follow this thread since the beginning, i read every single post.

Machinbird says: (of post 4426/4427 - link (http://www.pprune.org/rumours-news/376433-af447-222.html#post5202948))
Quote:
"....Why not a simple deceleration into a stall with heavy turbulence and a cockpit full of warning lights as a distraction? It seems to fit the event time line better."

Overtalks answer to that:
Quote:
So the case for it having been a Mach Crit encounter is there (IMHO - and unless some of the cognoscenti have a contrary argument).

Why do we assume, that the icing up of the pitot-tubes and the subsequent automatic system-reactions contributet to an drastic increase in IAS followed by desaster?

A few thoughts to augment my question.
Would it be logical to assume, that icing took place not only within the pitot-tubes but as well on other critical aircraft parts/ surfaces as Flight-controls?

Would it also be logical, that the heated pitot-tubes would be the last parts being affected by icing due to the heating of those?

What would that weight increase be, how would it effect aerodynamic lift and how much would it increase aerodynamic drag?

How much elevator trim would be necessarya to counter those effects given a stable speed?

How much would the AOA increase to maintain level flight?

How much power is availabel at the given altitude to maintain straight and level under such icing conditions, or even accelerate, and if that is possible, how long would an acceleration take?

If my thinking concerning those questions above are correct (and forgive me, i have no practical expierience on heavies) AF447 might have picked up icing, autopilot compensates for loss of lift and increase of weight, thrust increases to maintain not only speed (the wrong one) but also to maintain altitude, and finally within short time autopilot and autothrust reach their limits to maintain controlled flight. Icing up of the tubes leads to the final desaster of droping an aircraft into the lap of the crew, which just has departed controlled flight.

I dont know the timeframe in which this could have happened to AF447 (if at all), in my F4 2 decades ago it came out of nowhere in a climbout in military power at around Fl 250. Even selected afterburner didnt help in maintainig level flight. It took me 10.000 feet down to regain full authority over my aircraft and being able to get rid of the ice.

[Peter H]

RetiredF4 (http://www.pprune.org/members/302846-retiredf4) asked ...

Would it be logical to assume, that icing took place not only within the pitot-tubes but as well on other critical aircraft parts/ surfaces as Flight-controls?

Would it also be logical, that the heated pitot-tubes would be the last parts being affected by icing due to the heating of those?

I believe that the suggestion is that AF477 was in abnormal icing conditions, where ice would only build up on heated surfaces. [See references to engine core icing earlier in the thread.]

Regards, Peter

I'm still struck by the apparent near-simultaneous failure of the pitot-tubes. It might be irrelevant to the eventual outcome, but it seems surprising there wasn't an observable gap between the failures.

[Dagger Dirk]

Part ONE: Air France Flt 447 (http://tinyurl.com/n4a6pr)

Part TWO: The AF447, QF72 and 9M-MRG comparison (http://tinyurl.com/msbpkl)

The contents of those links is the nearest I've seen to a credible explanation for AF447. To understand how a competent well-trained crew, used to avoiding enroute severe weather, could be sucked into a scenario, you need to entertain an insidious technological circumstance having sneaked up on them - for a TOTAL surprise - full of uncertainty and confusion. This scenario at those links paints just such a picture.

What's more, flying through layered thick CirroStratus and quietly accumulating ice crystal build-ups (uniformly) in the pitot heads isn't in any way beyond belief. In fact it accords with exactly what was known about the major deficiency of that mark of Thales pitot head. Its pitot heat was unable to cope with prolonged exposure to thick Cs cloud - which is composed of super-cooled ice crystals. The pitot heaters were thermally overrun and the Airbus automation disguised that fact, sufficient to allow an autopilot diisconnect, several system alerts and a flight control degrade at speed and height. Sometimes that's all it takes to induce an LOC. It's not as if there weren't numerous precedents with exactly the same type build-up, even though lacking the eventual onset of a terminal development. At night, above the thick thunderstorm clouds of the ITCZ made the fatal difference.

So I'd urge you to disregard this input below as a total red herring (for all the above reasons)
Why do we assume, that the icing up of the pitot-tubes and the subsequent automatic system-reactions contributet to an drastic increase in IAS followed by desaster?

A few thoughts to augment my question.
Would it be logical to assume, that icing took place not only within the pitot-tubes but as well on other critical aircraft parts/ surfaces as Flight-controls?

Would it also be logical, that the heated pitot-tubes would be the last parts being affected by icing due to the heating of those?

What would that weight increase be, how would it effect aerodynamic lift and how much would it increase aerodynamic drag?

How much elevator trim would be necessary to counter those effects given a stable speed?

How much would the AOA increase to maintain level flight?

How much power is availabel at the given altitude to maintain straight and level under such icing conditions, or even accelerate, and if that is possible, how long would an acceleration take?
.

[BenThere]

Huck has the right idea in addressing faulty digital instrument feedback. GPS speed, corrected for wind and altitude, is another arrow in the quiver.

To sustain cruise in the absence of airspeed indications, apply a known/normal power setting and deck angle. Fuel flow, if available, works too. In addition, mechanical feedback/feel occurs with the onset of initial buffet on most aircraft.

I think you should disconnect autothrust as well, as FADEC, with erroneous input, can deliver erroneous output. Finally, it's good to know that TOGA is always TOGA, and IDLE is always IDLE.

There is a self-powered artificial horizon on all air transport certified aircraft.

[RetiredF4]

Thanks for disqualifying my questions in that mannor.

Quote: Dagger Dirk
So I'd urge you to disregard this input below as a total red herring (for all the above reasons)

http://www.caa.govt.nz/safety_info/GAPs/Aircraft_Icing_Handbook.pdf

It states on page 13

Quote:
Generally, the worst continuous icing conditions are found near the freezing level in heavy stratified clouds, or in rain, with icing possible up to 8,000 ft higher. Icing is rare above this higher altitude as the droplets in the clouds are already frozen. In cumuliform clouds with strong updrafts, however large water droplets may be carried to high altitudes and
structural icing is possible up to very high altitudes. Further, in cumuliform cloud the freezing level may distorted upwards in updrafts and downwards in downdrafts, often by many thousands of feet. This leads to the potential for severe icing to occur at almost any level

I did´nt ask those questions without any background, so i think it would be appropriate to allow other readers to make their statements as well.

[cessnapuppy]

people are just starting to realize that the behavior and physical properties of micro sized particulate matter is often extremely different to more commonly sized particles. Especially in the engine icing evaluation. Many of previously established observations (used in certification) have to be re-evaluated.

Like square windows on the De Havilland comet, there are just some things we didnt know, not at all.

[Belgique]

Retired F4
Nobody's denying your right to comment but the very valid point is that:
.
a. An experienced crew wouldn't soldier on into heavy icing conditions without diverting off-track.

b. Because cumuliform cloud (and assoc up/downdrafts) is highly localized, I'd very much doubt that a "downed by heavy icing" scenario would be a player at Flt Lvl 350.

c. From that same pdf file you're quoting comes:
.
"1.3.4 High-Level Clouds
High- level clouds, such as cirrus clouds, with their bases above 20,000 ft, are usually composed of ice crystals that will not freeze onto the aeroplane, and so the risk of structural icing is slight when flying at very high levels." But it's not structural icing that we speak of here. It's a compilation over time of supercooled ice crystals inside pitot tubes - in a continuous layer of cloud dense enough that the pitot heaters' heating capacity is being overcome thermally by the super-cold ice-crystals (not a theory, an admitted fact that's now being belatedly addressed by an AD).

d. Because there's no turbulence or structural icing in dense CirroStratus, there'd be nothing on their Wx Radar and no cause for concern whatsoever for the crew about icing. No instrument tells you that the pitots are ALL icing up and crews normally monitor the Fuel synoptic page, not the Engines page. With those non-moving thrust levers of Airbus and crews relying upon their ECAM for engine-related warnings, they'd just not notice that the thrust was increasing incrementally to offset the "system (but not crew) perceived CAS loss" - and causing them to fly perilously fast.

So it's a really nasty set-up for a nasty surprise just as soon as the split between the two sources of static pressure starts becoming so significant that BARO hold is rejected and the autopilot drops out. Pitch-trim state when the autopilot drops out? Another potential ball-of-wax. Where's the THS taking its auto-trim cue from? The increasingly duff CAS? How much (by way of out-of-trim) pitch force was being HELD by the autopilot. Take that a bit further and you might conclude that when the autopilot dropped out the aircraft was trimmed for the HIGHER speed and the nett result was a strong and instant nose-down BUNT. Just imagine them instant apples!! Straight into Mach Tuck - courtesy of the nose-heavy mis-trim? I'd guess so.

Another question might be: "If the baro hold was being corrupted by a false "computed" static pressure, was the aircraft maintaining a genuine FL350 on 1013Hpa?"

Don't know exactly how the ADIRU calculates its static pressures for baro-hold, so can't really comment upon that. But you can be sure that the static pressure component reported by the pitots' ADM's would be increasingly different to the valid one being reported by the uncorrupted static ports, as the pitots became increasingly blocked.

If you disagree, then dismantle the argument with some sort of well-argued counter-proposition or an indication of where the theory fails.

That crew wasn't a made up of fools, just pro-pilots doing a job and likely getting caught out by a very insidious cascade of cumulative error leading to an instantaneous happenstance. I'd guess that any A330/A340 crew would have lost that battle. We owe it to that lost crew to deduce their predicament by utilizing the best tool that's ever likely to now become available - and that's deduction based upon known precedents.

[RetiredF4]

Belgique

Thank you for your explicit and detailed answer.

It was not my intention, as mentioned in all other posts of myself before (There only had been a few) to blame anything on the aircrew. I dont assume that they flew blindly and willingly in a known ice scenario.

But isn´t it a fact, that we tend to look at possible causes in a single-minded way? I mean in a way, where we look at only one thing happening, excluding thereby other possible happenings. Could the chain of events not unfold in several parallel happenings in a quick and as proved deadly mannor? By the way, that is the way most accidents happen. It is called chain of events.

That there was no report of icing at that level or that the crew didn´t observe any icing on radar (which point was discussed highly emotional in this thread) does not neccessarily prove, that it did not develop within an updraft within a short time period. Nature has a lot of surprises at hand, and sometimes they are not yet known to us because nobody cared or nobody expierienced them or nobody reported them.

In accident investigation you look at the familiar, at the unfamiliar, and finally if you dont come to a satisfactory conclusion also at the unthinkable.

The High-Speed-Event does IMHO not fit to the final touchdown in the ocean (Time, location, attitude, speed, sinkrate, found evidence), there must be something else.

[Will Fraser]

With respect, you make the mistake you describe, F4, in exactly the sequence you relate. You have eliminated here the last relic of your sequence, though it is common. BEA (not unthinkingly, and hence not unthinkable) may be off base. I say this with respect for their mission. No 'conclusion' is at hand, it says that in the report itself. They write what is likely, as they see it. Just because two outcomes seem unlikely, they may coexist in a very logical way. No one wants to believe this a/c lost parts (important ones) at high altitude in overspeed. I don't. I don't want to entertain that the pilots were inattentive rookies, or weren't up to the crisis. Belgique has a possibility that fills in alot of important blanks; I like it because, as a pilot, it makes sense, and as a human, seems least alarming of other possibilities (Plausibility). It too wants scepticism. The problem here is many posters are jumping to conclusions (I have, admittedly) and defending them. The Defense is what is off-putting. As an investigator, it borders on the ridiculous in some cases. Disclosure also requires me to admit that it is almost a perfect explanation of what I think happened here.

[TheShadow]

Pages 222/223 and 224 are probably the most important of this thread (for indisputable bottom lines):
.........
However we are getting this "illogical non-sequitur" rejoinder from a number of posters. i.e. Why would a high-speed autopilot disconnect and possible Mach Crit encounter terminate in a high descent rate, nose-up, wings-level, slow-speed arrival at the impact point? Perhaps some extracts from prior posts can clarify "how":

The Conundrum
#4433
....however I am having great difficulty in understanding how an overspeed induced departure will lead to other than a sky full of confetti.or a high speed impact with the water. The fact that AF447 arrived at the surface apparently essentially intact and apparently at low speed and high angle of attack, high sink rate and perhaps in as little as 5 minutes requires an involved process if one assumes an initial overspeed departure from controlled flight.

and #4461
The High-Speed-Event does IMHO not fit to the final touchdown in the ocean (Time, location, attitude, speed, sinkrate, found evidence), there must be something else.

==> the responses

#4428
Disorientation after a Mach Crit/Mach Tuck encounter inducing a loss-of-control could easily later lead to a nose high/stall entry type ituation. Why? See later (see #4430 et seq - below).

Personally not sure about the plausibility of a double flame-out (from a post-disorientation stall/spin scenario) and failure to relight - culminating in an attempted engines-off ditching (as an explanation for
the assumed wings level water-entry attitude, high RoD and low speed).

The 4 minutes (only) from height could be explained away by the high speed/high RoD required for relight attempts OR that those 4 minutes just represented the time from height to losing all useful electrics (to the ACARS) due to a LOC induced double flame-out.

#4430
Note 1: "Ok, lets follow that line of thought a bit further. The nose starts to tuck (i.e. drop) as trim limits are reached (because of the shifting center of pressure on the wing as you go transonic) and the nose starts to fall, altitude starts to unwind quickly and the crew reacts by reducing power and deploying speed brakes. Assuming they are successful in arresting the plunge, what is the next thing they would encounter? It would be a transonic pitch-up as they decelerate (caused by the center of pressure moving back to its normal subsonic position) as all the nose up trim makes itself felt. Say the aircraft bottomed out at FL 250 while pulling maximum permitted g, and just below M Crit. In an F-4 for example, this type of transition to subsonic could cause a 50% 'g' overshoot because it happens very quickly. Can the Airbus G protection mitigate this 'g' spike quickly enough to keep the wings from breaking (while in alternate law and with an aft cg)?
Would the wings stay on? I don't know since I don't have enough aircraft data, but if the wings did stay on, then you would probably soon find the nose pretty high in the air since the crew would be unlikely to have the presence of mind to drop a wing. Then you could get into a deep stall very quickly. But, can the critical Mach recovery even be made in Alternate Law?


#4434
For a non T-tail, a sustained deep stall is not really on the cards. A flat spin maybe? Not really. The A330 aerodynamics don't support either proposition. A double flame-out due to a nose-high departure and auto-rotation following a Mach Crit encounter and loss of control? YES, most affirmatively. WHY?
.
Well Airbus test-pilots don't test for any flame-out proclivities during stall or coffin corner auto-rotation, however the A330's engines would be quite vulnerable to that at cruise height (see recent Pinnacle Airline's CRJ example). My guess is that the AF447 crew were burning off height at a great rate attempting relights all the way down and then, logically, were eventually forced to give up on the relight attempts for an engine-off, best configured/best attitude/best speed arrival at ditching station "terra oceana". That's what could have happened to Air Transat's A330 - if the Azores hadn't been in their sights all the way down.

Conclusion: Yes Virginia, a loss of control, stall/incipient autorotation/spin could cause a double flame-out due to intake blanking. The ensuing high-rate/high-speed descent would quickly dump altitude (relights are notoriously unsuccessful at higher altitudes anyway). Eventually the crew would have to give up relight attempts for a controlled engine off arrival at sea-level.

There's a good chance that this would explain the condition of the recovered debris and bodies. Degraded flight controls, nil flap, nil L.E. devices and sea-state would have made any such attempted ditching valiant - but doomed to failure.

[singpilot]

Will, Belgique and F4.

Your three passionate positions and postulations have been argued ad nauseum about 2500 posts ago.

It is actually tough watching the same pig roll arround in the same mud again and again.

It becomes almost irresistable to want to jump in and cite the same sources and references again and again.

But most of us do exactly that.

The answers are in the CVR. I suspect the reolved report will embarass most posters here.

[cessnapuppy]

well, the first article is totally reasonable and really, as obvious as looking down at your shoe and seeing a stream of piss. Dont have to be a rocket scientist to put two and two together.
The disaster of Air France Flight 447 was the result of a preventable mix of human and technical failures..isnt that what EVERYTHING IS??

To say we have that, is to say we have airplanes, people and air.

[BJ-ENG]

Some more opinion....?
Charles Bremner - Times Online - WBLG: The four reasons why Air France 447 crashed (http://timescorrespondents.typepad.com/charles_bremner/2009/09/the-four-reasons-why-air-france-447-crashed-.html)

[Basil]

There is a self-powered artificial horizon on all air transport certified aircraft.
Unfortunately, with some main instrument specs, it is an Acceptable Deferred Defect. A colleague, who insisted that his was replaced at base before departure, found himself invited for tea without biscuits.

p.s. This was on a 744

[Will Fraser]

As I understand it, the AH is optional on the 330. If fitted, it is top left at LHS panel.

[vovachan]

-- There was a malfunction in the ADIRU, the three air data computers which feed information to the flight system and the pilots.

All 3 of them? And what was the malfunction exactly? :confused:

[john_tullamarine]

I note we have inherited this thread from elsewhere.

Main rule is that the thread stay on tech related matters otherwise it goes to a more appropriate forum.

regards,

JT

[singpilot]

John;

Where would that be?

Jet Blast?


Just askin......

[HeathrowAirport]

-- The aircraft flew into an area of storms which other aircraft avoided by steering around them.
-- The pitot tubes (speed sensors on the front of the plane) suffered faults
-- There was a malfunction in the ADIRU, the three air data computers which feed information to the flight system and the pilots.
-- The pilots may not have had sufficient training to retain control of the malfunctioning aircraft.

Charles Bremner - Times Online - WBLG: The four reasons why Air France 447 crashed (http://timescorrespondents.typepad.com/charles_bremner/2009/09/the-four-reasons-why-air-france-447-crashed-.html)

-- The pilots may not have had sufficient training to retain control of the malfunctioning aircraft.

I find that very wrong and feel like complaining, but Ill get sued. That is one of the most upsetting statements Ive ever read, absolute bs, It just points the finger at two people who actually tried to save the lifes of all on board, very very wrong.

[Hamrah]

Actually, it points the finger AWAY from the two individuals, who, sadly would not, and should not be blamed as they are not here to defend themselves. The fact they were unable to successfully deal with the situation they found themselves in, would leave open the POSSIBILITY that they had not received adequate training from their company in limited panel flying, recovery from unusual attitudes, and operation in alternate and direct law. And that possibility would form one more hole in the " swiss cheese" , leading to an accident.

[Will Fraser]

Beyond that, partial panel, unusual attitude recovery are 'recoverable' because they are trained in a setting where the pilot will know if his inputs have corrected the upset. Here, if it happened due to Unreliable airspeed, AP chasing crap IAS and trimming as if it was part of a fairy tale, there is no reason to think the pilots could have recovered from an unknown and uncued 'status'; when would they know they had succeeded? Without cues to rely on (demonstrably absent if UAS is the culprit), where is straight and level? what is our position? where is up? Unreliable airspeed recoveries as reported in other instances have proven resistant to a checklist; it is perhaps possible to train UAS in conditions similar to what we imagine existed for 447, but why? Who will determine what 'Recovery' looks like on the panel? Repetitive loss of airspeed is demonstrated in this type involving thousands of feet lost in altitude, and visual extra cockpit cues for reference.

More important to me would be an a/p that annunciates its actions, with visual cues on the glass, so the pilot can 'get' the a/c by panel when the pitots go astray, knowing that what he has is flying, and what is required is constant duplication by manual handling after disconnect, which itself would be announced prior to, not after its occurrence, and that by surprise.

Oh, and an Artificial Horizon.

Let me ask a quick question. If the pilot had been hand flying the a/c in Normal Law, what's the probability of losing it to Alt Law2 after loss of pitot probes? This flight went to AltLaw2 because the a/p quit. If the a/p isn't in the mix, would the outcome have been substantially different?

[JD-EE]

Indeed, Will. And despite lawyers and cultural norms, sometimes <censored> happens.

I suspect that describes the situation better than a lot of commentary here. The burr under my saddle is a desire to find the contributing causes, not a apportion any sort of blame. With the data I want engineers can work to prevent it happening again. And I am just techie enough that I would enjoy hearing outlines of ideas for improvement of equipment such as people have had.

One such idea is new pitots. An even better idea is being adopted, probably for the wrong reason, with two new probes and one old Thales probe on the same plane. Different probes give different failure mechanisms, even if only slightly different. That would give computers something to chew on.

One idea I've entertained is phase tracking GPS as a means of detecting attitude using three or better four antennas, wing-tips, aft, and optionally forward. The GPS pretty much has to be tracking carrier phase to derive meaningful attitude data. The nice thing about phase tracking GPS is that you don't need to know precisely where you are to determine relative differences in position of nearby locations to surprising degrees of precision. The breaking point for this is that this does not account for up or down drafts that are not perfectly up and down. At some altitudes flying over mountain ranges can give winds at rather odd angles, I've observed on the ground. I don't know if that holds at altitude.

What I don't know is whether floating such technical ideas in the group to see what actual pilots salute and what they kiss off is within this group's purview.

JD-EE

[BOAC]

I'll allow for journalistic mis-quoting, but where is the evidence that

-- The aircraft flew into an area of storms which other aircraft avoided by steering around them. - I was not aware that the precise track of 447 was known?-- There was a malfunction in the ADIRU, the three air data computers which feed information to the flight system and the pilots? I was under the impression that the ADIRUs were thought to have behaved exactly as designed, rejecting supposedly conflicting information - ie intially a detected IAS change of at least 30kts in one second?

It would be of significant interest to AB operators to know what particular 'malfunctions' were fed into the simulator in these tests, what sequence of warnings were generated (eg did you receive a cascading failure of ADIRUs?), and what instrumentation was then left available to the crew - eg did the standby attitude still function correctly?

I think we are all pretty much on the same track generally, John, but to state categorically 4 primary individual causes of the accident is indeed a bold step.

[cribbagepeg]

If I recall correctly, this has been used for a long time as part of fighter jet stabilization technology, and I wonder why it hasn't been brought into commercial aviation. Gee, it first came over my horizon in the early 1990s... Hardly rocket science by today's standards.... ?? / CP

[Will Fraser]

BOAC

To my memory, the ship had deviated left, the buzz about 'lightning', company 'pirep' for 'fortes turbulence' and Msr. Gourgeon's claim that 447's aircrew had been 'unlucky' in reading the Radar were red herrings.

Been awhile, but is GPS to Mil standard nowadays? Used to be purposely degraded to prevent folks like google earth to have the capability of Uncle's satellites.

GPS in hyper accurate mode x4 would very nearly provide sufficient data to turn a wide body into a 'drone'. Oh-Oh, incoming.

[cribbagepeg]

Mil sets work on a different frequency and use a highly encrypted PN (Pseudo Noise) code, which, if not known by the receiver, prevents use of the inherently higher accuracy mil signals. The consumer grade PN code is, I think, 1023 bits long, while the mil one is "months" long, and is changed at shorter intervals than that, so there are never any repeated binary streams that would give a clue to decrypting it.

On the Civilian (consumer) side, there was something called "selective availability (SA) which caused the satellites to "lie" about what time it was, on a purely random basis, thus increasing the amount of error introduced at a receiver. One of the recent Presidents had that removed from service, primarily to allow aviation to have the best possible (non-mil) GPS accuracy for nav purposes.

SA was turned off, by the way, during the Desert Storm operation, to allow Civilian sets to be used by tanks, as there was a shortage of mil GPS receivers for deployment. And there are other stories and anecdotes, of course.

The phase-tracking used in attitude detection is a different animal. The wavelength at GPS frequencies is roughly (very) 25cm, so the theory predicts that one receiver moving vertically (e.g.) relative to a second one, toward or away from the satellite(s), would experience a detectable phase difference in the order of centimeters. Needs superfast processor and GPS chips, but it works....

[HarryMann]

Thanks cribbagepeg, good account, makes sense

[QJB]

Hi everyone,

Just a thought, I don't know if this has been raised previously as I don't have the time to read the last 200 pages of posts. Given the speculation on a departure from controlled flight due to either stalling or mach tuck, and the idea that this was due to the discrepancy between indicated airspeed and actual airspeed. Couldn't one consider upgrading the flight computer system to challenge the Air Data based on the aircrafts angle of attack and power settings.

For example, ice blocks the pitots slowly, CAS remains the same but the A/P slowly decreases AoA and increases power. Surely if a certain number of parameters are known ie. performance based on CAS AoA and power settings C of G, Trim etc. The aircraft would be able to tell if performance is not meeting what is expected and alerts the pilots.

Just a thought, I am no expert at all but it seems with so much automation and cross checking by the automation systems it could be wise to have this.

J

[BJ-ENG]

Air France crash victims' families to meet judge - BusinessWeek (http://www.businessweek.com/ap/financialnews/D9ATLMCO1.htm)

[Graybeard]

Back to your post 4435 on 21 Sep, Belgique:

The ADMs, Air Data Modules, used in the A330 can be pretty dumb sensors, equivalent to the blind encoders that came out 25 years ago: just an absolute pressure transducer and a digital output. I'm not intimate with the A330, but here's a logical way to build a pitot/static system with modern devices:

Each ADM for static pressure puts out a 429 word labeled, ALT, which is fed to its companion ADR with minimal monitoring. The ADR passes the ALT on to the using devices, such as pilot displays, AP and transponder. The using devices receive ALT from two or three ADR for redundancy and/or voting.

No airspeed input is needed or used in the altitude calculation.

For airspeed measurement, we use an identical ADM, but connected to a pitot probe, and its output word coded for impact pressure. The ADR merely subtracts ALT from impact pressure to calculate IAS, which is then forwarded on. There is no reason for the ADR to report ALT Fail if it can't compute IAS. Each output from an ADIRU stands on its own.

So, I come back to my original premise: blocked pitot tubes do not cause TCAS Fail to be reported. There must be another cause of the TCAS Fail that was reported by the ACARS.

Beyond that, if there were ALT Fail out of the ADR it would have caused the transponder to revert to Mode A,
thereby causing the TCAS to report TCAS OFF to the ACARS, and not TCAS Fail. There is no direct connection between the ADR and the TCAS processor.

TCAS Fail is reported in case of:
TCAS processor computation fail
TCAS directional antenna fail
Loss of valid data from transponder

The first ACARS reports mentioned a TCAS Antenna Fail, which should have been coded in the report.

Again, I agree with the BEA report: the TCAS Fail is unexplained. It may be a symptom of an event that was otherwise unreported.

http://upload.wikimedia.org/wikipedia/commons/f/ff/Airspeed_indication_system_-_fly_by_wire.pngGB

[rgbrock1]

@graybeard:

Where are the TCAS antenna located on the AB-330?

[Graybeard]

The TCAS antennas are roughly overhead and beneath the forward fuselage just aft of where the nose transitions to constant diameter. A diagram of antenna locations on the A330 was posted in this thread, back about 9 June.

GB

[Peter H]

I feel that the accurate statements previously made about GPS absolute accuracy give a misleading impression of the utility of present GPS systems for measuring civilian aircraft attitude.

There are lots of causes of GPS inaccuracy; such as deliberate encoding, atmospheric effects, and engineering imperfections. However these effects are similar for two GPS readings taken at positions close in space and time.

This effect is used in the various differential GPS systems in operation, in which base stations broadcast correction factors. For measuring aircraft attitude its even easier -- the error is surely [almost entirely] canceled when you take the difference between two GPS readings; e.g. the difference in altitude of the two wingtips.

Wikipedia suggests that differential GPS -- with all the bells and whistles -- can provide accuracies of the order of 10 cm. I cannot see why local differencing should not be at least as accurate.

I'm not advocating such a system, just commenting on its engineering feasibility.

Regards Peter

Unsettling idea of the week.
Some years ago I read in the popular scientific press of an idea for increasing runway throughput. Basically you bolt two wide-body jets together. They share a wing and of necessity fly in close formation. You only have pilots in one body; and rely on a data link between the cockpits and GPS sensors all over the place to ensure that the autopilot in the second body "doesn't overstress anything".

[cribbagepeg]

Depends upon a fixed station having a known and precise location, somewhere nearby, and thus able to quantify the magnitude and direction of the "lie" or inaccuracy at any given moment. This parameter is then used by the GPS receiver that does NOT know its precise location, so that it can apply the error measured by the reference station to its own computed location, to provide additional accuracy. Operative word is "nearby", else the unknown GPS could be experiencing a totally different error, to say nothing of getting the differential error reading from the ref. station.

[Peter H]

cribbagepeg (http://www.pprune.org/members/303352-cribbagepeg)

Sorry for any lack of clarity. Differential GPS is well-known strategy for correcting the effects of local-ish GPS errors when calculating absolute positions. I was pointing out that when you calculate relative positions the local GPS errors cancel out anyway, so no such correction is required.

As I stated:
There are lots of causes of GPS inaccuracy; such as deliberate encoding, atmospheric effects, and engineering imperfections. However these effects are similar for two GPS readings taken at positions close in space and time. ... This effect is used in the various differential GPS systems in operation, in which base stations broadcast correction factors.

As you state, this base station needs to be at a known location, so that the [local] GPS error can be measured, and transmitted to interested parties. These parties can then apply this as a correction to their readings to get first-order correction for their GPS errors .

However if you want to know the difference in altitude between your wingtips you are interested in relative not absolute positions. You may know that there is a local GPS error, but you don't actually need to worry about its value. As the error is the same for all local GPS measurements, its value disappears when you take differences.

So I repeat:
[I]For measuring aircraft attitude its even easier -- the error is surely [almost entirely] canceled when you take the difference between two GPS readings; e.g. the difference in altitude of the two wingtips.

So for the measurement of absolute positions differential-GPS is far more accurate than normal GPS (as it removes the effect of local GPS errors). While for the measurement of relative positions the two systems provide the same high accuracy (as local GPS errors have no impact). Making the accurate measurement of aircraft attitude, based on civilian GPS technology, a very real possibility.

Again:
I'm not advocating such a system, just commenting on its engineering feasibility. ... [But] I feel that the accurate statements previously made about GPS absolute accuracy give a misleading impression of the utility of present GPS systems for measuring civilian aircraft attitude.

Regards, Peter

If you prefer an algebraic argument.

Let the altitude of the left and right wingtips - as measured by their GPS receivers - be l & r.
Let the altitude component of the GPS correction required locally be c (perhaps as transmitted by a friendly neighbourhood differential base station).

The corrected altitudes of the wingtips are (l+c) and (r+c).

The corrected altitude of left wingtip relative to the corrected altitude of the right wingtip is then ( (l+c) - (r+c) ) = (l-r).

Which is, of course, the same as the simple difference in GPS readings (l-r); as any differential GPS correction simply cancels out in the calculation.

[cribbagepeg]

read message 4463 - what you're talking about is phase tracking...

[Will Fraser]

From another thread, EASA are considering an AD on Trent 800 for Airbus 330. It was only a matter of time. The FOHE inlet/interface is being altered for 777 equipped a/c. A Northwest 777 had rollbacks over the Rocky Mountains subsequent to a suspicion of icerestricted FOHE's. This following BA038's short arrival at LHR.

Odd that on this large thread the possibility of engine rollbacks hasn't gotten much interest. I believe NWA incident occurred at 35,000 feet.
Ice is Ice.

For clarity, the EASA is considering extending the AD to include Trent 700 and 500.

[Notsonew]

I believe about the early sixties over Sudan. Engines suffered N over Root T Surge - (or so the Board of Enquiry speculated -or perhaps the crew were talking to somebody). Double flameout due to low IAS. Aircraft broke up as it plunged into TS.

I don't suppose modern bypass engines suffer N over Root T Surge.

Any relevance to the Air France accident?

The thought of this occurring to me frightened me for most of my 50 year flying career. The nearest I let myself get to any TS was looking at them from 10 miles away (at night). No Weather Radar in the ancient old aircraft I have flown.

Totally irrelevant I suppose but I keep getting messages from PPRUNE saying 'you haven't posted for a long time'

[mm43]

I'm throwing a new graphic into the mix, but before going any further lets have a look at the AOC reported positions. On departure Rio de Janerio the 10 minute AOC reports were noted at 09, 19 etc.., but prior to passing NATAL it is assumed that AF Operations reset the report timing to 10.5, 20.5 etc., probably so that they would get regular sequencing of reports from multiple aircraft, rather than a disorganised dump every 10 minutes. To complicate the issue the BEA produced a route chart showing the report times as clearly occurring on the minute. Based on the timings produced by the BEA, many moons ago I deduced that AF447 was overhead INTOL at 01:32:32 whereas it can now be assumed the time was 01:33:02. This is important because there is currently no rational for the apparent deviation from the track originally noted at 02:10:00 to have occurred prior to the upset that happened at 02:10:06 when the ACARS commenced phoning home.

02:10:10 - AUTO FLT AP OFF
02:10:16 - AUTO FLT REAC W/S DET FAULT
02:10:23 - CTL ALTN LAW
02:10:29 - FLAG ON CAPT PFD SPD LIMIT
02:10:34 - 02:10:30z AOC Position Report [injected into ACARS sequence as priority]
02:10:41 - FLAG ON F/O PFD SPD LIMIT
02:10:47 - AUTO FLT A/THR OFF
02:10:54 - NAV TCAS FAULT
02:11:00 - FLAG ON CAPT PFD FD

Other than the AOC position, it can be assumed that remaining items all originated at 02:10:06 (4 secs to receipt at AF Maintenance Base). Note the AUTO FLT AP OFF, AUTO FLT A/THR OFF and NAV TCAS FAULT are possibly due to discrepancies in Pitot ADM and Baro ADM static pressure data [Note:: The rejection by the EFCS of an invalid IAS due to more than 30KTS reduction in 1 second, doesn't happen until just over a minute later]. On the otherhand, the initial ACARS fault messages could have been caused by control parameters being exceeded, e.g. extreme turbulence, updrafts / thermal elevator, or extreme wind shear involving Loss of Control in what would be a Coffin Corner situation. A Mach Critical event seems to have been avoided.

http://i846.photobucket.com/albums/ab27/mm43_af447/AF447-bank-med.png

A larger scale graphic is available at -
http://i846.photobucket.com/albums/ab27/mm43_af447/AF447-bank-lge.png

A turn radius for a 20 degree bank (grey circle), and the 02:10:30z AOC position would have resulted in a deviation from the track initiated at 02:09:30z. Indications are that the GS from the 02:00:30z position to the 02:10:30z AOC position had remained constant at 463KTS (475KTAS). However, what was happening to the OAT?

Consider each of the following scenarios -
(1) That the Cb cell updrafts in the ITCZ were conveying an unusual amount of water vapour/latent heat which was carried out into the anvil stratus cloud radiating from each cell. The a/c encountered this cloud around 0208z and the incremental ice-up of the pitot tubes, some other surfaces and potentially the engine cores took place over the next two/three of minutes. Likewise the ATHR augmented decreasing IAS/CAS with increasing power. Whether the left turn that is already evident in the 02:10:30z AOC position was crew initiated or took place as a result of a LOC event is unknown - my supposition is that its related to the 02:10:06z events.

A turn radius for a 35 degree bank (white circle), and the 02:10:30z AOC position would have resulted in a deviation from the track initiated at 02:10:00z.

(2) Take onboard the first paragraph in (1), then assume that the a/c effectively penetrated the active Cb cell, hit the wall and rode the thermal elevator, then the 02:10:30z AOC position represents where it had been thrown as it was spewed out of the mesoscale system. The BEA know a lot more about the 0210z position than they have let on - enough said.

Throw in a double flame-out, the AP/ATHR disconnect, ADIRU's disagreeing, unbelievable IAS along with sundry chirps and bells, then it doesn't take you long to realise the only way is down and how the hell do you manage it. On top of all that the FBW software, when it gave up, gave you back the a/c with control limitations!

A turn radius for a 45 degree bank (cyan circle), and the 02:10:30z AOC position would have resulted in a deviation from the track initiated at 02:10:06z, i.e. AP/ATHR OFF.

The debris distribution and current data indicate that the a/c continued in a westerly direction and descended in probably heavy turbulence to possibly FL100 over the next 3min 10sec - averaging nearly 8,000 feet/min with a KTAS of about 408 (+/- wind) and GS of 400KTS. If a high altitude 2 x flame-out had occurred, then sufficient turbine rpm was being maintained to power the essential service bus during this descent. Attempts to relight may have been hampered by turbulence and ice load. Reducing the rate of descent near FL100 then resulted in electrical power loss at 02:13:10z and it is presumed the APU was started as evidenced by resumption of the SATCOM link at 02:13:40z.

Remember, the a/c was deep in the ITCZ descending through numerous cumulonimbus cells and associated out-flowing anvil cloud with the propensity for ongoing icing highly likely.

http://i846.photobucket.com/albums/ab27/mm43_af447/3N31W-bath_posn.png

Putting together a new graphic to represent more clearly what may have occurred, I looked at the 3 separate positions I had previously calculated for the possible impact position and decided they represented the proverbial "cocked hat". Bisecting the internal angles through the center of each opposite side gave me a position of 3°03.4'N 31°04.5'W, and this position when plotted gave the track (magenta line) from the Last Known Position as plotted tangential to the 35 degree bank curve.

As previously suggested, the Cabin Vertical Speed advisory gives an indication of when the a/c was passing through about 8,000 feet - 5 secs after the external pressure exceeded the cabin pressure and cabin vertical speed exceeded 1,800 ft/min.

In summary:-
(1) WX radar faulty or crew didn't detect Cb cell(s). Probably former.
(2) LOC at FL350+/- was as a result of extreme conditions encountered when penetrating an active mesoscale system.
(3) Icing that took place was probably 'rapid' as opposed to 'gradual'.
(4) Intake blanking in the updrafts resulted in a 2 x flame-out.
(5) Recovery was achieved, but relights were unsuccessful due to engine core ice load.
(6) The low level LOC could have been compounded by an aft C of G problem.
(7) Tail yawing to port? A 'flat spin' or just surface wind 025°T x 21/35KTS.

Finally, I'm just the messenger!

mm43

[Lazerdog]

Greybeard.... Your query is certainly worth further study. There is likely to be an intitiating event followed by further contributing factors that caused this accident. I used to research airborne lighting suseptability for a major avionics company and the TCAS antennas appear to be in areas that are prime for lightning attach points. Couple that with the photos showing rudder static dissipator tufts missing and it points to a possible event that needs to be eliminated or studied further. The root cause of the initiating event (beyond flying into a highly convective area) is not known, so all possible causes have to be fully explored and analyzed.

[robertbartsch]

Is anyone following the latest issues with the faulty tork readings on the "new" Goodrich pitots?

[SaturnV]

mm43, thanks again for your effort and analysis.

I am hoping that the next BEA report contains the transcript of all relevant communications between ATLANTICO and the three flights immediately preceding and following AF447 on the track that night (IB6024, AF459, and LH507). LH507 preceded AF447 by 20 minutes and deviated west because of the weather appearing on its radar. Presumably communication about that deviation between LH507 and ATLANTICO should have been overheard by AF447, as AF447 should have been on ATLANTICO's frequency from 0133 until 0220 hours.

[PJ2]

Re high altitude icing, engine issues and so on, I see that there is a "Winter Operations Conference" being hosted by the Air Canada Pilots Association at the Royal York Hotel in Toronto on these and other topics. The dates are October 7 & 8 with registration on the evening of the 6th. The home website is here (http://www.winterops.ca/) and the agenda is here (http://www.winterops.ca/agenda).

mm43;
(1) WX radar faulty or crew didn't detect Cb cell(s). Probably former.
First, I acknowledge the "messenger" status and the "perhaps" status of your observations. So it is with respect that I offer some small points.

With regard to the radar serviceability, I don't think there is likely justification for saying, "probably former" (in the quoted passage), as there are no ACARS messages in the mix received indicating a radar failure. From experience, there are definite ECAM and Maintenance messages associated with such a failure. There may no issues at all regarding why the encounter, or there may be "sole causes" as a result of the encounter either as a result of lack of knowledge are pure unavoidability. In short there is nothing we can say about the crew. We simply do not know what went on in the cockpit. I believe we can say in the absence of ACARS messages however, that the radar was working.

As I posted in July, while we cannot state that the engines were flamed out, while we don't have any hard data from the manufacturer, the likelihood of the engines continuing to run with a high angle of incidence is low; hydraulic power from the RAT would be similarly reduced due to the relatively low forward speed as described in the BEA Report. The RAT requires at least 140kts over the blades to generate some hydraulic pressure. Whether ice or high incidence would cause re-start difficulties cannot be stated, nor can we say the APU was running although that would certainly be something the crew may have considered/attempted at some point.

I have earlier posted reasons why I think an aft CG would not be a strong factor in any LOC but could be a contributing factor in abnormal attitudes or post-LOC. In other words, I doubt very much whether an aft CG would in and of itself, even in heavy turbulence or reduced airspeed, (though still well above Vls), would cause a loss of control.
On top of all that the FBW software, when it gave up, gave you back the a/c with control limitations!
The reasons why the autoflight system "gives the pilot the airplane" has been discussed and isn't unusual in transport aircraft. No autopilot is designed or certified to handle an aircraft beyond the accepted limits indicating loss of control. All other transports do the same thing and I think including the statement is incongruous with your excellent analysis. Whether it is causal or not is another matter, mainly for the designers. Suffice it to say that an autopilot capable of recovering an aircraft from unusual attitudes/LOC while managing power and 'g' loads is a long way off; -the best responder is still the human one.

These aren't meant as criticisms of your continuing fine work but observations which I believe must attend any such mapping speculations.

best,
PJ2

[Will Fraser]

PJ2

My casual observation of this monstrous thread is that engine issues have been remarkably lightly addressed. The first time I noticed it quite some time ago, you may recall, I brought up a severe yaw causing blanking and at least one engine failure perhaps as a result or cause of VS separation.

That aside, EASA have noticed a probable (?) extension of the Trent 800 AD relative to rollback resulting to the Trent 7 and 5. Regardless of type, Icing pitots would certainly suggest other Ice related issues, to extend to core or even fuel path. Relative to ACARS and engine data, it seems unsupportable to embrace only one narrow Ice induced possibility, at least to me. Perhaps there was no 'upset' at all, merely a long descent (to include either rapid or reasonable RoD) ending in an unpowered and failed entry into the Sea. Is there some amount of intelligent speculation relative to eliminating this possibility?

[PJ2]

Will;

Yes, I recall the dialogue on yaw-blanking and engine failure. In my view, such yaw angles would have to be severe to upset an engine sufficiently to put the fire out. I wouldn't be prepared to entertain such lateral forces but clearly cannot rule such a scenario out.

In terms of evidence for one theory or the other regarding the descent, for me, the damage pattern of the parts found indicated a low forward speed impact, simply because they are in large, undeformed chunks and not in shattered pieces with evidence of high-velocity impacts either with one another or with the sea.

Any forward motion of a flying airplane vice one that is fully stalled and falling vertically would produce, in my non-expert view, a substantially different damage pattern in the surviving parts we have. A no-flap approach speed for 205k kg for the 330 would, (just estimating, no references to the books at the moment), about 180 - 200kts +/-, or about 300ft/sec, perhaps 200ft/sec if they got some flap out. There is NO evidence of a high forwards-speed impact or shrapnel markings in the wreckage we have seen but good evidence of high compression loads. I have never, therefore, considered the "Mach-tuck" stall/LOC or high-speed descent a viable explanation.

Independent judgement can determine whether that is "intelligent speculation" or not! The older I get the less amazed I am at how wrong I can be - the basis for all truth! :)

[mm43]

PJ2,
Thanks for your comments.

mm43
(1) WX radar faulty or crew didn't detect Cb cell(s). Probably former. The fact that no ACARS messages were received regarding WX radar faults doesn't necessarily rule out some insidious problem that failed to trigger a fault warning. With regard to the above quote, I agree totally that we know nothing about what went on in the cockpit, but at this juncture I chose to give the crew the benefit of any doubt.

Suffice to say that if penetration of an active mesoscale system took place, then all bets are off and the events I described may or may not bear any resemblance to the truth. In fact, the only thing we do know is that the a/c sent a raft of ACARS messages and finished up in the Atlantic in a wings level, nose up attitude, with little forward velocity, tail yawing to port and a high sink rate. We don't even know where with any degree of certainty.

SaturnV,

Presumably communication about that deviation between LH507 and ATLANTICO should have been overheard by AF447, as AF447 should have been on ATLANTICO's frequency from 0133 until 0220 hours.Once the SELCAL had checked at 0135 it appears the crew selected SELCAL watch as ATLANTICO's attempts to contact them a few seconds later went unanswered. Why ATLANTICO failed to SELCAL them is another matter. We don't even know if AF447 had selected 123.45, but no one has reported hearing them on either HF or VHF after 0135. A failed ADS-C connection at 0201 with DAKAR OCEANIC is the only evidence of cockpit activity.

mm43

[PJ2]

mm43;

Thanks for your response. While no messages from a failing radar would be highly unusual especially given the pattern of other messages, you are right in that "nothing issued" does not prove nothing happened, nor does it substantiate failure. As a safety specialist, I choose neither to give the crew the benefit of the doubt or look to them for answers but await where whatever evidence can be mustered, leads us. In the absence of the recorders (and even with them) we must stick with open questions in all areas, even the more difficult-to-accept ones such as crew performance until, somehow, they can be eliminated one by one towards a probable scenario, but I strongly suspect you already know and appreciate this necessity.

I am curious if the search continues either under the auspices of Airbus etc or informally and if so, are they using any of your information. I know that is speculative but for me it seems wholly reasonable. Perhaps they are already thinking along the same lines but I am a believer in "what, not who" and if good data or thinking can be had, the source is less critical than the use of same.

PJ2

[mm43]

PJ2,

I have previously raised doubts about some of the surface current data produced by NOAA/OSCAR and hope that SHOM specialists onboard the "Pourquoi pas?" during its recent two prolonged periods in the search area have gathered as much surface current data as possible. If they have done that, they surely will be able to analyze the actuals against those produced by the OSCAR project and ultimately be able to produce more factual vectors and speeds for the first 7 days of June.

The "Pourquoi pas?" is currently berthed at Horta, Azores and is engaged in its programed research - tectonic plate movements. I understand it sails for Brest on 30 September. Enter 38.53283333, -28.62133333 into Google Earth will take you to Horta.

The vessel's position is updated by satellite each hour at H+30 and is plotted at:-
Localisation des navires océanographiques de l'IFREMER (http://www.ifremer.fr/posnav/PosnavWeb/WFAccueil.aspx)

mm43

[Dutch Bru]

Where is the second interim report which the (still*) BEA director Arslanian announced on 1 September "within the next weeks" ? (* Arslanian's retirement seems imminent)

France Info reported on 24 September that according to the previsions of BEA, the effective search for the black boxes should recommence at the very beginning of next year ("Et selon les prévisions du BEA, la recherche effective des boîtes noires devrait reprendre en tout début d’année prochaine.").

[SaturnV]

mm43, thanks for your reply.

If they were in SELCAL watch mode, learning after the fact what they might have heard had they been listening on the HF really matters for naught at this point.

It does raise retrospectively whether switching to SELCAL watch was the prudent choice in the circumstance that AF447 found itself that night, when crossing the ITCZ in an area of SIGMETs and having received an ACARS message from dispatch at 0031 hours, saying "PHOTO SAT DE 0000Z : CONVECTION ZCIT SALPU/TASIL". The transcript of the brief communications between AF447 and ATLANTICO around 0133 hours reveals no concern about the enroute weather.
_______________
As best as I can interpret the times and positions from the BEA report.

LH507 is at ORARO at 0140 and chooses then to deviate west by 10 NM because of what its radar is showing.

AF447 is at ORARO at 0200

IB6024 is at ORARO at 0212, encounters turbulence and cumulonimbus buildups, deviates east by 30NM when about 30(?) NM south of TASIL and then rejoins the airway in clear air close to TASIL

AF459 is at "the level" of ORARO at 0237, earlier (some time after 0200) this flight had deviated to the west by 20NM to avoid an area of radar echoes. During the deviation, the radar, while on max gain, reveals an extensive squall line ahead. AF459 then deviates east of the airway by 70-80 NM. and rejoins the airway north of TASIL at the ASEBA waypoint.

[mm43]

SaturnV,

AF459 is at "the level" of ORARO at 0237, earlier (some time after 0200) this flight had deviated to the west by 20NM to avoid an area of radar echoes. During the deviation, the radar, while on max gain, reveals an extensive squall line ahead. AF459 then deviates east of the airway by 70-80 NM. and rejoins the airway north of TASIL at the ASEBA waypoint.I note that the above is a repeat of your 10 July posting. The problem I have is that the original interview with the AF459 F/O seems to have lost something in translation. So much so that its difficult to determine where and when they actually made their deviations. The "at the level" of ORARO could mean either abeam or at the same latitude. Really need INTOL time and TASIL estimate plus time at ASEBA to make much sense of where they actually went or were.

I still sense that the AF447 crew were preoccupied with the ADS-C log on with DAKAR. They didn't know that DAKAR hadn't received their flight plan, nor were they aware that DAKAR had created a virtual flight plan after receiving details from ATLANTICO, and that the existence of only a VFP prevented their ADS-C log on. Notwithstanding, the aviate, navigate and communicate rule should have applied.

The CVR is a "must have".

mm43

[Unusual Attitude]

A resumed search is indeed being looked at using more suitable technology given the anticipated water depth. I cant say any more for now however.

[grizzled]

UA -- thanks for that. The French Authorities have been saying for a month now that a new phase of searching would certainly occur, but no one has been forthcoming with any details. Your post, though sparse, gives some hope at least . . .

[mm43]

The starboard outer spoiler recovered according to the FAB from a position 415km Northwest of St Peter & St Paul rocks on 13 June by a merchant vessel, was in fact recovered from a position 005°T x 41NM from TASIL at about 1300z. I do have the actual position and time, but in the meantime those who are interested will be able to identify it from the BEA's debris graphics in the preliminary report.

I am currently analyzing OSCAR surface current data in relation to the spoilers identified position, and as I had already suspected, the published current velocities need to be increased by about 40%. The possible impact position shown on graphics in post #4476 on page 224 is still valid.

Positional data supplied by the FAB was IMHO designed for media consumption and to be deliberately misleading for any other use.

mm43

[grizzled]

mm43 -- surely you're not suggesting that the FAB, or Airbus, were/are concerned that someone else might find things before they do? As in Bob Ballard?

[mm43]

grizzled -- "Keep y'r cott'n pick'n fingers off" is pretty close to the mark.:ok:

[Peter H]

It's deeply embarrassing to be disagreeing with somebody who obviously knows more about GPS and aircraft than I do, especially as we seem to be totally at cross purposes.

cribbagepeg (http://www.pprune.org/members/303352-cribbagepeg)
read message 4463 - what you're talking about is phase tracking...

In 4463 you said ...
The phase-tracking used in attitude detection is a different animal. The wavelength at GPS frequencies is roughly (very) 25cm, so the theory predicts that one receiver moving vertically (e.g.) relative to a second one, toward or away from the satellite(s), would experience a detectable phase difference in the order of centimeters. Needs superfast processor and GPS chips, but it works....

I'm talking about taking the difference in readings between two bog-standard GPS receivers at the wing-tips. Bog-standard, without superfast processor and GPS chips. So how can I be talking about the phase tracking you refer to?

I was trying to make a simple observation. Which I still feel is correct, and is supported by the maths at the end of message 4472 ...
If you take the difference of the positions reported by two bog-standard GPS receivers on your plane, then the accuracy you achieve is the same as you would have achieved using two civilian differential-GPS receivers [and a nearby base station].

If you have an argument directed against this observation, I'm really interested. Perhaps offline as we're taking bandwidth.

Regards, Peter

[EmBee]

Differential GPS: This requires an accurately surveyed site to broadcast correction data – typically it needs to be within 100km of the user to be effective. It is therefore mostly used for maritime navigation close to land. A more useful variant is to the link the correction data from a host of accurately surveyed sites across a landmass to a central site and then generate a contour map of errors, a bit like pressure isobars. This map is unlinked to a satellite and rebroadcast on one of the spare GPS channels for use in the GPS receiver to give significantly improved accuracy. This is known as a Satellite Based Augmentation System (SBAS) but has only limited landmass coverage (WAAS in the USA, EGNOS in Europe and MSAS in Japan). These are intended for aviation use including Category I approaches. For obvious reasons it will not be available over large oceans, but then it is not necessary to know your location that accurately in cruise.
GPS Attitude: This does not require accurate GPS location information (e.g. Differential GPS or SBAS) but relies on the phase differential of the received carrier as seen by a number of closely spaced antenna. For an example of equipment capable of generating GPS attitude data refer (opens as .pdf):-
http://www.promagellangps.com/assets/datasheets/ADU5_DS_Len_16Jan08.pdf

It should be noted that GPS attitude measurement requires a number of antenna on the aircraft whose 3D location geometry is accurately known. The further apart the antenna are the better, but any unintended variation in their relative position will result in attitude calculation errors, so mounting them on wing tips is not ideal due to flexing. I have heard engineers talking of errors resulting from flexing of the fuselage in flight and these variations may be difficult to characterise and thus correct. However, attitude accuracies of about 0.2 degrees can be achieved with a separation of only about 2m and adequate structural stability at this distance should be readily achievable.

Use of standard GPS for attitude determination: The concept proposed by Peter H should work in theory, but two matched GPS receivers will not produce identical results. A long baseline (separation) would be required e.g. wing tips, and with residual GPS errors and wing flexing I would expect a roll error of typically 1 to 5 degrees. Differential carrier phase measurement technology would improve on this by at least an order of magnitude.

[chrisN]

I have started a separate thread on GPS accuracy and two GPS readings, if the mods let it stand. I have a separate question, as well as being interested in the one posed by Peter H, and my interest is nothing to do with AF447.

Chris N.

[edit: posted before I was able to see EmBee’s helpful answer to the question, above. I still have another question, on the other thread.]

[JD-EE]

Embee, let's review the goals with regards to attitude determination in an airplane absent conventional instrumentation or observation. Working and highly visible bog standard artificial horizon equipment may be the best way. But if somebody insists it is not there then GPS can provide some answers with a degree of roughness that depends on dynamics of the aircraft and expense you're willing to undergo.

Basically you need to know the relative positions of the two wing tips and the nose or tail to sufficient precision to determine an accurate attitude. GPS is one way to do it. Both differential GPS and phase tracking have been mentioned. A third method exists that might be called differential phase tracking, which can apply and will likely be cheaper to implement.

If we review differential GPS the conventional use requires, as you stated a precisely surveyed reference. Conventionally you need to know your position relative to physical features of the Earth. Thus the well surveyed reference position. Suppose a plane is flying near the surveyed site and you measure distances to both wing tipss and the nose. To get the attitude you play with the geometry of those three positions. The simple way is to note that the left wing tip is at some distance from the surface while the right wing tip is at some other distance. That gives you some attitude data. But it doesn't account for lateral distances along the surface of the Earth. Geometry gets messy.

Now presume the left wing tip is your "precisely determined position". Certainly it is, relative to the plane. And what you want is information about where the rest of the plane is relative to that wing tip. Once you know this you can shift the "reference" to the CG of the aircraft if that makes instrumentation read easier. What you need to know is all differences of position. If the left wing is higher than the right wing your plane is banked. You could care less if this is at FL 100 or FL 350. You know you are banked and can estimate how much. Instantaneous measurement precision for the GPS track for all three receivers limits your notion of how severely banked your plane is.

Phase tracking has a similar feature. It just gives more precise "where I am" information. If you simply measure relative carrier phases, which requires relatively little additional computer power you can get pretty accurate notions of position. (If you lose track you're more or less sunk, however. You have an ambiguity of 20 cm (roughly) to resolve. In turbulence it's fairly easy to have the dynamics kick the GPS
receiver out of lock. The loop time constants are large enough that the plane could move out of its established track by several times 20 cm quite easily.

So you're generally stuck with conventional differential GPS unless you have really good inertial measurement units to aid the GPS receivers in a military manner. (Or you can presume in designing the receiver that the loop time constants can be made much shorter to allow high dynamics tracking by sacrificing some of the GPS signals fairly dramatic anti-jamming margin. But I've already gotten too technical for this group, I suspect.)

GPS can be used. I'd need to see some analysis to show me it's usefulness for a differential GPS application before I'd endorse it for the application. It has promise. But the cost would probably make the artificial horizon gyroscopic approach sound exceptionally attractive.

JD-EE

[VR-HFX]

I thought I posted a note saying that I saw a French newspaper this morning blaming the pilots.

I can only assume it was deleted cos someone has pprune by the short and curlies.

Tell me it in't so.

[BOAC]

Who knows? What I see is SPAF (the union) seeking to absolve the crew of blame. Le Journal du Dimanche article (http://translate.googleusercontent.com/translate_c?hl=en&sl=fr&u=http://www.lejdd.fr/Societe/Justice/Actualite/AF447-Pour-l-honneur-des-pilotes-139187/&prev=/search%3Fq%3Dla%2Bmonde%26hl%3Den%26client%3Dfirefox-a%26rls%3Dorg.mozilla:en-GB:official%26hs%3DTxo&rurl=translate.google.co.uk&usg=ALkJrhjfjjWWLws-uENk_SEgGUMZg0C43w)(Google translation into English [acknowledgements naturellement]) explains

[atakacs]

Seems to be picked up by many news media without any background about where this "report" is coming from :ugh: