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AF447

Old 22nd Jun 2009, 12:48
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Wily flier,
I seem to recall that a freighter picked up a spoiler about 45 km NW of StPeter & St Pauls. This matches Takatas latest Hypothesis but doesnt show on his plot.

It also seems to support a more consistent and constant rate of drift from the discovery point of the first most southerly items

(The report came on PPrune after the VS was first picked up, but I havent been find it . There is a post #1325 June 13 which has a pic of freighter and spoiler, but I cant find any seperate report text now,

.....the merchant ship picked up that piece of the plane north of Tasil on June 13.

See the Powetpoint slide for June 13 on the Brazilian Air Force site:
FORÇA AÉREA BRASILEIRA - Asas de um povo soberano
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Old 22nd Jun 2009, 13:06
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The Opposite I Believe

I've noted an increasing amount of speculation that the aircraft might have hit the ocean in-tact. I think all the evidence we have points to the contrary.

I think an excellent example, in relation to mid-air break up, is the Air India Flight 182 in the mid 80's. Do a search on 'you tube' for Air India 182, and watch the documentaries relating to that incident.

Note the condition of the bodies found in that case: no clothes on the majority of bodies found; fractures to hips, shoulders and other joints (known a 'flail' injuries, resulting from violent tumbling through the air); and no sign of drowning (ie they were not breathing when they hit the water). Also note the conclusion that the pathologist and investigators drew based on those facts: "based on the injuries, we could only say the plane had broken up at 31,000ft". I think the similarities between the bodies found in this instance, and the Air India accident, are too common to be ingnored. It seems quite obvious, then, that the unfortunate people on AF447 suffered a similar fate to the passengers on the Air India jet. What remains to be answered is 'what caused it to break apart?'

The other interesting fact from the Air India case (which involved a 747) is the size of the debris field: 16 x 6km. Speculation that various elements of AF447 could be hundreds of miles apart seems unlikely in light of that fact.
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Old 22nd Jun 2009, 13:16
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For the U-turn hypothesis and the infered crash area, is it possible that an airliner (at the assumed flight point, airspeed and altitude) bank with such a short radius curve ? (as plotted on the map)
Just remembering the order for the recovery of the debris and bodies: the first piece collected (on june 6) was the crew rest cabin remain (where is the mobile crew rest deck in the A330 ?), less than 2 days later, the vertical stabilizer was found, and latter other groups of bodies/debris (the whole with a large dispersion)
Doesn't it suggest that these people and pieces were first lost in flight after the last ACARS, that the VS was lost and the rear part of the A330 fuselage may have been severely damaged in mid air ? (In this case, the airplane didn't try to make a U-turn but simply tried to control its attitude and its altitude)
Apart from a stall, how can an airliner break up in mid-air in cunjunction with all the reported avionics faults ? (a cumulonimbus breaking a plane does not need the ACARS faults: would-it explain them ? whereas the stall possibility can stem from these).
Why isn't it interesting to consider the early leakage from the LAV L54 (which had already problems on the 10th of May) toward the rear of the plane: isn't the BEA right when it suggests that combined to the very low temperatures encountered may have frozen a part of the composite structures, weakening them, making them more prone to a structural failure under heavy stress ? What is the volume of the fluids that may have leaked ? (<100 l, 500 l ?), from which part of the wasted fluids circuit, and in which areas would it flow in more than 3 hours ?
Can't we assume that the A330 tail and other control surfaces were under heavy constraints (no longuer protected by the normal law) while trying to recover from assumed situation of emergency ? (possibly creating a huge torgue of the rear part of the fuselage)
Is an airliner without its VS still in control in a turbulent atmosphere ? would it be in ideal flight conditions ?
To conclude, can't there be a large initial dispersion that was increased by the several days drift ? The A330 airspeed gradually decreasing between 02:10 and 02:14, then a final trajectory initiated by a stall with a right bank, loss of VS/rear part of the fuselage, gradually loosing passengers and pieces, ending 10-20 NM south east of TASIL. Then a few days NW drift of this initial distribution)
Jeff
PS) my apologies if these questions were already answered.
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Old 22nd Jun 2009, 13:38
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takata,

thank you for your thorough and very interesting analysis.

I would make several points.

a.) From looking at the plots, the Brazilian Air Force's search grids are systematic on June 1, and between June 2 and 5 are systematic only to the east, south, and southwest of the last reported position. Much of the searching between June 2 and June 5 seems centered on various targets observed on the sea surface than on a systematic grid search.

b.) Why the Brazilian Air Force did not look immediately west or north of the last reported position before the June 6 search grid remains a question. Was this due to the operational limits of the recon aircraft? Did the Air Force immediately focus on the first sightings of possible wreckage?

c.) If the prevailing current was from south to north, why did the Air Force initially expand the search grid to the south, rather than to the north?

d.) Was the Air Force using the meteorology for June 1 and June 2 to infer that the thunderstorm complex encountered by AF447 moved south or east, and that winds from the complex probably pushed the lighter debris in that direction?
________________
Where did you get the chart showing the surface current speed and direction on June 5 2009?

Last edited by SaturnV; 22nd Jun 2009 at 13:40. Reason: clarify
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Old 22nd Jun 2009, 14:02
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Internal AF document 18-06

This is the English traduction of an Air France internal document addressed to Cockpit Crew dated 18/06/09 that you can find here : (may be elsewhere I don't know)



Les dossiers noirs du transport aérien

Scroll down to 21.06.2009
or direct link :

http://henrimarnetcornus.20minutes-b...1453557506.pdf


It's an automated translation plus some personal adjustments.



HEAD OFFICE OPERATIONS AND QUALITY
DIRECTION OF SAFETY
DIRECTION OF THE AIR OPERATIONS
ALL PNT
Roissy, On June 18, 2009
INFORMATION ALL PNT N° 5

On June 15, a point on the inquiry was made by the Management of the safety of the company in front of executives PN of the Air Operations. This "N°5" information" recapitulates all the points approached at the time of this presentation.

INVESTIGATIONS
The accident of AF447 took place in the international water; this is thus the State where the aircraft is registered that leads the technical inquiry. Four working groups were made to this end by the Bureau d'Enquêtes et d'Analyses. Air France contributes to this investigation in bringing its expertise to work with these groups of which each members is engaged to respect the confidentiality of information.
Only the BEA is authorized to communicate on the progress of the inquiry. It will publish a preliminary report before the the 30th of June.
In parallel to the technical inquiry and in accordance with the French Right, a judicial enquiry is carried out by the GTA (Gendarmerie du Transport Aérien) under control of an instruction judge of the Court of Paris.
The rules specific to the company envisages in addition the installation of an internal inquiry. For this reason the Head office designated 5 permanent members including two flight crew staff representatives.
Finally 2 other investigations will be led at the initiative of the CHSCT PNT and PNC.


FACTS AVAILABLE AND THE PRELIMINARY REPORT OF THE BEA.

At the time of the accident the plane was leaving a zone of convection related to intertropical convergence. The satellite photos diffused to date show clouds spreading out at high-altitude, but these photographies do not indicate directly the position of the stormy cells that the crews of different companies flying on this road met. A complementary work of analyses is in progress.
The main informations that we have about the plane result from automatic maintenance messages.
These messages are embodied in the information transmitted by the plane without intervention of the crew to alow maintenance teams to prepare the interventions upon the arrival of the plane. These messages are not easily exploitable for an investigation and cannot replace data from CVR (Cockpit Voice Recorder) and DFDR (Digital Flight Dated Recorder).
More particularly, the format of the messages and logics of transmission do not allow to reconstitute with certainty the chronology of appearance of the anomalies in the cockpit.

The majority of these messages are the consequence of the anomalies and the inconsistencies of aerodynamic speeds; they were detected by the flight control calculators and the automatic pilot. Among these one can be quoted:
The loss of characteristic speeds
The passage in secondary law of flight (Alternate Law)
These associated anomalies and their consequences are tested during the certification of the plane; this allows to guarantee that the plane remains controllable in this situation.
All of these messages and their significance will be very certaily published in the preliminary report of the BEA.
At this stage, nothing in these messages allows to establish:
- A loss of power supply,
- A loss of the screens of piloting (PFD and Stand-by horizon),
- A faulty operation of the ADIRU which could have involved an incident of the type of which Qantas company knew recently.

Only one certainty: the sequence of the messages does not allow to explain the accident by itself.

PROBES OF PITOT

Many erroneous assertions were advanced in connection with the anemometric probes equipping the Airbus fleet. We present to you in chronological order a summary of the reports and especially of the actions carried out by the company since 2001.

August 2001:

Following fluctuations and/or losses of the indications of the aerodynamic speed on A330 and A340 reported by certain companies, the DGAC publishes an “Airworthiness Directive” (AD) by plane type, to impose the replacement of the probes of Pitot ROSEMOUNT P/N 0851GR, either by probes GOODRICH P/N 0851HL, or by SEXTANT (THALÈS) P/N C16195-AA; this operation having to be finished before the 31 December 2003.
Indeed, the official services allot these events to the presence of crystals of ice and/or of quantities of water which exceeds the specifications of the probes Pitot ROSEMOUNT P/N 0851GR. In accordance with the “Airworthiness Directive”, the model SEXTANT (THALÈS) P/N C16195-AA is installed on the Air France A340 fleet ; as from December 2001, Air France receives its first A330 which is origin-equipped of the probes SEXTANT (THALÈS) P/N C16195-AA. No event of this type will be reported on Air France A330 and A340 until May 2008.

September 2007:

Airbus emits technical notes (Service bulletins or SB) which recommend, without being mandatory and outside all context affecting the navigability of the planes, the replacement of the probes THALÈS P/N C16195-AA installed on fleets A320/A330/A340 by new model probes THALÈS P/N C16195-BA.
It is indicated that this model improves the behaviour of the probe by limiting the consequences of water ingestion by strong rains and by reducing the risk of icing. After analysis, the Air France technical teams decide to launch this modification on the A320 fleet which has incidents with losses of speed indications at low altitude in case of strong rains. They decide to replace probes on A330/A340 by the new models only in the event of failure, the A330/A340 fleet having then no incidents with loss of speed informations.

May - August 2008:

A first incident of icing of the probes occurs on a Air France A340 with temporary loss of speed indications; followed by a second incident in July 2008 and then of 3 incidents in August 2008, all on A340. Airbus is immediately questioned on the origin of these incidents and to the measures allowing to cure it.

September and October 2008:

Many exchanges with the Airbus technical teams take place. An exploitation incident is recorded in September and one in October 2008. In six months, 7 incidents were thus recorded, when no incident of this kind had been reported before.
Airbus answers that:
o The supposed origin of these incidents is a icing by crystal formation in the probes of velocity measurement,
o The new model THALÈS P/N C16195-BA was not conceived to answer the problem of icing and thus should not bring significant improvement with this problem,
o The probes installed are in conformity and even exceed the lawful requirements in term of airworthiness and of safety of the flights.

November 2008:

Following various follow-up from Air France technical services, Airbus corrects its September 2007 technical notes in a dated November 12, 2008 edition that withdraws any mention of a contribution of the probe THALÈS P/N C16195-BA improved resistance to icing.
On 24 November2008 a meeting between the technical directions of Air France and Airbus discusses lengthly of the incidents with loss of speed informations. Air France requires that a technical solution be quickly brought to solve these incidents. Airbus confirms again that the origin of these incidents is an icing of the probes, that the last model THALÈS P/N C16195-BA does not treat of the subject and that the probes installed are in conformity with the airworthiness requirements and safety of the flights.

February 2009:

Facing our insistence to find a solution, wind-tunnel tests are undertaken by Thalès and Airbus on the behavior of the probe THALÈS P/N C16195-BA.

March 2009:

At the end of March 2009, two new incidents of exploitation are recorded of which a first on A330. That brings the total number of incident to 9, including 8 on A340 and one on A330.
Airbus, again requested on several occasions, answers by confirming the presumption of icing of probes and refers to a procedure of maintenance and checking of the probes.

April 2009:

In a letter of April 15, 2009, Airbus informs of a new element: the probe THALÈS P/N C16195-BA does not have vocation to answer the problem of icing of the probes, but the tests carried out by Thalès show a behavior definitely better than that of the former model. Taking into account the limitations of the wind tunnel tests, Airbus suggests an experimentation on Air France planes to check if an improvement is confirmed in real situation. Without awaiting this experimentation, Air France decides to immediately extend this measure to its entire long-distance Airbus A330/A340 fleet and to replace the totality of the probes speed. One internal technical document launching the modification is established dated April 27, 2009. The beginning of the planes modification is planned as of reception of the parts, at a rate of several planes per week, from June 1.

May 2009:

Air France requires THALÈS to accelerate the delivery schedule of the probes. Those are delivered starting May 26, 2009 at a rate of 12 tubes of Pitot per week. The program thus could be accelerated.

Since the accident:

Without prejudging of a link between the anemometric probes and the inconsistencies in the indications of speeds presented to the pilots, Air France has decided to accelerate its plan of replacement of the probes THALÈS P/N C16195-AA on the fleet Airbus. Since last June 12, all A320,A330,A340 Airbus, in exploitation within Air France are equipped with the probes of last generation THALÈS P/N C16195-BA.
Nevertheless in an information bulletin published on June 8, Airbus confirms that the Airbus world fleet can be exploited with one of the 3 types of anemometric probes which equips world fleet, namely THALÈS P/N C16195-AA, THALÈS P/N C16195-BA and GOODRICH P/N 0851HL.

CONCLUSION

We intend to recall that any step of prevention imposes three requirements;
- a requirement for transparency,
- a requirement for reactivity,
- and a requirement of pro-activity.

Whatever the circumstances, it is advisable to proceed in this way.
This is why, we have decided to keep you regularly informed of the state of advance of the inquiry and this, in an agreement with the BEA that remains the only one in charge of the communication of the factual elements.

In addition, we named two staff representatives within the Internal Commission
- Mrs L G for Commercial flight crew
- Mr O R for the Technical Flight crew.
This commission reserves the right to raise recommendations constantly if it feels it need.

----------------------------------------------------------
2 names deleted.
PNT : Personnel Navigant Technique (Cockpit Crew)
PNC : Personnel Navigant de Cabine (Cabin Crew)
DGAC: Direction de l'Aviation Civile
CHSCT Comité d'Hygiène, de Sécurié et des Conditions de Travail
The members of the CHSCT are elected Unions members. CHSCT is competent for all matters related to the security, hygiene and work conditions of the employees in a given society.

-----------------------------
My own comments if you allow:
This document is an internal one but the fact that some terms such as CVR or DFDR are translated in "plain" language (or even the GTA acronym) indicates 1/ That the AF PNT is really stupid or 2/ May be this document is intended for the PNT but also for the entire world. And written knowing that it might leak out. In this case who is the Charming and who is the Villain?
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Old 22nd Jun 2009, 14:07
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777 Direct Mode

Just for my understanding, what is that "basic airplane" you're getting? I thought you would still be using the control column to provide inputs to the fly-by-wire computers. I didn't think the 777 had direct mechanical linkages to all control surfaces.
When the 777 is manually switched to "Direct" mode you are effectively removing the Primary Flight Computers and may control the aircraft via unmodified commands using ANALOGUE electrical signals that are passed directly to the control surface actuators.

Max
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Old 22nd Jun 2009, 14:44
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Hi,
Harry Mann: Irrespective of speculation on mode of ejection, injuries etc.... it would be expected to a high probability that most/all would be seat-belted in 'strong turbulence', as reported shortly before.
The BEA pointed that she was flying at cruise settings Mach 0.82 @ 0210Z and autothrust was ON (self-disconnected at 0210Z); unlikely a 'fortes turbulences' mode which would be at reduced speed to Mach 0.80 and autothrust OFF (like in Air Caraibes case). See my first hypothesis post about the so-called 'fortes turbulences' report issued at 0200Z.

In a note dated on 6 Nov. 2008, Air France informed its crews of speed discrepancy problems with its A330/340 Fleet: http://www.eurocockpit.com/docs/OSVAF.pdf
- loss of airspeed data;
- numerous ECAM messages displayed;
- configuration warnings (sometime)

The turbulence context is specified for 6 flights:
- Turbulences 'light to moderate'
- 2 cases with 'Fortes Turbulences' and 'MSS/Turbulence' applied.

So, if the 'fortes turbulences' occured (who know?), they would came at the same time of the pitots freezing or later.

S~
Olivier
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Old 22nd Jun 2009, 15:11
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SaturnV:
thank you for your thorough and very interesting analysis.
I would make several points.

a.) From looking at the plots, the Brazilian Air Force's search grids are systematic on June 1, and between June 2 and 5 are systematic only to the east, south, and southwest of the last reported position. Much of the searching between June 2 and June 5 seems centered on various targets observed on the sea surface than on a systematic grid search.

b.) Why the Brazilian Air Force did not look immediately west or north of the last reported position before the June 6 search grid remains a question. Was this due to the operational limits of the recon aircraft? Did the Air Force immediately focus on the first sightings of possible wreckage?

c.) If the prevailing current was from south to north, why did the Air Force initially expand the search grid to the south, rather than to the north?

d.) Was the Air Force using the meteorology for June 1 and June 2 to infer that the thunderstorm complex encountered by AF447 moved south or east, and that winds from the complex probably pushed the lighter debris in that direction?
________________
Where did you get the chart showing the surface current speed and direction on June 5 2009?
The charts are part of the SHOM pdf linked previously: Services Hydrographiques et Océanographiques de la Marine,- SHOM, 6 juin 2009:
http://www.bea.aero/fr/enquetes/vol....hom.050609.pdf

For questions a) to d), of course, I can't give you an answer in place of the FAB!
But I do remember that the bad weather somewhat disrupted the SAR and the aircraft were searching at one point mostly where they could make observations at sea level rather than following a rigid search pattern obstructed by the clouds.

S~
Olivier
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Old 22nd Jun 2009, 15:41
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Just to clarify a point.

The bodies recovered from the Lockerbie Air Disaster, that were ejected at high altitude were fully clothed, partially clothed or naked.

I dont see any relevance in the bodies being either clothed or unclothed in this matter as you cant draw any real clues to the height they left the aircraft.
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Old 22nd Jun 2009, 16:22
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Hi Jeff,
Hyperveloce:
For the U-turn hypothesis and the infered crash area, is it possible that an airliner (at the assumed flight point, airspeed and altitude) bank with such a short radius curve ? (as plotted on the map)
Certainly not as I have no clue of what happened between 0210Z and 0214Z (and later) - beside the ACARS which are revealing nothing about the course- up to the zone where the plane might have crashed.

The point (as it is specified) was not to reconstruct an accurate course between 0210Z and the hypothetical crash zone. The body drift infered a position where a U-Turn was mandatory for F-GZCP to end there. The first hypothesis then was an heading to Fernando de Mononha for an emergency landing, the second, taking into account the wreckage spotted on 02 June, pointed to another spot and a more desesperate alternative (crash landing near St Paul's Rocks?).

But the third logical hypothesis would be that they had no plan left at all with an aircraft uncontrolable which ended in this zone.

Just remembering the order for the recovery of the debris and bodies: the first piece collected (on june 6) was the crew rest cabin remain (where is the mobile crew rest deck in the A330 ?), less than 2 days later, the vertical stabilizer was found, and latter other groups of bodies/debris (the whole with a large dispersion)
Yes I remember. The large rigid pieces of the airframe are much more exposed to the wind than nearly fully immersed bodies. The wind was turbulent and somewhat contrary to the drift at some point (this is ITCZ where the weather is fairly complex).

Doesn't it suggest that these people and pieces were first lost in flight after the last ACARS, that the VS was lost and the rear part of the A330 fuselage may have been severely damaged in mid air ? (In this case, the airplane didn't try to make a U-turn but simply tried to control its attitude and its altitude)
It seems unlikely that the aircraft broke up just after 0214Z, loosing passengers, and end there (my only hypothesis is to show that, not to explain it). The distance is about 110+ NM back South-East and more than 12 mn at cruise speed @ FL350 in straight line.

Apart from a stall, how can an airliner break up in mid-air in cunjunction with all the reported avionics faults ? (a cumulonimbus breaking a plane does not need the ACARS faults: would-it explain them ? whereas the stall possibility can stem from these).
The ACARS do not suggest the plane was breaking up in mid air. The end of the ACARS and the lack of further communications only suggest that the plane could not communicate any more, but not that she was unable to 'pilotate' and possibly 'navigate' for a while...

Why isn't it interesting to consider the early leakage from the LAV L54 (which had already problems on the 10th of May) toward the rear of the plane: isn't the BEA right when it suggests that combined to the very low temperatures encountered may have frozen a part of the composite structures, weakening them, making them more prone to a structural failure under heavy stress ?
The BEA did not suggest anything like that. The press did. It is like those so-called 'autopsy' reports 'close to the investigation'. Let's see what will be actually released by the officials and we will compare the report to those 'leaks'. I have read two completely opposite versions of the 'autopsy leaked' published at about the same time

To conclude, can't there be a large initial dispersion that was increased by the several days drift ? The A330 airspeed gradually decreasing between 02:10 and 02:14, then a final trajectory initiated by a stall with a right bank, loss of VS/rear part of the fuselage, gradually loosing passengers and pieces, ending 10-20 NM south east of TASIL. Then a few days NW drift of this initial distribution)
Look at the map scale and the sea drift speed. There is 11 NM between 2014Z and the first bodies recovered. Adding 20 NM is not going to make a good count for a nearly crash zone. Everything else is very hypothetical but this pattern of body and their drift speed is nearly certain as well as the utlimate positional report following by the ACARS sequence.

S~
Olivier
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Old 22nd Jun 2009, 16:44
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Per the AF report above, The Rosemount/Thales pitot probes have been problematic for years. Since Airbus insisted the newer -AB probes do not claim improved performance in icing, the prudent course of action for AF would have been to replace all Thales probes with Goodrich.
GB
It sounds like the Rosemount/Goodrich ones have been redesigned because of icing as well. Also in both redesigns it has been to improve resistance to icing not necessarily prevent it completely.

I think we still need flight control systems and procedures (beyond the current) that can deal with this issue as well.


"FEATURES OF MODEL 0851HL
Improved Design Features
In order to meet the Airbus extreme icing conditions specification, the Model 0851HL Pitot Probe has been designed as a replacement for the Model 0851GR. These performance enhancements were accomplished by
increasing the power density in the tip region by 35% over the existing probe, and incorporating the high power density in the drain hole region to ensure proper drainage during severe icing conditions."
http://www.goodrich.com/portal/goodr...t%200851HL.pdf
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Old 22nd Jun 2009, 16:49
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the two leaks about the autopsies are separated by several days: the first group of autopsies showed traumas consistant with a free fall and a high velocity impact with the sea surface, the second group of autopsies (and leakage) suggested that some passengers impacted the sea surface sitting in their chair. While we must certainly be cautious with these non official forensic data, these are not necessarily contradictory: some passengers may have been lost in mid-flight (with the VS and then the rear part of the aircraft) while the others might have continued their flight with the main part of the aircraft toward the "crash area". I was suggesting that multiple biases on the airspeed may have triggered a stall after ou around 02:14Z, a stall accompanied by a right bank/sideslip. to me, this is necessary to explain
-that the ACARS satcom link was severed: the attitude of the A330 was exceeding the steering angular range of the satcom beam,
-the exiting of the flight enveloppe and the bad situation that may have led to a destruction of the VS
-the drift of the bodies/debris and where they were collected (but there is here a high degree of uncertainty about the prevailing surface currents and surface winds)
As for the wasted fluids leakage, we are not definitive about the source of this hypothesis but is it possible to assess its plausibility as a contributing factor to a structural failure ?
Jeff
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Old 22nd Jun 2009, 16:58
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I know it was brought up forever ago but would be interesting to see if the satellite kept any logs about transmission strengths or other data regarding the uplink or attempted uplink(s). Might give some clues about location, speed, direction...etc.
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Old 22nd Jun 2009, 17:08
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Locations of bodies #1 and #50. 145km apart in 19-20 days.



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Old 22nd Jun 2009, 17:09
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"The distance is about 110+ NM back South-East and more than 12 mn at cruise speed @ FL350 in straight line."

That, of course, only 3000fpm.
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Old 22nd Jun 2009, 17:14
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Actually a number of drifting buoys have been dropped in the area on June 15, possibly to keep track of debris.
From Weather observations and positions of ships at sea.
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Old 22nd Jun 2009, 17:23
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The post above by ACLS65 about Goodrich Sensor System 0851HL Pitot Probe is describing in short the the Pitot functions in the second page; the end of it is interesting to draw a direct link between the pitot's failure and the cabin vertical speed control also. Then, the advisory (no warning, no check list) at 2014Z might be also linked to the unreliable Air data provided by the pitots as Thales and Goodrich probes are interchangeable.

The 0851HL pitot is also functionally
interchangeable with existing pitot probes certified on
A318/319/320/321/330/340 manufactured by Goodrich
competitors.

DESCRIPTION
Sensor Systems Model 0851HL Pitot Probe is an integral
part of the Air Data System of the aircraft. Sensor Systems
pitot probes provide vital information for aircraft flight
control. Pitot pressure measurements are used for
calculating flight parameters, which include pressure
altitude, airspeed and Mach number. Air data probes also
provide information for secondary purposes such as
engine control and
cabin pressure differential.
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Old 22nd Jun 2009, 17:41
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Pinger strength

I have no connection with the aircraft industry but have been following with interest some of the very technical discussions on this forum.

One thing I do not understand is why the pinger signal is so weak. I would have expected that there would have been a massive 'ping', perhaps every hour, which would allow those searching to at least obtain an approximate bearing. Limiting a higher output to each hour would make almost no difference to battery life.

Submarines have very sensitive listening gear and one would expect them to locate the recorders more readily. Or have I missed something?
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Old 22nd Jun 2009, 17:53
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Some interesting information on the FDR pinger here:

Black Box: Locating Flight Recorder of Air France Flight 447 in Atlantic Ocean | MarineBuzz.com

It talks of the range being one mile, say 6000 feet, and that might be explained by the high frequency in use. In turn this suggests that th eonly way of detection will be by a towed array at a depth of 10000 feet. A two-mile length tow is a lot of tow and a 2 mile sweep width means a lot of steaming to cover the area.
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Old 22nd Jun 2009, 17:54
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Pitot Envy

Thanks for the correction, ALCS; I thought Rosemount had been bought by Thales, and not Goodrich. I just visited the Goodrich site, and see you are correct. I'm sure I had read somewhere in this thread that Thales had acquired Rosemount. Not so.

Whose probe business did Thales acquire?

I'll delete my post of Today: 08:40

GB
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