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AF 447 Search to resume

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AF 447 Search to resume

Old 20th Apr 2011, 18:47
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jcjeant, the analysis by the Russian Interstate Aviation Group and BEA concluded there was about a 55 percent probability that the impact would be within 6 NM from the "start of the emergency", and nearly 70 percent probability it would be within 8 NM. It seems the Metron analysis used the LNP as the "start of the emergency" for purposes of its calculations. But the LNP is rather late in the sequence,

Perhaps a reason the BEA is not releasing the exact coordinates is that it may be closer to the LNP then many of us assume, and if so, both Brazil and France would have overflown the impact point on both June 1 and June 3. (France clearly overflew it on June 1 (wherever it turns out to be) given the search graphic in the Metron analysis for June 1.)

If visual conditions for the search on June 1 were poor, one would think that search would be repeated when conditions were improved. That seems not to be the case.

I am certain that an impact quite close to the LNP would raise all manner of questions about the adequacy of the initial searches, and that would be a subject that the BEA and the French and Brazilian military would rather not be distracted by at this point. There was also a ship, the Douce France, that searched in the area of the LNP on June 1, but its track has not been publicly released.
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Old 20th Apr 2011, 19:09
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I think it more likely that if at impact, the VS separated and was thrown back.

The Pressure vessel terminates at the Aft Bulkhead, and the a/c essentially flies (and crashes) in close formation with the Tail. If tail first, the dynamics of Hydraulic action would emanate differently than at the Fuselage, not to mention the likelihood that the Tail may have completely separated from the body at impact. If there was a separation at impact, the angle of attachment would grow progressively more acute, suffering the remaining structure to progessively separate from its closest neighbors still connected to the hull. The fuselage, having acted in essence as a giant airbag, would accelerate the loss of velocity of the fuselage as the tail continued. If the body 'rebounded' (that certainly would need explanation), the tail may have been 'rejected' (rather emphatically) by the Fuse and the VS pulled itself loose from the forward lug/bracket and flew backwards to escape corruption by a presence in the chaotic debris of the main impact area. This would basically (sic) explain the damage to the VS' LE via contact with the dorsal area of the fuselage at initial deceleration, (the tail having 'folded over' this area) and the corrupted corner of the Rudder as the Fin/Rudder rolled over the tail cone in aft fashion with the violent pull on the empennage by the fuselage remaining essentially near the surface after initial contact.


What is seductive to me is some verbiage expressed by the BEA that may lead to false assumptions.

It seems completely apparent that 447 departed controlled flight. The late portion of the fall by BEA's description is of a free fall with some horizontal component, and a slight lateral rotation of the airframe, with the a/c essentially intact.

There was no aerodynamic flight.

447's trajectory was down, and her hull had no heading, by their own explanation. Intact, this aircraft's nose would have a heading only after all its rotation had ceased. It's nose was unwinding the compass' rose in a left rotation, laterally.

There was no heading.

No Flight, No Heading. No "En Ligne de Vol". I wager 98 per cent of the reading public think the aircraft was in controlled flight on her way to Paris when by misfortune she hit the water.

Words have meaning.
Old 20th Apr 2011, 20:14
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One scenario

Instead of not having enough altitude for a square loop, imagine a transition from a wings-level high-speed pullout during a spiral dive recovery to a relatively low-forward speed, nose-up, high-sink rate impact with the water:

Aviation Video: FA-18 MCAS El Toro Crash | Patrick's Aviation

A loss of control eventually resulting in a spiral dive also keeps them in the vicinity of the LKP.
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Old 20th Apr 2011, 20:17
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Originally posted by bearfoil ...

There was no aerodynamic flight.

447's trajectory was down, and her hull had no heading, by their own explanation. Intact, this aircraft's nose would have a heading only after all its rotation had ceased. It's nose was unwinding the compass' rose in a left rotation, laterally.
Technically, your "no aerodynamic flight" is true, but you need to consider that the attitude the aircraft attained was an aerodynamic compromise. Rightly, or wrongly my interpretation of the BEA's description, backed by their photographic evidence of impact damage, was that the aircraft had entered an unrecoverable stall regime whereby the attitude and bank angle had become stabilized in the lost lift vortex in which it was slowly rotating. Its trajectory was certainly down with a high angle of attack and high rate of descent, though in your terminology, "winding the compass' rose in a right-hand rotation, laterally."

That resulted in the tail swinging to port (left) on impact and following the culmination of the forces acting on its clevis joints in all planes and vectors, not forgetting the reciprocal buoyancy forces, the Vertical Stabilizer finished up in the water on its port-side with its rudder hard to starboard.

At the time of the impact, the wind was from the north at 25~30 knots, and the rudder aspect was such that the V/S was quite capable of "sailing" away from the scene.
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Old 20th Apr 2011, 22:26
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At the time of the impact, the wind was from the north at 25~30 knots, and the rudder aspect was such that the V/S was quite capable of "sailing" away from the scene.
But certainly not in a order of 10 Km or more
So I stay with ONE of my wonder: (provided the VS separated on impact)
Why this VS was not discovered during the first aerial researches in the vicinity of the LKP.... ?
This VS is not the size of a little plastic bag or a lifevest and have not the abilities of a submarine (dive and surface at his will)
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Old 20th Apr 2011, 23:32
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Originally posted by jcjeant ...

Why this VS was not discovered during the first aerial researches in the vicinity of the LKP.... ?
I am sure there were issues with the initial searches, be they from the air or sea surface. As you are well aware, search grids have been posted in this forum, but whether the published grids were actually flown is another matter. Basically, the SAR phase was the responsibility of the Brazilian military, and showed a lack of precise direction and purpose, e.g. chasing rainbows.
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Old 21st Apr 2011, 00:22
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bonjour. The VS was semi submerged when spotted, its colors probably difficult to discern. The structure gave me the impression of never being 'proud' of the surface, and I assumed it acted as its own sea anchor from loss to discovery. BEA stated that the Rudder was flapping, and had no resistance to pressure in its axis of sweep. I do not think it "sailed" at all. I can not remember its position when found, but was it not WNW of LKP a fair bit? Does this not conflict with your winds from 000 at ~25-30 ??

I also conclude the VS did not sink with other structure, to break free and surface on its own. It would have had to retain some air in pockets, and at 50 meters, it would have experienced permanent rib collapse, no?

Permit me a display of ignorance or inattention, (both?) but the LKP at 02:10, is that actual, timed transmission stamp, or receipt by ACARS??

My feeling is twofold, and I cannot blame BEA and/or ABI/AF. No one involved who had a stake in this accident wanted to believe that this sota a/c fell out of the sky, steeply, especially having lost some bits. I think their bias to 40 nm away or further reflects some wishful thinking on their part. Understandable.
Old 21st Apr 2011, 01:14
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VS sighted June 6 @ 13h38 @
3.61 N
30.62 W

VS recovered June 7 @ 18h35 @

On June 1, north of the LKP, surface winds were blowing from the NNE to NE direction, with much convection.

On June 2 and days following, winds became more easterly, and decreased. Convection was less as well.

On June 1, the drift group's optimal interpolation of the current near the LNP is that it was from the N/NNE toward the S/SSW, South of 3N, the current quickly turns SE and then east.
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Old 21st Apr 2011, 01:21
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If AF447 lost its VS in flight, it would have resulted in a CG shift forward. I don't know the mass of the VS, but would it have been enough of a shift to prevent a level attitude, if not the presumed slight nose high, at impact?
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Old 21st Apr 2011, 01:32
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If the VS separated when the tail was submerged, especially the closer the wreckage got to the bottom, I suspect to some degree it would glide to the surface. Depending on which area has the most buoyancy it might make a series of gliding loops, or swirl like Sycamore seed. In most pictures the rudder was also positioned to the starboard side, if firmly enough in that position it would also affect the ascent.

My guess would be that the deeper the VS separated the more likely it is to be found farther from the impact site. Even if it were to rise perfectly vertical the subsurface currents would have a longer time to act upon it.

A piece of wreckage like a cabin section might tumble upon ascent, but seems less likely to glide or sail than something aerodynamic.

Once upon the surface it will all depend on wind and currents, and whether there is more submerged or exposed area to be acted upon by each. Wreckage with a similar profile might stay together, but again over time one would expect those items more driven by wind or currents to separate.
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Old 21st Apr 2011, 03:13
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I'm obviously missing something, I would have thought that if the VS separated at any sought of real depth it would still be down there?
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Old 21st Apr 2011, 03:46
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Superb post.

Last edited by grizzled; 21st Apr 2011 at 07:47.
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Old 21st Apr 2011, 07:40
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Grizz, I completely agree. BJ-ENG's post is in my view required reading. Understanding the difference between aircraft structures impacting solid ground and water is, I think, important to understanding what the photographs have shown us in terms of the "stopping" capacity of water vs level ground, (ie, Tripoli vs what we see here thus far). I think how BJ-ENG's post describes this difference has added a great deal to the thread's knowledge.
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Old 21st Apr 2011, 08:06
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Originally Posted by cc45; post #1116 (p.56)
The VS weighed about 1800 kg and had an area of 53 m^2.
PS: Just a flimsy illustration to BJ-ENG's post.

Last edited by HazelNuts39; 21st Apr 2011 at 12:02. Reason: PS
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Old 21st Apr 2011, 09:55
  #3735 (permalink)  
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jcjeant - that's right - the great unknown in all of this is the behavior of composite structures under atypical stresses - there are many competing models, often mutually wildly divergent, all highly non-linear, of composite failure under stress.
Did you care to have a look at the wreckage photos of BEA's second report?
If you had done so you would have noticed that it was primarily the METAL support structure that broke not the composites. In contrary the composites survived the loads much better than the 'tin' (as is often the case btw.).
That makes any philosophying about the strength of composites obsolete.
Sorry if I sound a bit rude but it starts to get annoying having unfounded generalisation (which oviously does not apply in this case) repeated over and over again.

.. as a consequence of the loss of VS in flight is that you get a plane that is no more controllable ... what appears to have been the case for AF447
If an airliner loses its 'feathers', the result will very likely not be a 'pancake' impact at 150kts vertically and 50kts forward but a high speed forward impact.
AA587 impacted in a spiral dive, not flat btw.
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Old 21st Apr 2011, 10:11
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Originally Posted by bearfoil
Permit me a display of ignorance or inattention, (both?) but the LKP at 02:10, is that actual, timed transmission stamp, or receipt by ACARS??
Time-stamped 2:10, received 2:10:34, so presumably the actual position at 2:10:30? slotting in as high priority message in the initial bunch of errors, re-presented here

AF447 ACARS MESSAGES - Color Coded & Interactive Version

BEA use these receipt times to report

end of the flight between 2 h 14 min 26 and 2 h 15 min 14
There was an analysis a long time back of 10 minutes sector times, distance travelled and speeds, which made it clear the actual position time within the minute must shift. Assumed, but never confirmed as far as I know, that AF systems must adjust this timeslot to avoid aircraft using same satellite at same time.

If you want to repeat this the numbers used by the BEA in the flight path graphic time in seconds 'rounded to nearest minute', decimal location to ACARS 2 decimal place precision given in


Last edited by sensor_validation; 21st Apr 2011 at 10:50.
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Old 21st Apr 2011, 11:09
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VS (FIN & Rudder) Sailing Performance

Quote[FONT=Verdana][SIZE=2] from SaturnV:
LNP @ 2.58.8'N 30.35.4'W
VS sighted June 6 @ 13h38 @ 3.61N 30.62W
VS recovered June 7 @ 18h35 @ 3.47N 30.68W

Just to point out that the quoted positions appear to be defined as follows:
LNP (LKP) position is in degrees/minutes/decimals-of-minutes.
However, VS positions are in degrees/decimals-of-degrees.

VS (fin) posn June06/1338: N03.61/W030.62 N0336.6'/W03037.2'
VS (fin) posn June07/1835: N03.47/W030.68 N0328.2'/W03040.8'

I don't know how accurate the "sighted" position would have been, but here goes the number-crunching. (Not sure if the VS position-timings are GMT, but that doesn't affect the issue.)

In roughly 29 hrs, 6 days after the accident, the VS apparently moved
9.1 nm (16.9 km) on mean TRK 203T

Taken on face value, this may support mm43's suggestion that:
"the rudder aspect was such that the V/S was quite capable of "sailing" away..."
Others may comment on wind and current.

In case it's of interest:
VS (fin) recovery position, relative to LKP (N0258.8'/W03035.4), is
29.9 nm (55.4 km) BRG 350T


Last edited by Chris Scott; 22nd Apr 2011 at 01:36. Reason: (1) PS (Caveat). (2) PS now deleted.
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Old 21st Apr 2011, 12:41
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Chris, thanks for correcting my non-use of the silent K in the acronym.

The positions are from Table 1 of the Drift Analysis report. The only position observation in that table which is qualified is that for "Galley G2" sighting on June 6. (The qualification probably stems from the sighting and recovery coordinates being identical, even though the two events are four hours apart.)

In re-looking at the Drift Analysis report, the only model of the eight used that came close to an impact near the LKP was the U.S. Navy's HYCOM model, and regarding its results:

This [HYCOM] model gives a crash point near 315N 3030W, and has been discarded from our analysis, on the basis that the velocity field is not realistic enough and the backtracked debris were scattered over 93 km (Figure 37). However the Ursulla sighting is backtracked not far from our 95% confidence area.
The 95% confidence area had a lower bound roughly at 320N at 3030W

The Ursulla object sighting was one of six objects for which trajectories were calculated backwards in time in each of the models. Interesting that the VS was not one of the six reference objects.
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Old 21st Apr 2011, 14:39
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It assumes all have accepted the discovered site as close to the LKP, but what are we considering "close?" Given the BEA's close to the vest attitude, the "close" could mean about anything. The bones thrown by BEA really do not provide enough information to formulate any true picture, only continued speculation. However, I expect a lot of our speculation to be right on point.
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Old 21st Apr 2011, 15:31
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Aviation Week Summary

An update to a lot of what's being talked about on this forum

Aviation, Defense and Space News, Jobs, Conferences by AVIATION WEEK

(Bloomberg) - Investigators seeking to explain why Air France flight 447 plunged into the night ocean two years ago will rely on gear pioneered by telecommunications and oil companies as well as a Hollywood director to unlock the mystery.

The wreckage of the Airbus SAS A330 jet was discovered this month 3,900 meters (12,800 feet) deep in the Atlantic Ocean off the coast of Brazil after multiple searches. Few aircraft salvage missions have probed the same depth, where the sea is perfectly black, temperatures approach freezing and water pressure is equal to the weight of a car on a postage stamp.

Diving deeper than the Titanic's final resting place, a robot tethered to a surface ship will sift through the aircraft debris in search of the two flight recorders bolted inside the tail of the fuselage. Their data promises the best chance yet to explain the crash, the deadliest in Air France's history. Complicating the mission is the presence of numerous bodies, some still strapped into their seats and preserved by the cold water and lack of oxygen or light.

"At that depth, it is pitch black, and the difficulty is knowing where you are while keeping track of things," said Dave Gallo, director of special projects at the Woods Hole Oceanographic Research Institute in Falmouth, Massachusetts, whose robots helped locate and map the wreckage. "It's a question of operational skill."
No Survivors

The Airbus disappeared en route to Paris from Rio De Janeiro on June 1, 2009, leaving no survivors among the 228 aboard. While some fragments and bodies were recovered from the surface of the sea, most of the jet remained missing until this month. The data recorders are built to withstand submersion and extreme impact, though until retrieved there is no certainty the data they stored will be readable.

The expedition will gather at the port in Dakar in Senegal tomorrow, before traversing the Atlantic on the Ile de Sein vessel to the location of the aircraft, about 435 nautical miles off the coast of Brazil.

French phone-equipment maker Alcatel-Lucent SA is providing the 140-meter ship, which normally lays deep-sea cables. Aboard will be 70 people, including members of the French BEA air accident authority, investigators from the U.K. and Brazil, experts from Airbus and Air France, as well as one psychologist. Family members of the victims were not permitted aboard.
Robot Submarines

Underwater engineering company Phoenix International Holdings Inc. is sending one of its two "Remora" robotic submarines, or ROVs, equipped with high-resolution cameras and two manipulator arms. The basket on the ROV can recover as much as 200 kilograms (440 pounds) of debris in a single mission.
"There are about six to eight ROVs in the world capable of descending as deep" as the Remora, said Tim Janaitis, business development manager at Phoenix, who spoke from Largo, Maryland. Typically, the robot's missions include work on deep-sea oil drilling, and a recent descent took the vehicle to the Titanic wreck in the northern Atlantic, Janaitis said.

The search for the remains of the doomed ocean liner in the mid 1980s, and the 1997 blockbuster movie directed by James Cameron helped advance deep-sea technology, spawning high- resolution cameras and robots that can scour through wrecks.
Nazi Battleship

Following the success of the Titanic movie, which won 11 Academy Awards and cost about $200 million to make, Cameron embarked on an underwater expedition to Nazi battleship Bismarck, which sank in the Atlantic in 1941.
"Stuff like that is enough at times to help keep research going," said Robert Jensen, chief executive officer of Kenyon International Emergency Services, a Houston-based company that helps airlines handle disasters. "Look at what they spent on the Cameron movies. He went down on several submersibles to look at ships, to recreate as realistically as possible what happened."

The Remora robot can work as far down as 6,000 meters. To ensure steady operation, a team of nine Phoenix experts will operate the 900-kilogram sub from the ship using large video monitors to track its progress. Every movement of the vessel at the surface is translated to the Remora's umbilical cable with a delay, said Brennan Phillips, manager of ROV operations at the University of Rhode Island in the U.S.
Delayed Reaction

"If the ship moves, it takes half an hour for the vehicle to feel it," he said. "You need an extremely stable ship."

Of the almost 100,000 photos taken of the wreck and surrounding area, BEA publicized several black-and-white images of the landing gear, an engine, a wing and parts of the fuselage. While the black boxes have not been spotted, the robot has located the part of the tail that normally houses the recorders. Investigators withheld images of bodies and made them available only to researchers involved in the mission. For some, the sight was too much to bear.

"There were many bodies, and our people initially said they would not like to participate in any such recovery operation," said Peter Herzig, director of the Leibnitz Institute of Marine Sciences in Kiel, northern Germany, whose Remus 6000 robot sub was one of three that located the wreck.

Team members later changed their minds, though in the end, Herzig's group wasn't asked to participate, he said.

Should the recorders be found, they will be pried from the wreck, lifted aboard the Ile de Sein and immediately placed under seal, before being transported by a French Navy vessel to a French port. From there, they will be sent by air to the BEA under the responsibility of a judicial police officer.
Recovering Bodies

Recovering the victims is a more complex and contentious task. Only 51 bodies, including the pilot, were recovered from the ocean surface in the weeks after the crash.

Nelson Marinho, who leads a group of victims' relatives, said not all families want to see corpses brought up, though they recognize the obligation to present forensic evidence for a criminal probe. A French prosecutor is pursuing allegations of manslaughter against both Airbus and Air France, and autopsies may help answer questions such as whether passengers were still alive when the plane sank. BEA said all decisions concerning human remains will be made by France's Justice Department.
"The worst feeling, for us, is the risk of even more damage to these corpses," Marinho said. "French officials want to transport them to France, but we want to bring them directly to Brazil." Among the victims were 58 passengers from Brazil, 61 from France, 26 from Germany, and other nationalities including travelers from China and South Korea.
TWA Crash

Past aircraft salvage missions have managed to recover the bodies of victims. The U.S. National Transportation Safety Board brought up all the bodies from TWA flight 800, which crashed off Long Island in 1996, and EgyptAir 990, which went down 60 miles from Nantucket in 1999, former director Jim Hall said.
"I think as human beings, it's the humane practice, and it would be a disservice to family members by the airline and regulators not to recover them," he said.
The greatest technical challenge will remain operating at an extreme depth. Only one past air crash has forced salvage teams to dive deeper. The wreckage and black boxes of a South African Airways Boeing 747 that disappeared near Mauritius in 1987 were located 14 months later under 14,000 feet of water.
"It's only relatively recent that we even have the technology to consider these kind of recoveries," said Paul Hayes, director of safety at London-based aviation consultant Ascend Worldwide Ltd. "And it sounds simplistic, but I think we tend to forget how vast the oceans are."
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