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Position Reports
The latest official report from BEA was posted three days ago on 22 April. It stated simply the search area covered by Phase Three tows by Anne Candies and Seabed Worker, and offered a follow-on report on May 2. A news report claimed both ships would be returning to Recife for stores.
On that same day, according to third party satellite position reports (per broadreach and mm43 from Lloyds), the search vessels stopped "mowing the lawn" and both worked their way southwestward to a point a few kilometers from mm43's VS-drift calculated point of entry (see post #738). By the afternooon of April 24, both search vessels seemed to be holding station close by each other. Absent a briefing from BEA, we can but second-guess the activity aboard both vessels: if they are still on station by end of the weekend, we can hope they are characterizing a target of interest. If they are heading to Reciefe, then it's perhaps onward to a Phase Four. Eagerly awaiting position updates, hoping like grizzled for the best of luck, and still wishing for a live feed from the control room... Without black boxes and other structural evidence, this is an extraordinarialy difficult investigation with too many unknowns and finger-pointing what-ifs. GB |
I find the wording if the BEA 22nd April press release interesting..."The initial search zone will have been entirely covered by the end of the week. The Seabed Worker and the Anne Candies will return to port at Recife for a technical stopover in the next few days."
"The initial search zone" implies to me that there are other places to visit during this search phase. Probably like many here I do wish they had an FTP site to download their images, perhaps they have enough data to analyze in something like ArcGis, whatever, it might be useful to share the data. One thing, when they get into port they will be able to surf the internet with less expense and someone might read MM43's position theory, fingers crossed. |
A question at this point in the search is if the plane -- assuming there are large pieces -- is within the area recently surveyed, what is the probability it would have been found? That is, are the bottom contours in this area such that current technology should either readily find or could easily miss the plane?
This may be the most difficult bathymetry yet in trying to locate a plane on the ocean bottom. |
Hi,
is within the area recently surveyed, what is the probability it would have been found? That is, are the bottom contours in this area such that current technology should either readily find or could easily miss the plane? So .. if they check their screens(not like some security screeners employees :) ) if pieces of plane are there they will be detected .. AFAIK. |
Bathemetry Data
Curiously, in 1988 and again in 1999 the Russian Research Vessel AK N. Strakhov visited almost precisely the same area of the Atlantic where the AF447 search is currently taking place. The two Russian multibeam expeditions produced extensive bathemetry data which has been archived in a world repository accessible through NOAA.
http://i958.photobucket.com/albums/a...etry1988-s.jpg View full-size image here. In this photo, the 1988 Russian surveys are in yellow; the 1999 in olive. The single en-route scanning track above the Russian search area (blue) is a 1996 voyage by the Knorr from Woods Hole. Use the multibeam viewer here for more information. In examining the metadata files, I couldn't discover "why" there was such interest and intense activity here a decade ago. Backoffice: ArcView shapefiles seem to be the standard format for representing contour lines and other bathymetric features among oceanographers and geologists, but it might be that the Remus and Orion sonar data need to be looked at pixel-by-pixel, kilometer-by-kilometer in raw form to interpret anomalies and potential targets. I believe the BEA's control room video showed Fledermaus being used for 3D visualization. The Fledermaus folks do offer a 30-day free evaluation of their software; all you need now is the raw data from BEA to be useful as another set of eyes. In any case, I'm sure many sharp eyes have been and are at work. Perhaps if the experts can't find our needle in the haystack, they will release the data for the rest of us to try... without outrageous nuisances and amateur claims. Years ago at the checkout counter of the supermarket, I remember one startling tabloid headline that screamed "DC3 Found on Moon!" with a blurry photo that could have had many interpretations. http://i958.photobucket.com/albums/a...edermaus-s.jpg View full-size here. |
"Seabed Worker" & "Anne Candies" - 25 April positions.
The "Anne Candies" seems to have had the "day off", and is stationary as depicted in the cyan circle with the yellow center.
The "Seabed Worker" appears to be tending her Remus AUV's that are now working outside the south-west corner of the search area. http://i39.tinypic.com/fe050l.jpg Thanks again to broadreach for supplying the data. mm43 |
jcjeant, I think one concern has been if the plane is resting somewhat vertical on a canyon wall, the profile presented may be a fuselage cross-section. I( don't know whether the technology is good enough to detect such a profile in these circumstances.
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Bathemetry Data
GreatBear,
Does the archived data actually overlap with any of the existing search? If it did then you could use the prior data as a baseline, produce a differences database and look at the changes. Of course I have no idea what the tolerances would be, but from the wobble around zero we would get a local error estimate that would allow us to decide it any (greater) differences were statistically significant. So: Do we have any genuine overlap in the prior & post (crash) data? What is the noise/error level like between the two sets? What is the chance that there should be a piece of wreckage big enough to stand out over the noise? paul |
Latest Air France crash search proves inconclusive
Posted on 25 April 2010. http://updatednews.ca/wp-content/the...=180&zc=1&q=90 An international search to locate the black box recorders from an Air France plane that crashed near Brazil last year killing 228 people has so far proved inconclusive, French officials said on Friday. Air France flight AF447 between Rio de Janeiro and Paris crashed into the sea on June 1, 2009, killing everyone on board. The families of the victims hope the black box recorders from the Airbus A330 plane will be found in order to shed light on the disaster. So far, the search has cost 9 million euros ($12.10 million) and French Transport Minister Dominique Bussereau said on Friday he would ask the country’s BEA body — the authority in charge of investigating air accidents — to continue its investigation. The BEA plans to issue an update on the situation on May 4. A search last year found several pieces of wreckage and 50 bodies but the black box flight recorders have not been recovered and the causes of the crash remain unexplained. Reuters |
"Seabed Worker" & "Anne Candies" - 26 April positions
The "Seabed Worker" at 26/0420z was at 1°33'05''N 31°30'18''W, 199°T/11.6KT, ETA Port Suape [8°24'S 34° 58'W] 28/0900z (0600 Brazilian Standard Time).
The "Anne Candies" at 26/0418z was at 1°50'28''N 31°02'10''W, 197°T/9.3KT, and I'll give a Port and ETA for her tomorrow. mm43 |
I would have thought that the initial impact on the rear fuselage would have caused a nose up attitude and not down. I stand, readily, to be corrected though!
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Is there any information, though, on the likely altitude at which the VS separated? If it was effectively at zero, this would presumably be due to forces associated with impact, and this would give little information as to what caused the crash
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As explained by BEA, the center and rear attachments of the V/S failed under vertical inertia loads which pushed the V/S into the fuselage. The tail fin was damaged during its recovery and transport but the photographs available made it possible to identify the damage that was not the result of the accident. The middle and rear fasteners with the related fragments of the fuselage hoop frames were present in the fin base. The distortions of the frames showed that they broke during a forward motion with a slight twisting component towards the left. |
ST27;
thank you for correcting me. After re-reading both interim reports I must admit that I put rather too much of my own interpretation into that sentence. I apologize for that and I have gone back to my post to delete it. HN39 |
"Seabed Worker" & "Anne Candies" - April 27 positions
The "Seabed Worker" at 27/1528z was at 4°58'45"S 33°40'42"W, 199°T/12.6KT,
ETA Port Suape [8°24'S 34° 58'W] 28/1300z (1000 Brazilian Standard Time). ETD is 2 hours later, possibly for Recife. The "Anne Candies" at 27/0338z was at 1°10'17"S 31°50'36"W, 201°T/9.9KT, and I don't currently have a destination - though probably Recife. mm43 |
Extended search
Lefigaro.fr, citing 'a government source', reports today that the two vessels will return to the search zone by the end of this week for a prolongation of the phase 3 search, possibly enlarging the perimeter of the zone already swept.
HN39 |
A question (or two) for seismographers...
When Swissair 111 hit the water off Peggy's Cove, Nova Scotia, Canada in September 1998, a "seismic event" was recorded. Investigators therefore had a very precise time -- and location -- of impact. So, if no seismic event was recorded within the appropriate time frames for AF447, can one conclude that: 1 The aircraft did not impact the water with sufficient force to leave such a signature (which would tend to eliminate a scenario of an "uncontrolled plunge")? Or, 2 There may not be sufficiently sensitive seismic information available for that area? (I have no idea the practical science / instrumentation behind this, but I do know the USGS, for instance, receives / records even very small seismic events from all over the globe.) I am assuming that no such event was recorded because, if it were, the impact location would be known. Anyone? |
Good point!
Grizzled,
Damn good question! I too am no expert on this but I do not think that you have to be nearby to feel the earth move. My guess is it is 1> .Tends to confirm the BEA assumption that it was pretty much in level flight when it hit. I think that is, if anything, more upsetting (no pun intended) , to think that a few more feet and it might have been so different... |
Precisely !
Given only a few additional meters of altitude, the Airbus would have countered the unlucky pilots, who missed key Radar, defeated a monster Cell, perhaps for the first time in history, and made a pilotless recovery from high speed jet upset. Why didn't they think of that ! Great catch. bear |
How AUVs work
For those interested in the technical challenges faced by these underwater birds, here's an interesting site, with some videos of what goes on on the ship and underwater.
Plane Shaped Rocks | Search for Amelia |
Grizzled,
I learned some years ago of a case involving a pretty large freighter at sea, which litteraly exploded at the surface of a smaller pond than the Altlantic, the Mediterranean sea, where such event should be clearer, once registered by sismographers. All sismic datas around the date and location of the explosion were carefully screened. But nothing would tell any difference betwenn that explosion - or impact, in case of an a/c crash - and usual sismic activity. It got lost in the "background noise", so to say. |
grizzled So, if no seismic event was recorded within the appropriate time frames for AF447, can one conclude that: 1 The aircraft did not impact the water with sufficient force to leave such a signature (which would tend to eliminate a scenario of an "uncontrolled plunge")? Or, 2 There may not be sufficiently sensitive seismic information available for that area? (I have no idea the practical science / instrumentation behind this, but I do know the USGS, for instance, receives / records even very small seismic events from all over the globe.) I am assuming that no such event was recorded because, if it were, the impact location would be known. At the time of the experiments conditions were ideal. The ocean was as calm as it ever gets off Delaware. And there were no storms in between. That is one data point. The second experiment I aided with was a precursor to something I kibitzed professionally 5 years later - using seismometers for intrusion detection with the intention of implementing it in Vietnam. Footsteps were very plain and very hard to disguise with shuffling and such. DC3s were uncannily obvious in the seismometer tape recordings WAY before the voice track could discern the plane's propellers. And there was a way to mask footsteps. Heavy winds made it difficult, and a DC3 going overhead also made it difficult. That's a second data point. If Swiss Air 111 hit the water within about 125 miles of Nova Scotia then the coupling for the event into the ground would be pretty good. (The Delaware tests were in comparatively shallow water.) The coupling for AF447 would be bad, it would have to hit with enough energy that it left a signature easily distinguishable from storm events, and you'd have had to have sensors closer to the event than the nearest real shoreline. Or such is my guess from limited but quite pertinent experience. Hydrophones might have had a better chance. And with vagaries of sound transmission in the ocean I am not convinced they'd do a whole lot better at locating the crash. They might be able to detect the crash event, though. Your idea was a good one had the water been substantially shallower and the crash been closer to land. As it is I'd consider it a bad bet. But at this juncture a bad bet may be better than none at all, such as after they've gone through mm43's magic triangle. {^_^} |
"Seabed Worker" & "Anne Candies" - 28 April positions
The "Seabed Worker" at 28/1411z was berthed at Port Suape [8°23'47"S 34°57'32"W].
The "Anne Candies" at 28/0338z was at 4°32'22"S 3°02'14"W, 199°T/8.5KT, and should berth at either Suape or Recife tommorow. ----------------- Hydrophone detection of explosions in the sea, is the normal practice when undertaking offshore oil exploration. The seismic survey vessel tows a long streamer (up to 1.5NM in length) fitted with in the range of 100 hydrophone detectors. The same vessel also tows about 100 meters from its stern, an array of air guns. The sensitivity of this system is such that geophysical structures over 5,000m below the the seabed can be detected. Higher resolutions can be had when two vessels work in tandem, and the differential signal is also recorded. So in short, the sound travels well in the water, penetrates terra firma and echoes back through the same path. All very well and good for what it is designed to do. Seismometers on the other-hand are designed to detect the vibrations caused by terra firma shifting. The energy generated even by a small tectonic plate shift is normally far greater than a non nuclear explosion on the sea surface, and a force 1 Richter quake would probably be detected a few hundred miles from its source. So, in the case of AF447, if the Atlantic had been ringed by sensitive hydrophones and the best noise cancelling techniques were used, I suspect that with the distances involved the chances of triangulating an aircraft crash by this means would be remote. I live 25km from an active though currently dormant volcano which has a number of seismometers embedded on its slopes, as detection of activity is difficult from any great distance. mm43 |
Seismic arrays
Large arrays of very sensitive sesmometers are operated by several countries around the world to verify that no "illegal" nuclear tests are made by anybody. I have tried to get their sensitivity and directional resolution, but failed. Here in Sweden they are operated by the military research institute (FOI). I know that the explosion of the Kursk was detected very much above noise. Does anybody know if similar very sensitive arrays exist in Brazil or Dakar?
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"Seabed Worker" & "Anne Candies" - 29 April positions
At 29/1948z both vessels were berthed at Recife, starboard side to, with the "Anne Candies" astern of the "Seabed Worker".
I suspect the "Seabed Worker" will depart for the search area shortly. Thanks to broadreach once again for the data. mm43 |
mm43, there is one significant difference between the towed array setup you describe and a plane crashing on the surface. That's the thermal layers that reflect sound. Once you get below them it's all fine. But anything above the layers is reflected and ducted all over the place, fairly efficiently, with a lot of dispersion and multiple path issues.
(I should have mentioned that in my prior note. I was trying to keep it short.) {^_-} |
JD-EE, That's where the significance of the air percussion guns come into play. The ELF (low audio spectrum) pulse is used because of its ability to penetrate the inversion layers as well as deep into the terra firma beneath the seabed. Lower frequency means "better" in this type of seismic operation, and the resolution is improved by the difference signal from a tandem operation.
- from Woods Hole Oceanographic Institution .... The air guns are relatively deep penetration sources, operating at 100Hz to about 1200 Hz, to identify subsurface geologic layers and define the subsurface structure. In studies that require less resolution but substantial penetration, the air gun is usually preferable as compared to a water gun, because it is far more efficient at producing low frequency energy. But back to seismic detection of aircraft crashes. It should be remembered that the WTC Twin Towers aircraft impacts were recorded, i.e. the buildings moved, but no meaningful amplitudes were measured over 200 miles miles away. Likewise, it is debatable that the UA93 impact at Shanksville, PA, was actually recorded due to the 3 minutes difference between DFDR/ATC and seismometer times. Perhaps the difference could mean that the vertical percussion wave generated travelled some distance into the earth before being reflected, as signal amplitudes just above the background noise were recorded and triangulation pointed to the crash site. mm43 |
Hi,
Le Figaro - France : Les pilotes mal formés au «décrochage» des avions INFO LE FIGARO - Several accidents have revealed that the procedures to recover an airplane that could lead to crash landed. Dazed in the cockpits. Reportedly, a major work is underway to develop safety procedures for crews of all companies in the world. Airbus, Boeing, Bombardier, Embraer, Air France as all companies ... Everybody is associated with what is now a major issue in aviation safety. Airbus announced this great project mid-March to its airline customers. Several recent accidents have revealed that the procedures "Stall" implemented in the event of stalling an airplane are not appropriate, and in some cases, they prevent the crew out of this dangerous situation, and sometimes dramatic. There is talk of dropping out of the plane, but it is actually the wing stalls. In conventional flight conditions, the air streams flow around the wing and conform to the shape. However, at too high incidence (the angle of the wing with the air), not reattach airflow over the airfoil. The lift of the aircraft decreases. He falls or continues its path because of its inertia and can only crash. In contrast, high speed, airflow can reach the speed of sound. This creates a shock wave that can cause loss of control of the aircraft. Dropout can occur at low speed, it is called "low stall speed," or high speed, it is called "high speed stall. Today in all cockpits, the procedure in case of stalling to full throttle to minimize loss of altitude. "This procedure has been pushed by mistake by U.S. authorities," said one familiar with the matter. In a few weeks, the new procedure will recommend only a control stick to reduce the incidence, that is to say things slightly, nosed the plane. This change of method should be common to Airbus and Boeing. "The whole aviation industry has gone astray for more than a decade," says one close to the matter. From Air France, the drivers are embarrassed to armholes because they do not test flight and can not have a final stance on the issue. They can only rely on the advice of manufacturers. "Air France Airbus maintains its commitment to change this procedure on all aircraft in the world fleet," said Stephen Lichtenberger, CEO of Flight Safety at Air France. The analysis of recent events suggest, in fact, that this change is necessary. " The company says it lights will implement the new procedure as soon as possible, "as soon as we have been addressed by manufacturers having been validated by the certification authorities, namely the European Agency for Safety (EASA). Flight test The other major issue is that of training. For today, not a flight simulator can not recreate the settings related to a stall and thus cause the drivers to cope. "We can train pilots to recover from a situation close to the stall, said an instructor of Air France, but not to recover from a stall." "Procedures have been made for people who have never lived on heavy airplane stall, said Claude Lelaie, head of security at Airbus. Only test pilots who know the stall. According to our information, Airbus will offer its customers boarding their flight instructors on board to offer test drive in situ. However, it is unrealistic to imagine all the drivers in the world to flight testing to practice stall recovery. Someone can confirm or infirm this ? More from the french newspapers .... http://www.slate.fr/story/20633/air-...7-victimes-vol Air France recently offered tickets to the families of victims of the crash of Flight AF447 Paris-Rio by offering to join Paris on exactly the same flight as the one who died tragically last year, reports the website of Der Spiegel. Families living in Brazil did not really need this unfortunate coincidence: the flight was offered to attend a ceremony at the Pere Lachaise Cemetery where a memorial in honor of the 228 people who died on June 1, 2009 must be opened. More than 120 victims' relatives planned to travel to Paris on this occasion. But many have not hidden their misunderstanding after learning of the flight schedule and mark-up is keeping them take: flight AF445, starting Sunday night in Rio de Janeiro aboard a Airbus. "This is exactly the same flight as one that took away our loved ones," said Maarten van Sluys, the president of an association of families of victims at the site of German newspaper. "I do not know what were the intentions of Air France, but it's bad taste and no respect for our very fragile emotional state," he added. Airbus used for the flight, whose name was changed from AF447 to AF445, would be far from completed, which upset a little van Sluys: "They just need to fill a plane and have decided to to our group of 100 people. " The victims' association has requested that Air France offers flights to another group, one of the two Boeings that connect Brazil and France every day to avoid having to relive the last moments of their loved ones, that an Air France pilot was described in the columns in Slate. "We would feel much better," said Van Sluys. Wednesday, April 28, the Office of Investigations and Analysis (BEA) announced that the research of black boxes and the wreckage of flight AF 447, who have still not been found eleven months after the tragedy, would continue . The issue of compensation also remains a thorny issue, a lawyer representing families of victims said Tuesday, April 27 insurers that Air France offered an amicable compensation differ depending on the nationality of the victims: 2.98 million euros per person in the United States, 560,000 euros to 186,000 euros in Brazil and Europe. |
"Seabed Worker" & "Anne Candies" - 30 April positions
"Seabed Worker" cleared the Recife breakwater bound for the Search Zone at 30/1430z (1130 Brazilian Standard Time). ETA Search Zone 03/0230z.
"Anne Candies" remains berthed at Recife. Update: "Anne Candies" departed Recife around 30/1500z. mm43 |
What is the frequency/resolution of the swathe/sidescan system of those AUVs which are deployed by Seabed Worker?
If a CVR/FDR has been flung clear of major wreckage, as sometimes happens in very severe impacts with a water surface, would the sonar have the resolution for such a contact to stand out like a dog's wotsits at the height above seabed at which the vehicles are 'flying'? Have they deployed a representative sized/reflectivity testpiece to the seabed to verify what such an item would actually look like in the depth, location and conditions of the searchsite with the kit that is doing the 'looking'? |
Low Flier;
The answers to most of your questions can be found in the Search for Amelia website of the Waitt Institute for Discovery. Go through the site carefully, and you will find everything you are looking for. mm43 |
I'm aware of the failed attempt by an enthusiastic amateur to find Amelia Earhart's wreckage. I'm also aware that the referenced website(s) merely say that the AUV can be fitted with either a single or dual frequency sidescan sonar.
My question is: what frequency is being used in the AF447 search? I could make an educated guess that the two frequencies are something like 120kHZ and 500kHZ. Therein lies a significant problem. The lower frequency probably lacks the resolution to 'see' a smooth sided object as small as a CVR/DFDR. The higher frequency probably lacks the range to insonify a significant swathe at a reasonable flying height for the AUV over such craggy terrain as the present search site(s). That's why I ask whether they have deployed a similar sized box onto the seabed to demonstrate what it would look like if insonified by the equipment being used. Sure, there will be a debris field, but in such a depth it is likely to be quite diffuse and probably enormous. An object as small as a recorder box really needs a methodology verifier. |
Low Flier, I believe the REMUS 6000 AUV fitted side-scan package consists of either:-
1. RESON Seabat 7125 Multi-Beam (200/400 kHz), or 2. Electronic Still Camera & Strobe, or 3. EdgeTech Dual Frequency (110/420 kHz) Side Scan Sonar and Sub-Bottom Profiler In this case I suspect that the Seabat 7125 is being used, and is operating in the low resolution search mode at 200kHz. The location of a bottom debris field, no matter how dispersed, will enable a systematic backtrack to where the DFDR/CVR will be if torn from their mounts at impact. The location of larger items on the bottom will probably give other clues, like the heading on impact. The engines for example will be nearly straight down, but other items may have variable glide slopes. The AUV will normally be programed to fly (it can not hover) at a predetermined height above the terrain at a speed commensurate with battery economy, e.g. 3 knots. Woods Hole Oceanographic Institution have some example imaging of a 14 foot boat with an outboard motor attached, which was located in 3,500 meters. The side-scan images are at 900kHz, and there is overlaid photographic imaging taken with the onboard strobe camera. The search team have a TRITON deepsea ROV available to them to do any close-up examination and recovery. Some of the more specific information you are requesting is not in the public domain, and time will probably reveal what was or wasn't done. mm43 |
Low Flier, what makes you think they are looking for the box? They first have to develop a notion of where to look with high resolution or even optics. They look for larger pieces of the aircraft, such as the engines, first. Then they start looking for the little stuff within an established debris field.
In round numbers the speed of sound in water is 1500 m/s. 120kHz gives a resolution of about 1500/120000/2 (half wavelength) or about 6 millimeters. Anything smaller than that will be hard to resolve. Something 10 times larger should be within the realm of detection without really fancy processing if it's outside the range of sizes of uninteresting objects in the area. Off hand I'm curious where you got the sonar resolution data you cited. I presume sonar is different from radar, where I do have some engineering know-how. I also do note that the radar problem is seldom trying to detect an object sitting on another object or the ground. I'm willing to learn. {^_^} |
Low Flier, what makes you think they are looking for the box? 120kHz gives a resolution of about 1500/120000/2 (half wavelength) or about 6 millimeters. |
Sounds like crossed wires....
Yes the boxes is what it's about but to find them it pays to localize the wreck first This is an almost uniquely great thread, I hope it stays that way. |
resolution
Angular resolution will be more like wavelength/effective receiver length. If its synthetic aperture then resolution will be much better than wavelength. Assuming the object reflects sound well enough the key thing will be to keep seabed clutter out of the resolution cell.
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Low Flier, I'm certainly willing to accept your expertise. The half wavelength would be the smallest detectable object. Resolving it to tell what it is would, of course, require a much larger object. I simply mumbled that the box is indeed much larger than the minimum sized object that will cause a reflection.
Is your experience operational or engineering design? If it's the latter I'd love to talk dirty (er engineering) with you. Do you have experience with chirp techniques? Do they help improve resolution? They certainly do for radar. And thanks for your information. I do like to learn. Thanks {^_^} |
Update: "Seabed Worker" & "Anne Candies" - 2 May 2010 positions
"Seabed Worker" at 02/14:44z was at 0°26'38"N 32°0'10"W, track 016°T/11.7KT, and heading for the search area.
"Anne Candies" at 02/1255z was 2°14'29S 39°20'56'W, track 304°T/11.1KT, and heading towards the Gulf of Mexico. Thanks to broadreach for the data. mm43 |
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