EgyptAir 804 disappears from radar Paris-Cairo
ELT?
In the US, ELT being reported located.
This is what is currently on CNN for example:
Airbus has detected signals from the Mediterranean Sea where EgyptAir Flight 804 crashed last week, Egypt's state-run Al Ahram news agency reported Thursday
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According to the marinetraffic web site the PMS Burullus spent a day moving at a snail's speed in a classic zig zag course coverign an area about 1Km by 1Km. Its position has not been updated for nearly 24 hours - at least on the "free" version of the tracker I have used.
The lack of an update is most likely due to the Burullus being in exactly the same area of poor radio coverage, with the added problem of its antenna for the tracking system it uses, AIS, being just a few metres above sea level. In fact there was a loss of coverage for a hour or so yesterday. Some vessels use a satcom version of AIS, but you have to have a rather expensive subscription to see that data. Anyone have access to the Satcom version? I do not know if the PMS Burullus is using satcom to broadcast its position though.
It could be that the "authorities" do not want the vessel's movements to be tracked of course, and the vessel has simply turned its AIS transmitter off.
There is no suggestion that the vessel is stationary - the last update is time stamped nearly 24 hours ago, so it is simply the data is not available.
It is also notable that there seems to be a big empty space around the Burullus clear of other shipping, though that may just be coincidence, or a consequence of the particular location.
What was interesting is two days ago the Burullus moved on a relatively long "base line" (my interpretation) NE to SW many Km long at quite some speed, before retracing its steps to roughly halfway along that line, then moving very slowly 2Km SW, perpendicular to that line and then starting this 1Km by 200 odd metres zig zag back and forth (see posts 784 & 785).
Could the base line be the "pinger" being heard and triangulated, approximately, and then the fine zig zag be a sonar scan? Post 808 gives some very helpful information about sonar, but makes the point the Burullus was moving rather slowly for a sonar fish. My logic would say the pattern was more closely spaced than you would need to home in on a pinger, which I understand has a range of several Km not the hundred or so metres the pattern suggests. Would you not "just" make one pass in an arbitrary direction, looking for the peak sound level, then pass through that peak point at right angles looking for a peak again, and thus, with a bit of trigonometry, home in on the source?
But the fact that a vessel has swept an area just 1Km by 1Km (2 square Km or so if it has kept going at the same rate for the past 24 hours while its position has not been updated) may suggest they are hunting something down. The press "noise" would seem to support this.
We will know in due course.
The lack of an update is most likely due to the Burullus being in exactly the same area of poor radio coverage, with the added problem of its antenna for the tracking system it uses, AIS, being just a few metres above sea level. In fact there was a loss of coverage for a hour or so yesterday. Some vessels use a satcom version of AIS, but you have to have a rather expensive subscription to see that data. Anyone have access to the Satcom version? I do not know if the PMS Burullus is using satcom to broadcast its position though.
It could be that the "authorities" do not want the vessel's movements to be tracked of course, and the vessel has simply turned its AIS transmitter off.
There is no suggestion that the vessel is stationary - the last update is time stamped nearly 24 hours ago, so it is simply the data is not available.
It is also notable that there seems to be a big empty space around the Burullus clear of other shipping, though that may just be coincidence, or a consequence of the particular location.
What was interesting is two days ago the Burullus moved on a relatively long "base line" (my interpretation) NE to SW many Km long at quite some speed, before retracing its steps to roughly halfway along that line, then moving very slowly 2Km SW, perpendicular to that line and then starting this 1Km by 200 odd metres zig zag back and forth (see posts 784 & 785).
Could the base line be the "pinger" being heard and triangulated, approximately, and then the fine zig zag be a sonar scan? Post 808 gives some very helpful information about sonar, but makes the point the Burullus was moving rather slowly for a sonar fish. My logic would say the pattern was more closely spaced than you would need to home in on a pinger, which I understand has a range of several Km not the hundred or so metres the pattern suggests. Would you not "just" make one pass in an arbitrary direction, looking for the peak sound level, then pass through that peak point at right angles looking for a peak again, and thus, with a bit of trigonometry, home in on the source?
But the fact that a vessel has swept an area just 1Km by 1Km (2 square Km or so if it has kept going at the same rate for the past 24 hours while its position has not been updated) may suggest they are hunting something down. The press "noise" would seem to support this.
We will know in due course.
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CNN reporter seem to think the ELT was transmitting from the wreckage on the ocean floor.
It's amazing that with all the coverage of AF 447 and MH 370.., reporters still don't understand even the most _basic_ aspects of the technology about which they report.
anyway, this info apparently originated from Egypt and something about it is wrong - ELT signals are not being received from the ocean floor
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Navire Hydrographique Laplace (A793)
The BEA just issued a communiqué tonight :
Marine Nationale Hydro. "Laplace" (A793) is sailing to the crash site with two BEA officers, in order to join the search for the CVR/FDR. She also boarded three pinger locators.
They are actually planning to send another vessel equiped with deep sea recovery assets.
The Egyptians authorities are still in charge of the search, assisted by the BEA.
A793 Laplace :
Laplace (A 793)
BEA :
https://www.bea.aero/fr/les-enquetes...enu-le-190516/
Marine Nationale Hydro. "Laplace" (A793) is sailing to the crash site with two BEA officers, in order to join the search for the CVR/FDR. She also boarded three pinger locators.
They are actually planning to send another vessel equiped with deep sea recovery assets.
The Egyptians authorities are still in charge of the search, assisted by the BEA.
A793 Laplace :
Laplace (A 793)
BEA :
https://www.bea.aero/fr/les-enquetes...enu-le-190516/
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Alseamar DETECTOR 6000 System boarded on Laplace:
Underwater Detection Systems DETECTOR | ALSEAMAR
Black Boxes Relocation | ALSEAMAR
The other company contracted for next step might be DOS (Deep Ocean Search)
Deep Ocean Search - Home
The cost of operational search is actually shared by Egypt and France.
Underwater Detection Systems DETECTOR | ALSEAMAR
Black Boxes Relocation | ALSEAMAR
The other company contracted for next step might be DOS (Deep Ocean Search)
Deep Ocean Search - Home
The cost of operational search is actually shared by Egypt and France.
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AT1's interpretation is pretty good.
The absence of nearby vessels is almost certainly a consequence of a day shape signal which either declares that the vessel is manoeuvring with difficulty or is "not under command". All ships will see that signal either by day, in the form of a ball over a double cone (diamond shape) over a ball, or by red/white/red vertically arranged lights at night and will give her a wide berth. There are variations on that theme, such as "engaged in underwater operations", but the message is pretty much the same: please push off out of my way. Furthermore the ships watchkeepers on the bridge will be watching any traffic within a dozen or more miles on radar and will call them on CH16 marine VHF (similar to 121.5) and request that they stay well away.
If the vessel appears to be almost stationary on AIS then one interpretation might be that she has deployed her ROV.
The way that works is that the ship maintains station on the ROV at a predetermined number of metres laterally and longitudinally from the ROV in "follow sub" mode and the ROV therefore controls the ship. It's quite cumbersome as the ROV is the size and weight of a Ford Transit or Galaxy and the ship weighs several thousand tons. The ROV therefore has to manoeuvre very gingerly and avoid making suddenly turns or accelerations. If the ship has to make very large thruster inputs to try to maintain station you can get aeration of the water under the ship which can cause loss of acoustic contact with the ROV and a massive muddle ensues. Angry words are exchanged on the intercom between the bridge and the ROV control shack. That's another reason why the bridge will want all other vessels to stay well away, preferably at least a mile or two.
It may perhaps interest Prooners unfamiliar with how these things work for me to explain a little about underwater nav.
There are two principal methods. Long baseline and (ultra) short baseline.
USBL works in one of two different modes. The first involves the ship sending out an interrogation pulse from a transducer which extends below the hull telescopically rather like a military submarine's periscope, only in the opposite direction. The ROV has a transponder which waits a known number of milliseconds and transmits a reply pulse. The ship's USBL transducer is a small cruciform affair and by measuring the phase difference at the four transducers you derive the angle at which the pulse arrived. Thus you get a 3-D position with respect to the ship. The other USBL mode involves sending the interrogation pulse electrically down the umbilical and a "flowerpot" responder on the ROV replies with a pulse just like a transponder. Advantage is that the interrogation is almost instant and not prone to raypath anomolies or acoustic noise on the outbound signal.
Long baseline is completely different. It involves setting out an array of seabed transponders and co-ordinating them. The ROV then self-navigates by doing what amounts to a DME/DME fix, using at least three and preferably four or five transponders. It then telemets its self computed position up the umbilical. Much more practical for deep water work like this job than USBL which will be slow and wooly. I'd be adversely surprised if these guys haven't deployed an LBL array around the locus by now.
The absence of nearby vessels is almost certainly a consequence of a day shape signal which either declares that the vessel is manoeuvring with difficulty or is "not under command". All ships will see that signal either by day, in the form of a ball over a double cone (diamond shape) over a ball, or by red/white/red vertically arranged lights at night and will give her a wide berth. There are variations on that theme, such as "engaged in underwater operations", but the message is pretty much the same: please push off out of my way. Furthermore the ships watchkeepers on the bridge will be watching any traffic within a dozen or more miles on radar and will call them on CH16 marine VHF (similar to 121.5) and request that they stay well away.
If the vessel appears to be almost stationary on AIS then one interpretation might be that she has deployed her ROV.
The way that works is that the ship maintains station on the ROV at a predetermined number of metres laterally and longitudinally from the ROV in "follow sub" mode and the ROV therefore controls the ship. It's quite cumbersome as the ROV is the size and weight of a Ford Transit or Galaxy and the ship weighs several thousand tons. The ROV therefore has to manoeuvre very gingerly and avoid making suddenly turns or accelerations. If the ship has to make very large thruster inputs to try to maintain station you can get aeration of the water under the ship which can cause loss of acoustic contact with the ROV and a massive muddle ensues. Angry words are exchanged on the intercom between the bridge and the ROV control shack. That's another reason why the bridge will want all other vessels to stay well away, preferably at least a mile or two.
It may perhaps interest Prooners unfamiliar with how these things work for me to explain a little about underwater nav.
There are two principal methods. Long baseline and (ultra) short baseline.
USBL works in one of two different modes. The first involves the ship sending out an interrogation pulse from a transducer which extends below the hull telescopically rather like a military submarine's periscope, only in the opposite direction. The ROV has a transponder which waits a known number of milliseconds and transmits a reply pulse. The ship's USBL transducer is a small cruciform affair and by measuring the phase difference at the four transducers you derive the angle at which the pulse arrived. Thus you get a 3-D position with respect to the ship. The other USBL mode involves sending the interrogation pulse electrically down the umbilical and a "flowerpot" responder on the ROV replies with a pulse just like a transponder. Advantage is that the interrogation is almost instant and not prone to raypath anomolies or acoustic noise on the outbound signal.
Long baseline is completely different. It involves setting out an array of seabed transponders and co-ordinating them. The ROV then self-navigates by doing what amounts to a DME/DME fix, using at least three and preferably four or five transponders. It then telemets its self computed position up the umbilical. Much more practical for deep water work like this job than USBL which will be slow and wooly. I'd be adversely surprised if these guys haven't deployed an LBL array around the locus by now.
Long baseline is completely different. It involves setting out an array of seabed transponders and co-ordinating them. The ROV then self-navigates by doing what amounts to a DME/DME fix, using at least three and preferably four or five transponders. It then telemets its self computed position up the umbilical. Much more practical for deep water work like this job than USBL which will be slow and wooly. I'd be adversely surprised if these guys haven't deployed an LBL array around the locus by now.
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Bit of verbal diarrhea... but a bit more aint going to make a lot of difference...
During the mid nineties I was involved in bringing 5 ex-RCAF (CC-117) Falcon 20's onto the UK civil register. Three of these aircraft had previously been used for transport work and the other two for Electronic Warfare training. The transport variants were fitted with a detachable panel at the bottom of the fin. This panel carried a 121.5 / 243 /406(?) self powered Crash Locator Beacon; essential equipment given the RCAF operating environment in the wastes of the Arctic.
Deployment of the panel was initiated either by the crew and a switch in the cockpit, or in the event of a crash, by one of 5(?) Vacuum Crash switches, three along the lower fuselage and one in each wing tip. Operation of any one of these switches would deploy the panel and set the CLB to transmit. The boxes involved had been removed when the aircraft were retired but the activation mechanism was still in place...
As the Avionics Lead on the mod program, initially this and other role equipment wiring left me head scratching because the wiring diagrams for the said role equipment were 'not available'... but since we were going to remove all unidentifiable role equipment wiring it didn't matter too much. But the detective work was fun!
To the point however... I have often wondered why aircraft manufacturers don't design in something similar into modern airframes... an automatically deployable floating panel carrying a 406MHz ELT... ELT's are OK but once the aircraft submerges thats it... finito.
I always thought my former employers positioning of the required ELT was a bit stupid... the antenna was located forward of the tailcone at the base of the fin, but the ELT Transmitter was in the tail cone itself, the two connected by a length of RG-400 coax... in the case of a land crash the tailcone tends to separate from the rest of the airframe, thereby removing the Antenna from the transmitter... oops?
During the mid nineties I was involved in bringing 5 ex-RCAF (CC-117) Falcon 20's onto the UK civil register. Three of these aircraft had previously been used for transport work and the other two for Electronic Warfare training. The transport variants were fitted with a detachable panel at the bottom of the fin. This panel carried a 121.5 / 243 /406(?) self powered Crash Locator Beacon; essential equipment given the RCAF operating environment in the wastes of the Arctic.
Deployment of the panel was initiated either by the crew and a switch in the cockpit, or in the event of a crash, by one of 5(?) Vacuum Crash switches, three along the lower fuselage and one in each wing tip. Operation of any one of these switches would deploy the panel and set the CLB to transmit. The boxes involved had been removed when the aircraft were retired but the activation mechanism was still in place...
As the Avionics Lead on the mod program, initially this and other role equipment wiring left me head scratching because the wiring diagrams for the said role equipment were 'not available'... but since we were going to remove all unidentifiable role equipment wiring it didn't matter too much. But the detective work was fun!
To the point however... I have often wondered why aircraft manufacturers don't design in something similar into modern airframes... an automatically deployable floating panel carrying a 406MHz ELT... ELT's are OK but once the aircraft submerges thats it... finito.
I always thought my former employers positioning of the required ELT was a bit stupid... the antenna was located forward of the tailcone at the base of the fin, but the ELT Transmitter was in the tail cone itself, the two connected by a length of RG-400 coax... in the case of a land crash the tailcone tends to separate from the rest of the airframe, thereby removing the Antenna from the transmitter... oops?
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Wolf,
Good question.
What you do in soft sediment is deploy the beacon atop a long rope which is is attached to a bloody great big clumpweight and has a floatation collar on itself.
This keeps the beacon above the seabed, hopefully at a similar height above seabed level to that of its brethren in the array so that its depth does not vary much with the others in the array if the seabed current changes direction as a consequence of tidal or other current movements. If the current changes direction, the entire array sways and the resultant fix just goes with the flow, so to speak. They are generally five or so metres above the local seabed, but that depends on the planning of the array vis-a-vis intervisibility acoustically for the calibration of the array. They have to be able to 'talk' to eachother acoustically for them to to be able to self-calibrate trilaterally so that all of the baselines among the array are measurable.
The flot collar is there anyway to recover the beacon at the end of the job. There is an acoustically addressable release device at the base of the beacon. When you want to send the beacon up to the surface you send the command acoustically and the acoustic release releases the physical connection to the clump weight and the buoyancy of the transponder's flot collar sends it upwards. The flot collar is chamfered at its upper end so the the transponder floats nose down in the water at the surface and enables it to give ranging information to the recovering vessel. They cost several tens of thousands of Dollars/Pounds/Euros apiece and are not regarded as being expendable like the sonobouys that the military use with great abandon.
I've had a few rug-munching encounters with bean-counting bosses, without tea and biccies, when having to explain my failures to recover such beacons.
In the North Sea, they usually end up on the beaches of the Fresian islands. Rich rewards to be had by the cattlemen there!
Good question.
What you do in soft sediment is deploy the beacon atop a long rope which is is attached to a bloody great big clumpweight and has a floatation collar on itself.
This keeps the beacon above the seabed, hopefully at a similar height above seabed level to that of its brethren in the array so that its depth does not vary much with the others in the array if the seabed current changes direction as a consequence of tidal or other current movements. If the current changes direction, the entire array sways and the resultant fix just goes with the flow, so to speak. They are generally five or so metres above the local seabed, but that depends on the planning of the array vis-a-vis intervisibility acoustically for the calibration of the array. They have to be able to 'talk' to eachother acoustically for them to to be able to self-calibrate trilaterally so that all of the baselines among the array are measurable.
The flot collar is there anyway to recover the beacon at the end of the job. There is an acoustically addressable release device at the base of the beacon. When you want to send the beacon up to the surface you send the command acoustically and the acoustic release releases the physical connection to the clump weight and the buoyancy of the transponder's flot collar sends it upwards. The flot collar is chamfered at its upper end so the the transponder floats nose down in the water at the surface and enables it to give ranging information to the recovering vessel. They cost several tens of thousands of Dollars/Pounds/Euros apiece and are not regarded as being expendable like the sonobouys that the military use with great abandon.
I've had a few rug-munching encounters with bean-counting bosses, without tea and biccies, when having to explain my failures to recover such beacons.
In the North Sea, they usually end up on the beaches of the Fresian islands. Rich rewards to be had by the cattlemen there!
Last edited by Cazalet33; 26th May 2016 at 23:54.
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Hey Phalconphixer,
Your post regarding the detachable crash transmitter located in the base of the vertical fin, triggered electronically in the event of a crash, closely describes the system as fitted to the Lockheed P3C Orion, used widely by various navies throughout the world - great airplane!
Your post regarding the detachable crash transmitter located in the base of the vertical fin, triggered electronically in the event of a crash, closely describes the system as fitted to the Lockheed P3C Orion, used widely by various navies throughout the world - great airplane!
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Cazelet33
I didn't understand your reference to prop aeration muddling acoustic links between the ship and the ROV. The deep water installation vessels that I work with all have their ROVs powered and controlled via reeled umbilicals, I.e. the ROVs are physically connected to the ships and do not rely on acoustic signals between the two.
Even the AUVs (autonomous underwater vehicles) that I've worked with are pre-programmed, dumped in the water to do their sonar runs, then come back up at end of mission for recovery and data download - no acoustic comms during the scanning run.
I didn't understand your reference to prop aeration muddling acoustic links between the ship and the ROV. The deep water installation vessels that I work with all have their ROVs powered and controlled via reeled umbilicals, I.e. the ROVs are physically connected to the ships and do not rely on acoustic signals between the two.
Even the AUVs (autonomous underwater vehicles) that I've worked with are pre-programmed, dumped in the water to do their sonar runs, then come back up at end of mission for recovery and data download - no acoustic comms during the scanning run.
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@Cazalet33
At the time of my posts on Burullus early in the thread the message linked to the ship was something like "sub sea operations".
Early in the thread I also posted comments from a UK oceanographer who sketched specific sea floor shape and sediment issues which would make detection and search more complex than you might expect. Wonder if you can agree with his comments.
Just checked it - the label was “SUBSEA LOCATION”,
Was Dr Simon Boxall, an oceanographer from the Univ of Southampton ... see my post May 20th of around 10.20hrs
"engaged in underwater operations",
Early in the thread I also posted comments from a UK oceanographer who sketched specific sea floor shape and sediment issues which would make detection and search more complex than you might expect. Wonder if you can agree with his comments.
Just checked it - the label was “SUBSEA LOCATION”,
Was Dr Simon Boxall, an oceanographer from the Univ of Southampton ... see my post May 20th of around 10.20hrs
Last edited by A0283; 27th May 2016 at 09:45. Reason: “SUBSEA LOCATION” and Dr Boxall
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@Cazalet33
Burullus has been in the same spot at least since May 22nd, at the time it was in port, made a short move to Abu Qir (its home port), and then directly sailed to the spot at 9-10 knots. Quite early on there was a bit of an open 'circle' around it, but as i posted, quite a few ships still crossing close at between 10-16 knots. See Note *
As far as i can see B is supplied on station by a big French vessel. I have not detected a screen of navies vessels yet (like there was with AirAsia). But perhaps they have xpdrs off.
*Note: I checked the information that i have from the start of the surface search. Definition of "close" is when you look at it from the viewpoint of multiple ships making surface sweeps. When you look at it from the viewpoint of a single ship sounding around one specific location, then the 'circle' diameter was more than the 2 miles or so that Cazalet indicated.
I'd be adversely surprised if these guys haven't deployed an LBL array around the locus by now.
As far as i can see B is supplied on station by a big French vessel. I have not detected a screen of navies vessels yet (like there was with AirAsia). But perhaps they have xpdrs off.
*Note: I checked the information that i have from the start of the surface search. Definition of "close" is when you look at it from the viewpoint of multiple ships making surface sweeps. When you look at it from the viewpoint of a single ship sounding around one specific location, then the 'circle' diameter was more than the 2 miles or so that Cazalet indicated.
Last edited by A0283; 27th May 2016 at 11:10. Reason: typo and note*
FWIW it might be worth bearing in mind that if anybody quotes the likes of Reuters or AFP you can often cut out at least one middle man (in this case CBS) and do what most of the media do - go to the agency's own website. If you do that you often find subtle differences in wording and emphasis between what the relatively "raw" stuff the agencies often put out and what makes it into the more popular media output.
No new signal from EgyptAir jet since day of crash as search intensifies | Reuters
No new signal from EgyptAir jet since day of crash as search intensifies | Reuters
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I didn't understand your reference to prop aeration muddling acoustic links between the ship and the ROV.
An ROV can easily come to a dead stop, from a cruise speed of two or three knots in a matter of two or three metres. A 4,000 ton ship cannot. The DP system will command more and more thrust in an attempt to maintain station and that's when you get loss of acoustic link between the USBL and the sub. The ship can easily move out many tens of metres and start dragging the umbilical so much that the ROV itself can be jerked around. The tail starts wagging the dog and dogs don't like that. They bark and get quite snappy. The ROV crew blame the bridge crew and the bridge crew blames the ROV crew.
It can happen quite easily when, for example, the ROV suddenly encounters a snagged fishing net and has to make an emergency stop. It can also happen when the ROV suddenly finds an orange box on a job like this one!
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@.Scott
If true then:
a. surprising what Burullus is doing then ... certainly at this stage of the search ...
b. you would expect the search to 'spiral outward' then, say filling a circle of 25 nm diameter, perhaps Cazalet33 can say something about this,
c. the French research vessel referred to above and its patterns will tell us more later,
It is also not clear what kind of signals they are referring to ... was it a signal from the plane, from the radar, or a ULB (if not a spurious one) ...
Just thinking. Authorities could also decide that in modern times it is better to clearly state the main points of what they know, what they dont know, and what assumptions are the basis for the activities that are ongoing. This could also indicate and educate people on the complexity of these searches and investigations. All this leaking and anonymous stuff ... makes a bad impression on the general public.
An illustration of this could be the find of another probable MH370 fragment today. It was found by a guy who by chance had just seen a few photos of earlier finds. During the MH370 search an Australian SAR official was quoted who said that his experience was that people could not recognize such fragments as being from an aircraft - especially when they had been in the water for (even) a (short) while. After the fact other officials say that this find is a prove of the accuracy of the drift predictions. That also surprises me, if these predictions were so good as claimed, why did they not publish them as soon as possible with a request to the public to report possible finds. And the give the public (and seafarers) a number of examples of what they might expect to find and see.
The Reuters news agency quoted anonymous officials "close to the investigation" as saying no new signals from the plane had been detected "since day one."
a. surprising what Burullus is doing then ... certainly at this stage of the search ...
b. you would expect the search to 'spiral outward' then, say filling a circle of 25 nm diameter, perhaps Cazalet33 can say something about this,
c. the French research vessel referred to above and its patterns will tell us more later,
It is also not clear what kind of signals they are referring to ... was it a signal from the plane, from the radar, or a ULB (if not a spurious one) ...
Just thinking. Authorities could also decide that in modern times it is better to clearly state the main points of what they know, what they dont know, and what assumptions are the basis for the activities that are ongoing. This could also indicate and educate people on the complexity of these searches and investigations. All this leaking and anonymous stuff ... makes a bad impression on the general public.
An illustration of this could be the find of another probable MH370 fragment today. It was found by a guy who by chance had just seen a few photos of earlier finds. During the MH370 search an Australian SAR official was quoted who said that his experience was that people could not recognize such fragments as being from an aircraft - especially when they had been in the water for (even) a (short) while. After the fact other officials say that this find is a prove of the accuracy of the drift predictions. That also surprises me, if these predictions were so good as claimed, why did they not publish them as soon as possible with a request to the public to report possible finds. And the give the public (and seafarers) a number of examples of what they might expect to find and see.