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EgyptAir 804 disappears from radar Paris-Cairo

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EgyptAir 804 disappears from radar Paris-Cairo

Old 26th May 2016, 10:43
  #801 (permalink)  
 
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Originally Posted by MrPeabody View Post
I can't see anything from your link that answers the question.
The correct link is as follows:
http://www.pprune.org/9387723-post759.html
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Old 26th May 2016, 10:50
  #802 (permalink)  
 
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Are there airline crashes at sea where there were no large human remains? Or does the lack of large body parts not indicate anything definitive?
Yes, to both questions.

I was aboard the first specialist responder work vessel which attended the wreckage of the Itavia DC9 in 1980. We had been working in the straights of Messina and as we had two manned submersibles and a crew of hydrographers we were immediately despatched by the Italian Admiralty to investigate the scene. Our gear was limited to 600m and the depth at the locus was much greater than that, so our onscene work was limited to surface recovery only.

At the time, there was no doubt in the minds of the two senior officers who we had on board from the charterer that the aircraft had been shot down accidentally by the usual suspect, mistaking it for a known Libyan MiG intruder. Subsequent investigation of the seabed wreckage cast some reasonable doubt on that and it's a bit of an open verdict as to how the aircraft was brought down.

One's first impression on arrival at the scene was the incredible number of bits of paper were among the more solid flotsam. Thousands of pieces of paper. Of the human remains, there were a hundred or so that we recovered and the local fishing boats who arrived a few hours before we did recovered many more, but mostly very small. The largest were recognisable parts of limbs, but most were really quite small.

From other work on the seabed in other cases, I've found quite intact remains of almost whole bodies within and very close to airframe parts.

When an aircraft comes apart at very high speed and high altitude, eg the shootdown of an Iranian Airbus by the usual suspect, ejected occupants tend to be stripped of clothing by the airstream during the deceleration to terminal velocity.

From personal experience in several such field investigations I expect that the condition of size of the remains on the seabed will be quite different to those found on the initial surface search.

I doubt that the lack of large body parts indicates anything definitive. I also doubt that a bomb is indictated by the skimpy evidence we have so far, but we need more data before we can analyse the three principal postulates.
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Old 26th May 2016, 11:04
  #803 (permalink)  
 
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Thank you for this post describing a horrifying and unique experience; our thoughts go out to first responders in such situations. I thought the Itavia DC9 was brought down by a bomb in the rear lavatory?
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Old 26th May 2016, 11:30
  #804 (permalink)  
 
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Cooperplace, you may be right.

At the time, the Rear Admiral and Captain of the Italian Navy who were our client reps were in no doubt that the aircraft had been shot down. They knew that the suspect navy had been trying to engage the Libyan MiG which we later learned had crashed unseen on Italian territory.

The official theory, for public consumption was, as usual, a conspiracy theory of a bomb. That's quite normal in these cases. It exonerates almost everybody in positions of public responsibility and it stops the public from thinking.

I don't know the true story behind the downing of that Itavia jet, but I entirely understand why the USN made the radar record of the salient time 'disappear'. Out of sight, out of mind. You don't need to know. It never happened. Move along. Nothing to see here. Do not discuss, especially publicly. Wait until you are officially told what to think. Most especially, wait until you are told what you can say about what happened.
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Old 26th May 2016, 12:31
  #805 (permalink)  
 
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The AIS plot shown above is very strongly indicative of the search vessel looking at a credible search datum.

They are clearly using Dynamic Positioning (DP) to manoeuvre the vessel on the search pattern and they are clearly using a deep tow sensor. They are not 'towing' the side-scan towfish or deep-tow pinger locator like a trawler tows a net. It's not astern of them, most of the time.

Sidescan sonar seems quite likely, but you would use a very similar pattern to 'box in' a suspected target with a deep tow hydrophone to locate a pinger signal.

A sensible searcher would concentrate his efforts, at this stage in time, to getting best data from the battery-limited pinger.

The way you do that is not by triangulation but by measuring the signal strength as you pass by the source. You plot that out with signal strength in the Y axis and the distance along track on the X axis. You get a parabolic curve, albeit a lumpy bumpy one which can sometimes be a bitch to interpolate. Maximum strength suggests that that is where your line reached closest point of approach (CPA). That gives you an LoP to/from the target, perpendicularly. By repeating that line perpendicularly you get a cross-cut of that LoP. By covering the other two sides you eliminate the baseline side confusion and further refine the position. Voila. You have a good approximation to the actual co-ords of your Dukane (or whatever) pinger.

I do, however, concur with those who have pointed out that the line-spacing is more consonant with a medium frequency sonar run, eg 125kHz, than what you would choose for a broad-brush pinger locator run in anything other than very shallow water. The reason why I think it's more likely to be a pinger locator on the end of the wire than a side-scan is that the speed over the ground is something like half a knot. That's Okay for a hydrophone but would not be enough water speed to keep a side-scan towfish on any kind of of sensible heading and would make sonar trace interpretation impossible.

I therefore conclude that they've got a pinger within earshot and are boxing it in before putting an ROV onto it.

The water depth at that locus, btw, is approx 3106m. The seabed sediment consistency in that area is like baby-poop. ROVs will have to be negatively ballasted, ie positively buoyant at bottom depths, so that they don't stir up the fluffy sediment and blind themselves during recovery of high value items such as the 'box(es)'.
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Old 26th May 2016, 13:35
  #806 (permalink)  
 
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ELT Signal Detected

Per the WSJ an ELT signal was picked up by satellite and that is why they have localized the search area to where they are now.
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Old 26th May 2016, 14:04
  #807 (permalink)  
 
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Capry -

The article was clear that it was an ELT, which floats, sends a radio frequency beacon, and is detectable by satellite, unlike a ULB.

They are using the ELT to focus the search for the ULB.

There was no indication of when the ELT beacon was detected, but the PMS Burullis made a bee-line to their search location immediately after the crash.

Last edited by SysDude; 26th May 2016 at 14:07. Reason: Added Burullis sentence.
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Old 26th May 2016, 14:19
  #808 (permalink)  
 
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LKP-BURULLUS location

To note that distance from LKP (33.6757/28.79242) to last night's BURULLUS search location (33.5322/029.1371) is just under 20NM.

And perhaps more important (in view of the Greek Defense statement on their final radar images and the Egyptian denial of that) is that the BURULLUS location is on about a 100 course, East SE from LKP (noting that MS804 while at FL370 at LKP was heading 136).

If MS804 is found around BURULLUS' location, this implies IMO that the claimed left turn after LKP indeed would have to have taken place, while that in turn gives further credence to the also claimed subsequent 360 right.
Attached Images
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Capture3.PNG (477.8 KB, 125 views)

Last edited by D Bru; 26th May 2016 at 19:51. Reason: enhanced clarity ;)
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Old 26th May 2016, 14:29
  #809 (permalink)  
 
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ELT's have changed since my flying days.
There is now a digital 406MHz signal that includes information registered to the aircraft or ELT owner.

Last edited by .Scott; 26th May 2016 at 14:42.
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Old 26th May 2016, 14:29
  #810 (permalink)  
 
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Contact Approach...

I agree. If only it were that simple... The past few posts re ELTs and ULBs are a good example of why your perfectly sound idea doesn't work on these forums.

Somebody posts a quote from a newspaper (WSJ in this case), probably because they assume what is written in that article is "factual". A discussion then ensues based on completely wrong information about ELTs, first from the article itself, then made worse by answering another poster's question erroneously by citing that same article as a source of accurate info about ELTs and ULBs: where they are located on an aircraft, do they float, do ELTs transmit underwater, if so can the signal be received by a satellite, discreet ELT IDs (BTW... yes, one can tell what aircraft it's from) and on and on and on.

Which is why, with the utmost respect to the Mods whose job is so very difficult and frustrating, this should not be considered a "Professional Pilots Rumour Network" when reading this (Rumours and News) forum.

Sigh...

Last edited by grizzled; 26th May 2016 at 16:52.
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Old 26th May 2016, 15:35
  #811 (permalink)  
 
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@grizzled: for the edification of the casual reader/lurker/ we could point them to the Tech Log forum,
where there's a thread with a discussion of ELT's with at least one good post. Summary from that (PPruNer avspook)

  1. ELTs transmit on 121.5/243/406 MHz. (406 MHz contacts a satellite monitoring system. It uplinks messages to a Satellite that includes aircraft identifying information. Thanks to David Reid for the specifics in his post a few down from this one)
  2. Some ELT's are tied into the Navigation system to uplink last position.
  3. Many rely on the Satellite system to direction find the signal
  4. An ELT (due to the frequencies involved) is not able to contact the satellite from underwater. It is also not a waterproofed box.
  5. The aircraft hull mounted ELTs are typically set up to transmit when a G-load of a particular magnitude is detected (crash)
Sample product sheet (Honeywell; Thales and some other vendors also make products in this class).

FAA Spec TSO-C126A (Update: pages 9-16 of this link are TSO-C126b.
DO-204A, DO-160F are specs cited on some product sheets (DO-204b is pending based on some ICAO docs posted on line).

Last edited by Lonewolf_50; 26th May 2016 at 19:09.
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Old 26th May 2016, 15:53
  #812 (permalink)  
 
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guara
Agree with you regarding the size of (or lack of) the debris field. Any one familiar with the foot print left by an airplane making contact with the ground, or water, would be thinking it strange that more objects would have been seen, and or, collected. Too many whys creep into the possibility the crew flew the airplane into the ocean. Large things which separate from the airplane after contact will float, and debris will bleed quickly from inside the interior.
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Old 26th May 2016, 15:58
  #813 (permalink)  
 
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Originally Posted by Lonewolf_50 View Post
@grizzled: for the edification of the casual reader/lurker/ we could point them to the Tech Log forum,
where there's a thread with a discussion of ELT's with at least one good post. Summary from that (PPruNer avspook)

  1. ELTs transmit on 121.5/243/406 MHz. (406 MHz contacts a satellite monitoring system. It uplinks the serial No of the Box which the Satellite authority uses to look up the Regulatory authority, who keep a list of serial no's versus tail nos)
  2. Some ELT's are tied into the Navigation system to uplink last position.
  3. Many rely on the Satellite system to direction find the signal
  4. An ELT (due to the frequencies involved) is not able to contact the satellite from underwater. It is also not a waterproofed box.
  5. The aircraft hull mounted ELTs are typically set up to transmit when a G-load of a particular magnitude is detected (crash)
Sample product sheet (Honeywell; Thales and some other vendors also make products in this class).
FAA Spec TSO-C126A (not sure if an international spec is also in print) DO-204A, DO-160F are cited on some product sheets.
For the love of god! don't show them the way to tech log it's the last bit bit of sanctuary I have on here.....
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Old 26th May 2016, 16:06
  #814 (permalink)  
 
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Originally Posted by Lonewolf_50 View Post
ELTs transmit on 121.5/243/406 MHz. (406 MHz contacts a satellite monitoring system. It uplinks the serial No of the Box which the Satellite authority uses to look up the Regulatory authority, who keep a list of serial no's versus tail nos)
The ELT sends the (programmable) ICAO 24-bit address belonging to the aircraft (same as used for Mode S, TCAS, etc). That's sufficient to identify the aircraft without the need to maintain a separate database of unit serial numbers.
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Old 26th May 2016, 16:10
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In post 808 it is implied that the country that shot down Itavia DC9 in 1980 is the same that shot down the Iranian Airbus which everybody knows who fired the missile. This is misleading because if somebody shot down the DC9 it was not the same suspect. It is a fact that the USN and the Italians and the French hid and destroyed evidence but the usual suspect did not shot the DC9.

Last edited by A320FOX; 26th May 2016 at 16:21. Reason: Adding info.
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Old 26th May 2016, 17:29
  #816 (permalink)  
 
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Originally Posted by A320FOX View Post
It is a fact that the USN and the Italians and the French hid and destroyed evidence but the usual suspect did not shot the DC9.
It's generally accepted that nobody shot it down.
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Old 26th May 2016, 18:39
  #817 (permalink)  
 
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@FE Hoppy: apologies.
@David: Thank for the point on the ICAO 24-bit code.
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Old 26th May 2016, 19:23
  #818 (permalink)  
 
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Originally Posted by wes_wall View Post
guara
Agree with you regarding the size of (or lack of) the debris field. Any one familiar with the foot print left by an airplane making contact with the ground, or water, would be thinking it strange that more objects would have been seen, and or, collected. Too many whys creep into the possibility the crew flew the airplane into the ocean. Large things which separate from the airplane after contact will float, and debris will bleed quickly from inside the interior.
I'm so sorry if was understood that I claim THE CREW sent the airplane against the Med Sea INTENTIONALLY. Now my post is deleted by mods, buy what I wanted to explain is that the crew INTENDED TO MAKE THINGS RIGHT to control but weren't able to success.
What I suppose (and many in my circle) is that once things came to be really BAD, the PiC or the FO took command of the a/c with the intention of a controlled/smooth splash-down but coudn't (possibly with serious electrical damage/smoke/etc and in full darkness this may be very difficult). The lack of rational debris for an A320 (in quantity) makes me think of a relatively quiet sinking. I don't forget the pieces of bodies and some objects really torn by strong forces, but those maybe cause of a localized break in fuselage, leaving the remaining of the hull in one piece (and possibly passengers caught by belts and in their seats).
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Old 26th May 2016, 19:51
  #819 (permalink)  
 
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There was a CNN report this evening (26th May) quoting the Egyptians as saying that some sort of beacon has been detected, enabling the search area to be shrunk to a few km2.
According to the reporter, the Egyptians are attributing this information to Airbus, yet the beacon in question only has a transmission life of 2 days, suggesting that the information is a few days old. One set of specs on the Technical forum seems to indicate that these beacons transmit for much longer than two days. I was perplexed by the CNN report -- thanks to the Technical Forum I am at least perplexed at a slightly more informed level.
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Old 26th May 2016, 20:00
  #820 (permalink)  
 
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In the US, ELT being reported located.
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