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EgyptAir 804 disappears from radar Paris-Cairo

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EgyptAir 804 disappears from radar Paris-Cairo

Old 31st May 2016, 21:35
  #901 (permalink)  
 
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For a typical ELT, take a look at this Honeywell brochure and look at the features for a fixed installation (two of the models). Other manufacturers offer similar capability, as a variety of standards/specs are out there for compliant equipment. (No, I don't work for Honeywell. Thales and Artex make them as well). You could also read back a few pages, within five of this one, and find a variety of posts regarding ELT's. This is one such post . Within a page either side of it is some more info. You could also take a gander at the ELT threads in Tech Log.

Last edited by Lonewolf_50; 1st Jun 2016 at 12:29.
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Old 1st Jun 2016, 00:04
  #902 (permalink)  
 
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If it was from fixed ELT activated on impact, it would transmit until it is destroyed or submerged

If it was a portable ELT activated by cabin crew, it would transmit until it is destroyed or submerged

One thought I have, without any new technology, airlines should instruct cabin crew to turn portable ELT on at the first sign of trouble,ie., don't wait for the crash they can later call airline and give all clear, if everything is a OK. This works only if CC member can reach it, big if.

Bottomline there is no way to estimate the duration of transmission. Like I posted upthread, even though aircraft may have 3xELT,8xRaft Beacons and 2xULB all are useless.

Last edited by notapilot15; 1st Jun 2016 at 00:25.
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Old 1st Jun 2016, 00:16
  #903 (permalink)  
 
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the portable ELT's will also activate automatically when immersed.

I think a likely scenario is that on impact, the device became immersed enough to cause automatic activation.., but it never floated free of the wreckage. Then, the piece of wreckage to which it was attached popped up to the surface where it remained for a few minutes, broadcasting the 406mhz signal to satellites. Then,as trapped air escaped from that piece of wreckage, it sank, bringing the ELT with it, and the signal was no longer received by the satellites.

more or less the same thing could have happened with a fixed ELT that activated upon impact.

ELT's have unique identifiers that are broadcast with the distress signal, and it's possible that if the transmission was of long enough duration, they know whether it was a fixed or portable ELT that sent the signal.

The portable ELT's are actually designed to operate while floating in the water. So, if you ever find yourself in a life raft with an ELT.., what you are supposed to do is activate the ELT - if it hasn't activated automatically - and tie it with a lanyard to the life raft.., and let it float in the water alongside the liferaft. You are not supposed to keep it with you in the life raft.

Last edited by x_navman; 1st Jun 2016 at 00:51.
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Old 1st Jun 2016, 02:11
  #904 (permalink)  
 
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Sorry, but salt water to air transmission, especially SAT receiver, would be virtually impossible, especially at the frequencies and power noted. VLF radio waves (3–30 kHz) can penetrate seawater to a depth of approximately 20 meters.

Attenuation of radio signals in sea water is significant. Communication further than just below the surface are not possible unless very low frequencies (10 to 30 kHz) are used. Even if you could use the frequencies in this band, there are other difficulties:

Air to water refraction loss in this band is in the order of 60 to 70 dB.

Antenna dimensions would need to be very large, particularly for the above the surface antenna. (Even at 30 kHz, a wavelength is 10 km). Large transmitter powers are usually required to compensate for the high antenna losses inherent in the shortened low frequency antenna. (remember the Omega system?)

Atmospheric noise peaks to about 160 dB above thermal noise (KTB) at 10 kHz, limiting the minimum discernible receive level.
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Old 1st Jun 2016, 02:58
  #905 (permalink)  
 
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From Cospas-Sarsat spec C/S-T.001 "Specification for Cospas-Sarsat 406 MHz Distress Beacons." Rev 16, Dec. 2015 (for beacons above the water)

4.5.5.3 - The internal navigation device shall provide valid data within 10 minutes after its activation. Internal navigation device cold start shall be forced at every beacon activation. Cold start refers to the absence of time dependent or position dependent data in memory, which might affect the acquisition of the GNSS position.

4.5.5.4 - The internal navigation device within the beacon shall be activated immediately after the beacon is turned on. (details of this section are based on the spec version in effect at time of beacon manufacture)

4.5.5.5 - For a beacon designed to operate with an external navigation device, if appropriate navigation data input is present, the beacon shall produce a digital message with the properly encoded position data and BCH code(s) within 1 minute after its activation.

4.5.6 After activation, the beacon shall not transmit a 406 MHz distress message until at least one repetition period (as defined in section 2.2.1) has elapsed. [section 2.2.1 defines the 50 second interval].

From experience, many of the first alerts are "unlocated" , i.e. no position data, through the geo sats. Then in the next minute or so, a new solution with location data is provided (for beacons with internal or external GNSS). However, this first position may be the "cold start" position, with minutes in multiples of 15' (0, 15, 30, 45), for a beacon with internal GNSS. In the next minute usually comes a position update with more refined coordinates.

If one is lucky, one of the LEOSAR sats will come over shortly and provide an additional Doppler derived, and maybe GNSS, position.

Mike
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Old 1st Jun 2016, 03:35
  #906 (permalink)  
 
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It looks like the COSPAS-SARSAT rules are not made for this kind of situation - where the ELT may be shortly submerged or destroyed but there is a very large interest in locating the wreckage, survivable or not. I guess they value avoiding false alarms over occasional missed finds, but one would hope there would be a better way of signalling that an activation was false, so the 406 data burst could go out ASAP.

It has been my experience that non-survivable small aircraft accidents usually destroy the ELT or sever the antenna or antenna connection, but this is a different situation. It has also been my experience that ELT's go off way, way too often when there is no emergency, but again, different issue.
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Old 1st Jun 2016, 06:43
  #907 (permalink)  
 
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Those requirements listed above are for the current 406 MHz beacons. The "second generation beacon" (SGB) design is in work. The limitations of the current system are understoood.
Here are some requirements for the SGB, from C/S G.008, "Operational Requirements for Second Generation 406-MHz Beacons."

3.3.1 Requirements
>The beacon shall have first burst transmission characteristics to allow for independent location computation.
>The operational performance requirement is for first burst 2D independent location accuracy within 5 km, 90% of the time.
>The operational performance requirement is for 2D independent location accuracy of:
- 5 km, 95% of the time, within 30 seconds after beacon activation,

- 1 km, 95% of the time, within 5 minutes after beacon activation, and
- 100 m, 95% of the time, within 30 minutes after beacon activation.

3.4.1 Requirement
The beacon shall transmit a valid message within [3] seconds after activation. The transmission shall meet appropriate signal characteristics. [bracketed value not yet a hard requirement]
3.4.3(e) Consideration should be given to the timing of float-free EPIRB automatic activation under water, noting that the EPIRB may not have reached the surface 3 seconds after activation.

3.5.1 The operational performance requirement is for a 99.9% probability of detection of at least one valid beacon message within 30 seconds after activation and independent location accuracy as defined in section 3.3.
3.5.2 Analysis of previous incidents has shown that some beacons fail within the first 30 seconds of a distress situation. It is also important to detect and locate a beacon as soon as possible in all distress cases.

For these and other requirements to be met, the MEOSAR system needs to be fully operational. 20 or so of the 72 receivers are in orbit, all mounted on GNSS satellites (GPS, Glonass, Galileo). A limited early operational capability may be in place this summer.

Mike
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Old 1st Jun 2016, 07:42
  #908 (permalink)  
 
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An AIRBUS vice president says he's in is in favour of jettisonable & floatable CVRs & FDRs that would separate from an aircraft tail section in case of dislocation. Airbus se redit pour des boîtes noires éjectables après Egyptair "Ces enregistreurs «déployables» se sépareraient de la queue de l'avion lors de la dislocation de l'appareil pour aller flotter à la surface de la mer en émettant un signal de détresse. «Nous y travaillons» a déclaré mardi le vice-président d'Airbus pour l'ingénierie.
Le crash de l'avion de la compagnie aérienne EgyptAir, dont les enregistreurs n'ont toujours pas été retrouvés, milite en faveur de "boîtes noires" capables d'être éjectées avant un accident, estime Charles Champion, vice-président d'Airbus pour l'ingénierie. Des enregistreurs éjectables (ou "déployables") se sépareraient de la queue de l'avion lors de la dislocation de l'appareil pour aller flotter à la surface de la mer en émettant un signal de détresse.
La recherche des enregistreurs de vol de l'Airbus A320 d'Egyptair qui s'est abîmé en Méditerranée le 19 mai dernier avec 66 personnes à bord s'effectuent dans des eaux dont la profondeur peut atteindre 3.000 mètres. Les "boîtes noires" sont conçues pour émettre des signaux acoustiques pendant 30 jours après une catastrophe. Les équipes de recherche ont désormais moins de trois semaines les repérer. "Si nous avons un enregistreur déployable (éjectable), il sera beaucoup plus facile à trouver", a déclaré Charles Champion lors d'une rencontre avec la presse. "Nous y travaillons".
Recommandée par les enquêteurs après le crash d'un A330 d'Air France en 2009, l'idée a ressurgi après la disparition du vol MH370 de Malaysia Airlines en mars 2014. L'Organisation de l'aviation civile internationale (OACI) a demandé à ce que les données clés d'un vol soient récupérables "en temps utile" sur les avions livrés après 2021. Mais la façon d'atteindre cet objectif sera laissée au choix des compagnies aériennes et des constructeurs aéronautiques, qui pourront utiliser des enregistreurs éjectables ou tout autre moyen technique.
Les enregistreurs éjectables sont depuis longtemps utilisés dans l'armée. Mais certains ont exprimé des doutes sur leur utilisation sur les avions civils, faisant valoir qu'ils pourraient se déployer de façon accidentelle et constituer une nouvelle source de risque."

Last edited by formationdriver; 1st Jun 2016 at 09:43. Reason: typo
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Old 1st Jun 2016, 08:34
  #909 (permalink)  
 
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In English...




"These recorders" deployable "would separate the tail of the aircraft during the break-up go to float on the sea surface by emitting a distress signal." We are working, "said Tuesday the vice- Airbus President for engineering.
The plane crash airline EgyptAir, the recorders have still not been found, advocates of "black boxes" that can be ejected before an accident, said Charles Champion, Airbus Vice President for engineering. Of deployable recorders (or "deployable") would separate the tail of the aircraft during the break-up go to float on the sea surface by emitting a distress signal.
The search for the flight recorders of the Airbus A320 that crashed Egyptair in the Mediterranean on May 19 with 66 people on board are made into waters whose depth can reach 3,000 meters. The "black boxes" are designed to emit acoustic signals for 30 days after a disaster. Research teams are now less than three weeks locate. "If we have a deployable recorder (ejection), it will be much easier to find," said Charles Champion during a meeting with the press. "We are working on it."
Recommended by investigators after the crash of an Air France A330 in 2009, the idea has resurfaced after the disappearance of flight MH370 Malaysia Airlines in March 2014. The International Civil Aviation Organization (ICAO) asked that a key flight data is recoverable "in good time" on the aircraft delivered after 2021. But how to achieve this objective will be left to the choice of airlines and aircraft manufacturers, who will use deployable recorders or other technical means.
The deployable recorders have long been used in the military. But some expressed doubts about their use in civil aircraft, arguing that they could deploy accidentally and provide a new source of risk. "
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Old 1st Jun 2016, 09:05
  #910 (permalink)  
 
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Probably worth doing, but I would have thought it has to be at least questionable how often it would be beneficial to recover the flight recorders in the absence of the physical evidence to be found in the wreckage - or vice versa. To understand the "why" you still still generally need to find the aircraft, even if the recorders have given you a good idea of "what" happened.

I'd also point out that for all the feverish criticism of the current method of recovering flight recorders from crashes into water, the odds are very much in favour of it working in this case, even if it does take a little longer than some people would like.
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Old 1st Jun 2016, 10:03
  #911 (permalink)  
 
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804's ELT

All the rosy specs listed can't apply when an aircraft goes straight in to the sea and immediately sinks. Egypt says an ELT signal was picked up and that must have been the very brief transmission between the g-force switch activating on impact and the hull submerging. Thats all they have got and it doesnt seem they have been able to derive any position information from it.
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Old 1st Jun 2016, 10:38
  #912 (permalink)  
 
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Narrowing crash site

@ portmanteau
Well it looks like they were able to derivate a very close position of the crash site from 5 satelite pick up of two short beacon bursts at 00:36z. A previous report mentioned that those data were treated by Airbus (or Space Agency in Toulouse) for Egyptian authorities. The Gardian wrote something that is looking accurate yesterday:
Distress signal from EgyptAir flight 804 confirmed by authorities in Cairo and US | World news | The Guardian
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Old 1st Jun 2016, 10:56
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Takata tks that would seem to end the ELT debate. It worked and it brought the recovery teams to the right spot. Job done. Finis.
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Old 1st Jun 2016, 11:08
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"Job done. Finis"
I hardly think so ... it isn't the beginning of the end, but it might be the end of the beginning ... comes to mind.
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Old 1st Jun 2016, 11:17
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Underwater Search

There are now 3 surface vessels located in the area of interest - around 33°30'N 29°10'E; they are the PMS Burullus (Egyptian Offshore Support Vessel), Alnadorah (Tug), and the Laplace (French Navy Hydrographic vessel).

The Laplace arrived on scene over 12 hours ago, and appears to have done a Towed Pinger Locator (TPL) test run; the PMS Burullus is maintaining position nearby, while another vessel a small tug Alnadorah is currently alongside the Laplace.

The search for the ULB's (Underwater Locator Beacons) is about to get underway. The DFDR and the CVR each have an ULB attached to them, and these beacons emit a pulsed Ultrasonic sound wave with a frequency of approximately 37.5kHz. Approximately, because the frequency control parameters are set by resistive/capacitive circuitry, which results in no two beacon's frequency performance being exactly the same as another; handy when identifying multiple beacons in a search area.

With regard to the ELT transmissions received by satellite, there is always the possibility the automated fixed ELT was set to "ON" from the "ARMED" position by actions taken in the cockpit following LOC. This may have given the time needed for the vital positional data to be sent. That being the case, the ULB's will most likely be located relatively quickly [if functioning].
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Old 1st Jun 2016, 11:52
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Locator signals detected by French Ship: EgyptAir crash: Signals from deep in Mediterranean Sea 'could be flight MS804's black boxes' | Europe | News | The Independent
Sky News also reporting
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Old 1st Jun 2016, 12:10
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The BBC is now reporting
"French ship hears signals believed to be from EgyptAir flight that disappeared in Mediterranean, Egypt says"
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Old 1st Jun 2016, 13:46
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@formationdriver

Airbus has been talking about Deployable Flight Incident Recorder Set (DFIRS) since MH370. If I understand correctly DRS Technologies (a Finmeccanica subsidiary) close ties with EADS puts Airbus in a better position to offer this technology to customers. Hopefully Boeing will come along.

Deployable Flight Incident Recorder Set (DFIRS) 2100 | DRS Technologies, Inc.
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Old 1st Jun 2016, 14:02
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Originally Posted by notapilot15 View Post
@formationdriver

Airbus has been talking about Deployable Flight Incident Recorder Set (DFIRS) since MH370. If I understand correctly DRS Technologies (a Finmeccanica subsidiary) close ties with EADS puts Airbus in a better position to offer this technology to customers. Hopefully Boeing will come along.

Deployable Flight Incident Recorder Set (DFIRS) 2100 | DRS Technologies, Inc.
I suggest that further discussion on this particular topic belongs in another thread, or in tech log. If the FAA doesn't make this a requirement, why would Boeing (or Embraer, or anyone) have to "come along" as you put it. (Not saying it's a bad idea, but the flip side is does making this a requirement have a higher importance than something else? ) Is this a solution in search of a problem?
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Old 1st Jun 2016, 14:17
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Egypt aviation authorities update: signal picked up

Investigation Progress Report (4) by the Egyptian Aircraft Accident Investigation Committee
(actually, this is update 5)

"Cairo, 1st of June 2016

The French vessel “La Place” of the French navy; participating in the search for the two data recorders of the A320 that was downed in the Mediterranean mid of last month; has received through its search equipment signals from the seabed of the wreckage search area; assumed to be from one of the data recorders.
Extensive search efforts are being carried out to locate the two data recorders in preparation for their retrieval by “JOHN LETHBRIDGE” which is a vessel that belongs to DOS "Deep Ocean Search", which will join the search team within a week."
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