Malaysian Airlines MH370 contact lost
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ATSB Tender for MH370 Search
ATSB has, this morning, released the tender documents for the MH370 search. You need to be registered to download it but synopsis is available from AUStender at this link:
http://www.tenders.gov.au/?event=pub...BEB3C04BEB2FB0
The tender itself calls for a complete range of services and specifies the detail to which the search is to be conducted including the requirement to provide raw search data for others to analyse independently of the contractor and daily, weekly and monthly reporting of activities.
http://www.tenders.gov.au/?event=pub...BEB3C04BEB2FB0
The tender itself calls for a complete range of services and specifies the detail to which the search is to be conducted including the requirement to provide raw search data for others to analyse independently of the contractor and daily, weekly and monthly reporting of activities.
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Tim Clark Interview
If one would be willing to take Emirates Chairman Tim Clark's statement at face value, then passenger #240 has reared it's ugly head again.
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Curtin University Acoustic Signals
Acoustic signal received at Rottnest at 1:30am UTC. The final ping arc is about 2,000km from Perth. Sound travels 1500m/s in seawater. This means it would have taken 22mins to reach Rottnest from the final ping arc, which would be 1:08am UTC. Final satcom communication at 00:19am, 49mins difference. Is it possible to glide 49mins in a 777?
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flyball. Might the speed be less than 1500m/s?
Velocity of sound in sea-water Calculator - High accuracy calculation
Velocity of sound in sea-water Calculator - High accuracy calculation
The PhD who investigated this acoustic data gave a very comprehensive interview on radio 18 hours ago. He is almost certain (90% confidence) the noise was NOT MH370.
He feels more likely it represented a small earthquake or ice breaking off Antarctic shelf.
He did say low frequency sounds (at or below lower limit of human hearing) can be detected many thousands of km away. Main variables are:
1. topography of the bottom (helpful if the ocean bottom at the source sound was sloped towards the listener, as this will "lens" (reflect) noise towards the listener.
2. temperature layers (deep water channel)
He also confirmed frequencies in range of pingers would be limited to just a couple of km regardless of conditions.
Worth a listen if you are interested. Maybe available online (2gb.com). But he didn't leave much room for doubt.
He feels more likely it represented a small earthquake or ice breaking off Antarctic shelf.
He did say low frequency sounds (at or below lower limit of human hearing) can be detected many thousands of km away. Main variables are:
1. topography of the bottom (helpful if the ocean bottom at the source sound was sloped towards the listener, as this will "lens" (reflect) noise towards the listener.
2. temperature layers (deep water channel)
He also confirmed frequencies in range of pingers would be limited to just a couple of km regardless of conditions.
Worth a listen if you are interested. Maybe available online (2gb.com). But he didn't leave much room for doubt.
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Curtin University Acoustic Signals
Ornis, you may be correct, its hard to find accurate sea surface temperature measurements for the 8th of March and it also depends on whether the plane hitting the surface caused the signal or the plane imploding under the ocean caused the signal. The acoustic sensor is located at a depth of 400m so this affects the speed as well.
Using the image Minimbar posted the final ping is about 1600km away from Perth, so this would make it 17mins for the travel time of the signal and a further five minutes the plane would need to glide (54mins).
ETH961 glided for 27mins after last engine shut down from 20,000ft, (even with hijacker interference).
Using the image Minimbar posted the final ping is about 1600km away from Perth, so this would make it 17mins for the travel time of the signal and a further five minutes the plane would need to glide (54mins).
ETH961 glided for 27mins after last engine shut down from 20,000ft, (even with hijacker interference).
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The recordings of an identifiable noise (in fact two) happening at approximately the time that 370 was expected to have 'ditched' is an extreme coincidence.
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Speed of sound in water is APPROX 1500 mps but it varies with temperature, salinity, surface conditions and half a dozen other things
You use 1500mps as an approximation but it could be +/- 5%
You use 1500mps as an approximation but it could be +/- 5%
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ACARS, Disabled or Switched off
Bilby, Desparing Traveller et al,
ACARS "was deliberately turned off" was reported early on. Now ACARS 'logs on' and 'logs off' usually on aircraft systems power up and power down. ACARS using VHF often (regularly) loses contact as the aircraft flies out of line-of-sight. There is a difference to the system between just not getting any more transmissions and receiving a log-off. So it would be possible to know if the system was shut down via a pilot input or just 'stopped' as it would if out of line of sight of VHF, fire had burned through the power supply, or the pilot had tripped a circuit breaker.
The repeated statements that someone had "switched ACARS off" rather than we received no more ACARS transmissions after the last one at cruise, implies that there is evidence of a tidy log-off. This evidence is crucial as it would settle several hypotheses - a pilot with a cockpit fire or some other emergency, does not find the correct place to log off from ACARS. SITA/ARINC should have that evidence and it should have been in the initial report.
ACARS "was deliberately turned off" was reported early on. Now ACARS 'logs on' and 'logs off' usually on aircraft systems power up and power down. ACARS using VHF often (regularly) loses contact as the aircraft flies out of line-of-sight. There is a difference to the system between just not getting any more transmissions and receiving a log-off. So it would be possible to know if the system was shut down via a pilot input or just 'stopped' as it would if out of line of sight of VHF, fire had burned through the power supply, or the pilot had tripped a circuit breaker.
The repeated statements that someone had "switched ACARS off" rather than we received no more ACARS transmissions after the last one at cruise, implies that there is evidence of a tidy log-off. This evidence is crucial as it would settle several hypotheses - a pilot with a cockpit fire or some other emergency, does not find the correct place to log off from ACARS. SITA/ARINC should have that evidence and it should have been in the initial report.
@IanW
The Curtin University receivers are based off Rottnest Island, pretty much due west of Perth. I gather these receivers serve a scientific purpose (whales etc).
He explained the data had been cross referenced with data obtained from different receivers based quite a way south of Perth (off Cape Leeuwin). The purpose of these receives is to help monitor compliance with the comprehensive test ban treaty. He was a little vague regarding precise details at this point, perhaps deliberately so. But I got the impression differential timing suggested a source well to the south (he did specifically mention Antarctica as a likely source).
The Curtin University receivers are based off Rottnest Island, pretty much due west of Perth. I gather these receivers serve a scientific purpose (whales etc).
He explained the data had been cross referenced with data obtained from different receivers based quite a way south of Perth (off Cape Leeuwin). The purpose of these receives is to help monitor compliance with the comprehensive test ban treaty. He was a little vague regarding precise details at this point, perhaps deliberately so. But I got the impression differential timing suggested a source well to the south (he did specifically mention Antarctica as a likely source).
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@IanW
As mentioned, the first acoustic transient, if originating from the final Inmarsat ping ring would have been produced approximately 50 minutes after the time of last Inmarsat ping.
The second acoustic transient was much later and would have originated approximately 4.5 hours after the last Inmarsat ping
Both signals received contain only low frequency energy, suggesting a large propagation range, and have rather different characteristics (frequency and time spread).
The recordings of an identifiable noise (in fact two) happening at approximately the time that 370 was expected to have 'ditched' is an extreme coincidence.
The second acoustic transient was much later and would have originated approximately 4.5 hours after the last Inmarsat ping
Both signals received contain only low frequency energy, suggesting a large propagation range, and have rather different characteristics (frequency and time spread).
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Hello, a first-time poster here with a couple of points I would like to contribute:
When Tim Clark talks about 3 systems disabled, he probably refers to the transponder, ACARS and SATCOM. Please note that ACARS and SATCOM are separate systems.
Transponder being disabled (turned off or failed) is self-evident.
Last ACARS transmission from the plane through SATCOM was at 1707 Z and none received after that, thus ACARS disabled.
In the Inmarsat logs, there is a gap of SATCOM transmissions between 1707 Z (after the last ACARS transmission) and 1825 Z (when the SATCOM in the plane initiated a handshake). In particular, the SATCOM modem didn't respond to a satellite query at 1803 Z. We can deduce therefore that SATCOM was disabled at least between 1803 Z and 1825 Z, and enabled at 1825 Z.
When Tim Clark talks about 3 systems disabled, he probably refers to the transponder, ACARS and SATCOM. Please note that ACARS and SATCOM are separate systems.
Transponder being disabled (turned off or failed) is self-evident.
Last ACARS transmission from the plane through SATCOM was at 1707 Z and none received after that, thus ACARS disabled.
In the Inmarsat logs, there is a gap of SATCOM transmissions between 1707 Z (after the last ACARS transmission) and 1825 Z (when the SATCOM in the plane initiated a handshake). In particular, the SATCOM modem didn't respond to a satellite query at 1803 Z. We can deduce therefore that SATCOM was disabled at least between 1803 Z and 1825 Z, and enabled at 1825 Z.
Curtin University researchers find possible acoustic trace of MH370
IanW, a brief media presentation by Dr Duncan. The 15 minute interview I heard was much more in depth, but you might be interested in this.
IanW, a brief media presentation by Dr Duncan. The 15 minute interview I heard was much more in depth, but you might be interested in this.
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Bilby, Desparing Traveller et al,
ACARS "was deliberately turned off" was reported early on. Now ACARS 'logs on' and 'logs off' ....
The repeated statements that someone had "switched ACARS off" rather than we received no more ACARS transmissions after the last one at cruise, implies that there is evidence of a tidy log-off.
ACARS "was deliberately turned off" was reported early on. Now ACARS 'logs on' and 'logs off' ....
The repeated statements that someone had "switched ACARS off" rather than we received no more ACARS transmissions after the last one at cruise, implies that there is evidence of a tidy log-off.
The log ons at 18:25 (from memory) and the 7th ping, are the satellite communication system itself, not the ACARS communications. Further, I believe it is established fact that MH370 was not configured to have the ACARS system use the satcom link, Satcom was only onboard to provide telecommunications for Business/First class (and potentially available to the flight crew for calls).
I have little technical knowledge of the ACARS system, but it appears to not intrinsically require a log on/log off process. It seems to just be a VHF/HF/Satcom store and forward system where individual data packages are sent to the central service for storage and then periodically polled or pushed until an ACK is received or a retry limit is hit.
It is also not clear to me that the Satcom system itself has any 'logoff' function and therefore if there would be anything to distinguish between the device being turned off/ put into standby/ loosing power/ being destroyed
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I have little technical knowledge of the ACARS system, but it appears to not intrinsically require a log on/log off process. It seems to just be a VHF/HF/Satcom store and forward system where individual data packages are sent to the central service for storage and then periodically polled or pushed until an ACK is received or a retry limit is hit.
It is also not clear to me that the Satcom system itself has any 'logoff' function and therefore if there would be anything to distinguish between the device being turned off/ put into standby/ loosing power/ being destroyed
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@IanW
Thank you for the explanations.
What I've taken away from this very interesting discussion is that possible the ground would know if the system had been tidily shut down because a logoff message would have been received, but that the existence of such a message hasn't been explicitly disclosed publicly. As you quite rightly say, if that evidence exists, it is crucial.
The preliminary report simply states:
Thank you for the explanations.
What I've taken away from this very interesting discussion is that possible the ground would know if the system had been tidily shut down because a logoff message would have been received, but that the existence of such a message hasn't been explicitly disclosed publicly. As you quite rightly say, if that evidence exists, it is crucial.
The preliminary report simply states:
It was later established that the transmissions from the Aircraft Communication and Reporting System (ACARS) through satellite communication system occurred at regular intervals starting before MH 370 departed Kuala Lumpur, Malaysia at time 12:56:08 MYT and with the last communication occurred at 01:07:49 MYT.
I was a bit surprised to read that paragraph, as I had been under the impression that ACARS was VHF only on this flight. Like others, I've also been under the impression that the 1:07:49 message was a routine engine report.