Malaysian Airlines MH370 contact lost
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Swiss Air 111 was able to communicate until the very last minutes. Had they not delayed to dump fuel on a relatively standard approach procedure and instead made an immediate emergency descent and landing they may even have survived.
To recap, under the MH370 catastrophe scenario:
MH370 is supposed to have had a catastrophic failure
AND
the crew not be able to use any of the aircraft systems to report the failure
AND
it took 10 - 15 minutes for these communications systems to fail
AND
be able to fly apparently under control back across Malaysia and around Indonesia then South with power to SATCOM and a working FMC for the next 6 hours
While everyone accepts the aphorism: Aviate, Navigate, Communicate - it has been my experience that even in extremely fast moving emergencies flight crew do tell their current controller or anyone on emergency frequency that they have a problem. It only takes one button to be pressed. It is possible to have catastrophic failures that prevent communications but they would appear to be ruled out by the subsequent conditions above.
To recap, under the MH370 catastrophe scenario:
MH370 is supposed to have had a catastrophic failure
AND
the crew not be able to use any of the aircraft systems to report the failure
AND
it took 10 - 15 minutes for these communications systems to fail
AND
be able to fly apparently under control back across Malaysia and around Indonesia then South with power to SATCOM and a working FMC for the next 6 hours
While everyone accepts the aphorism: Aviate, Navigate, Communicate - it has been my experience that even in extremely fast moving emergencies flight crew do tell their current controller or anyone on emergency frequency that they have a problem. It only takes one button to be pressed. It is possible to have catastrophic failures that prevent communications but they would appear to be ruled out by the subsequent conditions above.
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I do not know if the ACARS logs have been made available. But the ARINC 620 datalink specification has a 'logon/logoff' protocol. If the ACARS 'failed' or had its CB pulled, then there would be no logoff protocol messages. If the ACARS was tidily switched off then it would have followed the log off protocol.
The early statements implied that it had logged off, meaning someone who knew how to find the ACARS menu had switched ACARS off.
The early statements implied that it had logged off, meaning someone who knew how to find the ACARS menu had switched ACARS off.
Are you certain there is actually a logoff ACARS message (as compared to 'logging off' in the airplane as a planned way of causing the system to stop sending messages). I can't find any indication that such a message type exists. Equally, I can't see a 'logon' ACARS message (as compared to the satcom logon). The closest message type to logon seems to be Link Test.
Also, the 1:07 message, based on the Inmarsat log, looks to be 'large' (30 signalling units). What appears to be the ACK is only three signalling units. I would expect a logoff message to be similar in size to the ACK. That coupled with the fact that no official documents has said 'the last ACARS message at 1:07 was a log off message' leads me to believe the early comments of ACARS being 'turned off' were imprecise comments that should technically have been 'ACARS stopped transmitting expected messages or responding to interrogations some time after the last routine message at 1:07'.
One can easily understand how a briefer in the heat of the moment would use version one vs version two.
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Ian W
With Swiss111 there was an INMARSAT "log on" (renewal).
No "log off" was registered. No prior "log off" could be determined.
The report suggests there was a "power interruption".
With Swiss111 there was an INMARSAT "log on" (renewal).
No "log off" was registered. No prior "log off" could be determined.
The report suggests there was a "power interruption".
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If it was an electrical fire could the crew have removed all electrics including batteries and even climbing to stall the RAT.
Fire stopped successfully but during re-initialisation of systems didn't notice loss of cabin pressure ,aircraft remains on last set heading.
Fire stopped successfully but during re-initialisation of systems didn't notice loss of cabin pressure ,aircraft remains on last set heading.
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Ian,
Are you certain there is actually a logoff ACARS message (as compared to 'logging off' in the airplane as a planned way of causing the system to stop sending messages). I can't find any indication that such a message type exists. Equally, I can't see a 'logon' ACARS message (as compared to the satcom logon). The closest message type to logon seems to be Link Test.
Also, the 1:07 message, based on the Inmarsat log, looks to be 'large' (30 signalling units). What appears to be the ACK is only three signalling units. I would expect a logoff message to be similar in size to the ACK. That coupled with the fact that no official documents has said 'the last ACARS message at 1:07 was a log off message' leads me to believe the early comments of ACARS being 'turned off' were imprecise comments that should technically have been 'ACARS stopped transmitting expected messages or responding to interrogations some time after the last routine message at 1:07'.
One can easily understand how a briefer in the heat of the moment would use version one vs version two.
Are you certain there is actually a logoff ACARS message (as compared to 'logging off' in the airplane as a planned way of causing the system to stop sending messages). I can't find any indication that such a message type exists. Equally, I can't see a 'logon' ACARS message (as compared to the satcom logon). The closest message type to logon seems to be Link Test.
Also, the 1:07 message, based on the Inmarsat log, looks to be 'large' (30 signalling units). What appears to be the ACK is only three signalling units. I would expect a logoff message to be similar in size to the ACK. That coupled with the fact that no official documents has said 'the last ACARS message at 1:07 was a log off message' leads me to believe the early comments of ACARS being 'turned off' were imprecise comments that should technically have been 'ACARS stopped transmitting expected messages or responding to interrogations some time after the last routine message at 1:07'.
One can easily understand how a briefer in the heat of the moment would use version one vs version two.
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ACARS was only licensed and activated on VHF by the Malaysians it was not linked to INMARSAT SATCOM or to Boeing or Rolls Royce health monitoring. So the ACARS logon/logoff would be an ARINC/SITA protocol over VDL which I believe is ARINC 622 'ATS Data Link Applications over ACARS, or 618 Air/Ground Character-Oriented Protocol Specification.
two points.
1 - I can't see described in any of the protocols a logoff message (nor for that matter a log on) at the ACARS level (i.e. a message that would indicate that the ACARS system was logging off, rather than that the underlying transport layer was logging off). Equally, I am certain that the VHF transport layer does not log on or logoff as it is just open radio spectrum.
People have speculated the authorities have some indication the ACARS was 'logged off in a conscious deliberate way'. I can see no basis in the technology being used that would allow that possibly to be concluded with respect to the ACARS system. As such, I believe it is certain to have been a turn of phrase used by someone in an early briefing rather than anything relevant.
2 - People have represented that Malaysian Airlines did not use the satcom for ACARS, yet the official preliminary report declares it did, and that the 1:07 ACARS message was transmitted via satcom link, and finally, there is a satcom message originating from the aircraft at just before 1:07 and finishing just after 1:07.
Originally Posted by Preliminary Report
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 therefore believe, subject to some conclusive evidence of MA non-use of Satcom for ACARS, that MH370 was using Satcom as its ACARS link layer. And therefore, the reason we have no VDL ACARS logs for MH370 is because it wasn't using VDL, not because they exist but have not been released.
Last edited by mm_flynn; 12th Jul 2014 at 20:54. Reason: corrected VDL
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mm_flynn.
12:56:08 myt is not just before 01:07:49 myt. it is some 12 hours before in the early afternoon. 00:56:08 myt would be just before. note that aircraft took off at 00:41 myt.
12:56:08 myt is not just before 01:07:49 myt. it is some 12 hours before in the early afternoon. 00:56:08 myt would be just before. note that aircraft took off at 00:41 myt.
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The 12:56 time was not implied as shortly before 1:07. The Preliminary Report clearly implies a number of routine messages for an appreciable time prior to the last message prior to the loss of transponder contact. The quote is directly from http://www.dca.gov.my/MH370/Preliminary%20Report.pdf.
I was focused on the 'last ACARS message time' which matches exactly to the second with the last Satcom message (prior to the pings, missed calls, and two logons post IGARI). And which, I believe, establishes clearly that the Satcom message is from the ACARS system and that MH370 was using Satcom and not VDL to transmit its ACARS messages.
I have no idea to what the 12:58 time refers. It may be when the aircraft was first powered up that day (i.e. an earlier flight) or it may be some time near the Satcom initial login of 00:13 but documented incorrectly, or it could be some entirely different event that the preliminary investigators considered relevant in this context.
I was focused on the 'last ACARS message time' which matches exactly to the second with the last Satcom message (prior to the pings, missed calls, and two logons post IGARI). And which, I believe, establishes clearly that the Satcom message is from the ACARS system and that MH370 was using Satcom and not VDL to transmit its ACARS messages.
I have no idea to what the 12:58 time refers. It may be when the aircraft was first powered up that day (i.e. an earlier flight) or it may be some time near the Satcom initial login of 00:13 but documented incorrectly, or it could be some entirely different event that the preliminary investigators considered relevant in this context.
Last edited by mm_flynn; 12th Jul 2014 at 20:58.
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http://www.dca.gov.my/MH370/Preliminary%20Report.pdf
This doesn't quite make sense to me: asking for something DCA claims existed. And why would Acars be via satellite where VHF was available?
Search and Rescue (SAR). It was later established that the transmissions from (ACARS) through satellite ...
Safety recommendations. While the aircraft had the necessary communication equipment to provide information on its location, the last ACARS message ...
It is recommended that the ICAO examine the safety benefits of introducing a standard for real time tracking
Safety recommendations. While the aircraft had the necessary communication equipment to provide information on its location, the last ACARS message ...
It is recommended that the ICAO examine the safety benefits of introducing a standard for real time tracking
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Ian W
"Swiss Air 111 was able to communicate until the very last minutes. Had they not delayed to dump fuel on a relatively standard approach procedure and instead made an immediate emergency descent and landing they may even have survived."
This is not correct. Read the report.
"Based on these factors, it is evident that even if the pilots had attempted a minimum-time emergency diversion starting at 0114:18, it would have been impossible for the pilots to continue maintaining control of the aircraft for the amount of time necessary to reach the airport and complete a safe landing."
"Swiss Air 111 was able to communicate until the very last minutes. Had they not delayed to dump fuel on a relatively standard approach procedure and instead made an immediate emergency descent and landing they may even have survived."
This is not correct. Read the report.
"Based on these factors, it is evident that even if the pilots had attempted a minimum-time emergency diversion starting at 0114:18, it would have been impossible for the pilots to continue maintaining control of the aircraft for the amount of time necessary to reach the airport and complete a safe landing."
Ornis:
They're asking ICAO to examine a 'standard' for the real time tracking of aircraft. That is something that does not currently exist. There are systems available that can track aircraft outside radar coverage in real time, such as ADS-B/C, however only a few ATC centres have the capability and not all aircraft are equipped. Airline aircraft routinely transmit position information and engineering data via ACARS, but that information is not used to 'track' the aircraft in real time.
In the case of MH370, the aircraft had the capability to transmit its position via ADS-B and ACARS. However, that all stopped when the transponder and ACARS both stopped transmitting. I guess an ICAO standard would have to require an independent system that can't be tampered with or disabled by anyone onboard the aircraft.
Regarding the second part of your post, it all comes down to cost and availability. In some areas the airline's provider (SITA or ARINC) may not have the necessary VHF coverage, and in others (e.g. Japan) it is actually cheaper to route ACARS messages via satcom rather than VHF.
This doesn't quite make sense to me: asking for something DCA claims existed. And why would Acars be via satellite where VHF was available?
In the case of MH370, the aircraft had the capability to transmit its position via ADS-B and ACARS. However, that all stopped when the transponder and ACARS both stopped transmitting. I guess an ICAO standard would have to require an independent system that can't be tampered with or disabled by anyone onboard the aircraft.
Regarding the second part of your post, it all comes down to cost and availability. In some areas the airline's provider (SITA or ARINC) may not have the necessary VHF coverage, and in others (e.g. Japan) it is actually cheaper to route ACARS messages via satcom rather than VHF.
Last edited by BuzzBox; 13th Jul 2014 at 22:19.
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I wonder if such a bunch of trajectories would draw the attention of the Indonesian airspace surveillance chain (the location of the unidentified A/C matters versus a RoI, but also its radial speed ?), the best fit trajectory is slightly (a few NM) off Banda Aceh:
https://drive.google.com/file/d/0B3s...it?usp=sharing
The 18:40 C-channel BFO 88 Hz value is not an outlier for the predicted BFO enveloppe of my MC simulation and it does not degrade the BFO error optimization (as well as the 3rd handshake around 18:28), the following result (30 000 runs) is for a south turn occuring 6 min after 18:28, early trajectory not constrained by the ADS-B and radar tracks:
https://drive.google.com/file/d/0B3s...it?usp=sharing
The inclusion of this new BFO value does not alter the most probable area (between 28 and 32°S) along the last ping ring, the best fit trajectories last south leg remains at a relatively low true ground speed (around 410 kts) ending round 30°S ...and curvy (not a a great circle or a rhumb line):
https://drive.google.com/file/d/0B3s...it?usp=sharing
It does not modify the mean BFO error for each handshakes (as a function of time and true ground speed):
https://drive.google.com/file/d/0B3s...it?usp=sharing
The inclusion of a new BFO data point or of a delay (from 18:28) for the south turn does not seem to impact the simulation end result, what really does seem to have an impact is whether I allow the 1st part (till 18:28) of the trajectories to fluctuate & drift (resulting in a wider variety of trajectories and of injection points for the last south leg) or if I constrain them to the ADS-B & radar tracks (which seems to shift the most probable area more than 1° toward the south).
https://drive.google.com/file/d/0B3s...it?usp=sharing
The 18:40 C-channel BFO 88 Hz value is not an outlier for the predicted BFO enveloppe of my MC simulation and it does not degrade the BFO error optimization (as well as the 3rd handshake around 18:28), the following result (30 000 runs) is for a south turn occuring 6 min after 18:28, early trajectory not constrained by the ADS-B and radar tracks:
https://drive.google.com/file/d/0B3s...it?usp=sharing
The inclusion of this new BFO value does not alter the most probable area (between 28 and 32°S) along the last ping ring, the best fit trajectories last south leg remains at a relatively low true ground speed (around 410 kts) ending round 30°S ...and curvy (not a a great circle or a rhumb line):
https://drive.google.com/file/d/0B3s...it?usp=sharing
It does not modify the mean BFO error for each handshakes (as a function of time and true ground speed):
https://drive.google.com/file/d/0B3s...it?usp=sharing
The inclusion of a new BFO data point or of a delay (from 18:28) for the south turn does not seem to impact the simulation end result, what really does seem to have an impact is whether I allow the 1st part (till 18:28) of the trajectories to fluctuate & drift (resulting in a wider variety of trajectories and of injection points for the last south leg) or if I constrain them to the ADS-B & radar tracks (which seems to shift the most probable area more than 1° toward the south).
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I wonder if such a bunch of trajectories would draw the attention of the Indonesian airspace surveillance chain
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IMO anyone who thinks 9M-MRO overflew Indonesia is so focused on their mathematics that they've lost sight of reality.
Arthur Conan Doyle
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BTW, in another life I have been sitting at a surveillance radar console (onboard an anti aerial frigate) and both the position and the speed vector orientation (versus the protected area) of an A/C would draw my attention.
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Are you suggesting that the official investigation team has lost sight of reality when it produces such trajectories ?
Are you saying that graphic is from the Australian Government?
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“When you have eliminated the impossible, whatever remains, however improbable, must be the truth.”