Malaysian Airlines MH370 contact lost
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Quote:
"We couldn't say what direction it had gone in, but the plane wasn't standing still because the signals were getting longer, i.e. further in distance from our satellite."
Inmarsat Senior Vice President Chris McLaughlin
That's an odd choice of a word.
I read that as Doppler shift away from the satellite .
"We couldn't say what direction it had gone in, but the plane wasn't standing still because the signals were getting longer, i.e. further in distance from our satellite."
Inmarsat Senior Vice President Chris McLaughlin
That's an odd choice of a word.
I read that as Doppler shift away from the satellite .
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The Inmarsat guy has six hourly ping times to work with. It should be clear whether the aircraft was heading towards his satellite or away from it over that time to an accuracy of somewhere in the region of 100 km per hour.
It could be confounded by a delay in the transponder reply, but there's no other factors that can affect it. Inmarsat must know a great deal about transponder delays, and they could run the same test on every flight since MH370 to see how wrong they are against actual flight tracks.
He has no information apart from the round-trip time to the aircraft, and his satellite over the Indian Ocean sees the whole Earth disk.
It is possible that some other mysterious geostationary satellite might have collected the signals too, which would help a lot in locating them, but I doubt the Inmarsat guy would talk about that on the TV.
If he had six hourly GPS positions reported in the replies, this uncertainty would all be gone. For a few cents per seat per trip, this would seem to be a good idea in future. Then again, the wreck of AF447 still took 2 years to find, despite much more comprehensive satellite signaling.
It could be confounded by a delay in the transponder reply, but there's no other factors that can affect it. Inmarsat must know a great deal about transponder delays, and they could run the same test on every flight since MH370 to see how wrong they are against actual flight tracks.
He has no information apart from the round-trip time to the aircraft, and his satellite over the Indian Ocean sees the whole Earth disk.
It is possible that some other mysterious geostationary satellite might have collected the signals too, which would help a lot in locating them, but I doubt the Inmarsat guy would talk about that on the TV.
If he had six hourly GPS positions reported in the replies, this uncertainty would all be gone. For a few cents per seat per trip, this would seem to be a good idea in future. Then again, the wreck of AF447 still took 2 years to find, despite much more comprehensive satellite signaling.
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I don't understand the endless confusion between SATCOM pings and ACARS data...
SATCOM pings and ACARS data transmissions are completely independent.
The article states that the ACARS data transmitted included GPS coordinates from the plane. It doesn't matter how it was sent - the GPS coordinates were part of the data.
Those coordinates were then used to 'calibrate' the interpretation of the SATCOM ping sent (independently) around the same time.
Interesting article.
He seems to be talking about an upgrade to the INMARSAT SATCOM box, not the ACARS system? Which would make sense since he works for INMARSAT...
That statement only makes sense if ACARS at 1:07 already went via SATCOM, which would mean ACARS via VHF was deliberately? disabled before.
The article states that the ACARS data transmitted included GPS coordinates from the plane. It doesn't matter how it was sent - the GPS coordinates were part of the data.
Those coordinates were then used to 'calibrate' the interpretation of the SATCOM ping sent (independently) around the same time.
includes interesting bit about $10 upgrade to ACARS transmissions to send black box data in real time!
He seems to be talking about an upgrade to the INMARSAT SATCOM box, not the ACARS system? Which would make sense since he works for INMARSAT...
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HMS Echo
Broadlands - you would know! I can't find the post but somebody said that HMS Echo is equipped with one, maybe two, sounding lines with lead weights on them. I thought these went out with Capt Cook and Admiral Nelson? Perhaps it was a bad joke!
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It is probable that each ping is actually an exchange satellite to aircraft and back, or vice versa. This is the only way to ensure a secure identity check within each ping.
It is not clear which end initiates the communication. There are conflicting statements by experts.
In any case it does mean that each individual ping operation does get longer to conclude as the distance from satellite increases.
Along the published southerly path the distance from the satellite is increasing for the last several pings, at least. However, other possible paths can be matched as well.
It is not clear which end initiates the communication. There are conflicting statements by experts.
In any case it does mean that each individual ping operation does get longer to conclude as the distance from satellite increases.
Along the published southerly path the distance from the satellite is increasing for the last several pings, at least. However, other possible paths can be matched as well.
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- is there any link to this statement? Does Inmarsat know in detail what was happening to the signal elevation during the 7 hours? ?Assuming the reception angle is referenced to the earth vertical? I would assume from the above 'quote' that the elevation was increasing at some latter stage. If the information is refined enough it might be possible to re-create multiple paths of likely routes which when meshed with start pos would surely yield some clues? Initially we were told is was a '40 degree' signal, but that does not appear to be the whole story. Logically the elevation would decrease during the supposed 'turn back' and 'Malacca transit' - then what?
Satellite company official speaks out on tracking missing jet after it lost contact | Fox News
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BREAKING: The Telegraph has obtained the transcript of the last 54 minutes of comms
Malaysian Airlines MH370: live - Telegraph
16.38 The first was a message delivered by the cockpit at 1.07am, saying that the plane was flying at a cruising altitude of 35,000 feet. This message was unnecessary as it repeated a call that had already been delivered six minutes earlier.
Steve Landells, a former British Airways pilot who flew Boeing 777s, told The Telegraph that this second message was not required but he did not regard it as suspicious.
“It could be as simple as the pilot forgetting or not being sure that he had told air traffic controllers he had reached the altitude,” he said. “He might be reconfirming he was at 350 [35,000 feet]. It is not unusual. I wouldn’t read anything into it.”
16.25 BREAKING: The Telegraph has obtained the transcript of the last 54 minutes of communication aboard Flight MH370.
Related Articles
How MH370 vanished - and how it could have been avoided 21 Mar 2014
The final communication between the Malaysia Airlines flight cockpit and ground control can be revealed, from its taxi on the runway to its final message at 1.07am of “Alright, good night”.
The Telegraph's Jonathan Pearlman has seen the full communication record of MH370, including the crucial moments in the lead-up to the disappearance of the Boeing 777 and its 239 passengers. It reveals the messages relayed between the cockpit and air traffic controllers during the period when the plane is believed by investigators to have already been sabotaged.
More to follow...
16.38 The first was a message delivered by the cockpit at 1.07am, saying that the plane was flying at a cruising altitude of 35,000 feet. This message was unnecessary as it repeated a call that had already been delivered six minutes earlier.
Steve Landells, a former British Airways pilot who flew Boeing 777s, told The Telegraph that this second message was not required but he did not regard it as suspicious.
“It could be as simple as the pilot forgetting or not being sure that he had told air traffic controllers he had reached the altitude,” he said. “He might be reconfirming he was at 350 [35,000 feet]. It is not unusual. I wouldn’t read anything into it.”
16.25 BREAKING: The Telegraph has obtained the transcript of the last 54 minutes of communication aboard Flight MH370.
Related Articles
How MH370 vanished - and how it could have been avoided 21 Mar 2014
The final communication between the Malaysia Airlines flight cockpit and ground control can be revealed, from its taxi on the runway to its final message at 1.07am of “Alright, good night”.
The Telegraph's Jonathan Pearlman has seen the full communication record of MH370, including the crucial moments in the lead-up to the disappearance of the Boeing 777 and its 239 passengers. It reveals the messages relayed between the cockpit and air traffic controllers during the period when the plane is believed by investigators to have already been sabotaged.
More to follow...
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P3 S&R
These true experience revelations about the discomfort of low level S&R are most enlightening. There is no way you can get this kind of insight from conventional media sources. So let me express my thanks to all you professional posters whose original comments keep me coming back to this site every day.
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SATCOM pings and ACARS data transmissions are completely independent.
The article states that the ACARS data transmitted included GPS coordinates from the plane. It doesn't matter how it was sent - the GPS coordinates were part of the data.
Those coordinates were then used to 'calibrate' the interpretation of the SATCOM ping sent (independently) around the same time.
The article states that the ACARS data transmitted included GPS coordinates from the plane. It doesn't matter how it was sent - the GPS coordinates were part of the data.
Those coordinates were then used to 'calibrate' the interpretation of the SATCOM ping sent (independently) around the same time.
:To calibrate the signal path between satellite <-> A/C transceiver, you have to know the exact position of the A/C when a SATCOM transmission is made. My assumption - which may be wrong - is that precise secondary radar fixes where available until 1:21. If the SATCOM transmission, that was used to calibrate the signal path, was made at any other time than 1:07, it would make much more sense to take the secondary radar fix from the time of SATCOM transmission to calibrate the signal path.
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It is not clear which end initiates the communication. There are conflicting statements by experts.
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Sadly, I think all Inmarsat has to work with is the time of flight of radio waves between their satellite and the aircraft on the hour, plus the uncertain time lag required for the aircraft's satcom box to reply. My understanding is that for a few dollars more, Inmarsat would have an hourly GPS position transmitted from the aircraft in their archives.
The South China Sea information allows Inmarsat to be confident that the 0100 signals were consistent with a "red arc" that goes through that area.
As time goes by, the chances of finding anything in the ocean seems to be fading.
Hopefully, agencies that listen to radio signals from a high orbit, and scan the ocean surface for radar reflections can have a look back through their records and perhaps add something to the conversation.
If any commercial or military imaging satellites happened to be taking pictures of the Indian Ocean at the time (why would they? although Digital Globe seem to have been on 16th - perhaps in response to an order) then there's a possibility that MH370 might have accidentally been spotted traveling through the frame.
With a lot of effort, once it was daylight, it might also be possible for weather satellite data to be handled carefully to look for signs of a contrail in its wake, especially since it took a lonely route.
Perhaps some whole-Earth IR missile launch warning satellite images could be searched in the same way for some warmth from the engines.
Was there really no sign of anything out there on the Australian OTH radar?
The South China Sea information allows Inmarsat to be confident that the 0100 signals were consistent with a "red arc" that goes through that area.
As time goes by, the chances of finding anything in the ocean seems to be fading.
Hopefully, agencies that listen to radio signals from a high orbit, and scan the ocean surface for radar reflections can have a look back through their records and perhaps add something to the conversation.
If any commercial or military imaging satellites happened to be taking pictures of the Indian Ocean at the time (why would they? although Digital Globe seem to have been on 16th - perhaps in response to an order) then there's a possibility that MH370 might have accidentally been spotted traveling through the frame.
With a lot of effort, once it was daylight, it might also be possible for weather satellite data to be handled carefully to look for signs of a contrail in its wake, especially since it took a lonely route.
Perhaps some whole-Earth IR missile launch warning satellite images could be searched in the same way for some warmth from the engines.
Was there really no sign of anything out there on the Australian OTH radar?
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mobile phone (NOT Inmarsat) 'pings'
I've been thinking....
We all know that on every flight there is a certain number of phones that don't get switched off or put into 'flight mode'.
Now, these phones would try to lock on to a ground-based station during the flight. We've had this discussion here before and know it's perfectly feasible from 30+k feet.
IF the aircraft really headed out into the Indian Ocean, then it must have overflown Malaysia and Indonesia. Does anyone know if the Telcos in these two countries checked their logs for the night in question? If (and again, a big IF) any of the phones on board had tried to lock on to one or more of the cells in either country, then we would at least have proof of two things:
1) MH370 really did fly southwest
2) the time of passing overhead these points
Btw, same goes for the - now largely discounted - northern route.
We all know that on every flight there is a certain number of phones that don't get switched off or put into 'flight mode'.
Now, these phones would try to lock on to a ground-based station during the flight. We've had this discussion here before and know it's perfectly feasible from 30+k feet.
IF the aircraft really headed out into the Indian Ocean, then it must have overflown Malaysia and Indonesia. Does anyone know if the Telcos in these two countries checked their logs for the night in question? If (and again, a big IF) any of the phones on board had tried to lock on to one or more of the cells in either country, then we would at least have proof of two things:
1) MH370 really did fly southwest
2) the time of passing overhead these points
Btw, same goes for the - now largely discounted - northern route.
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don't forget a ?sinusoidal? rate of change if the TX crosses the concentric signal elevations.
Let me give a wild example that I personally witnessed a number of years ago in a related context. Someone had put a wifi relay in a tree with a clear line of sight to a bedroom window in the guest house. During the day the guests kept complaining of congestion on the line, despite the fact they were the only ones at home. It was a puzzle because the ping time got steadily worse during the day and then quickly recovered at night. A full wifi site analysis was done and no radio interference was found.
The culprit that was eventually discovered? The wind. Wait, how can wind affect the radio waves? It can't, directly. But what the wind was doing was blowing the small branches of the tree around. The location experienced a great deal of diurnal heating and as the heat increased during the day so did the wind and so did the amount of interference from the tree branches and so the ping time increased during the day and fell off at night in rhythm to the wind. The owner of the guest house had put the wifi relay in a tree because he felt it was unsightly and so long as there was no wind his plan worked correctly.
The point--radio waves are a tricky thing. In a normal situation there are not many causes of interference between an airplane at 35K and a satellite. But nothing about this situation appears normal. So I think it is something of a leap of faith to say that increasing ping times=increasing distance. It's a decent assumption but we've already seen how other reasonable assumptions have turned out to be wrong.
The Inmarsat Exec said the statement "the satellite wants to see if you still want service." That indicates to me that the satellite, not the SATCOM, initates the ping. It sounds like, after 60 minutes of silence, the Satellite wants to confirm that you are still on it's network. If you don't respond, it takes you off of its active device registry until you come back online and initiate contact.
Last edited by MountainBear; 21st Mar 2014 at 17:11. Reason: avoid double post
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Originally Posted by oldgrumpy
yes there is and if you had bothered scrolling back a few pages you would have found posted by cyanr
Originally Posted by Mountain Bear
So I think it is something of a leap of faith to say that increasing ping times=increasing distance. It's a decent assumption but we've already seen how other reasonable assumptions have turned out to be wrong.
Originally Posted by awblain
The South China Sea information allows Inmarsat to be confident that the 0100 signals were consistent with a "red arc" that goes through that area.
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172,
Phantom phone tie ins from air to ground could perhaps rule out the "Northern Route". The phone providers of the missing passengers should know whether anything was received or sent from a live phone after take off.
In any case, a better look at the Thai and Malaysian (and Singaporean and Indonesian?) radar records should eventually be able to work out whether the reported zigzags over the Andaman Sea actually happened.
However, there's no mast to talk to from a cellphone all the way from Java to Antarctica on the "Southern Route", and while Three Letter Agencies are supposed to be able to listen to calls from a distance, a phone inside a 777 is not nearly as clear to listen to as a phone outside a 777.
Phantom phone tie ins from air to ground could perhaps rule out the "Northern Route". The phone providers of the missing passengers should know whether anything was received or sent from a live phone after take off.
In any case, a better look at the Thai and Malaysian (and Singaporean and Indonesian?) radar records should eventually be able to work out whether the reported zigzags over the Andaman Sea actually happened.
However, there's no mast to talk to from a cellphone all the way from Java to Antarctica on the "Southern Route", and while Three Letter Agencies are supposed to be able to listen to calls from a distance, a phone inside a 777 is not nearly as clear to listen to as a phone outside a 777.
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BOAC,
I think the only thing that rules out the "Northern Arc" is the lack of any reported radar returns that way consistent with a mystery 777, and also a lack of a wrecked 777 out that way, but then there's a lot of nothing in central Asia.
It could have avoided radar coverage on an early weekend morning, and be waiting to be found in a hole in the desert or mountains somewhere.
But if it impacted on land, you might expect to have heard from the ELT beacon?
I think the only thing that rules out the "Northern Arc" is the lack of any reported radar returns that way consistent with a mystery 777, and also a lack of a wrecked 777 out that way, but then there's a lot of nothing in central Asia.
It could have avoided radar coverage on an early weekend morning, and be waiting to be found in a hole in the desert or mountains somewhere.
But if it impacted on land, you might expect to have heard from the ELT beacon?
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In any case, a better look at the Thai and Malaysian (and Singaporean and Indonesian?) radar records should eventually be able to work out whether the reported zigzags over the Andaman Sea actually happened.
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Thanks TelecoAg. It does make much more sense to me that the satellite initiates the ping each hour.
In any case, the satellite has to send a message and get a return message as part of the ping exchange in order to be sure of the identity of the plane. Typically it would encrypt a random number using the specific plane's public key and check that the supposed plane was able to decrypt that message and return it encrypted with the satellite's public key.
The satellite's accurate clocks can then record timestamps for the sending and receiving parts of that message.
The journey of the message each way would take about 130 millseconds while it would only take 1-2 millseconds for the plane's equipment to process the incoming message and send a response back. Thus most of the 262 milliseconds difference in timestamps would be travel time.
This gives a pretty good estimate of distance between satellite and plane.
In any case, the satellite has to send a message and get a return message as part of the ping exchange in order to be sure of the identity of the plane. Typically it would encrypt a random number using the specific plane's public key and check that the supposed plane was able to decrypt that message and return it encrypted with the satellite's public key.
The satellite's accurate clocks can then record timestamps for the sending and receiving parts of that message.
The journey of the message each way would take about 130 millseconds while it would only take 1-2 millseconds for the plane's equipment to process the incoming message and send a response back. Thus most of the 262 milliseconds difference in timestamps would be travel time.
This gives a pretty good estimate of distance between satellite and plane.
Last edited by ana1936; 21st Mar 2014 at 17:44. Reason: typo
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Mountain Bear,
But you were looking through a tree in that example, and there are none between a 777 and the satellite.
The "ping time" in that example I think is also a time required to transmit a certain amount of data across your network, so you were measuring a data rate being slowed by the whirling tree, and not a time of flight/path length increased with time like Inmarsat were.
Inmarsat have many hundreds of thousands of flight records that they can test their method against. I'm sure they wouldn't broadcast faulty information.
But you were looking through a tree in that example, and there are none between a 777 and the satellite.
The "ping time" in that example I think is also a time required to transmit a certain amount of data across your network, so you were measuring a data rate being slowed by the whirling tree, and not a time of flight/path length increased with time like Inmarsat were.
Inmarsat have many hundreds of thousands of flight records that they can test their method against. I'm sure they wouldn't broadcast faulty information.