Malaysian Airlines MH370 contact lost
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Interpretation of the SATCOM signals is key. What radios were the signals received on, which beams, was there a pattern visible in signal strength that can be attributed to potential terrestrial weather attenuation or triangulated to a track?
Rule out where the aircraft could not possibly be.
Rule out where the aircraft could not possibly be.
Last edited by davionics; 15th Mar 2014 at 07:42. Reason: Minor addition
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Hell of a thread you guys have going. Don't want to interrupt, but thought you might like a general understanding of the sat location process.
When the satcom transmitter checks in with the satellite, the satellites keep a registration of what the received signal level was. It's obvious that this is all they are going off of now.
When you've got an object moving in the third dimension it will significantly expand the range that you have to consider for the transmitter to be in. What they are doing here is building an area within a received signal level (RSL) threshold where both satellite A and satellite B would be receiving a range of signal levels. For instance, you limit it to an area where sat A receives between -85 to -90db and Sat B receives between -40 to -45 DB. There are lots of other considerations such as interference levels and noise to be considered.
Once you have that area mapped, you have to mirror it across the line of latitude shared by the two satellites in geo. This is because you only have two satellites, and points where similar signal strengths intersect would happen in both places. It's kind of like picking the two spots where the circumference of two circles in a Venn diagram would cross.
Great stuff on this thread.
When the satcom transmitter checks in with the satellite, the satellites keep a registration of what the received signal level was. It's obvious that this is all they are going off of now.
When you've got an object moving in the third dimension it will significantly expand the range that you have to consider for the transmitter to be in. What they are doing here is building an area within a received signal level (RSL) threshold where both satellite A and satellite B would be receiving a range of signal levels. For instance, you limit it to an area where sat A receives between -85 to -90db and Sat B receives between -40 to -45 DB. There are lots of other considerations such as interference levels and noise to be considered.
Once you have that area mapped, you have to mirror it across the line of latitude shared by the two satellites in geo. This is because you only have two satellites, and points where similar signal strengths intersect would happen in both places. It's kind of like picking the two spots where the circumference of two circles in a Venn diagram would cross.
Great stuff on this thread.
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A few posters have suggested that if, indeed the aircraft was hijacked/stolen, the hijackers/thieves would likely want to communicate with a ground crew somewhere, and for this they would need the aircraft's SATCOM capability.
I beg to differ. A simple satellite phone would do nicely. They are small enough to easily be taken on as hand luggage.
Coincidentally, a satellite phone call could well be handled through Immarsat.
Immarsat haven't said precisely what data they handled. Read into it what you will.
I beg to differ. A simple satellite phone would do nicely. They are small enough to easily be taken on as hand luggage.
Coincidentally, a satellite phone call could well be handled through Immarsat.
Immarsat haven't said precisely what data they handled. Read into it what you will.
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Its obvious to me that the aircraft is "pinging home" sending packets of data back to a control centre, where they get distributed to various people depending on what they are and who subscribe to them.
MAS do not subscribe, so they don't get them.
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Thanks for the insight! So would it likely be comparing the levels between the IOR and POR satellites here?
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why is that obvious?
I don't think the transmitted data is carrying anything meaningful in terms of the location, or they'd be going off of that.
What I've seen so far indicates RSL measurements from 2 receiving antennas.
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I agree with LongTimeInCX, the logistics of having to look after 239 pax and crew on some bush airstrip, with or without the heightened interest of the whole World watching, is just inconceivable. A friend has suggested that North Korea could, and might have, coped with such a problem, and certainly the aircraft had the fuel to reach there, assuming that all ATC units en route ignored a silent target and also that North Korea was expecting it - else they would have shot it down as it crossed the border - but there seems to be incontravertible evidence that it went the other way.
I think it is now undoubtedly at the bottom of the Deep Blue Sea - but where?
Location of the FDR will confirm how it got there, but only the CVR ( voice recorder ) will determine why, and if that is never found we might just as well consign the event to history right now and get on with Life.
I think it is now undoubtedly at the bottom of the Deep Blue Sea - but where?
Location of the FDR will confirm how it got there, but only the CVR ( voice recorder ) will determine why, and if that is never found we might just as well consign the event to history right now and get on with Life.
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Even more astonishing
It is, of course, all too easy to persuade oneself that one might have thought of X at the time: "hindsight is 20/20".
However, even bearing this principle in mind, it is breathtaking that the Malaysians failed to look carefully at their own primary radar recordings (civilian and military) around the place and time of loss of contact.
Similarly, as discussed at some length here earlier, civilian and military radar systems should have worked to make sense of each and every aircraft overflying peninsular Malaysia, including aircraft flying between established waypoints.
Either these basic steps were neglected over several days, or Malaysia's establishment balked at confronting the likely religious motivation behind a hijacking.
However, even bearing this principle in mind, it is breathtaking that the Malaysians failed to look carefully at their own primary radar recordings (civilian and military) around the place and time of loss of contact.
Similarly, as discussed at some length here earlier, civilian and military radar systems should have worked to make sense of each and every aircraft overflying peninsular Malaysia, including aircraft flying between established waypoints.
Either these basic steps were neglected over several days, or Malaysia's establishment balked at confronting the likely religious motivation behind a hijacking.
I'd hoped the 45,000 feet figure had been kicked into touch by the time I got back here, seems it's still being argued over.
IMHO a Rolls powered T7 at that stage of that flight isn't going to close to getting get up there.
And yes I've done many performance courses and operate (at times) a Rolls powered T7.
Now OTOH if there's proof that there were significant height excursions and that that the aircrfat then continued onwards in stable flight I am minded to think back to a notorious incident a European airline had probably well over a decade ago.
IMHO a Rolls powered T7 at that stage of that flight isn't going to close to getting get up there.
And yes I've done many performance courses and operate (at times) a Rolls powered T7.
Now OTOH if there's proof that there were significant height excursions and that that the aircrfat then continued onwards in stable flight I am minded to think back to a notorious incident a European airline had probably well over a decade ago.
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@p.j.m.
Because when the aircraft is pinging home, it doesn't do so directly, it is relayed via satellite. This is exactly the kind of stuff Immarsat does
As has been previously noted in the thread, the pings would have been sent out even though MAL does not subscribe to Boeing's Health Check software.
Because when the aircraft is pinging home, it doesn't do so directly, it is relayed via satellite. This is exactly the kind of stuff Immarsat does
As has been previously noted in the thread, the pings would have been sent out even though MAL does not subscribe to Boeing's Health Check software.
Props are for boats!
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The Presidents statement doesn't quite add up...
"Today, based on raw satellite data that was obtained from the satellite data service provider, we can confirm that the aircraft shown in the primary radar data was flight MH370. After much forensic work and deliberation, the FAA, NTSB, AAIB and the Malaysian authorities, working separately on the same data, concur.
According to the new data, the last confirmed communication between the plane and the satellite was at 8:11AM Malaysian time on Saturday 8th March. The investigations team is making further calculations which will indicate how far the aircraft may have flown after this last point of contact. This will help us to refine the search.
Due to the type of satellite data, we are unable to confirm the precise location of the plane when it last made contact with the satellite."
Surely if the satellite data can't confirm precise position how can they confirm the Military Primary plots then. Something is a miss here......
"Today, based on raw satellite data that was obtained from the satellite data service provider, we can confirm that the aircraft shown in the primary radar data was flight MH370. After much forensic work and deliberation, the FAA, NTSB, AAIB and the Malaysian authorities, working separately on the same data, concur.
According to the new data, the last confirmed communication between the plane and the satellite was at 8:11AM Malaysian time on Saturday 8th March. The investigations team is making further calculations which will indicate how far the aircraft may have flown after this last point of contact. This will help us to refine the search.
Due to the type of satellite data, we are unable to confirm the precise location of the plane when it last made contact with the satellite."
Surely if the satellite data can't confirm precise position how can they confirm the Military Primary plots then. Something is a miss here......
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With the "New" information in mind, I return to a post I made this time yesterday. An American General interviewed by Fox suggested that the aircraft was bound for Pakistan. Again, that was before the NW OR SW corridors had been speculated.
IMHO, if it did head NW, Pakistan is the most likely destination because I can't believe a T7 would get anywhere near Afghanistan or beyond unnoticed. That part of the world is full of US assets, including drones. Conversely, large areas of Pakistan are under the effective control of the Taliban. If it was piracy, this would be the most likely destination.
If it was a suicide mission by whomever, the Southern track out over the Southern IO would be more likely. And that probably explains why US asssets were already being positioned in the Indian Ocean.
If indeed the aircraft did go up to FL450 immediately after going silent, that suggests that hostages were not an issue. So unless there was an extremely valuable cargo (And we still haven't seen a cargo manifest) it would seem to point to the suicide mission by a person or persons unknown, in which case the IO seems more probable.
Even if it is found, the CVR will be useless as it only records two hours. The DFDR won't, necessarily, provide anything definitive either?
IMHO, if it did head NW, Pakistan is the most likely destination because I can't believe a T7 would get anywhere near Afghanistan or beyond unnoticed. That part of the world is full of US assets, including drones. Conversely, large areas of Pakistan are under the effective control of the Taliban. If it was piracy, this would be the most likely destination.
If it was a suicide mission by whomever, the Southern track out over the Southern IO would be more likely. And that probably explains why US asssets were already being positioned in the Indian Ocean.
If indeed the aircraft did go up to FL450 immediately after going silent, that suggests that hostages were not an issue. So unless there was an extremely valuable cargo (And we still haven't seen a cargo manifest) it would seem to point to the suicide mission by a person or persons unknown, in which case the IO seems more probable.
Even if it is found, the CVR will be useless as it only records two hours. The DFDR won't, necessarily, provide anything definitive either?
Last edited by philipat; 15th Mar 2014 at 08:06.
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Difference between FACT and INFERENCE
Let us recognize that the Malysian PM is most likely not trained as a physicist (an inference of mine), and when he starts hinting at what he thinks are facts, he is actually speaking of deductions, or inferences.
We already have the Facts of the take-off, destination, last radio contact, message, and no transponder signal. We have as Fact the last known Heading and Altitude.
We have these indications of "pings" being picked up, with no further details. That event gets transposed in the "fact" that the ping(s) came from this aircraft, but that is not fact, that is inference. From that, we have the deductive inference that this aircraft is still flying around at altitude for some 7.5 hours after last contact. Again, this inference gets transposed into "fact." Except it isn't.
Absence of events are also facts. Factually, nobody has seen this aircraft. Nobody has reliably reported seeing it land in Tajikistan, or anywhere else. Nobody has seen it crash, and nobody has seen any wreckage. There is no factual basis to indicate that it has crashed over water. There is no factual basis to say it has not, conversely. Equally, there is no factual basis that it crashed into terrain; nor that it did not.
There have been some rather short, and snippy, even pejorative sniping by highly experienced professional pilots at other pilots, which leads me to the inference (not fact) that everybody's nerves are getting frayed. And you fellows, who are historically exceptionally cool under pressures that would crack any mere mortal, should know better. Since you have ice water in your veins, now is the time to show it.
We can make some inferences based on plausibility. Is it plausible that this aircraft is still flying around, thousands of miles from where it should be, at altitude, and not near any place to land, some 7.5 hours after last radio contact? Nope. It is plausible that the aircraft flew right across India for hours and was undetected? Nope. It it plausible that it flew undetected towards Perth? Nope. Is it plausible that it was taken over by hijackers, flown around by amateurs, landed in the dark on the undercarriage on some 7,500-ft surface capable of handling the weight, without lights or any ILS - and nobody in authority knows anything about it? Nope. Is it plausible that it splashed and left no vast field of debris and bodies - as all other water crashes have done? Nope.
Is it plausible that, after 7 days with no facts linked directly and observably to this aircraft, and that we still do not know what ocean (or land mass) this aircraft is in, we may never know? Unfortunately, Yes. That is plausible.
We already have the Facts of the take-off, destination, last radio contact, message, and no transponder signal. We have as Fact the last known Heading and Altitude.
We have these indications of "pings" being picked up, with no further details. That event gets transposed in the "fact" that the ping(s) came from this aircraft, but that is not fact, that is inference. From that, we have the deductive inference that this aircraft is still flying around at altitude for some 7.5 hours after last contact. Again, this inference gets transposed into "fact." Except it isn't.
Absence of events are also facts. Factually, nobody has seen this aircraft. Nobody has reliably reported seeing it land in Tajikistan, or anywhere else. Nobody has seen it crash, and nobody has seen any wreckage. There is no factual basis to indicate that it has crashed over water. There is no factual basis to say it has not, conversely. Equally, there is no factual basis that it crashed into terrain; nor that it did not.
There have been some rather short, and snippy, even pejorative sniping by highly experienced professional pilots at other pilots, which leads me to the inference (not fact) that everybody's nerves are getting frayed. And you fellows, who are historically exceptionally cool under pressures that would crack any mere mortal, should know better. Since you have ice water in your veins, now is the time to show it.
We can make some inferences based on plausibility. Is it plausible that this aircraft is still flying around, thousands of miles from where it should be, at altitude, and not near any place to land, some 7.5 hours after last radio contact? Nope. It is plausible that the aircraft flew right across India for hours and was undetected? Nope. It it plausible that it flew undetected towards Perth? Nope. Is it plausible that it was taken over by hijackers, flown around by amateurs, landed in the dark on the undercarriage on some 7,500-ft surface capable of handling the weight, without lights or any ILS - and nobody in authority knows anything about it? Nope. Is it plausible that it splashed and left no vast field of debris and bodies - as all other water crashes have done? Nope.
Is it plausible that, after 7 days with no facts linked directly and observably to this aircraft, and that we still do not know what ocean (or land mass) this aircraft is in, we may never know? Unfortunately, Yes. That is plausible.
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Its obvious to me that the aircraft is "pinging home" sending packets of data back to a control centre, where they get distributed to various people depending on what they are and who subscribe to them.
I think that no location data is included in the pings and even if it was it would not be decoded on sat, so they will have to work with just signal analysis, not even exact triangulation, as someone explained before, from that the "corridors" notion.
Last edited by lapp; 15th Mar 2014 at 08:36.
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Motive...
If it is piracy then what is the motive. Either very VIP PAX we haven't been told about or cargo. Why aren't they telling us about the cargo if that is all so innocent? and why aren't the press jumping up and down asking about it? 
I have been inside the E/E compartment of the 777 during flight. We had to push back a few CB's which were not pushed back during a hangar visit. (all lavatories didn't fuction) we found out about 30 minutes after departure when the first passengers started going to the lavatories.
Took a portable O2 bottle with me, in case of decompression while I was down below. took about 3 minutes total time. Saved us from having to turn back.
Took a portable O2 bottle with me, in case of decompression while I was down below. took about 3 minutes total time. Saved us from having to turn back.
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These reports of looking in Turkmenistan AND northern Thailand are surely misrepresentations, unless the news editors' atlases were just open at T in the index. Turkmenistan is as far from KL as Beijing is, but a long long way from northern Thailand.
The intention of the press statement was presumably to say that there's the possibility of looking along a track from Turkmenistan to Thailand - since it presumably wasn't seen by either Chinese or Indian radars.
The intention of the press statement was presumably to say that there's the possibility of looking along a track from Turkmenistan to Thailand - since it presumably wasn't seen by either Chinese or Indian radars.
