Malaysian Airlines MH370 contact lost
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Apologies if this is a dumb question (this is definitely not my area of expertise) but I remember reading that it was possible the 18:25 ACARS log on request could possibly have been triggered by a sharp turn? Would it then fit that the plane may have turned south at 18:25, meaning it would definitely have completed the turn and be flying south by 18:40?
There are other possible interpretations - BFOs are strongly affected by vertical speed, so it could be that it was headed south while climbing (there are irregularities in 18:25 .. 18:28 period indicative of climbing) - but the simplest one is that the turn took place after 18:28 and before 18:40.
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The new location is still in the area being surveyed for the Australian government.
The new location is a bit further south-west than the previous one, based on new analysis of the data.
What, exactly, is supposed to look clueless about that?
I agree Richard C10. Up to a point. That is probably how you would like to analyse the satellite data and model the possible tracks. As a purely scientific exercise.
However real life is always more messy, and there were many other factors and agendas going on.
1. Inmarsat was breaking new ground here. The BTO analysis came out first, and this data was easily understood and was presumably readily accepted. So we had the north and the south arcs. The south arc was initially seen as more likely as no one (especially India) had observed the plane over the northern arc.
2. As soon as the south Indian ocean was identified as a possible area, everyone with a satellite started finding debris.
3. Then the BFO analysis came out. This was far more complex than the BTO analysis. It took time, It required corroboration by independent scientists. And there was likely a degree of circumspection in various quarters. None the less, the BFO analysis identified a likely area - not so far away from the area now thought to be most promising.
4. Then came an air search. Due to all the delays, it was already very late when this was started. Even if debris had been found, it would have been difficult to backtrack. However it was the best hope at the time, and so began a multinational air search that was complicated by the distance from land and poor weather. This was only called off when it was clear the delay meant that backtracking would be futile.
5. At some point, the search area moved a long way NE along the arc. It has never been made clear why this happened. People have speculated that a UK submarine detected something that could have been a pinger, but we will likely never know the explanation for this. Ships went to this new area and seemed to have immediate success finding the pinger. It turned out there was no pinger and the noise heard came from the ship. Yes that was all a bit of a screw up.
6. Hence back to the BFO data. The highest probability area was calculated on the basis of detailed calculations and utilising different models, and is fairly close to the earlier area. So they started to map the ocean floor (this area is practically unknown) in preparation for another search.
7. They have now incorporated information from an unanswered call to help refine the search area. Presumably this data pushes the search area a little further SW.
On top of all this has been significant political and diplomatic pressures. There was certainly an initial reluctance on the part of the Malaysians to tell all they knew. The Australian Prime Minister was under pressure, and jumped the gun based on satellite photos of debris.
Its not been perfect. Far from it. Things are always easy in retrospect.
In fairness, it has probably been about as good as could have reasonably been expected in the real world. This is especially true given this event was unprecedented, and given we have been using technology in novel ways.
However real life is always more messy, and there were many other factors and agendas going on.
1. Inmarsat was breaking new ground here. The BTO analysis came out first, and this data was easily understood and was presumably readily accepted. So we had the north and the south arcs. The south arc was initially seen as more likely as no one (especially India) had observed the plane over the northern arc.
2. As soon as the south Indian ocean was identified as a possible area, everyone with a satellite started finding debris.
3. Then the BFO analysis came out. This was far more complex than the BTO analysis. It took time, It required corroboration by independent scientists. And there was likely a degree of circumspection in various quarters. None the less, the BFO analysis identified a likely area - not so far away from the area now thought to be most promising.
4. Then came an air search. Due to all the delays, it was already very late when this was started. Even if debris had been found, it would have been difficult to backtrack. However it was the best hope at the time, and so began a multinational air search that was complicated by the distance from land and poor weather. This was only called off when it was clear the delay meant that backtracking would be futile.
5. At some point, the search area moved a long way NE along the arc. It has never been made clear why this happened. People have speculated that a UK submarine detected something that could have been a pinger, but we will likely never know the explanation for this. Ships went to this new area and seemed to have immediate success finding the pinger. It turned out there was no pinger and the noise heard came from the ship. Yes that was all a bit of a screw up.
6. Hence back to the BFO data. The highest probability area was calculated on the basis of detailed calculations and utilising different models, and is fairly close to the earlier area. So they started to map the ocean floor (this area is practically unknown) in preparation for another search.
7. They have now incorporated information from an unanswered call to help refine the search area. Presumably this data pushes the search area a little further SW.
On top of all this has been significant political and diplomatic pressures. There was certainly an initial reluctance on the part of the Malaysians to tell all they knew. The Australian Prime Minister was under pressure, and jumped the gun based on satellite photos of debris.
Its not been perfect. Far from it. Things are always easy in retrospect.
In fairness, it has probably been about as good as could have reasonably been expected in the real world. This is especially true given this event was unprecedented, and given we have been using technology in novel ways.
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Instead we have Inmarsat guarding their company secrets,
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New analysis of the data has been used multiple times already. It means that the former analysis has been incomplete, has been wrong, has been what?
None of this satellite data was ever designed to be used to locate a missing aircraft. The BTO was thought to be a means of extracting some information to help locate an aircraft in an incident like AF447 where we already knew the approximate area, but not to find one that had vanished without trace. No-one expected to find useful information in the BFO data, because the aircraft was supposed to correct for frequency offsets, so this has all come from reverse-engineering the corrections made.
And all of the detailed position estimates are heavily reliant on knowing where the aircraft turned south. Anything that changes the estimate of that position inevitably changes the final position.
So the odds are good that it won't be found exactly where they're now predicting, because there are so many other variables that can only be estimated. But it's the best place to start, to minimize the amount of time spent searching the area they're now mapping.
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We should all remember that the disappearance of this aircraft is the subject of a criminal investigation and as such, not all information available to the investigating team is available to the public.
The investigating team and their advisors may look ill informed but it is wise to remember that they probably have more information than we do.
The investigating team and their advisors may look ill informed but it is wise to remember that they probably have more information than we do.
"We should all remember that the disappearance of this aircraft is the subject of a criminal investigation and as such, not all information available to the investigating team is available to the public.
The investigating team and their advisors may look ill informed but it is wise to remember that they probably have more information than we do."
then it would be fair from them to say "we have some informations that we can not disclose at this point", not look totally inept calculating numbers that at first aren't reliable enough to prove anything
The investigating team and their advisors may look ill informed but it is wise to remember that they probably have more information than we do."
then it would be fair from them to say "we have some informations that we can not disclose at this point", not look totally inept calculating numbers that at first aren't reliable enough to prove anything
It's not an easy task. Trying to determine ground speed and heading over many hours from a handful of values for velocity away from a satellite.
Agree that vertical velocity will influence velocity relative to satellite. But not sufficient to produce a false (of to conceal a real) major heading change.
To me it seems very good news if we have been able to significantly narrow down the time when the aircraft turned south.
Agree that vertical velocity will influence velocity relative to satellite. But not sufficient to produce a false (of to conceal a real) major heading change.
To me it seems very good news if we have been able to significantly narrow down the time when the aircraft turned south.
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The transcript of the press conference after the tripartite meeting has been published:
Transcript of Press Conference, 28 August 2014
The answer about the investigation is not, IMHO, very clear.
And perhaps an update after somebody undestanding the Chinese will be found?
Transcript of Press Conference, 28 August 2014
The answer about the investigation is not, IMHO, very clear.
And perhaps an update after somebody undestanding the Chinese will be found?
chronus:
Utterly disagree with your demand / appeal for more info release on the criminal investigation. Considering the nature of this from the criminal aspect, the law enforcement folks are better off keeping as low a profile as possible as they undertake their very difficult investigation.
As above, you do not have a need to know, nor any right to know, about the ongoing investigation. When they are complete, I am confident that there will be sufficient press releases and public disclosure to meet public information requirements.
Are you?
If not, why not?
I also suspect that the criminal investigation is stalled pending retrieval of the aircraft and such data as that eventual discovery may provide. More leads, albeit cold.
Whilst public attention is focused on the search effort, no reports are released on the criminal investigation which continues under wraps. Is it not high time the authorities release some information as to progress on this aspect of the search for answers.
As above, you do not have a need to know, nor any right to know, about the ongoing investigation. When they are complete, I am confident that there will be sufficient press releases and public disclosure to meet public information requirements.
Are you?
If not, why not?
I also suspect that the criminal investigation is stalled pending retrieval of the aircraft and such data as that eventual discovery may provide. More leads, albeit cold.
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It's not an easy task. Trying to determine ground speed and heading over many hours from a handful of values for velocity away from a satellite.
Agree that vertical velocity will influence velocity relative to satellite. But not sufficient to produce a false (of to conceal a real) major heading change.
Agree that vertical velocity will influence velocity relative to satellite. But not sufficient to produce a false (of to conceal a real) major heading change.
The difference between BFOs at 18:28 and 18:40 (and the difference between heading northwest and heading south) is around 55 Hz.
According to ATSB, aircraft systems don't compensate for vertical velocity at all. (Unlike horizontal velocity, which is compensated for, but with assumptions about stationary satellite.)
Total (or uncorrected) horizontal velocity is much greater than vertical velocity. But are you suggesting the aircraft corrects for its own ground speed? And so vertical velocity becomes relatively greater when compared to horizontal velocity corrected for ground speed? That is, vertical velocity makes a significant contribution to BFO because horizontal velocity is corrected for ground speed.
Have I got that right?
Presumably the aircraft uses GPS to establish its ground speed. Would GPS always have been available? Presumably GPS does not rely on satcom, and someone piloting the aircraft around the tip of Sumatra would have relied on GPS.
How about the postulated fuel exhaustion at the end, and the final partial log on perhaps due t APU. Would the aircraft system have a GPS derived ground speed available in order to apply the necessary correction at this log on. Or would ground speed still be in the process of being established at the time of the satcom log on, and would a ground speed of zero be assumed and no correction be applied (it would make sense I guess for the system to initially assume aircraft not moving when system booted up).
Sorry for all the questions. A lot of this technical stuff is beyond me.
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I'm trying to understand this.
Total (or uncorrected) horizontal velocity is much greater than vertical velocity. But are you suggesting the aircraft corrects for its own ground speed? And so vertical velocity becomes relatively greater when compared to horizontal velocity corrected for ground speed? That is, vertical velocity makes a significant contribution to BFO because horizontal velocity is corrected for ground speed.
Total (or uncorrected) horizontal velocity is much greater than vertical velocity. But are you suggesting the aircraft corrects for its own ground speed? And so vertical velocity becomes relatively greater when compared to horizontal velocity corrected for ground speed? That is, vertical velocity makes a significant contribution to BFO because horizontal velocity is corrected for ground speed.
The aircraft can get ground speed and heading from GPS as well as from the inertial reference system. Both sources would agree with each other under normal circumstances. I'm not sure what would happen if circumstances are less than normal (an in-flight power outage would scramble the state of the IRS and necessitate manual realignment, and there may not be anybody in the cockpit to do this.)
Last edited by hamster3null; 3rd Sep 2014 at 07:41.
Thanks for that. I had understood about the satellite not being truly stationary. However I had forgotten the bit about the aircraft correcting for its own speed.
I wonder if the BFO for the final partial handshake was wildly different to the previous ones, which is what you might expect if the correction was not available for this final event. The graph I have seen (included in link below) does not seem to show this final 0019 UTC event.
MH370: What does Inmarsat ping data reveal? | Air Traffic Management | Air Traffic Management - ATM and CMS Industry online, the latest air traffic control industry, CAA, ANSP, SESAR and NEXTGEN news, events, supplier directory and magazine
This link also gives the 0011 data but not the 0019 data
Aqqa on MH370
One thing I noted in this graph is the progressive increase in BFO over time. Presumably this is not because of increasing ground speed, but because the plane was flying an arc. That is, as the plane flew further south and the satellite became progressively lower in the sky, the relative velocity between plane and satellite progressively increased (even though ground speed may have remained constant).
I wonder if the BFO for the final partial handshake was wildly different to the previous ones, which is what you might expect if the correction was not available for this final event. The graph I have seen (included in link below) does not seem to show this final 0019 UTC event.
MH370: What does Inmarsat ping data reveal? | Air Traffic Management | Air Traffic Management - ATM and CMS Industry online, the latest air traffic control industry, CAA, ANSP, SESAR and NEXTGEN news, events, supplier directory and magazine
This link also gives the 0011 data but not the 0019 data
Aqqa on MH370
One thing I noted in this graph is the progressive increase in BFO over time. Presumably this is not because of increasing ground speed, but because the plane was flying an arc. That is, as the plane flew further south and the satellite became progressively lower in the sky, the relative velocity between plane and satellite progressively increased (even though ground speed may have remained constant).
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The spokesman was very careful not to overstate the significance. Faced with a phenomenon like this, is it likely that they will investigate this immediately or simply wait until they get to that location with the search plan?
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The preliminary sea-bed mapping of the area has found areas where the water depth is as shallow as 600 metres and within a couple of kilometres, it has gone to 6000 metres. It has also found undersea volcanoes. "Challenging" is the understatement of the month for this piece of seabed, and the location and recovery of any critical MH370 wreckage is going to be one of the most difficult undersea operations ever mounted.