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Malaysian Airlines MH370 contact lost

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Malaysian Airlines MH370 contact lost

Old 24th Jul 2014, 16:20
  #11421 (permalink)  
 
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Wind-Tunnel,
I am a bit bothered too with the data. Here are my last (Montecarlo simulation) results:
The last south legs of all the simulated trajectories are at constant speed (and altitude) and the south turn occurs randomly between 18:28 and 18:40: it is assumed that the C-channel BFO measure of 88 Hz at 18:41 is a valid one (it is included in the observed BFO profile the trajectories are trying to mimick) and suggests a south bearing at 18:41. The constant (ground) speeds span from 330 kts to 530 kts, the crash latitudes from 22S to 41S:
https://drive.google.com/file/d/0B3s...it?usp=sharing
https://drive.google.com/file/d/0B3s...it?usp=sharing
The first part of all the trajectories comply with the ADS-B measures (they are not randomized on this first leg), and roughtly with the Butterworth radar track above the Malacca strait (supposedly linked to the MH370 ). When the south turn is triggered, a constant speed reference trajectory is built (intersecting two kinds of small circles on the earth spheroid: the ping rings and the positions reachable from one given location at a given constant speed) from the A/C position and randomized:
https://drive.google.com/file/d/0B3s...it?usp=sharing
The trajectories best fitting to the observed BTO/BFO values are around 460 kts (true gound speed) and end near 36S, not near 30S (ATSB):
https://drive.google.com/file/d/0B3s...it?usp=sharing
https://drive.google.com/file/d/0B3s...it?usp=sharing
the BFO errors versus the crash latitude:
https://drive.google.com/file/d/0B3s...it?usp=sharing
the BFO errors versus handshake instants and ground speed:
https://drive.google.com/file/d/0B3s...it?usp=sharing
the BFO and the BTO enveloppes of the 50 000 flights:
https://drive.google.com/file/d/0B3s...it?usp=sharing
But we do not know clearly what was the injection/turning point toward the last south leg in the ATSB report.
Jeff
PS) Rerunning the simulation (16h run time) to confirm these results.
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Old 24th Jul 2014, 18:19
  #11422 (permalink)  
 
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So, are we assuming that the 19:40 ping line was traversed in an easterly or westerly direction? Assuming the plane was travelling south east initially makes sense but then forces a much more southerly heading for the timing to be right for the 20:40 ping. Assuming the 19:40 ping occurred with the plane travelling west requires "the hook to the north" between 18:28 and 19:40 referred to in the Australian report but then allows a more plausible track through the 20:40 arc and results in a constant speed track which intersects the Northern end of the proposed search areas.

In the midst of all this, there is a glaring anomaly which doesn't go away unless and until you have accurate fuel figures. They have not been released AFAIK.

When all is said and done, you cannot make a good enough prediction of the terminal position unless you have certainty about the direction of travel at 19:40 and the fuel load. Even then, you must indulge in some educated guesswork to narrow down the possible tracks.

In the report, we have some clues which I think are important. The report states the likelihood that the southerly track was flown on autopilot and therefore, I am inclined to believe that any solution which would require any heading or speed changes becomes highly unlikely. This in turn, implies (to me at least) that the 19:40 direction was west because that fits in with the 20:40 ping and a plausible speed and heading.
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Old 24th Jul 2014, 19:17
  #11423 (permalink)  
 
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"The report states the likelihood that the southerly track was flown on autopilot"

I have seen it but never found out reason why.
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Old 24th Jul 2014, 20:08
  #11424 (permalink)  
 
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There is much information which is accessible to the investigation team but, not to us. We must await their conclusions.
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Old 24th Jul 2014, 20:53
  #11425 (permalink)  
 
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Ulric:
Your analysis is fine if one supposes that the tip of Indonesia is in fact,
the starting point of the southern track. This is far from clear from the known
data.
Ulric, I am not trying to build the ATSB's current model (and best estimate). I am trying to show you what the ATSB model (and best estimate) would have looked like in the March 17-27 era. Their report explicitly states (on p.5) that their working model at that time assumed a turn at the NW tip of Indonesia.

The reason replicating those (now obsolete) assumptions is important is because I go on to prove that the model update they (claim to have) made on March 27 could not possibly have supported the DECISION they made on March 28 - which was to move the search dramatically NE.
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Old 24th Jul 2014, 21:20
  #11426 (permalink)  
 
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I think that is a reasonable thing to do. Any projection of course is based on some set of assumptions and I think the report is laced with clues about what those assumptions were. You will appreciate that there are possible scenarios implied by the data which do not sit very well with public statements made by officials. We all realise (at least I assume we must by now) where these anomalies lie and that the data necessary to resolve them is not yet available to us.

Patience is a virtue in this case.
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Old 24th Jul 2014, 21:40
  #11427 (permalink)  
 
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Still think you're missing the point, Ulric. ATSB issued a release March 28 saying, "plane had less fuel, so we're moving search 1,100km NE". It is a matter of simple geometry to prove that, if the starting point doesn't change (Appendix A suggests it didn't), and the Inmarsat arcs didn't change (they have always been taken as gospel), then their statement is false - the decision is counter-indicated by what would have HAD to have been their model's reaction to less available fuel.

When the ATSB issues key statements (this fuel analysis underpinned the critical decision precipitating an 8 week waste of time and money up at s20 lat) which are provably false - and when this falsehood can be demonstrated by the ATSB's own data (which suggests they ought reasonably to have KNOWN they were false) - I for one feel that patience is one of the last things called for. On this, you and I may have to agree to disagree.
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Old 25th Jul 2014, 07:09
  #11428 (permalink)  
 
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I think the assumptions made by the investigating team are only provably false if you have certainty about some of the variables and in particular, the point at which the SSE course was assumed. Once you have fixed this point, speed and heading are covariant and the range of terminal points becomes constrained in exactly the way you describe. If you take away the certainty about the starting point, and I think we must, the range of available terminal points matches those assumed by the investigation team.

The message is clear - information about the starting point is not available to the investigators. I believe that should make us circumspect about accusing the investigation team of incompetence.
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Old 25th Jul 2014, 11:05
  #11429 (permalink)  
 
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Hyperveloce/Wind Tunnel

Excuse me if I am missing something but if the aircraft was on autopilot for the last southern leg (an assumption by ATSB) what effect would magnetic variation have on your calculations or is this allowed for? I am trying to get my head around the reasons the ATSB may have made that assumption other than "best fit model".
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Old 25th Jul 2014, 12:08
  #11430 (permalink)  
 
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This might help
https://upload.wikimedia.org/wikiped...ation_2010.pdf
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Old 25th Jul 2014, 16:40
  #11431 (permalink)  
 
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Post Fuel on board: 49,200 kg at 16:41.

Originally Posted by Ulric View Post
unless and until you have accurate fuel figures.
A "1641 492" fuel on board update (49,200 kg at 16:41) was included in the 16:41:58 ACARS OOOI off event:

The above may also be of interest for "Ian W", as it provides an example of an ACARS message, being forwarded via Satcom.
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Old 25th Jul 2014, 17:24
  #11432 (permalink)  
 
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Thank you very much for that. It is one of the outstanding pieces in the puzzle!
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Old 25th Jul 2014, 18:54
  #11433 (permalink)  
 
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Ulric,

Your last post claimed to rebut mine by pointing out that the turn point was not known. Good grief - where do I claim that it is? All I'm trying to do is accurately build the ATSB's first two performance models - for this project, then, "correct" means "what they were using as an assumption", not "where the plane actually turned". Please stay with me on that concept.

Why do I have confidence that my starting point - NW tip of Indonesia - is an accurate depiction of what the ATSB was assuming in late March?

1) That's what they said they used. On page 5 of their report. That was their assumed turn point for both March 17-27 (per p.5) and March 28-April 1 (per Appendix A) performance limits.

2) I have independently replicated their endurance line using a systematic endurance vs speed study from a paper by Delgado/Prats. When I calibrate one point of their model to the ATSB's endurance line, I find the Delgado/Prats model matches the ATSB line almost perfectly. The green line in my illustration is, in fact, the Delgado/Prats result. If I had a materially wrong starting turn point, the two curves (ATSB, Delgado/Prats) would have diverged. They match.

Last edited by Wind_Tunnel; 25th Jul 2014 at 20:32. Reason: concision
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Old 25th Jul 2014, 20:34
  #11434 (permalink)  
 
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All I'm saying is that if the start point is not known, the end point is not known because one is dependent on the other. The investigation team presumably have access to more information than we do and at some point they changed their minds about what they thought happened.

I don't have a problem with that but when you come along and start to claim that their working hypothesis back in March was "provably false", those are strong words and I have to respond by saying that it is probably irrelevant at this point in time.
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Old 26th Jul 2014, 01:02
  #11435 (permalink)  
 
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Ulric: your first two statements are completely true, and completely irrelevant to my point, for reasons already explained. They CERTAINLY have changed their mind about where the turn occurred - but not by March 28th.

Yes, "provably false" are strong words. Which is why I presented strong proof. If you don't understand it, just ask: I'm here to help; if you refuse to TRY to understand it, that's not my problem.

I have proven the ATSB went against (what they have described as) their own analysis in sending the search NE on March 28. They either...

1) stink at performance analysis,
2) lied (in release AND report) about why they REALLY moved NE, or
3) intentionally misdirected the search

I HOPE it's "only" 2) - and that the March 28 shift was for LEGITIMATE reasons. But if so, they should have told us what those legitimate reasons WERE; teams of spectacularly astute independent experts are working very hard trying to help find the plane; but they are working blind because of 2).

HIGHLY relevant, I'm afraid.
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Old 26th Jul 2014, 07:27
  #11436 (permalink)  
 
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teams of spectacularly astute independent experts are working very hard trying to help find the plane; but they are working blind because
Well they can't be particularly astute "experts" if they are working blind without access to the information that only those directly involved have..... sounds more like armchair investigators.
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Old 26th Jul 2014, 12:24
  #11437 (permalink)  
 
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I HOPE it's "only" 2) - and that the March 28 shift was for LEGITIMATE reasons. But if so, they should have told us what those legitimate reasons WERE; teams of spectacularly astute independent experts are working very hard trying to help find the plane; but they are working blind because of 2).

HIGHLY relevant, I'm afraid.
Indeed, it is highly relevant that the investigation team seems to have made a set of assumptions which is at odds with their public statements. There are however, good reasons for these discrepancies.

There are two bodies of information here which are qualitatively different. One is the set of public announcements made by various bodies which may be coloured by perceptions and motives that are not transparent. The other is the data. If one treats these two sets of information as separate, it becomes clear that there are differences in the implied track of the aircraft depending on how much weight one gives to each set. It also becomes clear why the investigators may be making assumptions which look inconsistent and are unable to be forthright about why they have done this.

I don't think this implies any impropriety on the part of the investigation team since I believe that the decisions they have made are sensible based on the data alone.
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Old 28th Jul 2014, 17:44
  #11438 (permalink)  
 
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Just one question for those on this forum with technical knowledge....


If the auto-pilot was set to a heading of 180 degrees, would the plane fly to the Magnetic, or Geological, South Pole? And would the flight path be a straight line, or deviated by the differing winds aloft?
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Old 28th Jul 2014, 17:58
  #11439 (permalink)  
 
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the auto-pilot was set to a heading of 180 degrees, would the plane fly to the Magnetic, or Geological, South Pole?
Heading is always magnetic unless your are very close to the Poles.

And would the flight path be a straight line, or deviated by the differing winds aloft?
Yes, the aircraft would be subject to winds aloft so its path would not be a straight line.
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Old 28th Jul 2014, 18:47
  #11440 (permalink)  
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Heading is always magnetic unless your are very close to the Poles.
- no. It is selectable at any latitude to either magnetic or true. Sometimes Grid at high latitudes.
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