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Malaysian Airlines MH370 contact lost

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Malaysian Airlines MH370 contact lost

Old 26th Jun 2014, 12:04
  #11161 (permalink)  
 
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Statistical Search Methods

Has any information been published on which, if any, mathematical/statistical models have been deployed in the MH370 search?

Bayesian methods were mentioned back in this post but only in relation to AF447.
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Old 26th Jun 2014, 13:11
  #11162 (permalink)  
 
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How do we know that an emergency descent was not initiated, making the groundspeed lower and the range much less? The latest ATSB report doesn't appear to discuss that possibility?
There probably several things that could increase the size of the search area but it's already vast. It seems to me sensible to make some assumptions to narrow it down. If they don't find anything they can always widen the area later.

Edit: The assumptions are on page 21.
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Old 26th Jun 2014, 13:30
  #11163 (permalink)  
 
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A very good and comprehensive report. It shows how professional the working groups are trying to resolve the problems.

The only thing I am missing is:
in which AP lateral mode (mag track? mag hdg?) would the 777 have flown, if LNAV along waypoints was ruled out?
A "direct to" is unlikely as the curved path does not seem to correspond to a great circle path.
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Old 26th Jun 2014, 14:36
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Originally Posted by Shadoko
- is it known how the BTO data published ("raw data" PDF) were measured? It is evident that the digits are not the whole go and back signal time.
It's clarified in the latest ATSB document. The BTO is the time between the time the transmission from the aircraft is received and the start of the timeslot when it should have been received. The aircraft calculates that timeslot by using the signal from the satellite as a reference. At the 'nominal location', the two should be perfectly synchronized.

See page 23 of: http://www.atsb.gov.au/media/4911984...370-report.pdf
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Old 26th Jun 2014, 14:48
  #11165 (permalink)  

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Three Miles
The only thing I am missing is:
in which AP lateral mode (mag track? mag hdg?) would the 777 have flown, if LNAV along waypoints was ruled out?
I think they have jumped to a conclusion that isn't justified. There is no reason why the aircraft couldn't have flown using LNAV to a waypoint or destination miles beyond its endurance. My theory stated many times is Wilkins Runway as destination and that is being backed up by the evidence in the report.
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Old 26th Jun 2014, 15:06
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Very interesting stuff!

After a quick reading, a probable stupid question: at the last page (58), table 6:
Downlink Doppler: -79.5 -75.1 -70.7 Hz Satellite movement, which I understand as the Doppler of the down link (the DeltaFdown variable of page 56), so between 3F-1 and Perth
Why does this value change with the latitude of the aircraft?
Does this value include the error for the faulty compensation from the aircraft because the satellite is assumed to be in another location it actually is?
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Old 26th Jun 2014, 16:13
  #11167 (permalink)  
 
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From page 34 of the ATSB report just released:

End of flight scenario

Note: Given the imprecise nature of the SATCOM data, it was necessary to make some assumptions regarding pilot control inputs in order to define a search area of a practical size. These assumptions were only made for the purposes of defining a search area and there is no suggestion that the investigation authority will make similar assumptions.

The limited evidence available for MH370 was compared with the accident classes listed previously.

In the case of MH370, there were multiple redundant communications systems fitted to the aircraft (3 x VHF radios, 2 x HF radios, SATCOM system, 2 x ATC transponders). However, no radio communications were received from the aircraft after 1719.29, 7 hours prior to the last SATCOM handshake at 00:19. Analysis of the SATCOM data also showed that there were probably no large changes to the aircraft’s track after approximately 1915, about 5 hours prior to the last SATCOM handshake.

Given these observations, the final stages of the unresponsive crew/ hypoxia event type appeared to best fit the available evidence for the final period of MH370’s flight when it was heading in a generally southerly direction:

 loss of radio communications
 long period without any en route manoeuvring of the aircraft
 a steadily maintained cruise altitude
 fuel exhaustion and descent

This suggested that, for MH370, it was possible that after a long period of flight under autopilot control, fuel exhaustion would occur followed by a loss of control without any control inputs.

Note: This suggestion is made for the sole purpose of assisting to define a search area. The determination of the actual factors involved in the loss of MH370 are the responsibility of the accident investigation authority and not the SSWG.
Once again, expensive assets redirected on what seem to be very speculative assumptions. Unless, of course, there is significant evidence that has not been made public.

Here's a New York Times article with an overview of the ATSB search area report:

http://www.nytimes.com/2014/06/27/wo...light-370.html

This discussion of possible MH370 waypoint and airway routing is on pages 36-37 of the ATSB report:

MH370

Radar data showed that after take-off MH370 tracked in accordance with its flight-planned route to waypoint IGARI and then turned right towards waypoint BITOD. Secondary radar data was lost shortly afterwards. Primary radar data then showed that MH370 deviated from its flight-planned route.

Primary radar data showed that the aircraft tracked along the Malacca Strait. During this time the aircraft passed close to waypoints VAMPI, MEKAR, NILAM and possibly IGOGU along a section of airway N571.

Southern air routes/waypoints

Air routes and waypoints were then examined to see if there was any correlation with the possible southern tracks for MH370 obtained from the analysis of the SATCOM data. Relevant southern air routes that MH370 may have intersected/traversed were N509, N640, L894 and M641. Waypoints associated with these air routes were also considered as possible points on the MH370 flight path.

N509 ELATI 0200.0S 08957.7E
PORT HEDLAND
N640 TRIVANDRUM
BIKOK 0817.0N 07836.0E
COLOMBO
LEARMONTH
MOUNT HOPE
ADELAIDE

L894 KITAL 2003.0N 06018.0E
MALE
SUNAN 0028.7S 07800.0E
DADAR 0200.0S 07927.1E
PERTH

M641 MADURAI
BIKOK 0817.0N 07836.0E
COLOMBO
COCOS IS

The waypoints at MUTMI and RUNUT were also considered as possible points that MH370 may have crossed. However ground tracks through these points did not correlate well with the most favoured paths generated through the analysis of the BFO and BTO data.

Air routes/ waypoints summary

Although waypoints and air routes were examined and compared to possible tracks derived from analysis of the SATCOM data, there was insufficient evidence to positively determine whether MH370 intersected any waypoints associated with published air routes in the Southern Indian Ocean.

Last edited by Airbubba; 26th Jun 2014 at 17:59.
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Old 26th Jun 2014, 19:42
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http://www.nytimes.com/2014/06/27/wo...-370.html?_r=0
Advocates of the hypoxia theory argue that pilot suicide cases tend to involve pilots who crashed their planes suddenly, not after hours of flight. A clinical psychologist advising the investigation has been very skeptical of the suicide theory, saying it would be highly unusual for a suicidal person to proceed with such a deadly plan over many hours, investigators said.
If Zahari's aim was to hide the plane forever, to punish the Malaysian government or whatever, he might have seen the prospect of his own death as collateral damage. During times of war, men sometimes do things even when their death is inevitable; we regard them as brave warriors. One clinical psychologist talking about his experience of typical suicidal patients is irrelevant, there is nothing "usual" about this case - it is weird, whatever the "final" explanation is presented to us.
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Old 26th Jun 2014, 20:04
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Gysbreght: about the deltaFdown.
In my satellite model (which happens to differ slightly from the table 4 page 56 (0.5 to 1.5 km)), if I use a 4GHz value for the frequency, I have (at 17:05) a -82.7 BFO from the speed of the sat relative to "Perth" GES (mine is -31.80 115.89). Relative speed: ~6.2m/s.
I have a -71.4 value at 17:27.
To have -71,4 at 17:05, I have to use 3.45GHz for the downlink frequency.
All this with a very simple model and using a spherical Earth.
What is sure, IMHO, is that the aircraft have nothing to do with that [part of] BFO.
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Old 26th Jun 2014, 22:06
  #11170 (permalink)  
 
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370 latest search area

so 65000 sq m to be covered. presume they will use at least two sets of wreck location equipment, starting from opposite sides or ends of the search area and finishing in the middle. using only one might result in the worst case scenario of not finding the aircraft until the very end or of course the opposite happy outcome of finding it on day one.
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Old 26th Jun 2014, 23:03
  #11171 (permalink)  
 
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"If Zahari's aim was to hide the plane forever, to punish the Malaysian government or whatever, he might have seen the prospect of his own death as collateral damage. During times of war, men sometimes do things even when their death is inevitable; we regard them as brave warriors. One clinical psychologist talking about his experience of typical suicidal patients is irrelevant, there is nothing "usual" about this case - it is weird, whatever the "final" explanation is presented to us."

but he wouldn't have to kill himself nor anyone else, landing on one of australian islands would do a job

when we are at that, have they searched the northern areas at all?
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Old 27th Jun 2014, 00:35
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Would they not have made a radio call if the above were true. It appears the aircraft flew normally and was not damaged or in distress.
Perhaps, but perhaps not if their radios comms were damaged. I think there are lots of gaps that investigators are filling in with assumptions, simply because they don't know. This can be a blessing and an Achilles heel in their investigative process.

These highly ranked officials coming out and making claims about what happened is really poor showing in my mind. They stuffed up the sonar pings and they were so Gung-ho confident prior to that. It appears they haven't even confirmed the source of the so called false pings. Thus were they really false? when prior they were extremely confident.

Deputy PM now claims the plane was likely on auto pilot. He could be right but that's not a proven fact. What if they used GPS navigation? I think the officials should only be reporting facts, but I guess they have few to go on so they are filling in the gaps, however given the errors they have already made, it's difficult to have confidence.
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Old 27th Jun 2014, 00:45
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These highly ranked officials coming out and making claims about what happened is really poor showing in my mind.
They are merely assumptions intended to narrow down the search area. The report is quite clear on this pointing out that the assumptions have no bearing on the accident investigation.
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Old 27th Jun 2014, 01:09
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They are merely assumptions intended to narrow down the search area. The report is quite clear on this pointing out that the assumptions have no bearing on the accident investigation.
Perhaps, but that sounds contradictory. If assumptions are intended to narrow down the search area, then how can they not have a bearing on the investigation process? I grant they need to make some assumptions and test them, but I think the public reporting of unproven assumptions might not be beneficial, as it creates public speculation and false expectations.
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Old 27th Jun 2014, 02:12
  #11175 (permalink)  
 
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Of course they need to make assumptions

And if they had not made, used and explained their assumptions we'd have had another 6 months of incessant whining about "why are they concealing the details?" or "how can they do this without giving me, personally, every detail of their actions and decision making along with hourly updates?"
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Old 27th Jun 2014, 07:13
  #11176 (permalink)  
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Hey, it is apparent that your reading differs from ours.

Investigators are those that will determine the possible or probable causes. There is no certainty that they will discover the certain cause.

The search organization's only link with the investigators is to deliver evidential material to them. Assumptions are purely there to create a viable search plan. Those assumptions may be modified in time.

Now politicians are different again. They are generalists, and while experts at saying one thing and meaning something else, the are not technicians. They may not appreciate or reflect the nuances in the experts report.

For those that are aware, the report is a model or clarity and caution.
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Old 27th Jun 2014, 08:16
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using only one might result in the worst case scenario of not finding the aircraft until the very end or of course the opposite happy outcome of finding it on day one.
Strange logic.
If you have just one you start most likely in the most probable place - say the center of the yellow rectangle and then proceed in circular/rectangular motion around it.
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Old 27th Jun 2014, 09:13
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assumption: flight ends with spiral

From the report
http://www.atsb.gov.au/media/4911984...370-report.pdf

"- loss of radio communications
- long period without any en route manoeuvring of the aircraft
- a steadily maintained cruise altitude
- fuel exhaustion and descent
This suggested that, for MH370, it was possible that after a long period of flight under autopilot
control, fuel exhaustion would occur followed by a loss of control without any control inputs.
Note: This suggestion is made for the sole purpose of assisting to define a search area.
The determination of the actual factors involved in the loss of MH370 are the responsibility
of the accident investigation authority and not the SSWG
.
Also allowing for the fact that a maximum glide distance of 100+ NM would result in an
impractically large search area, the search team considered that it was reasonable to assume that
there were no control inputs following the flame-out of the second engine. Accordingly the aircraft
would descend and, as there would be some asymmetry due to uneven engine thrust/drag or
external forces e.g. wind, the descent would develop into a spiral."

I still haven't got that. Maybe because I'm just a CPL/MEPL, but why should fuel exhaustion under autopilot end in a spiral dive? Is the auto pilot on the B777 completely disconnecting on fuel starvation? I'd guess the Ram Generator would deliver the power for autopilot + controls, the envelope protection of the AP would prevent a stall and the AP would maintain the track. That would place the center of the search area about 100 NM forward in flight direction.
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Old 27th Jun 2014, 09:18
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An airline that has shown the world how badly it was caught out with such a a long list of outstanding safety recommendations that it had failed to implement must be very frustrating for investigators.
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Old 27th Jun 2014, 09:22
  #11180 (permalink)  

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I'd guess the Ram Generator would deliver the power for autopilot + controls, the envelope protection of the AP would prevent a stall and the AP would maintain the track. That would place the center of the search area about 100 NM forward in flight direction.
It all depends on whether the A/P throws out on loss of power to its bus (it probably does) and what bus the RAT powers on double engine failure.
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