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Malaysian Airlines MH370 contact lost

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Malaysian Airlines MH370 contact lost

Old 16th Jul 2014, 18:10
  #11401 (permalink)  
 
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I'm guessing this will somehow involve X.25, sixteen layers of different protocols on top of each other, and about a billion configuration options where any misconfigured option will prevent you from talking to anyone else.
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Old 16th Jul 2014, 18:24
  #11402 (permalink)  
 
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I agree. I think it is highly unlikely that a ping coincidentally occurs at the furthest westerly extent of the track.
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Old 16th Jul 2014, 19:04
  #11403 (permalink)  
 
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From the website:
About ITU. ITU is the leading United Nations agency for information and communication technology. For nearly 150 years, ITU has coordinated the shared global use of the radio spectrum, promoted international cooperation in assigning satellite orbits ... ITU is committed to connecting the world.
Nearly 150 years doing what? ITU was founded in Paris in 1865 as the International Telegraph Union.

Sounds to me like more empire building from the UN, using an "excuse-me" from Malaysia.

Surely private communication companies can come up with straightforward solutions acceptable to ICAO and airlines that meet ITU approval (if needed).
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Old 16th Jul 2014, 19:31
  #11404 (permalink)  
 
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me too, I'd put it some ~200 miles lower
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Old 16th Jul 2014, 19:53
  #11405 (permalink)  
 
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The ITU have responsibility for anything the transmits in any spectrum. ICAO the UN, BT or the BBC all work to ITU standards. So the ITU will define a new standard for a new data transmission regime
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Old 17th Jul 2014, 13:43
  #11406 (permalink)  
 
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ITU, satcom and ACARS

ITU is a UN body funded by countries hosting the major players in their sphere of influence, with lobbying by those players aimed at preserving their monopolies or at least dominant positions within their respective industries. In this case, I suspect the satcom carriers and perhaps a/c nav equipment providers would be the major forces. Follow the money.

Satcom LINK management, as outlined very early in this very large body of comments, uses "pings" to set up and maintain said link between the a/c and ground. A link to an a/c may be used to carry communications under subscription agreements between that a/c's operators and the satcom provider.

The takeaway summary: satcom link messages exist without ACARS data messages, the latter being subject to subscription payments. Please don't conflate the two.
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Old 17th Jul 2014, 16:05
  #11407 (permalink)  
 
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I'm guessing this will somehow involve X.25, sixteen layers of different protocols on top of each other, and about a billion configuration options where any misconfigured option will prevent you from talking to anyone else.
Could be worse, they could get SITA involved.
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Old 17th Jul 2014, 22:24
  #11408 (permalink)  
 
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I remain confused as to ACARS and Pings

ACARS is, I believe, a maintenance information collection and transmission system. The next stop will have manuals open to the correct pages and spare parts close at hand and appropriate test equipment since they have received information as to what systems have reported error states en route. Reports go to the cockpit after a one minute suspense window that groups them by priority.

A "Ping" is merely an electronic handshake at the network level and does not mean anything at all about intending to transmit information or expecting to receive information; it is simply confirmation of the existence of a network connection.

Now for some reason the Carrier did NOT pay to have its ACARS data sent via satellite so the question for me is: Why would anyone try to disrupt the ACARS system if it was known that the Carrier did not pay to have ACARS data transmitted. Does such an attempt to disrupt the ACARS system indicate lack of familiarity with the carrier's operations?
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Old 17th Jul 2014, 23:18
  #11409 (permalink)  
 
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Two points:

First, ACARS is not simply a 'maintenance information collection and transmission system'. Broadly speaking, it is a communications and reporting system that is used to transmit all sorts of information to and from the aircraft. That information includes maintenance and systems data that is sent automatically by the aircraft to the airline and airframe/engine manufacturers. The system is also used by the crew and airline personnel to send operational information to and from the aircraft, including operational messages, weather reports, NOTAMS, flight plans and ATC clearances, etc.

Second, although there has been speculation here on PPRuNe that MH did not pay to have ACARS data sent by satcom, I don't believe that has been verified. Indeed, the Malaysian Ministry of Transport's MH370 Preliminary Report states:

'It was later established that the transmissions from the Aircraft Communication and Reporting System (ACARS) through satellite communication system occurred at regular intervals starting before MH 370 departed Kuala Lumpur, Malaysia at time 12:56:08 MYT and with the last communication occurred at 01:07:49 MYT'.

That report seems to indicate that ACARS transmissions were sent via satcom.

Position information is sent automatically by ACARS together with the engineering data. The crew would not necessarily know whether that information was being sent by VHF or satcom. If MH370 was the result of a deliberate act to make the aircraft 'disappear', then I would think the culprit(s) would make every effort to disable any systems that could transmit its position.

Last edited by BuzzBox; 17th Jul 2014 at 23:29.
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Old 17th Jul 2014, 23:22
  #11410 (permalink)  
 
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then I would think the culprit(s) would make every effor
making "every effort" doesn't necessarily equate with succeeding.
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Old 17th Jul 2014, 23:42
  #11411 (permalink)  
 
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BTO values in the communication log

From the communication log, I get the following BTO values
TimeBTO=[0 12 13 25 37 118 191 251 311 371 461]; % min from 16:30
BTO =[14920 14940 14920 15200 15600 12500 11500 11740 12780 14540 18040]; % s
and applying the BTO formula (1) page 54 of the ATSB report, I get the following ping ring radiuses:
PingRad =[2243 2241 2238 2267 2309 1904 1758 1798 1953 2194 2621]; % NM
and the following elevation angles:
ElevAng =[46.72 46.76 46.81 46.27 45.48 53.10 55.87 55.12 52.17 47.63 39.70]; % degrees
(I have also generated kml files for these ping rings to compare visually with those of the figure 18 of the ASTB report)

Do you get similar values ? (radiuses and elev. angles). They seems to differ from Duncan Steel's.
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Old 20th Jul 2014, 20:47
  #11412 (permalink)  
 
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ACARS data

BOAC mentioned:-
It would still be useful to know what data was being sent from Acars via SAT
Perhaps ...

I seem to recall reading on PPRuNe that the engines were leased from RR (power by the hour?) and that RR used ACARS for engine data. Perhaps RR paid for satellite acars for their data?

There would likely be engine start messages, who knows? Once in the cruise no more messages due to stable engine operation?

I forget now, is there some evidence that the satellite acars was turned off or disconnected leaving the bare satellite terminal doing its ping thing? I vaguely recall that there is. Presumably fuel exhaustion would generate some engine acars messages but none were received.

So many questions, so few answers.
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Old 21st Jul 2014, 07:25
  #11413 (permalink)  
 
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My knowledge of engine health monitoring is a few years out of date but IIRC the engines were reporting continuously from start to shutdown, would expect RR to have a similar system however I fail to see what good this would be as they only transmitted engine useage/health monitoring parameters but no positional data.
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Old 21st Jul 2014, 11:07
  #11414 (permalink)  
 
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Before the hamster wheel spins up again - this was all discussed earlier in the thread and discounted.

The engine health monitoring to Rolls Royce and the aircraft health monitoring to Boeing via ACARS were both inactivated with no subscription paid. There was no subscription for any ACARS activity over SATCOM only over VHF and that was routine 30 minute reporting the last of which was at 1.07. The only reason that the SATCOM was operative at all was the SATCOM phone facility was still available.
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Old 21st Jul 2014, 16:40
  #11415 (permalink)  
 
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Originally Posted by BOAC
mm - if there is 'Acars Data' floating around as you say, where is it and what does it contain?
The problems with ACARS and analog new type of communication - RR engines' management messages- is that they are said proprietary. That fact put their messages out of the ICAO operators' rules. i.e. AF447 ACARS told in one page and real time what happened helping a high probability analyse. That analyse has been confirmed two years later by the Flight Data Recorder. But the Crew missed that analyse from ACARS available in the cockpit at the same time because certified procedures did not use them. Congratulations to the BEA who published ACARS in the report.
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Old 23rd Jul 2014, 16:01
  #11416 (permalink)  
 
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Originally Posted by Ian W View Post
Before the hamster wheel spins up again - this was all discussed earlier in the thread and discounted.

The engine health monitoring to Rolls Royce and the aircraft health monitoring to Boeing via ACARS were both inactivated with no subscription paid.
That is probably true, but I have not seen anything more substantive than 'someone on PPRuNe said it' and the lack of any info from these companies as the basis. For the comment,

Originally Posted by Ian W View Post

There was no subscription for any ACARS activity over SATCOM only over VHF and that was routine 30 minute reporting the last of which was at 1.07. The only reason that the SATCOM was operative at all was the SATCOM phone facility was still available.
You have said this part over and over. Your statement is flatly contradicted by the preliminary report, this has been mentioned on every spin of the hampster wheel with a request to provide some insight as to why your assertion might be true and, on every occasion you have chosen not to provide that insight.

Last edited by mm_flynn; 24th Jul 2014 at 16:55. Reason: Removed potentially confusing final paragraph
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Old 24th Jul 2014, 06:41
  #11417 (permalink)  
 
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Search site moved March 28 - why?

Using p.5 of the ATSB's June 26 report, it is easy to replicate their working endurance model, March 17-27 (in, say, Google Earth):

Start at NW tip of Indonesia
Assume nil wind
Pick an arbitrary speed, s (say, 490 KGS)
Draw straight lines between Inmarsat arcs of length (time between arcs)/s
After 7th Inmarsat arc, keep going until you hit S1-S3 SE border
Repeat for several other speeds (say, 20kt intervals, down to 330KGS)

You have now precisely replicated the ATSB's working endurance model, March 17-27. (SE border of S1/S2/S3 has been publicly confirmed to be the ATSB's March 17-27 working endurance limit.)

The feasible range (S1/S2/S3) is the set of points bounded by the 6th Inmarsat arc, and the endurance line you've just reproduced.

Here's where it gets good:

Perform the update to this model the ATSB claims to have performed on March 27 - take away starting fuel. How do you do this? Easy: just shorten each flight path by the exact same PROPORTION. For example, make every flight path 5% shorter. Or 3%, or 7% - we don't know exactly how MUCH fuel they took away, so maybe try several different reductions. The key point is that each path is still going the same speed, and thus must still hit each arc at the exact same spot - the lack of fuel simply shortens the length. By the SAME X% FOR EACH PATH. Because that's precisely how a set reduction in available fuel would AFFECT each path's range.

You will find that, as you take fuel away, the S3 search zone becomes infeasible much faster than does S2. In fact, there is absolutely NO amount of fuel that could be taken away that could rule S2 out, yet S3 in.

So here's my question: why, then, did the ATSB move the search from S2 1,100km NE into S3, after taking AWAY fuel?

Illustrations (overview & close-up):
https://drive.google.com/file/d/0B-r...it?usp=sharing
https://drive.google.com/file/d/0B-r...it?usp=sharing

Something doesn't add up. At all.
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Old 24th Jul 2014, 14:10
  #11418 (permalink)  
 
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I think that to draw any sort of sensible conclusion about the track terminal, you must make an assumption about the starting point of the track since displacement of one, results in displacement of the other. 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.
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Old 24th Jul 2014, 16:15
  #11419 (permalink)  
 
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I know the contract for survey of new search area has been let. Has the contract for actual search been let?
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Old 24th Jul 2014, 16:20
  #11420 (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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