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Malaysian Airlines MH370 contact lost

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Malaysian Airlines MH370 contact lost

Old 31st Aug 2014, 20:13
  #11501 (permalink)  
 
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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.
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Old 31st Aug 2014, 23:20
  #11502 (permalink)  
 
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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."

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
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Old 1st Sep 2014, 05:06
  #11503 (permalink)  
 
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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.

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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Old 1st Sep 2014, 22:44
  #11504 (permalink)  
 
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Originally Posted by AreOut View Post
"
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

Why, they don't owe you anything and you have no 'Need to know".
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Old 2nd Sep 2014, 00:53
  #11505 (permalink)  
 
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hah, my country doesn't pay for the search so I indeed don't have the right to know, but taxpayers of countries involved in search certainly do
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Old 2nd Sep 2014, 00:54
  #11506 (permalink)  
 
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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?
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Old 2nd Sep 2014, 16:30
  #11507 (permalink)  
 
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chronus:
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.
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.
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Old 2nd Sep 2014, 23:44
  #11508 (permalink)  
 
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Originally Posted by slats11 View Post
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.
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.) Uncompensated velocity of 3000 fpm is equal to Doppler shift of 84 Hz at 1.645 GHz.

The difference between BFOs at 18:28 and 18:40 (and the difference between heading northwest and heading south) is around 55 Hz.
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Old 3rd Sep 2014, 05:08
  #11509 (permalink)  
 
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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.)
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.

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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Old 3rd Sep 2014, 08:16
  #11510 (permalink)  
 
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Originally Posted by slats11 View Post
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.
That's what they are saying. It corrects for its own ground speed, and the only reason why we have any meaningful data at all is that it corrects based on the assumption that the satellite is stationary, and in reality the satellite wobbles up to 1.5 degrees along the north-south axis. This gives us a compensation error which, added to a bunch of other terms, gives us BFO. See here http://www.atsb.gov.au/media/5243942..._18aug2014.pdf, page 55 and onwards.

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 08:41.
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Old 3rd Sep 2014, 11:22
  #11511 (permalink)  
 
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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).
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Old 5th Sep 2014, 08:49
  #11512 (permalink)  
 
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Hard objects on seabed found in search for MH370
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Old 5th Sep 2014, 16:20
  #11513 (permalink)  
 
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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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Old 5th Sep 2014, 21:21
  #11514 (permalink)  
 
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investigate now

i highly doubt that there would be any delay in immediately investigating this particular site much more closely.
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Old 6th Sep 2014, 01:59
  #11515 (permalink)  
 
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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.
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Old 11th Sep 2014, 15:03
  #11516 (permalink)  
 
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Today, it is precisely 13 years since a nutbag islamist on board United 93 switched off his transponder and caused problems for ATC tracking staff.

Earlier this year, the same appears to have happened to MH370.

I have heard various excuses varying between "far fetched" and "daft" for why this switch should not be capable of being disabled from the flight deck. Will the regulators ever wake up?

If they do, they could also consider why FDR and CVR batteries are so inadequate and why these should not operate in passive transponder mode.
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Old 11th Sep 2014, 16:52
  #11517 (permalink)  
 
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Smoke Removal and various versions of Cabin and/or flight deck Smoke and Fire drills often call at some point for electrical power to be removed from items (either by a switch or by disconnecting busbars) in order to try isolate the source of the problem.

Do you consider such drills " "far fetched" or "daft"?
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Old 11th Sep 2014, 17:04
  #11518 (permalink)  
 
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wiggy says: "Smoke Removal and various versions of Cabin and/or flight deck Smoke and Fire drills often call at some point for electrical power to be removed from items (either by a switch or by disconnecting busbars) in order to try isolate the source of the problem.

Do you consider such drills 'far fetched' or 'daft'? "


So far, we have lost two aircraft and their passengers. That is a high price to pay. We may have lost them anyway. Certainly, this crucial circuit should not interfere with drills; with good design, it does not need to.
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Old 11th Sep 2014, 17:10
  #11519 (permalink)  
 
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Today, it is precisely 13 years since a nutbag islamist on board United 93 switched off his transponder and caused problems for ATC tracking staff.

Earlier this year, the same appears to have happened to MH370.

I have heard various excuses varying between "far fetched" and "daft" for why this switch should not be capable of being disabled from the flight deck. Will the regulators ever wake up?

If they do, they could also consider why FDR and CVR batteries are so inadequate and why these should not operate in passive transponder mode.
Precisely how would souls have been saved if either UA93 or MH370 would have continued to squawk during its doomed flight?
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Old 11th Sep 2014, 17:23
  #11520 (permalink)  
 
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formulaban says:
"Precisely how would souls have been saved if either UA93 or MH370 would have continued to squawk during its doomed flight?"


ATC couldn't find UA93. The F-16s did not know where to go. As for MH370, the signals would have been of immense value, if only for investigative purposes.
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