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Malaysian Airlines MH370 contact lost

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Malaysian Airlines MH370 contact lost

Old 6th May 2014, 10:24
  #10481 (permalink)  
 
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the aircraft's actual GPS position appears not to be one of the required parameters for the FDR
It would be absolutely astonishing if the lat/long coordinates were not recorded. Can anybody confirm this?
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Old 6th May 2014, 11:22
  #10482 (permalink)  
 
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Originally Posted by Derfred View Post
Do you really think they wouldn't have bothered searching for AF, or indeed MH if they had the black box data already? Try telling that to the relatives of the deceased...

You are missing the point, they would have known WHERE TO SEARCH.

Last edited by oldoberon; 6th May 2014 at 16:40. Reason: correct sticky space bar
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Old 6th May 2014, 11:37
  #10483 (permalink)  
 
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EASA publishes new proposals for flight recorders and locating devices

As SLF I don't know if this is off-limits in this thread? If so feel free to delete.

The European Aviation Safety Agency (EASA) today announced new proposals for flight recorders and underwater locating devices which aim at facilitating the recovery of an aircraft and of its flight recorders in the unfortunate eventuality of an accident.

The new EASA requirements include the extension of the transmission time of underwater locating devices (ULD) fitted on flight recorders from 30 days to 90 days. EASA also proposes to equip large aeroplanes overflying oceans with a new type of ULD that have longer locating range than the current flight recorders ULDs. Alternatively, aircraft may be equipped with a means to determine the location of an accident within 6 Nautical Miles accuracy. In addition, the minimum recording duration of Cockpit Voice Recorders installed on new large aeroplanes should be increased to 20 hours from two 2 hours today.

Patrick Ky, EASA Executive Director said: “The tragic flight of Malaysia Airlines MH370 demonstrates that safety can never be taken for granted. The proposed changes are expected to increase safety by facilitating the recovery of information by safety investigation authorities”.

These new requirements are included in an EASA Opinion and, when adopted by the European Commission, will apply to the operation of aeroplanes and helicopters registered in an EASA Member State.
EASA publishes new proposals for flight recorders and locating devices | EASA
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Old 6th May 2014, 12:29
  #10484 (permalink)  
 
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Transmit the data and we don't have to search for the recorder. Saves a lot of money
Originally Posted by Derfred View Post
Do you really think they wouldn't have bothered searching for AF, or indeed MH if they had the black box data already? Try telling that to the relatives of the deceased...
If the data included the position of the aircraft then it is true you would not have to search - you would know where it was. This entire thread and for that matter the one on AF447 exists because nobody knows where the aircraft is and what happened. After AF447 BEA proposed that aircraft over oceans should make regular ADS-C reports down to as often as once a minute so that in an emergency the search and rescue/recovery knows where to start. The BEA proposal was discarded of course as the beancounters wouldn't pay. Now INMARSAT is offering a free service for this 'tracking' perhaps someone will start setting ADS-C contracts down to say 90 seconds. For FANS 1/A aircraft this could be done today without any equipage change and with INMARSATs offer it could be done at no cost.

Why isn't it being done?
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Old 6th May 2014, 15:52
  #10485 (permalink)  
 
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IRPilot2006: Nav Data must be recorded in the FDR where "available and used". It is not "required" per se.

One presumes that any GPS and WAAS systems would also be included here.

Operation Parameters ... Primary navigation system reference*: GNSS, INS, VOR/DME, MLS, Loran C, ILS

Those parameters designated by an (*) are to be recorded if an information source for the parameter is used by aeroplane systems and/or flight crew to operate the aeroplane.

Last edited by DrPhillipa; 6th May 2014 at 17:32.
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Old 6th May 2014, 16:10
  #10486 (permalink)  
 
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The hijack to Perth theory makes a lot of sense to me.

If it was the captain trying to disappear the aircraft, wouldn't it have been a whole lot easier to do it on a flight across the Pacific to LA?
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Old 6th May 2014, 16:52
  #10487 (permalink)  
 
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I thought that when I 1st saw the revised track, but decided no way.

If the pilot voluntarily or under coercion was heading for Perth, he could have flow across Indonesia, if detected they would not have shot MAH370 down

We don't know whether if need be he could have used the radio and spun them a mulfunction story, then continued to Perth.

To me the only plausible reason for the diversion around Indonesia was to hide the track/destination.
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Old 6th May 2014, 16:58
  #10488 (permalink)  
 
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And another place on the MH route network which would have made disappearing into the Southern Ocean even easier - Mauritius.
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Old 6th May 2014, 17:12
  #10489 (permalink)  
 
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Trying to avoid Indonesian Radar?

Tell me how flying directly towards (and overflying) Banda Aceh and the International Airport was a Indonesian Radar avoidance attempt.

Possible that "human control of the aircraft" changed hands????
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Old 6th May 2014, 17:17
  #10490 (permalink)  
 
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I see Google maps now has two patches of hi-res imagery for the search areas of the Indian Ocean west of Australia.
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Old 6th May 2014, 17:31
  #10491 (permalink)  
 
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I see no clear unequivocal evidence for any "diversion around Indonesia". Subsequent to the loss of transponder signals there are only a couple of Malaysian military radar points over the Malaccan Straights reported, one of which has been subsequently moved, original height data has also been modified (negated). It is also unclear if these are points logged, or a track between them was logged.

No contact was reported on the presumed flight from IGARI across the entire Malay Peninsula.

A ping position (arc?) has been posited for 18:27 broadly consistent with the limited radar data followed by a posited southerly path which only just misses the Indonesian land mass.

Thai and Indonesian radar has not publically reported any contact, they have also not publically confirmed which radar were manned, active or logged - or their range. It is strange that neither saw the plane. If its path was as proposed it would have flown well within 200Nm of both Thai and Indonesian airspace. No word from JORN either.

If there is only confidential (military) information available, its existence (or confirmed absence of contact) should have been reported even if no details were.
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Old 6th May 2014, 18:22
  #10492 (permalink)  
 
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But the Malaysian radar was corroborated by the Thai military (who were excoriated for not coming forward sooner). There is absolutely no requirement for these military authorities to satisfy you or anyone in the peanut gallery by publicly publishing their data. The people that need to know have the information. The lack of information would apply if it were an NTSB or BEA or other investigation; only limited information is made available to the public until the final report.
JORN was almost certainly switched off as it was a peacetime weekend.
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Old 6th May 2014, 18:49
  #10493 (permalink)  
 
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Originally Posted by mm43 View Post
However, that is not the end of the story, as it is the aircraft that senses the Doppler shift between it and the satellite and shifts its Tx frequency to compensate. If flying toward the satellite it would shift its Tx frequency downward so that any transmission from the aircraft would arrive at the satellite at the assigned and expected Rx frequency. Likewise when flying away from the Satellite, the Doppler shift would be deceasing and the aircraft would adjust its Tx frequency in the opposite direction, i.e. upwards.

The satellite has nothing to do with the Doppler correction; that is assigned to each individual aircraft, otherwise the satellite would have a very large job on its hands when communicating with many aircraft. What the Satellite does do, is transmit a constant carrier on the P Channel which the aircraft uses to sense the received frequency offset from the assigned channel and then adjusts its Tx channel(s) in the opposite direct to compensate.

Any Doppler shift between the the Ground Station (GES) and the satellite is corrected at the earth side, which allows the separate isolation of Doppler between the Sat and the aircraft (AES).

Now start thinking about where this "burst frequency offset" info is coming from.
mm43, are you sure that this P-channel continuous monitoring of the doppler shift between the A/C and the 3F1 satellite was implemented by the MH370 AES ?
I ask because the Inmarsat annex 1 clearly states (red circling D2) that "D2 is not corrected by system" (meaning both GES and AES) hence it is "the observed frequency offset". Furthermore, if the BFO were only residuals of such a correction, it would be a poor correction (not that we can expect from the P-channel monitoring) of the relative A/C to sat doppler. D3 is easily predictible via the 3F1 ephemeris so I guess that it is compensed at GES level to reduce the doppler shifts (and it is not red circled).
The meaning of D1 which is an A/C induced doppler is not so clear, D1 could either be the A/C contribution to the relative A/C to 3F1 doppler (but the annex 1 also states that D2 combines the satellite & A/C motion so that this comtribution should be encompassed by D2), or it could be the AES correction to D2 (the opposite of the P-channel doppler shifts, or estimated via the IRS data and satellite ephemeris, but Imarsat says that D2 is not corrected). Can you make sense of this ?
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Old 6th May 2014, 19:31
  #10494 (permalink)  
 
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@ Hyperveloce

The Inmarsat graphic is essentially a media release designed to smooth over technical details that would "complicate" matters.

If you refer to SATCOM manufacturer's data, they have very little to say about what goes on in the Satellite Data Unit or the Satellite Beam Steering Unit, and Inmarsat are also very quiet on the subject. The best way to find what is going on is to go through Patent applications for alternatives to the methods in use. For the Patent application to succeed, it must show why it needs to use the methods that it is promoting. So this is where are a lot of the detail can be found.

US Patent #6008758 will provide an insight into the mysterious "D1/D2".

The ADIRU also supplies data to the SBSU/SDU, and if certain parameters are exceeded, say momentary loss of the P Channel occurs, the AES may initiate an "I am here" handshake with the SAT.

Last edited by mm43; 6th May 2014 at 19:57. Reason: added D1
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Old 6th May 2014, 20:27
  #10495 (permalink)  
 
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Originally Posted by Hyperveloce View Post
mm43, are you sure that this P-channel continuous monitoring of the doppler shift between the A/C and the 3F1 satellite was implemented by the MH370 AES ?
I ask because the Inmarsat annex 1 clearly states (red circling D2) that "D2 is not corrected by system" (meaning both GES and AES) hence it is "the observed frequency offset".
All aircraft that ever enter the U.S. airspace (it would be pretty safe to presume that it means all 777's) are required by 47 CFR 87.145(d) 47 CFR 87.145 - Acceptability of transmitters for licensing. | LII / Legal Information Institute to correct their transmit frequencies for Doppler effect relative to the satellite and to bring them under 335 Hz.

Annex 1 could be interpreted to say that D2 is the real Doppler, D1 is the correction, and "measured frequency offset" is the part of D2 that is not subtracted by D1. It's a stretch but it is consistent with my first paragraph.
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Old 7th May 2014, 00:25
  #10496 (permalink)  
 
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Dr Phillips

QUOTE "If there is only confidential (military) information available, its existence (or confirmed absence of contact) should have been reported even if no details were."

Pardon?

It took the Captain of BA Flight 9 (volcanic ash over Indonesia) eleven years to find out from declassified information that satellite monitoring stations in Australia and Guam were following his flight.

Capt Moody's comment? "We don't know what they're watching."

I'm not sure why you would be expecting anything different in this case if more were known from confidential sources.
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Old 7th May 2014, 03:35
  #10497 (permalink)  
 
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Originally Posted by mm43
US Patent #6008758 will provide an insight into the mysterious "D1/D2".

The ADIRU also supplies data to the SBSU/SDU, and if certain parameters are exceeded, say momentary loss of the P Channel occurs, the AES may initiate an "I am here" handshake with the SAT.
In the patent link you give, we can read:
Originally Posted by US Patent #6008758
.../...However, in this situation, conventional AES terminals continue to reserve one channel for receiving P Channel signals for the sole purpose of monitoring Doppler shift. P Channel signals are conveniently used for this purpose since these signals are continuously available.
.../...
In general, customers who need only circuit-mode services are forced to order an AES terminal equipped with one more channel than the number of telephone calls the system must support. The additional channel needed is a costly, wasted resource.
.../...
One method that has been used in an attempt to address this problem is to pre-compensate the transmit frequencies based on a calculated Doppler shift rather than a measured Doppler shift. The method calculates the Doppler shift using the satellite location, the aircraft location, and data which defines flight characteristics (e.g., velocity, ground speed, heading pitch, roll, etc.). Much of the data needed to calculate the Doppler shift comes from the aircraft's Inertial Reference System (IRS). This method has been difficult to implement due to the many different types of IRS systems which are made by many manufacturers and provide inconsistent flight data. Thus, it has been difficult to produce an AES terminal which calculates Doppler shift and is compatible with different aircraft.
.../...
It would also be advantageous to provide a method for measuring Doppler shift in an AES terminal or communication system independent of P Channel inputs..../...
So, if MH370 used the "precompensation method", the wobbling of 3-F1 can't be included and thus the Doppler is not "perfectly" compensated as it could have been if the P channel was continuously monitored, the "total" Doppler measured and then used to transmit a frequency the sat will receive as the right one.
In this case, it could be useful to calculate the Doppler from the fixed points where MH370 might have been located at the times published on the Inmarsat Doppler graph. Could this may also explain why all the values on the graph are positive?

The words "This method has been difficult to implement due to the many different types of IRS systems which are made by many manufacturers and provide inconsistent flight data" could also explain why the tests made on other flights to improve the data have been made on B-777s.

Last edited by Shadoko; 7th May 2014 at 03:37. Reason: wording
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Old 7th May 2014, 04:11
  #10498 (permalink)  
 
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Do you really think they wouldn't have bothered searching for AF, or indeed MH if they had the black box data already? Try telling that to the relatives of the deceased...
You are missing the point, they would have known WHERE TO SEARCH.
On the contrary, I was proposing that instead of spending a lot of money on SAT bandwidth and onboard equipment for live FDR/CVR transmission, that money (or less) would be better spent mandating frequent ADS-C via SATCOM on all aircraft.

Then they would know WHERE TO SEARCH.

It would also improve ATC efficiency, reduce airspace congestion, improve day-to-day safety, a whole host of tangible benefits.
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Old 7th May 2014, 07:06
  #10499 (permalink)  
 
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If you read the rest of my post that you quoted you will find that is just what I suggested. ADS-C contracts of reports once every minute were suggested by BEA after AF447. if there is ever agreement on the use of ADS-C EPP there will be even more information available and as a standard 'out-of-the-box' system. Add an ACARS over SATCOM that reports exceptions which AF447 did have or health monitoring systems over SATCOM, all existing capabilities and a reasonably coherent picture of what is happening on the aircraft is continually available.

All of this could be done now - and by the generosity of INMARSAT it could be 'free' if considered tracking information.
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Old 7th May 2014, 09:26
  #10500 (permalink)  
 
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@ Shadoko;
Re: patent #6008758;
The method calculates the Doppler shift using the satellite location, the aircraft location, and data which defines flight characteristics.
If you are going to use the AES location and ADIRU data to cover its manouvering at any point in time, then the logical conclusion is that the AES will do the same for the SAT using a look-up table for the ephemeris data associated with the same time.

The SDU knows which satellite it is coupled with, and to my mind there is no reason for the above not to take place, i.e. the Sat is not about to do a "barrel roll" or look over the neighbors fence as it goes about its predefined orbital parameters.
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