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Malaysian Airlines MH370 contact lost

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Malaysian Airlines MH370 contact lost

Old 24th Jun 2014, 11:34
  #11141 (permalink)  

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As the aircraft is now assumed to follow designated waypoints as it flew NW it is likely that it was in LNAV.

If the assumption now is that the aircraft flew at cruise altitude and normal speed it follows that there could be 2 endurance times and distances
1 Pack on
2 Pack off. With the bleeds or packs off the endurance would be extended due to better fuel economy.

How does this tie in with the final ping timewise (which equates to empty tanks). On that basis it should be possible to draw a series of circles from the last probable waypoints; MEKAR IGREX or the FIR at 92E into the southern Indian Ocean.
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Old 24th Jun 2014, 13:00
  #11142 (permalink)  
 
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Search to take decades?

On whose dime?

This question is based on the practical matter of effort versus benefit. If the estimation is that the aircraft was in control and that a human agent was involved, is it really necessary to find the aircraft to arrive at some means of preventing such incidents in the future?

At some point, when dealing with the human mind, you can't engineer a "solution" to how people think and behave.

Looking for various loopholes that may have been exploited does not IMO require finding the aircraft on the ocean floor.
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Old 24th Jun 2014, 13:39
  #11143 (permalink)  
 
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Originally Posted by Lonewolf_50
Search to take decades?

On whose dime?

This question is based on the practical matter of effort versus benefit. If the estimation is that the aircraft was in control and that a human agent was involved, is it really necessary to find the aircraft to arrive at some means of preventing such incidents in the future?

At some point, when dealing with the human mind, you can't engineer a "solution" to how people think and behave.

Looking for various loopholes that may have been exploited does not IMO require finding the aircraft on the ocean floor.
There is a major issue here, that professional pilots need to take note of. That is the level of trust that people feel that they can put in the flight crew that have locked themselves away in the cockpit. This is the real reason for the need to find the airframe.

As we see here immediate offense taken at suggestions that the pilot may be the one that 'hijacked' the aircraft (and for the same reason this may be modded out). This immediate reaction is the reason that no FOQA or DFDR is streamed and that no CVR data is streamed from the cockpit. It is also the reason that video recordings are not made and streamed. IFF this was a pilot initiated incident then I suspect that legislative and insurance company action will be taken to enforce such data streaming. IFF it was not pilot initiated then perhaps trust can remain in pilots.

Taking offense at the suggestions and 'turning a blind eye' to the problem will not make it go away. The current mood is that it was pilot initiated. Without finding the wreckage and the recorders and numerous personal cell phones with recordings that mood will steadily swing toward less trust being given to pilots, and eventual enforcement of streamed recordings.

It is in everyone's interests that the wreckage is found and the reason for what happened is discovered.
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Old 24th Jun 2014, 15:49
  #11144 (permalink)  
 
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I'm not an engineer either but certainly on the 777 GPS timing is used by the airplane information management system (AIMS). Even the flight deck clocks/chronos are effectively "slaved" to the GPS timing signal via AIMS.

( Source is the 777 FCOM 2)
Thanks for looking this up, I appreciate it. I've never flown the Triple but have operated several other Airbus and Boeing glass products over the years.

I quite understand that on a professional pilots' forum, there is going to be considerable opposition to the idea that an apparently distinguished professional pilot might choose to down his plane. And I note this forum is deeply distrustful of journalism, which can be sensationalist and inaccurate in its reporting of civil aviation.

Yet pilot suicide has happened before (Egyptair 990) so it is not surprising that it is a major avenue of inquiry for MH370. In this case, it is 'the butler did it' scenario. So the moderators who deleted all the posts following yesterday's Sunday Times article are, it seems to me, in the same state of denial as the Egyptians who continue to blame a CIA conspiracy or mechanical failure for the demise of Egyptair 990.
I agree, not sure why these arcane technical posts about GPS timing survive but any discussion of possible human factors seems to be taboo in the modern commercial incarnation of PPRuNe.

I remember reading of the likely cause of the Silkair 185 crash here on PPRuNe a few days after the mishap from a poster with good sources and, sadly, family members on the plane. I also remember the healthy debate on the Egyptair 990 mishap.

Rumor in U.S. federal law enforcement circles has it that an FBI report on MH 370 is in limited distribution with analysis from the BRIU and computer forensics folks at Quantico. Perhaps some of the recent news reports stem from this alleged document which may be very speculative.
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Old 24th Jun 2014, 16:51
  #11145 (permalink)  
 
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BFO model

Something I don't understand about the D3 compensation: what is the purpose to send a pilot frequency from Italia or the Netherlands, so that the 3F1 satellite measures/observes the doppler shift versus a point in Europe
1) when a shift versus Perth has to be corrected ?
2) when the actual compensation seems to be implemented, not onboard the sat, but on the ground in Perth ? (why send a pilot freq. to the sat ?).

The south trajectories outputed by the MC sim at 470 kts trying to fit (best fit in green) all the BTO/BFO values (red plots) excepted for 16:55 and 18:27): they remain compatible with the radar track, cross only the northern tip of Indonesia (80 km east of Banda Aceh).
https://drive.google.com/file/d/0B3s...it?usp=sharing
https://drive.google.com/file/d/0B3s...it?usp=sharing
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Old 24th Jun 2014, 19:17
  #11146 (permalink)  
 
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Ian W, well answered on why there is global aviation industry value in finding out what physical evidence may tell about what happened, and a few hints at who and how.

Whose dime? My offered suggestion is Malaysia, and the Flag Carrier Airline of that country. Put the burden of cost on those with the formal oversight for safe and proper operations of their various aircraft and crews.

This may sound harsh, but I think is realistic and just.
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Old 24th Jun 2014, 20:07
  #11147 (permalink)  
 
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"BFO model":
What I understand is that there are two ways for the Doppler compensation from the aircraft unit:
- "hearing" a [constinuously?] transmitted signal from the satellite which frequency is known: from the difference between the supposed frequency and the received one, the shift of frequency to emit is computed,
or
- computing the necessary shift from the flight speed and direction, knowing the theoretical position of the satellite. From what the radial speed between the aircraft and the theoretical position of the satellite is computed has not been, IMHO, stated (GPS and/or ADIRU). What is admitted about this is that this compensation is faulty because the satellite is not in this position (north of it all the time of the flight) and because it moves.

It has been said that the first way was using a whole canal to do that, and so is not "economical" and MH370 used the second way which is not asking for a pilot frequency.
Without correction, the radio signal uses a larger bandwidth, so this correction allows much more canals inside the same band width.


Another thought: IMHO, people using precise BFOs values to guess a flightpath are surevaluating these data: or you take the option of a single direction and a single speed value after the [supposed] turn to south (that is, aircraft on AP), and you don't need BFOs to find a flightpath, or you presume changes in direction, speed and possibly flight level, and you can find such a large bunch of possible flightpathes that you can cross the 7th arc from Sumatra to something like 40S 70E, and flying a hundred miles more after fuel exhaustion (IFF the last ping was generated by fuel exhaustion, APU starting, ..., and not from the "same something" which made the system reboot at 18:25:xx).
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Old 24th Jun 2014, 21:13
  #11148 (permalink)  
 
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Something I don't understand about the D3 compensation: what is the purpose to send a pilot frequency from Italia or the Netherlands, so that the 3F1 satellite measures/observes the doppler shift versus a point in Europe
1) when a shift versus Perth has to be corrected ?
2) when the actual compensation seems to be implemented, not onboard the sat, but on the ground in Perth ? (why send a pilot freq. to the sat ?).
A communications engineer would be better placed to comment, but a couple of points:

a. it seems that the system design wanted the pilot frequency generators (for correction of the uplink and downlink Dopplers) on the ground rather than on the satellite. Perhaps this was to give flexibility in changing the frequency if needed, possibly due to interference, or to avoid having to provide on-board redundancy for that function.

b. the pilot frequency is received on-board at a shifted frequency, but this shift will be measured by the L-band receiver, so can be removed from the total Doppler on the pilot frequency when it is received at Perth.

This system concept seems to provide the required output parameter of the downlink Doppler.
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Old 24th Jun 2014, 22:54
  #11149 (permalink)  
 
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Purpose of pilot signal

My understanding is that the pilot is used primarily to measure frequency errors induced by the satellite when up or down converting between L and C bands. Doppler-induced errors are a lesser problem. Pilots won't originate on board the satellite since the idea is to mimic the end-end communications link.
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Old 25th Jun 2014, 14:14
  #11150 (permalink)  
 
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Originally Posted by Lonewolf_50
Ian W, well answered on why there is global aviation industry value in finding out what physical evidence may tell about what happened, and a few hints at who and how.

Whose dime? My offered suggestion is Malaysia, and the Flag Carrier Airline of that country. Put the burden of cost on those with the formal oversight for safe and proper operations of their various aircraft and crews.

This may sound harsh, but I think is realistic and just.
Perhaps the issue of who pays should be given more priority in the discussions that are currently in progress in the pan-national aviation organizations that are all coming up with various bureaucratic regulations on tamper-proof aircraft tracking.
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Old 25th Jun 2014, 15:25
  #11151 (permalink)  
 
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Other officials involved in the crash investigation have suggested that either of the plane’s pilots might have commandeered the aircraft in order to commit suicide
I'm not aware of any credible evidence that proves the pilots were responsible. The pilots might have been wrestling to control the aircraft for all we know and flying it around the coast to avoid crashing over populated areas. Something else might have caused multiple debris fields thousands of km apart, with the aircraft eventually coming down. For all we know the aircraft might have lost a key control component over the South China sea and dropped some debris there and then limped back to Malaysia and beyond.
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Old 25th Jun 2014, 15:56
  #11152 (permalink)  
 
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Improved tracking

'Perhaps the issue of who pays should be given more priority in the discussions that are currently in progress in the pan-national aviation organizations that are all coming up with various bureaucratic regulations on tamper-proof aircraft tracking.'


Forgive me, but something I have been wondering - was there a tangible demand for this sort of facility prior to March this year? Or is it a very recent phenomenon that has come about in the light of this event - a reaction to it specifically, rather than an idea that was around for some time and just required a 'push' in order to get to the top of the list?


I'm afraid I don't have the background knowledge to put this into context.


(not suggesting anything conspiratorial, by the way)


Thank you.
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Old 25th Jun 2014, 17:02
  #11153 (permalink)  
 
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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. Looks like from the precision of the routing it was a newly programmed route with LNav engaged.
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Old 25th Jun 2014, 22:20
  #11154 (permalink)  
 
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Originally Posted by susier
'Perhaps the issue of who pays should be given more priority in the discussions that are currently in progress in the pan-national aviation organizations that are all coming up with various bureaucratic regulations on tamper-proof aircraft tracking.'


Forgive me, but something I have been wondering - was there a tangible demand for this sort of facility prior to March this year? Or is it a very recent phenomenon that has come about in the light of this event - a reaction to it specifically, rather than an idea that was around for some time and just required a 'push' in order to get to the top of the list?
The French BEA report on AF447 - a similar case of an aircraft in open sea which was very difficult to find - made the recommendation that the periodic updates from ADS-C should be at closer intervals. The intent being that they would be close enough to narrow the search area to something useful.

This was not done as the airlines did not want to spend the extra money they thought they would be paying for SATCOM transmissions. After all a crash in the sea without position reports was very rare and the chances of that happening to their aircraft meant that it wasn't worth it. Anyway the search costs are not borne by the airline.

So the beancounters were not going to pay.

Along comes MH370. This is a real trigger for the regulators to get their act together as people are now saying- look its happened again! Perhaps not quite fair as apart from both (we think both) ditching in the sea there are no other commonalities. But the regulators (together with keen avionics marketers ) are now pushing for tamper proof tracking that would meet the AF447 recommendations _and_ prevent the loss of position reporting of MH370.

The problem is that we still don't know why or what MH370 did whatever it did. Perhaps all that is needed is to set the ADS-C period to say 4 minutes and ACARS to always report over SATCOM certain emergencies. This would provide all the tracking and information needs for 99% of incidents including MH370 without any new avionics and thanks to INMARSAT's offer of 'free' tracking it would not cost the airlines.

This is why it would be really really helpful to find the airframe.
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Old 26th Jun 2014, 06:15
  #11155 (permalink)  
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New ATSB report

New report from ATSB announced at press conference today (June 26)

http://www.atsb.gov.au/media/4911984...370-report.pdf
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Old 26th Jun 2014, 07:48
  #11156 (permalink)  
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PolAgnostic, if my reading of diagram 18 is correct then you are incorrect.

The tip of the arrow and the regular spacing of the ping times are a function of graphic design and not attempting to show the position of the aircraft at each ping.

What is relevant is the interval between displayed ping arcs.

Whilst the greatest interval is the penultimate one, this represents 90 minutes and not the previous 60 minutes. Note also the interval after 1825 is also 90 minutes and not 60.
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Old 26th Jun 2014, 08:39
  #11157 (permalink)  

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The orange area of search in the report page 47 is over the direct track from MEKAR IGREX and the FIR at 92E towards Wilkins Runway YWKS. Is there any coincidence? Can someone tell me whether YWKS appears in the B777 FMC database, it certainly complies with the criteria that I understood was used as the runway is in excess of 4000m long

It doesn't appear from my quick reading of the relevant pages that an LNAV constant track from those waypoints towards Wilkins has been analyised.

Last edited by sky9; 26th Jun 2014 at 08:46. Reason: additional information
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Old 26th Jun 2014, 09:50
  #11158 (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?
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Old 26th Jun 2014, 10:42
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Can someone tell me whether YWKS appears in the B777 FMC database, it certainly complies with the criteria that I understood was used as the runway is in excess of 4000m long
I can't tell you anything about the 777 FMC database, but I can tell you last time I landed at YWKS it was 3200m long.
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Old 26th Jun 2014, 11:44
  #11160 (permalink)  

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Compressor Stall, I'm sure you are right, I have taken my information on the Wikipedia list of Antartica runways. What is important is that the Boeing database generally records all runways over a certain length in the database. From memory it is somewhere around 5 to 6000 ft.
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