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Malaysian Airlines MH370 contact lost

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Old 28th Mar 2014, 08:24
  #8481 (permalink)  
 
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olasek

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Until that was done there would be NOTHING to navigate by and situational awareness could be rapidly lost.
Wrong. They weren't far from KL, they didn't need any FMC to turn back and return to their origination. No situational awareness would be lost, they were in VFR conditions, excellent visibility. It is simply preposterous to suggest that under the alleged dire emergencies they would even care about FMCs at all. We are talking (assuming) of course competent pilots.
olasek: To make such a strong statement about a theory from a current T7 driver I would assume you have experience with a multiple instrument failure, possibly including fire/smoke, at night, at altitude. Please provide your story in that case. Re return to KL, some T7 drivers have previously suggested that they might not want to return to KL due to terrain. In the meantime I find the plausibility of 777fly's theory way above average in this thread.
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Old 28th Mar 2014, 08:24
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with a multiple instrument failure, possibly including fire/smoke, at night, at altitude.
Yes, it makes it even less likely pilots would try to program things into FMC in such circumstances. Why rely on equipment which is failing around you, makes little sense.
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Old 28th Mar 2014, 08:31
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@hamster3null

SU-30's DON'T have Supercruise, therefore they have to switch on their burners to go Mach 1+......range of a SU-30 with burners on would be well under 600nm and would decrease substantially proportional to how fast over Mach 1 it was going.

Supercruise - Wikipedia, the free encyclopedia
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Old 28th Mar 2014, 08:34
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777fly

"My supposition is that the lat/long of Penang might have been entered incorrectly as a South latitude and that after a crew incapacitation the aircraft simply navigated south to that point."

How does this fit with the military primary radar data showing MH370 heading steadily WNW 200nm from Penang at FL295? They were long past Penang by the time the turn south was made.
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Old 28th Mar 2014, 08:55
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(I cannot read #8541 to #8560, or p428, so if this has been covered already, pls delete...)

The new search zone is closer to Malaysia. BBC and others report that this is because the a/c flew 'faster' than previously thought, and therefore ran out of fuel earlier.

But are we to ignore the Inmarsat 'pings'? The last one was at 0011UTC (or 0019..) You don't stay in the air for that same length of time by flying at a faster speed.

I have to say, I trust the Inmarsat evidence (for what it is) best.

Until we see a verified radar plot (if such a thing exists) I still think it more likely that the crew hit trouble near the FIR boundary, turned for home, and initiated an emergency descent to a safe level on autopilot. Overcome later, the a/c boodled along on that heading, unnoticed by any radar units, and ran out of fuel sometime after midnight UTC. Windmilling Trents kept the gennies going for a few more minutes, last chattering gasp of 240v ac at about 0019.

Last edited by martynemh; 28th Mar 2014 at 08:57. Reason: typo.
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Old 28th Mar 2014, 09:05
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Marty

It's difficult to work out exactly the reasoning for the vast change to the search area. However, they have publicly stated it is because of new analysis of the radar data between the South China Sea and the limits of where it was tracked to.

I've only seen a portion of that data - obviously there's more, and whilst other nations have confirmed or denied that their radars also did or did not pick up MH370, we can only surmise that possibly they have been able to define more precisely some creative flying in terms of altitude excursions and turns, and possibly speed, which has resulted in less fuel available for the flight south.

A previous contributor commented that perhaps the initial phases of the deviation were more rapid but later the aircraft slowed a little to extend range. It had seemed that Inmarsat were inferring a regular flight level for the southward journey - perhaps that may have been revised also which may have affected the ultimate range.

I think if the final position is ever determined, there will be food for thought for months on this one!
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Old 28th Mar 2014, 09:13
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Here's proof that I have too much time on my hands:

https://docs.google.com/spreadsheet/...iNWZrNVE#gid=0

I don't have a clear explanation for the mismatch in scales, and I don't know how to reproduce "their" point at ~17:07 (there is no apparent reason why Doppler shift would have decreased from 16:55 to 17:07). And I can't be sure that I didn't make some basic mistake in the formulas. But other than that, I think the results look pretty good. You can make your own copy if you have a Google account, type in any numbers in green fields and try to match the lines in the plot.
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Old 28th Mar 2014, 09:18
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Originally Posted by Blake777
It's difficult to work out exactly the reasoning for the vast change to the search area. However, they have publicly stated it is because of new analysis of the radar data between the South China Sea and the limits of where it was tracked to.
It's not difficult, it is impossible. We haven't been given the data.
That said, my understanding is that the analysis of the satellite pings requires an assumption of constant speed and heading. This does not give unique solution, because you need to know where the start point is (i.e. the point at which the a/c started flying south). If the a/c speed west over the Malay peninsula was higher than assumed up until now then the start point of the southerly track was farther westwards and the mathematical solutions to the satellite ping data have the a/c flying more easterly, ending up closer to Western Australia.

Last edited by glenbrook; 28th Mar 2014 at 09:19. Reason: trying to clarify
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Old 28th Mar 2014, 09:20
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Modelling the new route

I have looked at the potential ping modelling techniques in previous posts, and also the recently released INMARSAT Doppler data/model which I think I have understood.

The new AMSA map shows the aircraft speed to the new search area as 400kt, down from 472kt (average). A couples of points follow:

1. The new search area is directly on the published last ping arc so it is being assumed that the aircraft crashed directly after the last ping, the new range being only just enough to get to the arc.

2. If (if) the interim ping signals had been used, this constrains the heading and speed quite closely, if a Great Circle route is assumed. Capt Kremin proposed the constant magnetic heading idea some days ago which causes the aircraft to turn to the East late in the track. As I stated at the time, this would remain consistent with the ping data for a GC route, but reduces the modelled speed. The diagram I generated at the time is below, the yellow line is the constant magnetic heading, the red line the last ping arc. The penultimate point on the grey GC route (on the final ping arc) was chosen to roughly match the original search area – of course the interim ping signals/arcs have not been released.

3. Changing the assumed speed would cause problems for the Doppler model that INMARSAT used. This is very sensitive to the aircraft speed which has to be removed to reveal the spacecraft Doppler signal used to decide it was on the Southern route.

If (if) the interim ping arcs are being used and are still constraining the choice of route and hence search area, I would guess that the constant magnetic heading option is now being used, which allows a shorter required range.

I don’t know what the INMARSAT Doppler model will have to do to match the new modelled speed.



Yellow line is the constant magnetic heading, grey line the GC route with matching modelled ping arcs, the red line the published last ping arc.
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Old 28th Mar 2014, 09:28
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Originally Posted by Wantion
Still appears to be on the 40° last ping arc from the satellite, however it brings up the often asked but never answered question about the PREVIOUS ping data.

If we knew the possible arcs/postions from the previous pings we, and they co-relate to the current search area, we could have been looking here a week or more ago!
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Old 28th Mar 2014, 09:49
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'New credible evidence'

It's starting to feel like there's actually NO credible evidence in this case. Just pure speculation. Or is that just me that feels like that?
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Old 28th Mar 2014, 09:51
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Originally Posted by p.j.m
If we knew the possible arcs/postions from the previous pings we, and they co-relate to the current search area, we could have been looking here a week or more ago!
OK looking at the chart I'm now confused, not that I wasn't before, the Malaysians said the team's latest modelling (incl INMARSAT, AAIB, NTSB, RR, Boeing) led them to use a higher speed and the resulting search is now closer to PERTH. But today's search zone is arrived at from the slowest speed line (yellow plot, 400kts). What am I missing ?
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Old 28th Mar 2014, 09:54
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the resulting search is now closer to PERTH. But today's search zone is arrived at from the slowest speed line (yellow plot, 400kts). What am I missing ?
NB they are not searching where they think it crashed. They will search taking where they think it crashed, plus 20 days of appropriate drift. No idea of the details, but 1K of drift would now be ~500NM.
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Old 28th Mar 2014, 10:01
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Originally Posted by Golf-Mike-Mike
OK looking at the chart I'm now confused, not that I wasn't before, the Malaysians said the team's latest modelling (incl INMARSAT, AAIB, NTSB, RR, Boeing) led them to use a higher speed and the resulting search is now closer to PERTH. But today's search zone is arrived at from the slowest speed line (yellow plot, 400kts). What am I missing ?
This was published a week ago, and the current search location is well within the "reasonable" final probability position. Without previous ping data though we really aren't in a position to guess where on the 40° arc the aircraft actually went down. The authorities seem to be doing a very poor job disseminating information.

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Old 28th Mar 2014, 10:09
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Originally Posted by p.j.m
This was published a week ago, and the current search location is well within the "reasonable" final probability position. Without previous ping data though we really aren't in a position to guess where on the 40° arc the aircraft actually went down. The authorities seem to be doing a very poor job disseminating information.
@ P.J.M & NigelonDraft
Thanks for the clarifications. On top of all this, while the P3s can re-locate as of their next flight, the ships are always lagging behind and travelling maybe 10-15kts (?) if they're lucky, and only they are going to verify anything seen from satellite or search aircraft.
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Old 28th Mar 2014, 10:39
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Posted by 777fly: Yes, the initial wanderings are hard to explain but if one pilot (under stress) loaded a handful of waypoints, some correct (AGARI), some with errors, and then the crew were overcome before they could be crossed checked the aircraft could fly to some strange places. It only takes one wrong keystroke to produce hundred mile errors.
It's probably worth pointing out again that, at a press conference fairly early on, one of the Malaysian officials (their CAA CEO, I think) steadfastly and explicitly refused to confirm that the aircraft flew to the various waypoints on the zigzag track that has become so much a "given" in these discussions. He would only confirm that it flew back over the peninsula.

And today we learn that reanalysis of primary radar data has resulted in a re-evaluation of the aircraft's speed. Since one thing you can be positive about in respect of a radar return is it's timing, that very possibly means there has been a re-interpretation of one or more of the positions attributed to MH370.

Taking these things together, it wouldn't be the greatest surprise in the world to me if we learn at some point that MH370 didn't actually fly the wandering zigzag path that is so persuasive of criminal intent to many people.

Last edited by DespairingTraveller; 28th Mar 2014 at 10:46. Reason: spelling and clarity
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Old 28th Mar 2014, 10:42
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Originally Posted by DespairingTraveller
And today we learn that reanalysis of primary radar data has resulted in a revaluation of the aircraft's speed. Since one thing you can be positive about in respect of a radar return is it's timing, that is very possibly means there has been a re-evaluation of one or more of the positions attributed to MH370..
It would be interesting to know which primary radar this is. Presumably it must be some Australian radar, that we have been told previously was turned off at night?
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Old 28th Mar 2014, 10:49
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I don't think anyone has posted what the ATSB actually said this morning. If they have, apologies.

Australian Transport Safety Bureau Chief Commissioner Martin Dolan:
The ATSB, as Australia’s transport investigation agency, is working with a range of other international expert organisations to analyse available data and determine the best area to search.
The key pieces of information being analysed relate to early positional information from the aircraft and later polling of a satellite by an aircraft system.
The new information is based on continuing analysis of radar data between the South China Sea and the Strait of Malacca before radar contact was lost.
It indicated the plane was travelling faster than previously estimated, resulting in increased fuel usage and reducing the possible distance it travelled south into the Indian Ocean.
The international investigative team supporting the search continues their analysis, which could still result in further refinement of the potential flight path.
This has been combined with information about the likely performance of the aircraft—such as speed and fuel consumption for example—to arrive at the best assessment of the area in which the aircraft is likely to have entered the water.
The information provided by the international investigative team is the most credible lead we currently have in the search of aircraft wreckage.
However, this information needs to be continually adjusted for the length of time elapsed since the aircraft went missing and the likely drift of any wreckage floating on the ocean surface.
http://www.amsa.gov.au/media/documen...elease_000.pdf
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Old 28th Mar 2014, 10:57
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NZ plane spoted objects which can be related to MAS plane BBC reports. Its in the new search area. Details to follow.


The plane is now on is way back to Perth where the images would be analysed.
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Old 28th Mar 2014, 11:08
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Quote:
Australian Transport Safety Bureau Chief Commissioner Martin Dolan:
The ATSB, as Australia’s transport investigation agency, is working with a range of other international expert organisations to analyse available data and determine the best area to search.
The key pieces of information being analysed relate to early positional information from the aircraft and later polling of a satellite by an aircraft system.
The new information is based on continuing analysis of radar data between the South China Sea and the Strait of Malacca before radar contact was lost.
It indicated the plane was travelling faster than previously estimated, resulting in increased fuel usage and reducing the possible distance it travelled south into the Indian Ocean.
The international investigative team supporting the search continues their analysis, which could still result in further refinement of the potential flight path.
This has been combined with information about the likely performance of the aircraft—such as speed and fuel consumption for example—to arrive at the best assessment of the area in which the aircraft is likely to have entered the water.
The information provided by the international investigative team is the most credible lead we currently have in the search of aircraft wreckage.
However, this information needs to be continually adjusted for the length of time elapsed since the aircraft went missing and the likely drift of any wreckage floating on the ocean surface.



If you burn up the fuel faster, how do you remain in the air for the same length of time?
(Unless you disregard the Inmarsat data timed at 0011 UTC and 0019 UTC.)
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