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Malaysian Airlines MH370 contact lost

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Malaysian Airlines MH370 contact lost

Old 24th Mar 2014, 22:04
  #7881 (permalink)  
 
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Originally Posted by Unixman
Could someone just run the following bit of physics past them to see if I have got the important point about the Doppler shift right?

If the satellite was absolutely fixed then the Doppler shift would be the same irrespective of whether the plane was heading north or south BUT the sun and moon cause a slight - but predictable - wobble in the orbit of the satellite and since that wobble is also N/S that will add a very small but measurable extra value in the existing Doppler shift. If the satellite was heading south at the same time as the plane then the Doppler effect would be squeezed by a tiny bit and the wavelength decreased - ie very slightly blue-shifted. If the satellite was moving north whilst the plane was heading south then the radio wavelength would be stretched - very slightly red shifted.

Have I got that correct ?
Sun and moon gradually deform the orbit of a satellite in a geostationary orbit, causing it to "wobble" N/S daily unless the satellite spends fuel to correct. Most satellites do this periodically. If you look here List of satellites in geostationary orbit most satellites have "inclination" (wobble amplitude) of <=0.1 degrees. (If the satellite is left on its own, its inclination is going grow ~1 degree per year.) Fortunately for us, Inmarsat-3 F1 is an old satellite (launched in 1996 and the second oldest Inmarsat satellite in orbit), which means that it must be running out of fuel, which means that its owners are probably trying to conserve fuel and skipping N/S compensation maneuvers. It has inclination of 1.6 degrees.

The rest is correct.
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Old 24th Mar 2014, 22:07
  #7882 (permalink)  
 
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ELT activated within the aircraft.

I once had a passenger ELT activate accidentally.
((helicopter offshore ops) everybody has one plus the 2 on the helicopter, one jettisoned by impact or manually, plus the 2 in the rafts))
We could hear it but one of our helicopters less than 20 NM away could not.
I presume that the 777 fuselage is much "thicker" re radio emissions than a helicopter so perhaps an ELT activated within with no external antenna would not be picked up by SARSAT.
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Old 24th Mar 2014, 22:07
  #7883 (permalink)  
 
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Originally Posted by enola-gay
IF, and I say IF, this turns out to be an event managed from within the flight deck secure door and it ran its full course to the Southern Ocean without passenger incapacitation, then it must have been utter and unimaginable bedlam in the cabin for 7 hours.
It is hardly conceivable the door would be able to resist desperate and unhindered attempts of the Pax/CC to open it forcefully for 7 hours.
Crash axe and/or stuff from the galley or the cabin itself in the hands of multiple desperate People fighting for their lives would surely finally take its toll on the door and/or the floor.

It is therefore rather likely that at least in the latter phases of the flight no one in the cabin was conscious. Potentially in front of the door no one either.

What caused this is the big mystery for which we can only hope the CVR/FDR to be found and readable.
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Old 24th Mar 2014, 22:08
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As a one time PPL and regular SLF, I have not posted up to now, as I have no authority to discuss the matters at hand. Some of the technical input from the professionals on the site has, however, been incredible...and testimony to their knowledge.

So I'm not about to begin speculation, rather ask one question, and pose another. Firstly, if they are recovered, will the on board recorders offer any useful data? I ask this as I understand (maybe wrongly) that they overwrite after some time.

Secondly, given that it has taken (at least publicly) two weeks for the authorities to locate MH370, is now the time to mandate real-time location transmission? Had this been available for MH370, the military could have intercepted the aircraft in the early stages of their deviation from flightplan...if not to prevent anything, at least to understand it.

Whatever happened, I hope the poor souls on board were unaware of their fate.
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Old 24th Mar 2014, 22:14
  #7885 (permalink)  
 
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Originally Posted by NWSRG
Firstly, if they are recovered, will the on board recorders offer any useful data?
The flight data recorder should provide much useful information.
I ask this as I understand (maybe wrongly) that they overwrite after some time.
The typical Cockpit voice recorder overwrites every 2 hours or so. (Last one I looked up was 2.5 hours)
Secondly, given that it has taken (at least publicly) two weeks for the authorities to locate MH370 --
Nothing confirmed has been found, in terms of floating debris. If such debris is confirmed, the actual hunt for the aircraft begins. That will take more time.
, is now the time to mandate real-time location transmission?
IMO, no. Other opinions will differ. Automobile designers are not required to design their cars for the cases of people who run them off of cliffs. I see no reason, given how many flights take off and land each day the world over by people using aircraft for their intended purpose, to make such a rule when a great deal of tech is already required and installed to keep track of where aircraft are and are going.
Since it has not been confirmedHad this been available for MH370, the military could have intercepted the aircraft in the early stages of their deviation from flightplan...if not to prevent anything, at least to understand it.
The military from what nation?

Last edited by Lonewolf_50; 24th Mar 2014 at 22:22. Reason: spelling errors
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Old 24th Mar 2014, 22:26
  #7886 (permalink)  
 
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Media reports said last night that there are "no survivors".

The Prime Minister's statement and Malaysian Airlines statement did not state that there are "no survivors".

They said the "flight was lost" and the PM's statement and condolences were certainly downbeat to reflect the probability that all have perished.
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Old 24th Mar 2014, 22:28
  #7887 (permalink)  
 
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Thanks Lonewolf...

The military from what nation?
I'm assuming the Malaysians themselves would have taken an interest...given the initial track back towards Malaysia, without any comms.

IMO, no. Other opinions will differ. Automobile designers are not required to design their cars for the cases of people who run them off of cliffs. I see no reason, given how many flights take off and land each day the world over by people using aircraft for their intended purpose, to make such a rule when a great deal of tech is already required and installed to keep track of where aircraft are and are going.
A fair point...but for me, two factors would sway it the other way. First, the number of lives on board a 777. Second, the damage that aircraft can potentially do.
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Old 24th Mar 2014, 22:28
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What could the military do

Shoot it down quicker end I suppose and more chance of finding fdr/cvr with 100+ chinese om board would have thought there would have to be agreement by which time out of fighter range.

If not an accident and perpetrators conscious might end up with a nose dive and accusations that the military had forced the end.

Can't see they could force it down or help it down.
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Old 24th Mar 2014, 22:29
  #7889 (permalink)  
 
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Originally Posted by olasek
They had fuel for 7:30 hrs and the flight lasted over 7 hrs.
In view of the above it is you who has to prove there was no fuel exhaustion.
Demonstrating that there is an absence of proof for a hypothesis does not necessitate having to prove the opposite.
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Old 24th Mar 2014, 22:30
  #7890 (permalink)  
 
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...would the cabin crew have activated one of the ELTs especially if they found the biz class sat phones were not functioning?
Having been cabin crew for 10 years with a few different carriers (Asia / Pacific) the use of portable ELT was never taught in initial nor recurrent training as an "onboard" device. Before I read this post it never crossed my mind to use it in flight. We had extensive training about setting the ELT at a high point on land (survival scenario) or its use in water, but I have never contemplated the use on-board an aircraft.

I am not sure that a crew member on MH370 would have thought of that either given the varying scenarios.

I'm sure that given the outcome of the investigation there will be mandated changes for not only tech crew but also cabin crew too.

Cheers for the insight. Might have to incorporate that into a briefing!
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Old 24th Mar 2014, 22:32
  #7891 (permalink)  
 
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What could the military do
Provide information. Prepare those on the ground. Help locate the aircraft when it does come down. Take images that might help identify the root cause.

Surely getting eyes on the aircraft could only be beneficial...
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Old 24th Mar 2014, 22:35
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A good graphic that appeared today in news.com.au

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Old 24th Mar 2014, 22:56
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Something would wash up, on the West (or possibly South) coast of Aus IF it crashed where they are searching.
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Old 24th Mar 2014, 22:56
  #7894 (permalink)  
 
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We may never see the DFDR.
Yes, and if we do, there may be no data on it.
Someone might have pulled the C/B to shut it down.
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Old 24th Mar 2014, 23:03
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Sky News reporting that SAR efforts stood down for today due to bad weather.
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Old 24th Mar 2014, 23:06
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Originally Posted by Doc Quag
Sky News reporting that SAR efforts stood down for today due to bad weather.
Yes, quote from AMSA press release dated 25th March..
AMSA has undertaken a risk assessment and determined that the current weather conditions would make any air and sea search activities hazardous and pose a risk to crew. Therefore, AMSA has suspended all sea and air search operations for today due to these weather conditions.
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Old 24th Mar 2014, 23:06
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AMSA Search postponed today

AMSA has advised that the search has been postponed for today due to bad weather in the search area. No planes flying and the Success has left the immediate area because of the weather.

"Due to rough seas, HMAS Success departed the search area early this morning and is now in transit south of the search area until seas abate. A sea state ranging between 7 to 8 is forecast today with waves up to two metres and an associated swell of up to four metres.
The area is also forecast to experience strong gale force winds of up to 80km/h, periods of heavy rain, and low cloud with a ceiling between 200 and 500 feet."


The Success was not able to locate either of the items spotted by the Orion yesterday (and with that weather forecast you can assume they are not going to be anywhere near where they were by the time the weather improves.
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Old 24th Mar 2014, 23:11
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Something would wash up, on the West (or possibly South) coast of Aus IF it crashed where they are searching.
Doesn't mean it will be found anytime soon - most of the west and southern coasts of Australia are pretty isolated places so something could wash ashore and not be found for years.
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Old 24th Mar 2014, 23:14
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Slats11, the new doors fitted post 2001 would withstand automatic gunfire.
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Old 24th Mar 2014, 23:21
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This is costing the Chinese massively in Satellite resources.

Photo reconnaissance satellites typically follow a polar orbit. This goes over both poles, whilst the earth rotates underneath, so they spend equal amounts of time in the northern and southern hemispheres.
The timing of the orbits puts them over their targets early in the morning or late in the afternoon, in sun synchronous orbits, to get 3D perspective.
To change orbit to look at a different target uses up manoeuvre fuel. They obviously only have a finite amount of this so using it is incredibly expensive in terms of the life of the satellite.
About 50% right by my reckoning. They do follow sun-synchronous polar orbits. This gives them global coverage. So they are not "targeted". Hence no fuel used to change orbit.

Yaogan-19 is apparently a recently-launched Chinese spysat:Launch News Long March 4C launch with Yaogan 19, November 20, 2013 - Orbiter-Forum

Here's a list of times and inclinations for its passes with respect to 42S 95E which is more or less where they've been looking.
YAOGAN 19 - All Passes

(As far as I know the site mixes historically accurate information with predicted passes).

You'll see that it flew directly overhead at 16:47 (UTC) on the 21st March. Also that it is predicted to do so at 16:47 on the 28th of March; and that it did so at 16:47 on the 14th of March, and the 7th, and so on, going back for months.

No changes in orbit.

(NB that it goes *directly* overhead once per week, but that every day there will be at least one pass where it is reasonably high in the sky).
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