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Malaysian Airlines MH370 contact lost

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Malaysian Airlines MH370 contact lost

Old 9th Mar 2014, 23:36
  #1061 (permalink)  
 
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Mid-air theory is bogus, and so is the bomb scenario at FL 350... there would be a debris field that would have been discovered by now. This plane hit the planet intact.
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Old 9th Mar 2014, 23:48
  #1062 (permalink)  
 
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2014, not capable to find a plane...
You cannot find something until you start looking at the right place. In this case, we only have the last known position, but theoretically the plane might be anywhere within a 5000km radius. OK, you can cross some areas off where you can certainly tell it isn't, but still its a huge area. In this case search starts from last known position, then goes outwards in expanding circles.

We do have very sophisticated remote sensing technology, but for that to work it also needs to be zoomed in to a small 'area of interest'.
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Old 9th Mar 2014, 23:49
  #1063 (permalink)  
 
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RobertS975 Mid-air theory is bogus, and so is the bomb scenario at FL 350... there would be a debris field that would have been discovered by now. This plane hit the planet intact.

Anybody remember how was the Alaska MD found? It hit the water nose first, was there too much debris, or was it difficult to find if it wasn't for the witness pilot reporting its position?
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Old 9th Mar 2014, 23:49
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I am afraid you misinterpreted my post or deliberately tried to show your self-proclaimed ACARS "knowledge" to this community disqualifying my statement
@barrelowl: I see a lot of uninformed comments here, including yours:
I conclude that the ACARS downlink feed from the aircraft completely stopped at some point
How do you know there is a "downlink feed"? In my airline if all is ok there is only an engine trending downlink around TOC and nothing else for the rest of the flight.
How does it work at MAS? I have no idea, do you?
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Old 9th Mar 2014, 23:52
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Fastest possible descent rate? People have been asking….

For those keen to discuss shortest possible time of descent, and hence to assume a full throttle vertical dive, we can calculate very crudely, incorporating air resistance, thus:

Thrust to weight ratio of similar aircraft is given at about 0.2 to 0.3. Assume one third.
(A ratio of 1 would mean that sustained vertical climb was achievable).
So if the engines are achieving a certain stabilised speed in level cruise, then pointing the nose vertically down will in effect add three times as much thrust, due to gravity, giving four times the thrust.

The new stabilised speed will be such as to counter this 4 fold increase with 4 times the drag. Since drag increases with the square of speed, the speed will double.
So, very very crudely, the aircraft will stabilise its descent (terminal velocity) at twice its horizontal cruise speed.

We are ignoring:
A bit faster if we assume zero angle of attack (not actually flying).
And of course the air thickens on the way down, slowing us, and we should be talking actual speed, not IAS.
And the engine performance will presumably reduce in these conditions.

However, for these crude purposes I think we can say that the engines cannot drive us down vertically much faster than twice the speed they can drive us horizontally.

I don't think anyone is suggesting that this was in fact the mode of descent, just trying to get some idea of the fastest method imaginable.

Remember, very crude, ball park only. But it strongly suggests you can't get down vertically as fast 3 or 4 times cruise by running the engines.

And ignoring, of course the supervening break-up into slower falling bits

Not sure such a question is really very relevant, but the scenario intrigued me once posed, and I had to fiddle.

(Physics and math post grad, for my sins, so I shouldn't really do this in case I c**k it up, but I don't think it's wildly wrong)
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Old 9th Mar 2014, 23:55
  #1066 (permalink)  
 
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Oh, and when do the wings come off ?
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Old 9th Mar 2014, 23:57
  #1067 (permalink)  
 
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Hats of to the governments and military of these countries to allow so many other countries to send in ships and planes . Let's hope the right equipment can be working in the search area ASAP no matter where its from .
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Old 9th Mar 2014, 23:59
  #1068 (permalink)  
 
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BEA offers assistance
French accident board offers help recovering missing flight MH370


"We have communicated to Malaysian and Vietnamese authorities that we are ready to assist with the underwater search operations or recovery of wreckage," a spokeswoman for the Paris-based BEA accident investigation branch said on Sunday.
Isn't this the same group that couldn't find AF447?
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Old 9th Mar 2014, 23:59
  #1069 (permalink)  
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Sal - are you sure?
The NYT is quoting a source specifically saying that systems designed to pick up such flashes have not done so.
I would have thought that the whole of South East Asia would have been a prime area for the US DOD to be looking for flashes, given the proximity to at least three nuclear armed states, and others who have ambitions to be?
The two SBIRS birds in orbit are geostationary, and I would assume have sensitive enough detectors with wide enough fields of view to pick up a fuel-air explosion at that height and location?
Particularly given that it was dark at the time?
My apologies - it seems those satellites operate in highly elliptical orbits, so might not have seen any explosion - if there was one.
Returning to the topic now, and thinking of the relatives of those who are missing...

Last edited by tartare; 10th Mar 2014 at 00:04. Reason: Correction
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Old 10th Mar 2014, 00:06
  #1070 (permalink)  
 
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Originally Posted by Toruc Macto
Hats of to the governments and military of these countries to allow so many other countries to send in ships and planes
I think you somewhat misunderstand the situation. Parts of the South China Sea are claimed by all surrounding countries. Last known location was in international waters, so all nations having a territorial claim frantically sent off vessels to join the chase and "show the flag" to demonstrate that the area is (in part) theirs. I'm afraid in SE Asian politics taking advantage of such a situation is considered fair game.
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Old 10th Mar 2014, 00:07
  #1071 (permalink)  
 
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You're presuming that there was: a) an explosion, and b) that if there was an explosion that it met the intensity, duration, and wavelength criteria to not be rejected as noise.
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Old 10th Mar 2014, 00:08
  #1072 (permalink)  
 
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Tartare, I think that a fuel explosion from a ruptured wing would certainly be picked up as it would be larger than a missile exhaust plume which is what those satellites are looking for.

But...it is difficult to imagine a plausible scenario that ends with an ignition of a ruptured wing tank. Well, its not, but I will leave that to the speculatti.
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Old 10th Mar 2014, 00:14
  #1073 (permalink)  
 
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Perfect nosedive, engines off? How fast?

And of course, we can extend my previous crude argument to an engines-off perfect nose dive. The thrust provided by the weight will be three times that previously provided by the engines, giving a descent 1.7 (square root of 3) times faster than speed in level flight.
So the engines wouldn't really add much (1.7 to 2)
Once again, presumably break-up would supervene, making it all academic ?
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Old 10th Mar 2014, 00:15
  #1074 (permalink)  
 
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Also, I too find it rather baffling that a 20 foot Great White can be tracked to the nearest metre and that a plane can't, even in the event of catastrophic break-up.
I think some basic googling will help you there.

Happy for someone to provide some corrections , but I think you will find they only send data when the tag pops off, or the shark is at or near the surface.

Again electromagnetic waves don't go so well under water. (frequency dependence aside)

There are all sort sof 'add ons" that could be made to aircraft to enhance the "findability" in case of circumstances such as this. But it comes down to a cost analysis of what actual advantage you get in the rare circumstances that these things happen versus the pain in the @rse of setting them up.
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Old 10th Mar 2014, 00:16
  #1075 (permalink)  
 
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Ships will need to call in to port to re supply , equipment sent from not so friendly countries will be shipped to HCM . Information needs to be shared amongst the many countries taking part in the search . International waters or not its a recipe for a lot of tention in this part of the world . Generals of all nations will be looking to protect their interests or press for advantage . It appears like cooperation is happening and long may it continue . What's going on behind the scenes is another story .
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Old 10th Mar 2014, 00:18
  #1076 (permalink)  
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Australopithecus - you sound like you know what you're talking about.
Could you elaborate a bit more please?
My assumption was that a catastrophic airframe break up would see fuel lines and tanks ruptured, fuel vaporised and that with hot engine cores in close proximity, some sort of flash fire albeit very brief, very similar in IR signature to a rocket exhaust plume, would happen, which is why I wondered aloud.
But then I suppose it may be possible that air frame failure at 0.8 mach might just generate a lot of large pieces, depending on the modes of failure and the breakup sequence.
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Old 10th Mar 2014, 00:31
  #1077 (permalink)  
 
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Just to keep the humanity here, in among the tech discussion:

Danica Weeks anxiously waiting for news of husband on missing Malaysia Airlines flight - ABC News (Australian Broadcasting Corporation)
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Old 10th Mar 2014, 00:34
  #1078 (permalink)  
 
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Tartare...thanks. Its an illusion.

As someone else already mentioned the satellite data is filtered for characteristics, otherwise there would be a flood of data from lightning, gas flares, fireworks etc. But I believe, based on an article years ago, that the data stream can be retroactively inspected without the filters.

WRT to tank rupture/ignition. It takes a lot to get jet fuel to ignite...atomisation, lots of heat etc.. Cruise speed at FL350 would present a much smaller possibility of ignition than speeds, pressures and temperatures typical in landing accidents.
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Old 10th Mar 2014, 00:37
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Modern submarines are the best mobile platforms available for detecting sounds in the ocean. The whole front of a sub is a giant array of microphones coupled with major computing power all riding on a platform that itself is designed to be ultra-quite. AF447 included a French nuclear submarine in the initial search for the black boxes.


As SalNichols94807 commented, shallow water makes for a notoriously difficult acoustic environment. People familiar with the (wider) geographical area have stated on here that those waters are chock full of fishing vessels. Man made noise and natural noise in the water adds to the ambient noise, which will be much increased over that of an open ocean environment. Reverberations will be rife. There will be surface reflections and bottom bounce (depending what the bottom is made of). In deep water, sounds spread spherically, greatly dissipating the intensity. Shallow water, constrained by the surface and sea bed, causes the sound to spread cylindrically, meaning in a given volume the noise is greater. It's logarithmic and I can't be 4rsed digging out my old notes! 10Log versus 20Log.

That said, the shipping noise is low frequency whereas sonic locators on Flight Data Recorders is not. I hope the frequency will not be discussed. Ambient noise is still a factor.

In the Air France 447 case, the location was open ocean; much quieter acoustically and a submarine could manoeuvre in the deep water there. Submariners are notorious liars about where they are and where they've been but if they tell you they are loath to go anywhere a prang might ensue, I'd (guardedly) believe them. They don't like shallow water. I was about to quote Lance Corporal Jones but thought better!

They could use a surface vessel with a decent SONAR suite to listen for the location device. To cover any area AND listen is almost mutually exclusive. They may need to sprint and drift, otherwise their Own Ships Noise (OSN) may mask what they're listening for.

Otherwise, drop sonobuoys from fixed or rotary-winged aircraft. That might do it. I flew SAR on Air India 182 back in 1985. I was an acoustic specialist on my Nimrod Maritime Reconnaissance crew. We dropped buoys but heard nothing. The water there was over the 1000fathom line and was "quiet". Plus we dropped buoys at each of the 2 datums of wreckage so we were as near to the source as one could be, under the circumstances. We heard nothing. To be fair, sonic location devices then were in their infancy and I've no idea if the Air India 182 aircraft had been fitted out with such a device.

Other commentators here have questioned whether there COULD be wreckage and/or oil/fuel. All I can add is what I saw: In the case of the Air India182, each of the 2 datums (60 nautical miles apart) had an oil slick as a huge "lead-in" feature. At each datum there was a large collection of jumble; all that could float. That's all I'll say on that matter.

I used the word "oil", in all probability for convenience. Some people might nit-pick but such fluids from an aircraft wreck will come from a variety of hydrocarbon, mineral and synthetic sources. On that day, on the surface of the ocean, there was a very obviously "oily" film. The sea was calm. In fact it was a beautiful day and those facts messed with our heads in looking at what we were seeing!

There might be major differences in this particular sad case, today. And so, for what it's worth, I offer these recollections in the hope that they might help!
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Old 10th Mar 2014, 00:44
  #1080 (permalink)  
 
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Dai Farr, your signal to noise ratio is very very high. Thanks for the insights.
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