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Malaysian Airlines MH370 contact lost

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Malaysian Airlines MH370 contact lost

Old 26th Mar 2014, 03:21
  #8121 (permalink)  
 
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@Uncle Fred

For what it's worth, here is info on swell/wave size, wind speed, white caps etc
windwater.html

However, some white caps are not real problem in the southern Indian and southern seas generally. This article - Malaysia Airlines MH370: Rescue expert Aaron Halstead describes challenges of southern Indian Ocean search for possible debris - ABC News (Australian Broadcasting Corporation) - gives a good account of the problem in relation to swell height, visibility and depth perception from the SAR point of view (aerial and from ship height).
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Old 26th Mar 2014, 03:35
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Regarding the search, what height of wave brings about whitecaps, foam, and heavy spray? What height of wave then brings about the breakers that one sees in the video that was posted from the Telegraph? Does merely a confused sea cause a lot of foam or does there need to be a good blow over the water as well.

What I am trying to understand is how calm the sea and wind needs to be for even decent SAR spotting? I know they deploy in pretty foul weather, but I can imagine that a lot of white on the water makes the challenge a difficult one at best.
Uncle Fred, others have posted the various tables of Beaufort wind scales, sea state, etc. All I can add is an experienced searcher's perspective. Firstly, I think the video posted very recently gives a dramatic example of how difficult any sort of search can be under these conditions. In my opinion, the useful search range from the bridge of that vessel is going to be a couple of hundred yards, MAXIMUM!

Strong winds whip up the sea. Gradually, waves develop. Over a period of time a wind covering hundreds of miles causes the ocean to develop a swell. Wave-like, these swells can have enormous wavelengths and in open oceans 150m to 700m may not be uncommon. Local winds can produce waves on top of an established swell. If the wind is from a different direction to the swell, the surface will be even more disturbed. These local waves, depending on their wavelength compared with the wavelength of the swell they ride upon, may break and produce local white water. Anything that produces waves and/or swell will periodically mask anything afloat. Anything that produces white water will also detract from an observer's ability to see a solid object afloat or riding in neutral buoyancy at some depth under the surface.

Continued strong winds will, at a given rate, "rip" the tops of the waves and blow the spume downwind. In sea state 8 or more, all you can sea are lines of spume set in the direction of the wind. And a very difficult spotting environment this is.

To overcome the masking of something afloat by the presence of the waves and the swell, you need elevation. Too much elevation risks missing anything small!!

To the high swells from the Southern Ocean (lets face it, the area under consideration is on the borderline Indian/Southern Ocean) and the waves from recent strong winds in the search area, you must add the spume and local breakers to the factors that diminish an observer's ability to recognise a person or an object in the water.

A RADAR search of the surface may not be put off by the muddled visual spectrum of white and blue water. But swell and wave height will mask RADAR returns and even return unwanted ones called "clutter". And given that what may or may not be on the surface is almost certainly not going to be generously RADAR-reflective, that's not an enormous help either.

I have only experienced Nimrods as a search platform. At 200 feet, if you mentally extended the 4A tanks forward, you were looking at about 3 nautical miles from the aircraft. A similar exercise with the wingtips or Loral pods, 5nm. Looking for something the size of a person even out to 3nm is not easy, and even if they are wearing a dayglo vest. 5nm? Forget it!

This is an enormously difficult task in an enormously difficult and unfriendly part of the world.

Last edited by Dai_Farr; 26th Mar 2014 at 03:48. Reason: Added a bit I forgot earlier!!
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Old 26th Mar 2014, 03:45
  #8123 (permalink)  
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Dai - ineteresting post.
I thought military radar would be able to see through the waves to a certain degree - obviously wrong there!
Wouldn't something semi metaliic stand out very strongly on radar, even in a horrible State 8 sea?
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Old 26th Mar 2014, 03:51
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Good information. Thank you. Lends a bit of perspective as to what one sees below from FL 350...
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Old 26th Mar 2014, 03:51
  #8125 (permalink)  
 
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Originally Posted by MG23
Don't forget, the ground station compensates for Doppler from satellite motion, and the aircraft attempts to compensate for Doppler from aircraft motion. The former is probably very precise, since it can sync to the pilot signal from the satellite, the latter is probably not, since I suspect it just treats the satellite as located at a fixed position.

At least, I believe that's what the slides posted earlier today meant, when they said only aircraft->satellite Doppler wasn't corrected.

So you'd be looking at Doppler from satellite motion relative to the aircraft, plus any residual Doppler that the aircraft hadn't corrected for in its own motion.
If the aircraft did any compensating, it could compensate more or less to zero, since it has GPS. From the charts, it does not look like there's any compensating happening on the side of the aircraft. That's why Doppler shift jumps when it turns.

Anyhow, this is the best I could do to "reconstruct" their "reconstruction" of the south track. Scales are different, I have no idea why. Even the zero in the original chart is not a zero. (The "knee" around 20:00 UTC corresponds to the Doppler shift going through zero and changing sign as the aircraft passes the closest approach to the satellite, somewhere near the equator.) But at least qualitatively there's an agreement: http://i61.tinypic.com/abo2n7.png This corresponds to the aircraft going off at heading 185 at 450 kts from 18:30 UTC and beyond.

I can't quite tell how they came up with whatever north route they used. There seems to be no way to draw a route that agrees with their "predicted north track" and ends up at 40 degree arc. Here's one way to look at it: their "predicted north track" has no apparent sign changes after 18:30 (we can assume that their "100 Hz" is near real zero, and the red line on the official plot does not get near 100 Hz.). Therefore, the aircraft flying along their "north track" has large consistent Doppler shifts all the way. But they began at the ~32 deg. arc at 18:30 and got only to 40 deg. by 0:11.

I can draw an approximate mirror image of the south route and get good agreement with "measured data" if I send it over Bangladesh and Nepal into south Kazakhstan.

About the only real conclusion that can be drawn here is that there was nothing remarkable happening to the aircraft after 18:30. It was not zigzagging or making any sharp turns. If it went south, I get an OK agreement simply assuming a constant 185 deg. heading (even without corrections for magnetic declination a la Cpt Kremlin above). This is not the track of an aircraft that tries to avoid detection.
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Old 26th Mar 2014, 04:04
  #8126 (permalink)  
 
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Dai Farr

Firstly, I think the video posted very recently gives a dramatic example of how difficult any sort of search can be under these conditions. In my opinion, the useful search range from the bridge of that vessel is going to be a couple of hundred yards, MAXIMUM!
It's a fake video. Taken in Jan, 2013, most likely in the North Atlantic.

Always makes sense to confirm sources before commenting upon them.

https://www.youtube.com/watch?v=Aow2ErSP3dQ
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Old 26th Mar 2014, 04:29
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Anyhow, this is the best I could do to "reconstruct" their "reconstruction" of the south track. Scales are different, I have no idea why. Even the zero in the original chart is not a zero. (The "knee" around 20:00 UTC corresponds to the Doppler shift going through zero and changing sign as the aircraft passes the closest approach to the satellite, somewhere near the equator.) But at least qualitatively there's an agreement: http://i61.tinypic.com/abo2n7.png This corresponds to the aircraft going off at heading 185 at 450 kts from 18:30 UTC and beyond.
Interesting, hamster3null. One question - how does it look at lower or higher speeds? Do you get the same profile but just at a different heading? Or does the plot actually differ?

(As I understand it, and I may be wrong or missing something, they don't know the actual speed of the aircraft, or even that that speed was constant over the 7 hrs. Rather, they only know the difference in relative velocities at points in time. As a result, while the velocity and position for the satellite are known, one has to posit assumed heading/assumed speed pairs for the aircraft, each of which give the same difference in relative velocity, but correspond to a different track in real life.)

Last edited by auraflyer; 26th Mar 2014 at 04:35. Reason: silly typo
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Old 26th Mar 2014, 04:31
  #8128 (permalink)  
 
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I thought military radar would be able to see through the waves to a certain degree - obviously wrong there!
Wouldn't something semi metaliic stand out very strongly on radar, even in a horrible State 8 sea?
Unfortunately, radio waves are too attenuated by the medium of water to allow useful penetration from a RADAR detection point of view.

Semi metallic? I'm afraid it's the 64,000 dollar question. There are too many variables to come up with an answer anyone would feel comfortable with.

When we were out hunting Red October and its ilk, we had all manner of detection ranges given to us from a variety of sources. But the best way to catch the b****r was to literally test the water. We would drop in a bathythermal buoy. As the thermistor head descended it gave us a trace of the thermal profile of the water, locally. From this, once we had consumed our dairy cream sponges, we could establish a sound velocity profile.

If you want an accurate idea of the sort of track spacing to employ in "this" body of water, you would ideally lob something of comparable RADAR reflectivity and/or visual reflectivity into the water and do a RADAR and visual search for it. Of course, most maritime patrol aircraft don't carry conveniently-sized (for the launchers) objects in a variety of materials to experiment with in this way. Flotation devices on sonobuoys are not in dayglo colours.

One of our crew members had experimented with modifying a sonobuoy with a RADAR reflector. His idea had been that if he could convince the manufacturers to incorporate such a thing, then Nimrod Dry sensor operators (the above-water team) could draw some benefit from them (i.e. practicing RADAR homings) as well as we Wet sensor operators (the acoustics team) could derive from the data they were primarily designed to yield. Unfortunately, he was collared by the harbourmaster and almost sparked a live Search and Rescue incident when, in response to, "What the b****y hell are you doing?" he declared there was a buoy in the water! (NOTE: The phonetic impact of this ONLY works with the British pronunciation of "buoy".)

Track spacing in any search is one of those "what do you think" decisions. Might a droppable device, based on a sonobuoy, with a dayglo flotation device (as opposed to military green) help lookouts establish a realistic detection range? If the RADAR could pick it up, then you have a measured visual range, as opposed to a "guestimate". Calm seas are one thing. But in this case, the searchers are on a hiding to nothing. A measured visual range established like this also gives the rest of the world (including Prime Ministers, Presidents) an honest idea of what they are truly up against. Cost of such a device (plus delivery of course). Still peanuts by comparison with the overall operational cost!!
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Old 26th Mar 2014, 04:37
  #8129 (permalink)  
 
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nitpicker330

Anything above FL400 doesn't seem possible with their payload weight. If the airplane had an initial cruising altitude of 370-390 then it could get above 410
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Old 26th Mar 2014, 04:45
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Propduffer

That's not a fake video, it is very real and is representative of the kind of conditions that frequently are found in the southern ocean.

Good footage of heavy sea conditions are hard to capture, that's some outstanding footage. Who cares where it was filmed?

That said, the seas in the search area haven't quite reached that state yet.
While the video itself is real, it is clearly a misrepresentation of the circumstances surrounding the search, and when people make comments like "the view from the bridge of a search vessel", you know we have reached information BS at high levels.

This video is representative of conditions in the North Atlantic in Jan, 2013. Please spare us your attempts to show this is representative of the crash zone. It adds no information to an already confused situation.

PS: Google "heavy seas". Then click on "videos". Lots of 'footage' of high seas in many different circumstances. You want to post 50 or 100 of them as being "representative" as well?
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Old 26th Mar 2014, 05:00
  #8131 (permalink)  
 
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Here's a good graphic of the search region, around 43 deg S and 90 deg E, IIRC? The jagged yellow line is the South East Indian Ridge, the join line of the Indo-Australian and Antarctic tectonic plates.

If the aircraft ended up in the flatter regions of the S.E. Indian Ridge, it could be up to 4500M deep - if it just happened to lodge on top of one of the underwater volcanoes, it will more likely be a modest 2000M down.

File:Seir.png - Wikipedia, the free encyclopedia
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Old 26th Mar 2014, 05:05
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Modern radar from Fast Patrol boats of 20 years ago couldn't pick up low, non metallic boats in rough seas (typical seas you got South of Aus) unless we put up something metal on a pole. How that relates to wreckage - no reading ? but happy to be corrected.
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Old 26th Mar 2014, 05:55
  #8133 (permalink)  
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The SATCOM installation in 9M-MRO?

What model of SATCOM system was installed in this Aircraft. I haven't heard anything from Boeing or The SATCOM installer since this all began. I understand INMARSATs calculations but does the SATCOM system, have any more to it than we know.
If say for example the ADIRU Position speed heading data info sent to the SATCOM for the BSU Beam steering Unit. If the info was cut or missing, what would happen to the gear?
Would it work based on its last SPEED and HEADING input ie. stored in some type of buffer. Or would the system read an error and park the Antenna ( if it was a mechanical type) or just freeze the position say in a modern phased array type antenna?
We need to hear Avionics SATCOM techos out there people who work on the gear. Anyone know brand of gear it was, Rockwell Collins, Honeywell ?
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Old 26th Mar 2014, 06:12
  #8134 (permalink)  
 
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It would seem that air in the fuel tanks brought down MH377
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Old 26th Mar 2014, 07:19
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With the approximate final location now known, has it been confirmed which agency will lead the investigation once AMSA has completed the search?
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Old 26th Mar 2014, 07:22
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That footage was taken in a hurricane. Going by the BOM.gov.au sea/swell forecast charts, conditions appear relatively OK for todays search.


Last light in the general search area is at around 1230Z tonight, unfortunately coinciding with what looks like the last window of reasonable weather for some time.

Regarding the radar search...

The track spacing in poorer sea conditions has to be tighter, resulting in less area covered in the visual search. As the sea state increases, search radar like they have on the P3 must be brought down closer to the surface, resulting in decreased range and less efficient coverage.

So here's hoping they can pick up something of interest again this afternoon, pass it to a surface vessel and actually get some hard evidence.
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Old 26th Mar 2014, 07:28
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Like many people I have been rather skeptical of the data produced by
Inmarsat in which they claimed that the a/c flew along or near to the
"southern" arc produced by signal levels of the hourly pings.
I could see how they might deduce the arc , but not how they could tell if
the signals were north or south of the equator.
Of course all this assumed that , as was mentioned in the media Inmarsat at
63 degs was used [ 5 Flight 1 ]....but the system aboard MH370 was older and
didnt use GPS.
Then I suddenly realised that not only was the system old , but so was the
satellite.
These non GPS signals are sent via Inmarsat 3F1 at 64.18 east....not 62.7
east.
Not only that , but 3F1 launchedd in 1996 , is inclined by 1.6697
degs....so wobbles above and below the geo arc in an extended figure of 8
pattern every 24 hours.
INMARSAT 3-F1
1 23839U 96020A 14082.92914473 -.00000008 00000-0 10000-3 0 2891
2 23839 1.6697 73.1023 0005489 286.4812 220.7448 1.00274299 65821

At the time the flight took off the sat was 1 deg 11 mins N of the equator
.Three hours later it was at the top of its wobble one deg 40 minutes....and
by 2240 GMT it was back around one deg 11 minutes....having travelled around
the top of the figure of eight.
This gave Inmarsat the third refrence to allow a very approximate idea of where
the signal was coming from....and put it in the southern corridor , not the
northern.

Ref 1 the signals from MH370
Ref 2 the doppler from the wobbling satellite and the moving aircraft
Ref 3 the calculated behaviour of a signal from a "known" a/c within the
footprint of Inmarsat

Hardly cutting edge science...more basic orbital mechanics , but probably
the first time they have used the technique

All geostationery satellites move around a bit but are kept in position by
the operators station keeping.
As they get older they start to wobble more as the fuel runs out and to
extend their life , the operators carry out fewer regular burns.
Even the most stable geo sats. those we get our tv from , move
You can see this movement in the 80 minute time lapse video I took about
ten years ago of a group of TV satellites

The dots are the satellites 36,000 km out in space the streaks are stars
which appear to move due to the rotation of Earth


So there we are....thats probably how they did it.
No doubt someone from Inmarsat will correct me on some of the finer points....but these are the basics.

Of course , Inmarsat tracked the device emitting the ping....not
necessarilly MH370......but odds are the two were together.
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Old 26th Mar 2014, 07:32
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What model of SATCOM system was installed in this Aircraft?
It appears that MH370 had a Swift64 terminal onboard (or possibly an older Aero-H or H+ terminal), not one of the latest SwiftBroadband terminals according to this blog. Classic Aero Services.
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Old 26th Mar 2014, 07:41
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Regardless of the cause, this incident has sparked considerable debate about commercial flights.


Should the passenger emergency air be able to maintain life in a decompression at the maximum altitude achievable by the aircraft?

Should cabin crew have enough endurance in their portable air to stabilise passengers, then react and enter cockpit if during a decompression the flight crew are non responsive?

Should the cabin crew have independent means of communicating with the ground, a comms system that can't be turned off in the cockpit?

Should low cost PLBs be available for deployment by cabin crew and passengers?
If there were a dozen PLBs onboard and none were deployed after an accident this would speak to probable survivability.

Is a live camera view of the cockpit that can be viewed by cabin crew or passengers out of the question?


After watching a well produced documentary a few days ago about the Qantas A380 that suffered a runaway engine, I am of the view that both passengers and crew are distancing ourselves from the perils of flying at 500 knots at 35000ft over hostile terrain in a machine controlled by a computer.

Pilots can't see even their engines or control surfaces, in the case of the A380 an action list that took 45 minutes to scroll through, cabin crew somewhat isolated from pilots and 600 lives at stake. The pilot commented that he was very fortunate to have a spare pilot on the flight deck who could go back and report on what the hell had happened, in the meantime copilot worked his way through the onscreen warnings, but with no way of knowing how many pages of warnings there were and how long it would take to get through them.
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Old 26th Mar 2014, 07:49
  #8140 (permalink)  
 
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MickJoeBill,

I don't think this incident raises ANY of those questions..... YET. How about we just see what comes out of the investigation.
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