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Old 29th Mar 2014, 21:15   #8701 (permalink)
 
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What are the chances of hearing the black box signal, or even being able to retrieve it, if it is down at those depths?
Not much, realistic, available search and salvage operations end at depth of around 15,000 ft.
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Old 29th Mar 2014, 21:31   #8702 (permalink)
 
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So because they have found no evidence of any dodgy behaviour they are not looking hard enough?
It may be that much is being investigated, but that the public is not being informed, and /or that the western media doesn't know how to dig and probe in the context of an oriental culture.
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Old 29th Mar 2014, 21:45   #8703 (permalink)
 
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IMHO money should be spent on the decades-old detachable ELTs rather than lower frequency pingers on the FDR if you can only do one thing. We are all looking something going BEEP-BEEP with our ears in an area nearly the size of Australia right now. The 406 MHz signal wouldn't find the needle, but it would find the haystack
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Old 29th Mar 2014, 21:50   #8704 (permalink)
 
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The MIR can dive to 19,000 ft ( and also retrieve items ). Two were built in Finland , Titanic filmed most of their footage from MIR. Crew size is 3.
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Old 29th Mar 2014, 21:59   #8705 (permalink)
 
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Yes, Water landings are hard too!

To add to the many suggestions attempting to ponder the question regarding a water landing for any aircraft, and particularly a large wide body aircraft like a 777, it is worth pointing out some of the differences between ground and water impacts, much of which was covered in the AF447 thread.

When considering relatively slow speed aircraft impacts, water impacts vary from those on hard terrain in the following way. During an impact with rigid ground, the undercarriage, if deployed, absorbs a significant portion of the impact energy, with the remainder being transferred to the stiffest structural members such as the energy absorbing subfloor beams. These are generally designed to progressively collapse in order to limit to G load on the occupants. The key thing to think about here is “progressively collapse”. To give an example, drop tests on passenger sized airframes at NASA Langley Research Centre have shown how the cabin section experiences quite a pronounced deformation even for a 10m/s drop. The section progressively collapsed, as designed, and but remained intact.

For a water impact, the loading mechanisms differ significantly. The landing gear is unable to absorb the impact energy and instead the impact loads are distributed as a transient dynamic pressure load over the fuselage skin. This initial absorption by the skin momentarily slows the rate that force is applied to the structural members, and has the effect of inhibiting the buckling process to the extent that energy absorbing subfloor components become ineffective. This is why Navy helicopters are designed with additional features to improve their crashworthy response over both hard terrain and water.

In addition to the previous mechanism, the structure also experiences considerable hydraulic shock as the aircraft skin is penetrated and fluid is forced into the interior allowing large pressure forces to act directly upon the cabin floor and interior bulkheads, and as a consequence, actually increases the damage. The result is that vertical accelerations experienced by the occupants is higher due to the lack of initial buckling and rogressive collapse, compounded by the hydraulic shock effect on flooring.

In the Hudson river Airbus ditching on a smooth surface, the evidence for significant hydraulic surge is evident as can be seen from the damaged to the fuselage underside and the dislodged rear bulkhead.

http://graphics8.nytimes.com/package...9/original.pdf


http://www.aero-farm.com/museum/pa-ditch.jpg


How ditching should be done - Learmount
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Old 29th Mar 2014, 22:08   #8706 (permalink)

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One of the more accurate media comments:

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Old 29th Mar 2014, 23:03   #8707 (permalink)
 
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@hamster3null (#8555, 28 Mar 2014, 02:13)

Excellent spreadsheet!

The problem is made harder by having two sources of Doppler -- aircraft motion and satellite motion.

Even for a stationary satellite, the problem is still hard because of the unknown aircraft velocity vector orientation.

So all one can do is hypothesize a set of aircraft positions and velocities, and look for a decent fit to the measurements.

INMARSAT or AAIB must have done something quite similar.
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Old 29th Mar 2014, 23:23   #8708 (permalink)
 
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Quote:
And yes, the Australian government *ARE* going to get the bill for all the wear and tear, jet fuel, etc..
For their own aircraft/ships, etc, I suspect every participating country is paying their own expenses.
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Old 29th Mar 2014, 23:40   #8709 (permalink)

 
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The base cost for the military and the military aircraft is the same whether used on the search or not.
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Old 29th Mar 2014, 23:52   #8710 (permalink)
 
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BJ-ENG:

Interesting to note that in the Hudson River Airbus ditching, the NTSB report states that although the CVR remained in the plane and was physically undamaged, its underwater locating beacon (ULB) was tested and found to be non-functional.
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Old 30th Mar 2014, 00:27   #8711 (permalink)
 
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Former Australian Defence chief Angus Houston to help coordinate search for missing plane

Malaysia Airlines flight MH370: former Defence chief Angus Houston to help coordinate search for missing plane - ABC News (Australian Broadcasting Corporation)
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Old 30th Mar 2014, 00:45   #8712 (permalink)
 
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"Commodore Peter Leavy, the overall military commander of the search effort, said: ''This is a very, very big operation … Normally a military exercise involving different nations is the result of a lot of planning. Something like this … we had to come together very quickly and just get on with the job.''

This is a sign that the search is nearing its final stage.
To coordinate any kind of large, multinational effort, there needs to be a boss. He can allocate the resources and make the tough decisions, such as when to call it quits.
The reality is that nothing is being found and the odds are declining.

Only a boss can call a halt to an obviously futile effort without anyone losing face.

Last edited by etudiant; 30th Mar 2014 at 01:27.
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Old 30th Mar 2014, 01:04   #8713 (permalink)
 
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Olasek:
Then you don't know the B777 in alternate nav. All radios have to be tuned in alternate radio mode, no needles or ILS otherwise. There is no situational guidance unless you programme it in, its not a question of following the magenta line, its simply needing to know where you are. Looking out of the window at night is not enough.
I'm talking about a back up mode, not normal nav.
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Old 30th Mar 2014, 01:50   #8714 (permalink)
 
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Ambient Sheep. If it was a criminal act then misdirection could have been an important part of their plan. By manipulating the response to the satellite pings, the aircraft could have flown west whilst giving the search teams the impression that it was flying north or south.

Buttmonkey1; the existence of the pings might not have been widely known amongst the aircrew community but it will have been part of a specification and I would be surprised if that specification is secret. I would accept that this would require some detailed technical knowledge but I expect that this information was in the public domain, albeit not widely known.
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Old 30th Mar 2014, 02:15   #8715 (permalink)
 
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Skynews showing a graphic of the fdr/cvr as one unit, a cylindrical one mounted on a L shaped one, and 1 beacon, I always thought they were separate and two beacons, twice the chance of finding something.

Are they wrong or is the 777 a combined unit.?
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Old 30th Mar 2014, 02:37   #8716 (permalink)
 
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Quote:
Originally Posted by parabellum View Post
Forget all about LNAV in the immediate aftermath of a serious problem, it will be FLCH and HDG Select, bring up ARPT display and head for nearest suitable. Pumping in Lat and Long would be unnecessary and both time and attention consuming, maybe revert to LNAV when everything is under control but if it is an immediate landing even that is unlikely.
Yes, agreed. Actually if you look at the track that they were on at the time on airways R208 from IKUKO to IGARI, it has a reciprocal track of 197 deg M. Assuming they wanted to return to Kuala Lumpur immediately, could they have set a heading of 197 initially and for whatever reason, the aircraft wondered further to the west, possibly with a DIRECT TO WMKL (Langkawi) set in the FMC? Once having passed WMKL with no further waypoints to track to, could LNAV then later have disconnected due to flight track discontinuity and then reverted to HDG select with the original 197 Heading that was selected?

If so, this matches the heading of 197 deg M and associated track that Capt Kremin was suggesting in his post 7539 of where the aircraft may have ended up.
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Old 30th Mar 2014, 02:47   #8717 (permalink)
 
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Quote:
Originally Posted by oldoberon View Post
Skynews showing a graphic of the fdr/cvr as one unit, a cylindrical one mounted on a L shaped one, and 1 beacon, I always thought they were separate and two beacons, twice the chance of finding something.

Are they wrong or is the 777 a combined unit.?
2 separate boxes, although they are located side by side. There is a CVR and a DFDR. Both are equipped with a ULB (beacon.)
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Old 30th Mar 2014, 03:13   #8718 (permalink)
 
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Quote:

IMHO money should be spent on the decades-old detachable ELTs rather than
lower frequency pingers on the FDR if you can only do one thing. We are all
looking something going BEEP-BEEP with our ears in an area nearly the size of
Australia right now. The 406 MHz signal wouldn't find the needle, but it would
find the haystack
Absolutely! Something is very wrong that in this age of satellites, cpdlc, etc, we still lose track of airplanes. What if there had been survivors from this crash or AF? They'd have perished waiting for rescue. What if there was a aircraft issue or a handling/maint issue that leaves other aircraft in danger. We need those black boxes! We sent rovers to deliberately crash on mars and survive. Surely we can build a better ELT that is cheap, rugged and effective and spares us all the time, effort, money and heartbreak running around blindly.
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Old 30th Mar 2014, 03:20   #8719 (permalink)
 
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The airplane left a major airport with a competent crew, no known deficiencies and the best navigation and communication equipment available. It apparently ended up in the least accessible area it could reach with the fuel on board, and there is still debate about the possibility it did this without deliberate action on the part of a pilot. It keeps the story alive, but needs more imagination than fact, of which there is an unlimited supply of the former but very little of the latter, which only points in one direction. Somebody put this airplane wherever it is, and knew what he was doing.
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Old 30th Mar 2014, 03:55   #8720 (permalink)
 
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oldoberon-
Two separate boxes. Here is a link to the photo of the Asiana 777 CVR and DFDR next to each other in the NTSB lab. They look similar but note the size difference of the "box," while the cylinder with the memory cards and ULB appear to be identical https://twitter.com/NTSB/status/353891249230585856

Last edited by sardak; 30th Mar 2014 at 04:00. Reason: spelling
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