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Old 9th Apr 2014, 09:24   #9581 (permalink)
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They are trying to introduce the SAFE act again in Congress in response to MH370

Wikipedia quote
Proposed requirements[edit]

In the United States, the "Safe Aviation Flight Enhancement (SAFE) Act of 2003" was introduced on June 26, 2003 by Congressman David Price (NC) and Congressman John Duncan (Tennessee) as a bipartisan effort to ensure investigators have access to information immediately following commercial accidents.[27] On July 19, 2005, a revised SAFE Act was introduced and referred to the Committee on Transportation and Infrastructure of the U.S. House of Representatives. The bill was referred to the House Subcommittee on Aviation during the 108th, 109th, and 110th congresses.[28][29][30] On March 12, 2014 in response to the missing Malaysia Airlines Flight 370, Congressman David Price re-introduced the concept in the House of Representatives.[31] The SAFE Act calls for implementing the NTSB 1999 recommendations. Under the NTSB's recommendations, operators would be required to install two sets of combination Cockpit Voice and Data Recorder (CVDR) systems (or "Black Boxes"). The SAFE Act calls for making the second CVDR set "deployable or ejectable". The "deployable" recorder combines the cockpit voice/flight data recorders and an emergency locator transmitter (ELT) in a single unit. The "deployable" unit would depart the aircraft milliseconds before impact, activated by sensors. The unit is designed to "eject" and "fly" away from the crash site, to survive the terminal velocity of fall, to float on water indefinitely, and would be equipped with satellite technology for immediate location of crash impact site. The "deployable" CVDR technology has been used by the U.S. Navy since 1993.[32] The recommendations would involve a massive retrofit program. However, government funding would negate cost objections from manufacturers and airlines. Operators would get both sets of recorders for free: they would not have to pay for the one set they are currently required by law to carry. The cost of the second "deployable/ejectable CVDR" (or "Black Box") was estimated at $30 million for installation in 500 new aircraft (about $60,000 per new commercial plane). The SAFE ACT legislation failed to pass in 2003 (H.R. 2632) or in 2005 (H.R. 3336) or in 2007 (H.R. 4336).[33]
Interesting lets hope it passes now.
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Old 9th Apr 2014, 10:09   #9582 (permalink)
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Originally Posted by Sheep Guts
Commodore Leavy said that P-3C Orions would drop sonar buoys in the water today around the area of the Ocean Shield search area. He was saying during the JACC news conference today the RAAF technicians had modified the sonar buoys to detect 37.5 KHZ signal. He described how when sonar buoys hit the water they drop on a 1000ft wire a hydrophone into the sea below.
The buoys could be inoperative if tuned to 37.5 kHz.
Angus Houston has reported that the signals detected by Ocean Shield pinger locator are on 33.331 kHz.
Could that frequency drift of -11% be caused by hydrostatic pressure ?
I understand that a pressure of 50 MPa is compatible with a +/- 10^5 ppm drift.
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Old 9th Apr 2014, 10:10   #9583 (permalink)
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Press conference 9 April

Link to the JACC 9 April full press conference (including Q&A) - Press Conference by JACC on MH370 - (11.00am, 9/4/2014) | Astro Awani.
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Old 9th Apr 2014, 10:22   #9584 (permalink)
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The locations at which pinging was detected shown in the map in post 9647 are around 26 km apart. Wikipedia states
A 37.5 kHz (160.5 dB re 1 μPa) pinger can be detectable 12 kilometres (0.621.24 mi) from the surface in normal conditions and 45 kilometres (2.53.1 mi) in good conditions. A 37.5 kHz (180 dB re 1 μPa) transponder pinger can be detected 45 kilometres (2.53.1 mi) in normal conditions and 67 kilometres (3.74.3 mi) in good conditions
There have been numerous posts about convergence,ducting etc that could result in longer ranges and, I presume, that is how these pings are being detected so far apart. However it shows what a big area of uncertainty there must still be about the location of the pingers. I seem to recall that when the first announcements of hearing the pingers were made at the press conference a few days ago, Angus Houston said they were searching a 3 mile square area to narrow down the source - it now looks quite a bit bigger than that.
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Old 9th Apr 2014, 10:37   #9585 (permalink)
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Luc Lion,

I miss quoted the Commodore he said that the Aircraft equipment had been modified and not the sonar buoys themselves to receive the 37.5 khz. I believe they have taken into consideration the frequency drift that has occurred since the 1st acquisition on the weekend.

Last edited by Sheep Guts; 9th Apr 2014 at 11:18.
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Old 9th Apr 2014, 10:37   #9586 (permalink)
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just thought of something, the unions would probably scupper the whole thing as they would object to live CVR being transmitted in flight!
It would be interesting to see a debate between those unions and the relatives of the 239 missing people on MH370. Perhaps the time has come for something more constructive than worrying about unethical management oversight.
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Old 9th Apr 2014, 10:46   #9587 (permalink)
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ADV "Ocean Shield" - Current Position

The Ocean Shield is working its way to the south crossing at a right angle the tracks previously taken. The graphic below updates a previous one, and the latest position is noted in Orange. These are the ship's position and the TPL can be over a 1000 meters astern or even out to one side, depending on the effective "drift" component existing between the TPL and the towing vessel.

Bear in mind that the signal strength received at the TPL can vary considerably due to the effects of deep water sound channel ducting, but will show the least phase distortion and largest signal etc.. normally when the TPL is directly above the ULB.
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Old 9th Apr 2014, 10:58   #9588 (permalink)
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Link to the JACC 9 April full press conference (including Q&A) - Press Conference by JACC on MH370 - (11.00am,
9/4/2014) | Astro Awani
I've just watched the whole news conference. Very informative and I have to say I'm very impressed by Angus Houston. I know senior officers have media training, but he comes across as if he'd had years of experience of doing this and I would never have guessed that he was such a distinguished RAAF officer, if I hadn't known.

Speaking of officers, why is it that the RAN officer (Commander Leavy?) is wearing a camouflaged uniform? Is that normal shore-rig these days?
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Old 9th Apr 2014, 11:09   #9589 (permalink)
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India 42,

Speaking of officers, why is it that the RAN officer (Commander Leavy?) is wearing a camouflaged uniform? Is that normal shore-rig these days?
Commodore Leavy actually. Not Commander. Being a Commodore and the Commander of the Military aspect of the search. I would suggest he sets the dress and standards himself. After all it is an operation. Not a passing out parade!
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Old 9th Apr 2014, 13:50   #9590 (permalink)
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The fact is that for a primary radar the range limit will be about equal to the horizon. Factoring in a target altitude and the radar antenna elevation this will work out to something like 200 miles, probably a little more in practice. (The limitation of a radar's range will not be transmit power or receiver sensitivity, as even late 20th century technology has provided ample capability there.)
The detection range of a primary radar is dictated by the pulse repetition frequency - although ground clutter and the physical horizon limit the range at low elevations. A typical PRF for weather radar for example is 400 hz, supporting ranges up to 300 miles or more.

A military radar would use a low PRF for scanning, but would need to switch to a higher PRF for target acquisition and launch that would limit the range to about 90 miles or even less. I expect that is the "implied threat" in Indonesia's claim of a radar range of only 90 miles.
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Old 9th Apr 2014, 13:52   #9591 (permalink)
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Insurance Payout

Not sure if this has been mentioned - Malaysia Airlines has already been handed $110 million (67 million) by insurers over the loss of its missing Boeing 777 on flight MH370.

Flight MH370: insurers make first pay out on missing Malaysia Airlines plane - Telegraph
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Old 9th Apr 2014, 13:57   #9592 (permalink)
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The Sonobuoys that will be dropped as listening devices in the larger search area are indeed broad spectrum passive listening devices. The modifications to the aircraft equipment might allow for a narrow frequency spectrum to be more closely monitored so that the returned signal will only scan the chosen frequency range around 37.5kHz.
Depending on the pattern of the sonobuoys and the contact gained on one or many of the buoys, he contact could serve to localise and triangulate a more refined position of the signal source. This technique has been in use for decades but probably not used to date because of the modifications required. The buoys can be monitored by one or several aircraft at altitude depending on the number of buoys deployed and the number of receiver channels on each aircraft.

The limited depth of the sonobuoy hydrophone (about 300m) could make detection through varying thermal layers less likely with weak signals. At least all resources are being employed to solve this mystery.
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Old 9th Apr 2014, 14:31   #9593 (permalink)
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They are trying to introduce the SAFE act again in Congress in response to MH370

Yes, very interesting, SheepGuts.

Are you prepared to finance the government-sponsored/mandated retrofit of the US fleet? Would that have helped the Malaysians? After all, they couldn't be bothered to purchase the upgraded ACARS maintenance package; what makes you think the United States Congress and its knee-jerk reaction (if any) would make a difference in either AF or MH?

It's always up to the Brits, Aussies, or Yanks, isn't it?
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Old 9th Apr 2014, 14:55   #9594 (permalink)
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The latest TV news briefing said that the frequency received was 33.331 kHz, which is very precise.

Back of the envelope calculations assuming speed of sound in sea water at 4 degrees C and 4000 metres is around 1500 m/s, and the ship is towing at around 1 m/s, gives me a maximum doppler shift to the signal of around 20 Hz, which is an order of magnitude greater than the resolution indicated by the news report.

This is best case and assumes movement directly towards or away from the source, that there aren't effects due to currents, and that I haven't got my maths and assumptions wrong. Also, with 10 ms pings and the small windows of acquisition, there aren't that many waves to measure. Further, the signal seemed quite broad on the waterfall on the news report, but I couldn't make out bandwidth.

But - is it possible or even plausible that some further geometric information about the pinger's location wrt the receiver could be obtained this way? Perhaps the thread readers with DSP/hydroacoustic experience could comment...
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Old 9th Apr 2014, 14:55   #9595 (permalink)
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One question has occurred to me. It seems that MH370 may (and I say MAY) have been following airways towards Perth. Would an MH 777 have had a Kuala Lumpur - Perth route stored in the FMC library?
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Old 9th Apr 2014, 15:24   #9596 (permalink)
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wow! that TPL 25 is a LOT smaller than I thought. Never saw it in reference to another object before till now next to humans. I thought it would be perhaps the size of an automobile or something!@ LOL
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Old 9th Apr 2014, 15:34   #9597 (permalink)
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One question has occurred to me. It seems that MH370 may (and I say MAY) have been following airways towards Perth. Would an MH 777 have had a Kuala Lumpur - Perth route stored in the FMC library?
Malaysian operate direct flights between Kuala Lumpur and Perth so the answer must be yes.
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Old 9th Apr 2014, 15:45   #9598 (permalink)
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One question has occurred to me. It seems that MH370 may (and I say MAY) have been following airways towards Perth. Would an MH 777 have had a Kuala Lumpur - Perth route stored in the FMC library?
Given that MAS fly a scheduled non-stop service from KUL-PER (MH125) I'd say there was an excellent chance that the route was available in the FMC.
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Old 9th Apr 2014, 15:53   #9599 (permalink)
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They will use as much cable as possible and when mowing the lawn, will have to make large turns. The towed array is rated with a static depth, so the dynamic load of the towed speed and turn is important.
Due to the time required, they will not raise and lower the array when turning.

The distance between the parallel tracks is a function of the overlap at depth.

There are also Bluefin 21's in use.

They may also be towing a magnetometer, or multiple beam sonar array to image the bottom. I am sure if Ocean Shield isnt, others are.
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Old 9th Apr 2014, 15:56   #9600 (permalink)
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Doppler signature

Re: 9679

Agreed. Doppler signatures were used for ELT locating by satellite before GPS's were integrated with ELT's. The relative doppler shift is a tenth of the under water case.

The lower duty cycle ping pulse will make it challenging. A fellow on the Reddit MH370 group used matlab to find a 0.4 millisec slowing down during a playback of 20 seconds of pings from a news broadcast. Lets put Inmarsat on the case.

Last edited by Rollleft; 9th Apr 2014 at 16:20.
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acars, crash, elt, hf links, malaysian, mh370, missing, pingers, plane, vhf

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