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Malaysian Airlines MH370 contact lost

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Malaysian Airlines MH370 contact lost

Old 25th Mar 2014, 06:31
  #7941 (permalink)  
Join Date: Jul 2013
Location: USA
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Mesoman and others -
The 406 ELTs currently transmit on one of several different frequencies: 406.025, .028, .037 and .040, depending on when they were built. There are additional freqs reserved for future expansion of the system. A reason for this is a lot of science involving packet theory and collisions between the data bursts from the beacons.

The Doppler frequency is determined by the satellite and position is calculated on the ground at LEOLUTs (LEOSAR local user terminals). This Cospas-Sarsat document goes into much of the gory details: http://www.cospas-sarsat.org/images/...2_OCT_2012.pdf LUT locations are shown here: LEOSAR Satellite Coverage

The GEOSAR system consist of geostationary satellites that detect the beacons and GEOLUTs. No Doppler location is determined from them, they provide alerting and data burst relay including position for beacons with a global navigation system.

In development right now is the MEOSAR system, using receivers on GPS, Glonass and Galileo nav satellites. Among the features and advantages of this system is return-link (two-way) capability between the rescue coordination centers and the beacons. Intial operational capability is scheduled for 2018. References for all of these systems can be found on the Cospas-Sarsat website: International Cospas-Sarsat Programme

As for beacons transmitting from inside a plane being detected by the satellites, maybe, maybe not. From deep underwater, no. From a crash on land, maybe, maybe not. Lots of factors involved. The most recent published study on the effectiveness of beacons in crashes was published last year by the Australian Transport Safety Bureau. http://www.atsb.gov.au/media/4126629...-128_final.pdf

For more on ELTs, including a reference for the g-force activation criteria, deployable beacons and more, see this thread spun off from here: http://www.pprune.org/tech-log/53575...ml#post8376340

Final bit of info, the last week of January of this year was a meeting of the ICAO Asia/Pacific Regional Search and Rescue Task Force in Singapore. 15 of the 44 countries in the region sent representatives, as did ICAO, IMO, IATA and Cospas-Sarsat. Among the countries not in attendance were Malaysia, Vietnam and China. Counted in those which were are Australia, India, Thailand and the US.

Agenda items included (4) Asia/Pacific and inter-regional SAR planning, coordination and cooperation and (5) Asia/Pacific Regional SAR Plan. The minutes note: It was recognized that many States have difficulties in enacting SAR agreements with their neighbouring States.
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Old 25th Mar 2014, 06:45
  #7942 (permalink)  
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From FR24, when "something happened", the heading was 25 or 18. If (If) the "left turn and descent" was applied (decompression) and crew choose to return to KL with a reverse heading (205 or 198) and then things gone very bad for everybody in the a/c, could she fly to were she finished because of magnetic specificity of the south west of Sumatra?
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Old 25th Mar 2014, 06:59
  #7943 (permalink)  
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Originally Posted by downwindabeam View Post
In the 777, are the CVR and FDR circuit breakers in the cockpit? are they up above the overhead panel?
No, they are located below in the MEC otherwise known as the EE bay.
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Old 25th Mar 2014, 07:04
  #7944 (permalink)  
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From FR24, when "something happened", the heading was 25 or 18.
Actually the last two ADS-B returns on FR24 show a heading of 40.
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Old 25th Mar 2014, 07:13
  #7945 (permalink)  
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Have a look at Capt Kremin's post on this, currently sitting at #7541.
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Old 25th Mar 2014, 07:15
  #7946 (permalink)  
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Good piece about the awful performance of the media (which has clearly influenced many of the less thoughtful posters on this thread) here:

It's about the media, not the plane - The Drum (Australian Broadcasting Corporation)
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Old 25th Mar 2014, 07:20
  #7947 (permalink)  
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If the cb was pulled for the data voice recorders i am confident the perpetrator would have made a blunder in his grand plan as the initial cockpit struggle would be preserved on the cvr
Your theory that a cockpit struggle would have been evident assumes both pilots were in the cockpit at the same time. In the case of the Silk Air MIA 185 B737 suspected suicide crash, the circuit breakers for the CVR and FDR were found to have been actuated by physical means not an electrical fault. it was thought the most plausible scenario was the captain conned the co-pilot to leaving the cockpit on the pretext of sending him to the cabin to investigate an event (eg leaking door seal). It was speculated that once the co-pilot had left the cockpit the captain locked the door, and pulled both FDR circuit breakers (that action activates the Master Caution light).

It was considered very doubtful the captain pulled the dual circuit breakers for the FDR while the co-pilot was still in the cockpit, as the illumination of the Master Caution Light would have alerted the co-pilot something dodgy was being planned. There was evidence the captain had already previously pulled the CVR circuit breaker situated behind his own seat and out of the forward sight of the co-pilot. Easy done as he had practiced that before on the ground on a previous flight.

Pulling the CVR circuit breaker (B737) does not activate the Master Caution and the co-pilot would have been unaware the CVR circuit breaker had been pulled by the captain who had himself left the cockpit a few minutes earlier on a visit down the back.
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Old 25th Mar 2014, 07:26
  #7948 (permalink)  
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What was the genuine 'Last Known Position? Was it really 200nm WNW of Penang VOR (or variants of this), or was it 'close to the Malaysia/Vietnam FIR boundary?

And for Capt Kremin (#7541), if your coloured lines were drawn from the latter, how does that alter the 'final' assumed position?

If the crew made a left turn back from the FIR boundary towards 'home', be it PEN or KUL on HDG (I guess around 190 deg M or so), and were then overcome by events, where would that autopilot have taken them?
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Old 25th Mar 2014, 07:26
  #7949 (permalink)  
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Interesting article.

I was looking at some photos of the media at RAAF Base Pearce the other day, all quietly lined up and waiting patiently on the edge of the grass next to the runway with one military person watching over them. Same out the front of the base. Amazing what happens to the media when the law is laid down to them at the start
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Old 25th Mar 2014, 07:45
  #7950 (permalink)  
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I haven't seen much true wavering from the position that 200WNW of Penang was the last trace of MH370. Someone here posted a link to a Chinese paper which reproduced the military primary radar data as shown to Chinese relatives. I took a copy but no longer have the actual link.

It all depends if you believe there is sufficient evidence that the aircraft tracked west of the Malacca Straits, or whether you want to believe it could have been a ghost plane after a failed attempt to head to a nearby airport or perhaps KL.. Either way, I think Capt Kremin's point stands that a ghost plane scenario will have been determined to have been either true or false depending on the location of the final six pings. As we don't have that information, we can only surmise that investigators have come to the position that the diversion was a deliberate act because they do have that information, which would probably show that a direct heading south in a straight line had to have had human input and could not be simply a ghost plane flying itself after a catastrophe.

Time will eventually tell, and even though the search is daunting, I feel we will get some answers, even if not all of them. We must go wherever the evidence leads.
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Old 25th Mar 2014, 07:59
  #7951 (permalink)  
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All 'speculation' until MH370 debris found

Defence Minister David Johnston says until debris is recovered and positively identified as being from Malaysia Airlines flight MH370, any information about the search for the missing plane is speculation.

Malaysian Prime Minister Najib Razak told a press conference in Kuala Lumpur late on Monday that based on new analysis by the UK Air Accidents Investigation Branch and tracking firm Inmarsat, the plane flew along the southern corridor and crashed into the ocean west of Western Australia.

But Senator Johnston said while the British data is all the authorities have to go on, he stressed no debris had yet been recovered from the massive search area in the Indian Ocean.

"The turning point for us, I think, will be when we pull some piece of debris from the surface of the ocean and positively identify it as being part of the aircraft," he told reporters at the RAAF Pearce air base north of Perth on Tuesday.

"This is a mystery and until we recover and positively identify a piece of debris, everything is virtually speculation."

He said the search continued to be "fairly urgent" given there's only some 13 days of life left on the beacon battery that would pinpoint the location of the black box.
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Old 25th Mar 2014, 08:24
  #7952 (permalink)  
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Doppler accuracy

Doppler shift has not to be regarded in relation to the carrier frequency (1,6 Ghz) but in relation to the baseband bandwith, i.e the part of the signal that carries the payload.

5kHz is a number I found for channel spacing in Inmarsat-C. So with a doppler shift in the range of 1khz, speed accuracy should be pretty good.
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Old 25th Mar 2014, 09:02
  #7953 (permalink)  
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Originally Posted by eltonioni View Post
Beancounting is neither here nor there. ELT's are lifesaving equipment that transmit on internationally standardised frequencies to enable life saving, not underwater wreck recovery.
I believe the "beancounter" comment was made in respect of the ULBs (Underwater Locator Beacons) attached to the FDR and CVR.

Given that those are beacons to help in locating said objects underwater (the clue's in the name), the comment is entirely relevant.
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Old 25th Mar 2014, 09:12
  #7954 (permalink)  

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yup waiting for the weather to clear. Its pretty ordinary weather when the Australian Navy withdraws from the area to calmer waters until it clears.

Its pretty clear from the reports and my understanding of the area, the more assets you use and the more you look in these parts the more you will find, it's a really wild part of the ocean with winds and currents that run unrestricted by any land around the world.
it will be carrying years of debris that has fallen off ships or swept off beaches

Hardly anybody ever goes down that way for fun or commerce, except the crazy round the world yachting crazies and they have a horizon of less than a couple of miles. Usually the first they know there is a large piece of debris seatainer or such like is when they hit it.

IMHO they are better off concentrating searching for a pinger.

And I hope they haven't given up on the Northern end.
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Old 25th Mar 2014, 09:15
  #7955 (permalink)  
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I'm pretty sure they have given up on the Northern end, Gaunty.
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Old 25th Mar 2014, 09:18
  #7956 (permalink)  
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The radar plots after the turn back are patchy. What is the latest info they have on this with all the combined Radar. There have been many versions. What was their first heading or track immediately after turn back?
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Old 25th Mar 2014, 09:26
  #7957 (permalink)  
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"Its pretty ordinary weather when the Australian Navy withdraws from the area to calmer waters until it clears."

The Captain has seen action all around the world, she knows what she is doing.
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Old 25th Mar 2014, 09:32
  #7958 (permalink)  
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Finding things on the bottom ...

Originally Posted by 500N

The problem is of course finding those first bits !
The Towed Pinger Locators (TPL's) are to detect the Underwater Locator Beacons (ULB's) - one attached to the DFDR, and one attached to the CVR. They have a guaranteed battery life of 30 days, but the manufacturer will probably ensure that is extended to about 40 days. In the AF447 case, neither worked, and one was never found.

The ROV option is only useful when you have found something worth taking a look at. Initially, and if the ULB's are not located, a dedicated underwater search plan needs to be drawn up based on the best information available. In the MH370 case, the area selected to search will probably not be less than that which was searched using Autonomous Underwater Vehicles (AUV's) to find AF447, in which case this whole operation will take not weeks, but many months if not a year or more.

Why? The backtracking of surface floating debris is not a precise science, and the "butterfly effect" created by spurious vortexes that spin stuff off and then repeat the process, tends to confuse the issue.

Don't hold your breath.
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Old 25th Mar 2014, 09:42
  #7959 (permalink)  
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Yes that may be one obvious conclusion but hopefully the NTSB / AAIB / Malaysian / French investigators retain open minds; for example that all comms and pilots could have been wiped out by an event as yet unknown and it flew itself to its final resting point.
That's what I'm sticking with at the moment!
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Old 25th Mar 2014, 09:54
  #7960 (permalink)  

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I see that Inmarsat have used a speed of 450 kts for their calculation. Assuming that a 777 operates at 0.84 or there abouts that equates to a TAS closer to 500kts.

How would that affect the arcs that they have published and how far down those arcs the aircraft might have flown.
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