Isyarat mungkin dipancar kotak hitam...
Pasukan penyiasat Australia menyebut, kapal negara itu ADV Ocean Shield kini sedang menentukan kedudukan isyarat denyutan yang dikesan sebanyak dua kali dalam tempoh 24 jam lalu.
Ketua Penyelaras Pusat Penyelarasan Agensi Bersama (JACC) Angus Houston dalam satu laporan Reuters menyebut, kapal berkenaan juga sedang berusaha mengesan semula isyarat tersebut.
Tambahnya, isyarat tersebut mungkin dipancarkan dari kotak hitam pesawat apabila ia dikesan buat kali kedua.
"Ketika itu, dua ping berasingan dapat didengar. Apa yang penting, ia konsisten dengan pancaran dari perakam data penerbangan dan perakam suara kokpit,” katanya dalam sidang media di Perth, Australia.
Katanya ADV Ocean Shield mengesan isyarat tersebut untuk tempoh dua jam dan 20 minit sebelum terputus hubungan dan kini berusaha berpatah balik untuk membuat pengesanan semula.
Menurutnya, isyarat yang dikesan itu merupakan petuntuk terbaik buat masa ini.
Satu kenderaan bawah air, Bluefin 21 yang berkeupayaan menyelam ke kedalam 4,500 meter, akan ditugaskan untuk membuat siasatan lanjut selepas kedudukannya dikenalpasti, kata Houston.- mk
MH370: Apa kaitan ping 37.5 kHz dengan kotak hitam...
Kotak hitam, yang merekodkan semua data di dalam kapal terbang, adalah alat penting dalam penyiasatan kemalangan udara dan kerana kotak hitam, sembilan daripada sepuluh kemalangan dapat dijelaskan.Pesawat komersil akan membawa dua kotak hitam.
Perakam Digital Data Penerbangan mengandungi maklumat tentang kelajuan, ketinggian dan arah, manakala Perakam Suara Kokpit menjejaki perbualan kokpit dan bunyi dan pengumuman lain di dalam kabin juruterbang.
Ia sebenarnya berwarna oren ditambah dengan jalur putih agar ia mudah untuk dikesan. Setiap kotak hitam seberat tujuh hingga sepuluh kilogram (15-22 lb).
Diperkenalkan penggunaannya untuk penerbangan pada tahun 1960-an, perakam penerbangan diletakkan di dalam kotak besi agar ia dapat tahan lasak, elak dari kebakaran dan dapat bertahan di dalam air yang dalam.
Ia boleh bertahan sedalam 6,000 meter (hampir 20,000 kaki) di bawah air atau kepada suhu yang sangat panas iaitu 1,100 darjah selsius untuk satu jam. Ia dilengkapi dengan pengesan yang boleh mengeluarkan isyarat selama kira-kira satu bulan.
Isyarat itu kadang-kadang boleh berterusan selama beberapa hari selepas tempoh ini, kira-kira lapan hingga 10 hari, menurut ketua misi carian Australia, Angus Houston.
Frekuensi 37.5 kHz adalah denyutan yang paling biasa untuk perakam data penerbangan, menurut pakar . Ia adalah tahap yang sama di mana isyarat yang dikesan oleh kapal Cina Haixun 01 pada 5 April ketika pencarian dilakukan di selatan Lautan Hindi untuk mencari pesawat MH370 yang hilang.
Kotak hitam dapat dikesan dalam purata dua kilometer (1.2 batu).
Perairan dimana kapal China melakukan pencarian adalah 4.5 kilometer (hampir tiga batu) dalam.
Jadi, walaupun isyarat didapati datang dari pesawat namun kerja mencari tetap akan menjadi satu cabaran, kata Houston.
Pada bulan Mei 2011, selepas 23 bulan tenggelam pada kedalaman 3,900 meter di Lautan Atlantik, kotak hitam penerbangan Air France AF447 berjaya ditemui dengan data yang masih utuh.
Ini dapat membantu penyiasat untuk menentukan punca kemalangan yang berlaku pada 1 Jun 2009.
Two hours of ‘pings’ give MH370 black box search teams ‘best lead yet’...
A US pinger locator has detected signals consistent with those emitted by an aircraft black box, indicating a potential breakthrough in the month-long search for missing Malaysia Airlines flight MH370.
Two separate signals have been detected by a US device being towed by Australian Defence Vessel Ocean Shield in the northern part of the Indian Ocean search area, about 1700km north-west of Perth.
In what he called "a most promising lead", Air Chief Marshal (ret) Angus Houston, the head of the search's Joint Agency Coordination centre, revealed that "the pinger locator has detected signals consistent with those emitted by aircraft black boxes".
"It is the best information we have had in the search so far," he said.
The first detection was picked up on Sunday morning and held for about two hours and 20 minutes, before the ship lost contact. The pinger locator was in relatively shallow waters at the time.
On the return leg, hours later, a second detection was held for about 13 minutes, where two distinct pinger returns were audible.
The incidents were about 1800 metres apart and could have been from the same source, or two separate sources, said Commodore Peter Leavy, the man in charge of the search.
‘‘Significantly, this would be consistent with transmissions from both the flight data recorder and the cockpit voice recorder,’’ Mr Houston said, cautiously adding that authorities were "a very long way off" verification.
"We haven’t found the aircraft yet, we need further confirmation,’’ he said.
Commodore Leavy said pinpointing the origins of the sound would be a slow, challenging process as sound waves under water can distort by as much as 90 degrees.
"It is a markedly different environment to what you see with sound travelling through air," he said.
pinger locator
ADV Ocean Shield would continuing moving in a square around the 1800-metre detection zone in an attempt to relocate the signal over the next 24 hours, he said, it takes the ship about eight hours to complete a single leg.
"It is a very slow and painstaking process ... if the pinger is out there and it's still radiating we're confident that we should find it," he said.
The ADV Ocean Shield detection on Sunday came shortly after a Chinese patrol vessel, the Haixun One Zero, reported detecting two pulse signals on Friday night, and then again on Saturday at a frequency consistent with black box technology.
The ships are within a search area more than 300 nautical miles long, with the ADV Ocean Shield at the northern extremity and the Haixun Zero One at the southern end
Both ships are within the range analysts believe is where the plane was most likely to have entered the water. The data has been provided by expert in Malaysia working with satellite information.
"Their work has enabled us to come up with an underwater search area which is quite narrowly focused and with the acoustic events that we're getting in the area, we 're encouraged that we're very close to where we need to be," Mr Houston said.
The HMS Echo and RAAF aircraft were diverted to the Haixun's location on Sunday in a bid to verify whether the detections were linked to the missing plane's black box.
Malaysian Airlines flight MH370, with 239 people on board, vanished without a trace during a routine flight from Kuala Lumpur to Beijing on March 8.
Bluefin-21
Up to 12 aircraft - nine military and three civilian, and 14 ships were scheduled to assist in the southern Indian Ocean search on Monday.
Weather conditions in the 234,000 square kilometre search area were expected to deteriorate into the afternoon after a clear day.
The Ocean Shield will continue "runs" over the search area where it detected the signals for the next 24 hours.
If the signal can be picked up again and a source location identified, a Bluefin-21 autonomous underwater vehicle would be dropped to the ocean floor to search for wreckage. The Bluefin-21 is equipped with sonar and can carry an underwater camera.- smh.com.au
cheers.
No comments:
Post a Comment