Pings from the underwater locator beacon (UBL) of the recently downed Lion Air JT-610 were believed to have been detected on Wednesday. The pings were strongly believed to have been coming from the aircraft’s flight recorder, known colloquially as the black box.
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DANIAL ADE KURNIAWAN
Divers from the Jalamangkara Detachment (Denjaka), a counterterrorism elite special force of the Indonesian Navy, and Taifib, an elite reconnaissance unit of the Indonesian Marine Corps, prepare diving equipment on Wednesday (31/10/2018) to search for the black boxes based on the location detected by the Baruna Jaya I Research Ship on Karawang waters, Karawang regency, West Java. As of Wednesday evening, search activities had not produced results, but several divers said they had seen turbine machines on the seabed.
Pings from the underwater locator beacon (UBL) of the recently downed Lion Air JT-610 were believed to have been detected by Baruna Jaya I vessel’s ultrasoft baseline transponder on Wednesday (31/10/2018) at around 12:25 p.m. The pings were strongly believed to have been coming from the aircraft’s flight recorder, known colloquially as the black box. Lion Air flight JT-610 crashed on Monday (29/10) into waters off Karawang, West Java, on its way from Soekarno-Hatta International Airport in Jakarta to Pangkal Pinang’s Depati Amir Airport in Bangka Belitung Islands.
Retrieving the flight recorder will be an important step in finding out the cause of the crash. Flight recorders generally comprise a flight data recorder (FDR) and a cockpit voice recorder (CVR).
“The dive team from the Navy and the National Search and Rescue Agency [Basarnas} is still trying to find the black box. Aircraft debris and the black box are located 15 kilometers off Karawang’s coast,” Agency for the Assessment and Application of Technology’s (BPPT) deputy head of natural resources development technology Hammam Riza said.
The Baruna Jaya I, a research vessel equipped with the BPPT’s sophisticated equipment, has been deployed in the search for JT-610 since Tuesday (30/10/) at 5 a.m. Teams from the Indonesian Military (TNI) and the National Transportation Safety Committee (KNKT) are on board.
Signal detector system
A ping locator, which can detect signals emitted by black boxes located in the aircraft’s tail, is used in the search for JT-610. Black boxes emit an acoustic signal on a certain frequency, in accordance to the aircraft’s class. On wide-body aircrafts manufactured by Boeing and Airbus, the frequency range is between 10 kilohertz (kHz) and 20 kHz.
A black box will emit its signal intermittently with one ping every few seconds. “On detectors equipped with hydrophone, the black box’s signal will be heard as pings. This is why the equipment is known as ping locator,” said BPPT’s maritime survey technology agency head M Ilyas, who was involved in the search.
On Wednesday morning, the KNKT deployed three ping locators in its search for the downed JT-610. The Baruna Jaya I team also deploys its ultra soft baseline (USBL) transponder, which can also track black boxes’ signal, to optimize the search.
“The transponder is placed under the Baruna Jaya I vessel’s keel,” Ilyas said. The transponder works similarly to ping locators. It may detect signals ranging between 90 decibel (dB) and 120 dB, originating up to 3,000 meters deep.
Hammam said that the BPPT first used the transponder in the search for the missing Adam Air 574 over the Makassar Strait in January 2007 and the downed AirAsia QZ-8501 in the Karimata Strait in early 2015.
Success in locating black boxes is also determined by the endurance of their batteries. Generally, black box batteries can last up to 90 days.
US-made black box trackers known as the towed pinger locator (TPL) are also often used in underwater black box searches, such as during the search for Malaysian Airlines MH-370. The TPL is submerged and towed by a vessel along a predetermined route. At the same time, a towed hydrophone is also submerged up to 6,000 meters underwater.
The vessel will traverse on a predetermined route at a speed of 5.6 kilometers per hour. In one day, the vessel may cover 388.5 square kilometers of area. Black box signals within a radius of 1.6 kilometers from the vessel will be detectable. The equipment successfully located the black box of the downed TWA-800 in the Atlantic Ocean in 1996.
Apart from Western technologies, China also develops its own black box trackers, such as those attached on the Haixun-01 vessel. It may detect signals originating up to 5,000 meters underwater. With its advanced technology, the black box’s ping can be analyzed and its consistency verified with data from the FDR and the CVR.
Aircraft fuselage
Previously the KRI Rigel 933 vessel has located an object believed to be the downed JT610’s fuselage off the coast of northern Karawang. The vessel used sonar technology to locate the object.
Operational survey and mapping director Col. Haris Djoko Nugroho of the Navy’s Hydro-Oceanography Center, who was on board the KRI RIgel 933, told Kompas on Wednesday that the object was believed to be 20 meters long and 32 meters underwater.
The KRI Rigel 933 is a hydro-oceanography support (BHO) ship commandeered by Lieut. Col. Agus Triyana. The sophisticated ship, often touted as the best survey ship in South East Asia, is the Navy’s first multipurpose research vessel (MPRV).
The ship is equipped with an autonomous underwater vehicle (AUV) that can conduct underwater imaging up to a depth of 1,000 meters and send data periodically back to the main BHO ship.
