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Towed Pinger Locator
A towed pinger locator is a water-borne device used to locate the sonar "ping" from the underwater locator beacon which is fitted to the Cockpit Voice Recorders and Flight Data Recorders installed in commercial airliners. They can locate pingers at depths of up to underwater. The locator is mounted in a hydrodynamic shell, or "tow fish", connected by winch behind a surface vessel across the search area. The locator listens for the sound emanating from the beacon or "pinger". Once located, the beacon and its attached recorders can be retrieved by divers, submersibles or remotely operated vehicle (ROV), depending on depth. A model currently used by the United States Navy is the TPL-25, which has a weight of and a length of ; it is generally towed at . Most beacons transmit a pulse once a second at 37.5 kHz. The hydrophone must be positioned below the thermocline layer which reflects sounds, either back to the surface or back to the ocean floor. Since the pinger signal is re ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Towed Pinger Locator
A towed pinger locator is a water-borne device used to locate the sonar "ping" from the underwater locator beacon which is fitted to the Cockpit Voice Recorders and Flight Data Recorders installed in commercial airliners. They can locate pingers at depths of up to underwater. The locator is mounted in a hydrodynamic shell, or "tow fish", connected by winch behind a surface vessel across the search area. The locator listens for the sound emanating from the beacon or "pinger". Once located, the beacon and its attached recorders can be retrieved by divers, submersibles or remotely operated vehicle (ROV), depending on depth. A model currently used by the United States Navy is the TPL-25, which has a weight of and a length of ; it is generally towed at . Most beacons transmit a pulse once a second at 37.5 kHz. The hydrophone must be positioned below the thermocline layer which reflects sounds, either back to the surface or back to the ocean floor. Since the pinger signal is re ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nautical Mile
A nautical mile is a unit of length used in air, marine, and space navigation, and for the definition of territorial waters. Historically, it was defined as the meridian arc length corresponding to one minute ( of a degree) of latitude. Today the international nautical mile is defined as exactly . The derived unit of speed is the knot, one nautical mile per hour. Unit symbol There is no single internationally agreed symbol, with several symbols in use. * M is used as the abbreviation for the nautical mile by the International Hydrographic Organization. * NM is used by the International Civil Aviation Organization. * nmi is used by the Institute of Electrical and Electronics Engineers and the United States Government Publishing Office. * nm is a non-standard abbreviation used in many maritime applications and texts, including U.S. Government Coast Pilots and Sailing Directions. It conflicts with the SI symbol for nanometre. History The word mile is from the Latin word ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Towed Array Sonar
A towed array sonar is a system of hydrophones towed behind a submarine or a surface ship on a cable. Trailing the hydrophones behind the vessel, on a cable that can be kilometers long, keeps the array's sensors away from the ship's own noise sources, greatly improving its signal-to-noise ratio, and hence the effectiveness of detecting and tracking faint contacts, such as quiet, low noise-emitting submarine threats, or seismic signals. A towed array offers superior resolution and range compared with hull mounted sonar. It also covers the baffles, the blind spot of hull mounted sonar. However, effective use of the system limits a vessel's speed and care must be taken to protect the cable from damage. History During World War I, a towed sonar array known as the "Electric Eel" was developed by Harvey Hayes, a U.S. Navy physicist. This system is believed to be the first towed sonar array design. It employed two cables, each with a dozen hydrophones attached. The project was discontin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Malaysia Airlines Flight 370
Malaysia Airlines Flight 370 (MH370/MAS370) was an international passenger flight operated by Malaysia Airlines that disappeared on 8 March 2014 while flying from Kuala Lumpur International Airport in Malaysia to its planned destination, Beijing Capital International Airport. The crew of the Boeing 777-200ER registered as 9M-MRO, last communicated with air traffic control (ATC) around 38 minutes after takeoff when the flight was over the South China Sea. The aircraft was lost from ATC radar screens minutes later, but was tracked by military radar for another hour, deviating westward from its planned flight path, crossing the Malay Peninsula and Andaman Sea. It left radar range northwest of Penang Island in northwestern Peninsular Malaysia. With all 227 passengers and 12 crew aboard presumed dead, the disappearance of Flight 370 was the deadliest incident involving a Boeing 777 and the deadliest in Malaysia Airlines' history until it was surpassed ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
List Of Unrecovered Flight Recorders
Flight data recorders (FDRs) and cockpit voice recorders (CVRs) in commercial aircraft continuously record information and can provide key evidence in determining the causes of an aircraft loss. The greatest depth from which a flight recorder has been recovered is , for the CVR of South African Airways Flight 295. Most flight recorders are equipped with underwater locator beacons to assist searchers in recovering them from offshore crash sites, however these beacons run off a battery and eventually stop transmitting. For various reasons, a flight recorder cannot always be recovered, and many recorders that are recovered are too damaged to provide any data. See also *List of missing ships This is a list of missing ships and wrecks. If it is known that the ship in question sank, then its wreck has not yet been located. Ships are usually declared lost and assumed wrecked after a period of disappearance. The disappearance of a s ... References {{DEFAULTSORT:Unrecovered ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Korean Air Lines Flight 007
Korean Air Lines Flight 007 (KE007/KAL007)The flight number KAL 007 was used by air traffic control, while the public flight booking system used KE 007 was a scheduled Korean Air Lines flight from New York City to Seoul via Anchorage, Alaska. On September 1, 1983, the flight was shot down by a Soviet Sukhoi Su-15 interceptor. The Boeing 747 airliner was en route from Anchorage to Seoul, but owing to a navigational mistake made by the crew, the airliner drifted from its original planned route and flew through Soviet prohibited airspace around the time of a U.S. aerial reconnaissance mission. The Soviet Air Forces treated the unidentified aircraft as an intruding U.S. spy plane, and destroyed it with air-to-air missiles, after firing warning shots which were probably not seen by the KAL pilots. The Korean airliner eventually crashed in the sea near Moneron Island west of Sakhalin in the Sea of Japan. All 269 passengers and crew aboard were killed, including Larry McDonald, a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Air France Flight 447
Air France Flight 447 (AF447 or AFR447) was a scheduled international passenger flight from Rio de Janeiro, Brazil, to Paris, France. On 1 June 2009, inconsistent airspeed indications led to the pilots inadvertently stalling the Airbus A330 serving the flight, failing to recover from it and eventually crashing into the Atlantic Ocean at 02:14 UTC, killing all 228 passengers and crew on board. The Brazilian Navy recovered the first major wreckage, and two bodies, from the sea within five days of the accident, but the investigation by France's Bureau of Enquiry and Analysis for Civil Aviation Safety (BEA) was hampered because the aircraft's flight recorders were not recovered from the ocean floor until May 2011, nearly two years later. The BEA's final report, released at a news conference on 5 July 2012, concluded that the aircraft suffered temporary inconsistencies between the airspeed measurements—likely resulting from ice crystals obstructing the aircraft's pitot tubes— ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Emergency Position-indicating Radiobeacon Station
An Emergency Position-Indicating Radio Beacon (EPIRB) is a type of emergency locator beacon for commercial and recreational boats, a portable, battery-powered radio transmitter used in emergencies to locate boaters in distress and in need of immediate rescue. In the event of an emergency, such as a ship sinking or medical emergency onboard, the transmitter is activated and begins transmitting a continuous 406 MHz distress radio signal, which is used by search-and-rescue teams to quickly locate the emergency and render aid. The signal is detected by satellites operated by an international consortium of rescue services, COSPAS-SARSAT, which can detect emergency beacons anywhere on Earth transmitting on the distress frequency of 406 MHz. The satellites calculate the position or utilize the GPS coordinates of the beacon and quickly passes the information to the appropriate local first responder organization, which performs the search and rescue. As Search and Rescue approach the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Flight Recorder
A flight recorder is an electronic recording device placed in an aircraft for the purpose of facilitating the investigation of aviation accidents and incidents. The device may often be referred to as a "black box", an outdated name which has become a misnomer—they are now required to be painted bright orange, to aid in their recovery after accidents. There are two types of flight recording devices: the flight data recorder (FDR) preserves the recent history of the flight through the recording of dozens of parameters collected several times per second; the cockpit voice recorder (CVR) preserves the recent history of the sounds in the cockpit, including the conversation of the pilots. The two devices may be combined into a single unit. Together, the FDR and CVR objectively document the aircraft's flight history, which may assist in any later investigation. The two flight recorders are required by international regulation, overseen by the International Civil Aviation Organizat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thermocline
A thermocline (also known as the thermal layer or the metalimnion in lakes) is a thin but distinct layer in a large body of fluid (e.g. water, as in an ocean or lake; or air, e.g. an atmosphere) in which temperature changes more drastically with depth than it does in the layers above or below. In the ocean, the thermocline divides the upper mixed layer from the calm deep water below. Depending largely on season, latitude, and turbulent mixing by wind, thermoclines may be a semi-permanent feature of the body of water in which they occur, or they may form temporarily in response to phenomena such as the radiative heating/cooling of surface water during the day/night. Factors that affect the depth and thickness of a thermocline include seasonal weather variations, latitude, and local environmental conditions, such as tides and currents. Oceans Most of the heat energy of the sunlight that strikes the Earth is absorbed in the first few centimeters at the ocean's surface, which ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Underwater Locator Beacon
An underwater locator beacon is a device that guides search and rescue teams to a submerged aircraft by emitting a repeated electronic pulse. Application An underwater locator beacon (ULB) or underwater acoustic beacon, is a device fitted to aviation flight recorders such as the cockpit voice recorder (CVR) and flight data recorder (FDR). ULBs are also sometimes required to be attached directly to an aircraft fuselage. ULBs are triggered by water immersion; most emit an ultrasonic 10ms pulse once per second at 37.5 kHz ± 1 kHz. Research by the French ''Bureau d'Enquêtes et d'Analyses pour la Sécurité de l'Aviation Civile'' (BEA) has shown that it has had a 90% survival rate spanning 27 air accidents over the sea. The ULBs fitted in Air France Flight 447, which crashed on 1 June 2009, were certified to transmit at 37.5 kHz for a minimum of 30 days at a temperature of 4 °C. Investigating the crash, the BEA recommended that FDR ULBs' transmission period b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydrophone
A hydrophone ( grc, ὕδωρ + φωνή, , water + sound) is a microphone designed to be used underwater for recording or listening to underwater sound. Most hydrophones are based on a piezoelectric transducer that generates an electric potential when subjected to a pressure change, such as a sound wave. Some piezoelectric transducers can also serve as a sound projector, but not all have this capability, and some may be destroyed if used in such a manner. A hydrophone can detect airborne sounds, but will be insensitive because it is designed to match the acoustic impedance of water, a denser fluid than air. Sound travels 4.3 times faster in water than in air, and a sound wave in water exerts a pressure 60 times that exerted by a wave of the same amplitude in air. Similarly, a standard microphone can be buried in the ground, or immersed in water if it is put in a waterproof container, but will give poor performance due to the similarly bad acoustic impedance match. History The ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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