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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] |
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 Locator Beacon
An emergency locator beacon is a radio beacon, a portable battery powered radio transmitter, used to locate airplanes, vessels, and persons in distress and in need of immediate rescue. Various types of emergency locator beacons are carried by aircraft, ships, vehicles, hikers and cross-country skiers. In case of an emergency, such as the aircraft crashing, the ship sinking, or a hiker becoming lost, the transmitter is deployed and begins to transmit a continuous radio signal, which is used by search and rescue teams to quickly find the emergency and render aid. The purpose of all emergency locator beacons is to help rescuers find survivors within the so-called "golden day", the first 24 hours following a traumatic event, during which the majority of survivors can usually be saved. Beacon types COSPAS-SARSAT 406 MHz Distress Beacons Cospas-Sarsat is an international humanitarian consortium of governmental and private agencies which acts as a worldwide dispatcher for search ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sonar
Sonar (sound navigation and ranging or sonic navigation and ranging) is a technique that uses sound propagation (usually underwater, as in submarine navigation) to navigation, navigate, measure distances (ranging), communicate with or detect objects on or under the surface of the water, such as other vessels. "Sonar" can refer to one of two types of technology: ''passive'' sonar means listening for the sound made by vessels; ''active'' sonar means emitting pulses of sounds and listening for echoes. Sonar may be used as a means of acoustic location and of measurement of the echo characteristics of "targets" in the water. Acoustic location in air was used before the introduction of radar. Sonar may also be used for robot navigation, and SODAR (an upward-looking in-air sonar) is used for atmospheric investigations. The term ''sonar'' is also used for the equipment used to generate and receive the sound. The acoustic frequencies used in sonar systems vary from very low (infrasonic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Underwater Acoustics
Underwater acoustics is the study of the propagation of sound in water and the interaction of the mechanical waves that constitute sound with the water, its contents and its boundaries. The water may be in the ocean, a lake, a river or a tank. Typical frequencies associated with underwater acoustics are between 10 Hz and 1 MHz. The propagation of sound in the ocean at frequencies lower than 10 Hz is usually not possible without penetrating deep into the seabed, whereas frequencies above 1 MHz are rarely used because they are absorbed very quickly. Underwater acoustics is sometimes known as hydroacoustics. The field of underwater acoustics is closely related to a number of other fields of acoustic study, including sonar, transduction, signal processing, acoustical oceanography, bioacoustics, and physical acoustics. History Underwater sound has probably been used by marine animals for millions of years. The science of underwater acoustics began in 1490, when Leonardo ... [...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] |
