A towed pinger locator is a water-borne device used to locate the sonar "ping" from the

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 a ...

which is fitted to the

Cockpit Voice 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 The device may often be referred to as a "black box", an outdated name which has b ...

s and

Flight Data 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 The device may often be referred to as a "black box", an outdated name which has b ...

s installed in commercial airliners. They can locate pingers at depths of up to underwater. Navy Towed Pinger Locator

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,

submersible A submersible is a small watercraft designed to operate underwater. The term "submersible" is often used to differentiate from other underwater vessels known as submarines, in that a submarine is a fully self-sufficient craft, capable of ind ...

s or remotely operated vehicle (ROV), depending on depth. A model currently used by the

United States Navy The United States Navy (USN) is the maritime service branch of the United States Armed Forces and one of the eight uniformed services of the United States. It is the largest and most powerful navy in the world, with the estimated tonnage ...

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 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 potenti ...

must be positioned below the

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 ...

layer which reflects sounds, either back to the surface or back to the ocean floor. Since the pinger signal is relatively weak, the hydrophone must be within a

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 ...

(about ) to detect it. The hydrophone is typically deployed about above the ocean floor, where it can scan a swath approximately wide, on a flat, level surface.

References

{{reflist Aircraft emergency systems Beacons

See also

References