Underwater locator beacon
Encyclopedia
Flight recorder
A flight recorder is an electronic recording device placed in an aircraft for the purpose of facilitating the investigation of an aircraft accident or incident. For this reason, flight recorders are required to be capable of surviving the conditions likely to be encountered in a severe aircraft...
s such as the cockpit voice recorder
Cockpit voice recorder
A cockpit voice recorder , often referred to as a "black box", is a flight recorder used to record the audio environment in the flight deck of an aircraft for the purpose of investigation of accidents and incidents...
and flight data recorder
Flight data recorder
A flight data recorder is an electronic device employed to record any instructions sent to any electronic systems on an aircraft. It is a device used to record specific aircraft performance parameters...
. ULBs are also sometimes required to be attached directly to an aircraft fuselage
Fuselage
The fuselage is an aircraft's main body section that holds crew and passengers or cargo. In single-engine aircraft it will usually contain an engine, although in some amphibious aircraft the single engine is mounted on a pylon attached to the fuselage which in turn is used as a floating hull...
. When triggered by water immersion, the ULB emits an ultrasonic
Ultrasound
Ultrasound is cyclic sound pressure with a frequency greater than the upper limit of human hearing. Ultrasound is thus not separated from "normal" sound based on differences in physical properties, only the fact that humans cannot hear it. Although this limit varies from person to person, it is...
pulse of 37.5 kHz at an interval of once per second.
The devices are designed not only to survive accidents, but to function correctly after impact. Research by the BEA
Bureau d'Enquêtes et d'Analyses pour la sécurité de l'Aviation Civile
The Bureau d'Enquêtes et d'Analyses pour la Sécurité de l'Aviation Civile is an agency of the French government, responsible for investigating aviation accidents and making safety recommendations based on what is learned from those investigations. It is headquartered in Building 153 on the grounds...
showed that they have had an 90% survival rate spanning 27 air accidents over the sea.