emergency locator beacon/transmitter
emergency locator beacon/transmitter (ELT)
or water immersion and transmit a code on emergency frequencies (121.5, 243, or 406 MHz), enabling SAR (search and rescue) satellites or search units equipped with a direction finder (DF) to locate the crash or ditching site. ELTs aid in locating downed aircraft or personnel by radiating a sweeping audio tone two to four times per second. Sometimes called ADELT, automatically deployable ELT, or ELB, emergency locator beacon. Some of these transmitters are activated manually. Automatic fixed ELTs [ELT (AF)] are permanently attached to aircraft. Automatic portable ELTs [ELT (AP)] are rigidly attached to aircraft but can be readily removed after a crash. They can also be manually deployed. Survival ELTs [ELT (S)] are removable from an aircraft; they are stowed so as to facilitate their ready use by survivors.