ELT (Emergency Locator Transmitter) or EPIRB (Emergency Position-Indicating Radio Beacon), are tracking transmitters which aid in the detection and location of boats, aircraft, and people in distress. Strictly, they are radiobeacons that transmit signals to the worldwide offered service of Cospas-Sarsat, the international satellite system for search and rescue (SAR).
The ELT automatically activates during a crash and transmits the standard swept tone on 121.5 and 243.0 MHz. Every 50 seconds for 520 milliseconds (long message protocol), the 406 MHz transmitter turns on and transmits an encoded digital message to the Cospas/Sarsat satellite system. The ELT can be programmed with the aircraft’s 24-bit address as well as latitude/longitude information from the aircraft navigation system when used with the Artex ELT/NAV Interface -B (P/N 453-6501).
Acronym of the Day: ELT — Emergency Locator Transmitter pic.twitter.com/h5W26zG4dq
— Cardinal News (@EarlyReport) March 18, 2014
The B406-4 has been modified to interface with Boeing’s Master Caution System in conjunction with the DZUS mounted cockpit remote panel (P/N 453-0161) for the B737 and is furthermore approved for use on all models of the B747, B757, B767 and B777.
DZUS is type of proprietary quarter-turn lock fastener that is often used to secure skin panels on aircraft, and to secure plates, doors, and panels that require frequent removal for inspection and servicing.
According to NBC News, Boeing declined to comment on the type of ELT with which the missing Malaysia Airlines Boeing 777-2H6 was equipped. A 2009 report from the Airplane Owners and Pilots Association reported that newer ELTs successfully activate only about 82 percent of the time. Disturbances to the fastener tend to tighten the fastener, not loosen it.
See also …
406 MHz Emergency Locator Transmitter ELT
NBC News Emergency Beacons Not Fool-Proof When Jets Go Missing
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