As the economic activities in the ocean, security and rescue is a major problem for all shipping industry, especially when the accident occurred , often due to the ship sank , platforms watered, lose energy and power , electromagnetic disturbance and other factors, the communication device couldn’t be used , in which the use of mobile phones and radio is also affected by distance constraints , couldn’t normally be used in many waters .

To avoid rescue is not timely or unrescuable and caused casualties, nations included Canada, France, the United States, and the former Soviet Union established the international COSPAS-SARSAT satellite organizations in 1979 , and developed the Emergency Position Indicating Radio Beacon (EPIRB) specification.

COSPAS is a Russian Latin , the full name is “Space System For Search of Distress Vessels”, SARSAT is the “Search And Rescue Satellite Aided Tracking”, the system was later introduced as a geostationary satellite transponders, so the system changed its name to the International COSPAS-SARSAT .

The system is to function in the event of an emergency incident of vessels, can send a distress signal to the ground station through the COSPAS-SARSAT , if the ship sank , the system can automatically pop up float to the surface , sending signals.

In 2010, the system handled a total of 641 accidents, the successful rescue 2338 people.

Similar to the technology used in land called Personal Locator Beacon (PLB), aerospace applications product called Emergency Locator Transmitter (ELT), but ELT were early than COSPAS-SARSAT. Today, most aircraft are equipped with ELT system.

ELT were mandated in 1973, most GA aircraft were equipped with an ELT that transmits on the 121.5 MHz frequency, the designated international distress frequency. The original ELT were manufactured to the specifications of an FAA technical standard order (TSO-C91) and have an activation rate of less than 25 percent in actual crashes and a 97 percent false-alarm rate.

In 1985, a new TSO-C91A ELT was developed, which substantially reduces or eliminates many problems with the earlier model. The TSO-C91A provides improved performance and reliability (with an activation rate of 73 percent in actual crashes) at a reasonable cost to users ($200-$500 including installation). Since then, an even more advanced model of ELT has been developed — the C126 ELT (406 MHz).

This newest model activates 81-83 percent of the time and transmits a more accurate and near-instantaneous emergency signal by utilizing digital technology. This digital 406-MHz ELT also allows search and rescue personnel to have vital information specific to you and your aircraft. These ELT are more expensive, however, with the current cost around $1,000 or more per unit, not including installation.

The Malaysia Airlines ELT systems are manufactured by Honeywell, can provide emergency transmission for aircraft flying over land, automatically transmits a digitally encoded signal upon impact in the event of a crash. With a state-of-the-art, triple frequency transmitter and an extended battery life of ten years, once triggered, can keeps sending signals for 50 hours, is approved for use on numerous commercial aircraft.

An optional Navigation Aircraft Interface Module (NAIM) can allow the transmission of latitude/longitude information in the 406 MHz signal from the aircraft navigation system to speed up finding the aircraft in the event the system is activated.

Currently the new ELT system has been integrated GPS positioning technology to provide a more precise location information.