回复：黑匣子是事后分析事故用。救援用的是ELT。

Distress radio beacons, also known as emergency beacons,PLB (Personal Locator Beacon), 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 areradiobeacons that interface with worldwide offered service ofCospas-Sarsat, the international satellite system for search and rescue (SAR). When manually activated, or automatically activated upon immersion, such beacons send out a distress signal. The signals are monitored worldwide and the location of the distress is detected by non-geostationary satellites, and can be located by some combination of GPS trilateration and doppler triangulation.^[1]

The basic purpose of a distress radiobeacon is to help rescuers find survivors within the so-called "golden day"^[2] (the first 24 hours following a traumatic event) during which the majority of survivors can usually be saved.

Since the inception of Cospas-Sarsat in 1982, distress radiobeacons have assisted in the rescue of over 28,000 people in more than 7,000 distress situations.^[3] In 2010 alone, the system provided information which was used to rescue 2,388 persons in 641 distress situations.^[4]