A Signal From the Wreckage: How ELTs and Satellites Find Downed Aircraft

When an aircraft crashes or is forced down in remote terrain, the difference between life and death is often how fast rescuers can find it. For decades that search depended on the Emergency Locator Transmitter (ELT) — a self-contained beacon, usually mounted in the tail, designed to switch on automatically under the sharp deceleration of an impact and broadcast a distress signal. The system behind the signal is an international marvel called COSPAS-SARSAT, a partnership originally among the United States, Canada, France, and the Soviet Union, now global. A network of satellites listens for distress beacons and relays them to ground stations and rescue coordination centers, which dispatch search and rescue. Older ELTs broadcast on 121.5 MHz, but that analog signal was imprecise and prone to false alarms; the system transitioned to digital 406 MHz beacons, which carry a unique registered ID identifying the specific aircraft and, when GPS-equipped, can pin a location to within roughly a hundred meters — turning a days-long grid search into a direct vector to the survivors. Registration is what makes it work: a 406 MHz beacon tied to a registered aircraft and owner lets rescuers confirm who is missing and rule out false activations quickly. Many pilots flying remote or mountainous routes also carry personal locator beacons (PLBs) or satellite messengers as a backup that travels with them even if they leave the aircraft. The ELT is one of those systems a pilot hopes never to use, inspected at every annual and largely forgotten in between. But behind that small beacon sits a quietly extraordinary piece of international cooperation — a promise, stitched across competing nations and orbiting satellites, that an aircraft down in the wilderness will not stay lost.