Ocean Signal Explains How 406MHz EPIRB Alerts Reach Rescue Authorities

Ocean Signal has published an updated guide explaining what happens after a 406MHz emergency beacon is activated and how the international Cospas-Sarsat system turns that transmission into information for rescue authorities. For yacht crews, the useful part is understanding that an EPIRB is not simply a radio transmitter: it is one link in a global chain of satellites, ground stations, mission-control centres and rescue coordinators.

The guide was published for Global Search and Rescue Day on 10 September 2026 and draws on official Cospas-Sarsat and national rescue-system references. Ocean Signal says more than 70,000 people have been rescued with assistance from the system since 1982, illustrating why correct beacon installation, registration and maintenance remain basic but important parts of yacht safety management.

The distress signal first has to be detected

When a compatible 406MHz EPIRB or personal locator beacon is activated, satellites in the Cospas-Sarsat network detect the coded transmission. Depending on the satellite and beacon configuration, position information may come from the beacon's own GNSS receiver and can also be supported by the wider satellite system's location processing.

The satellite is not the final rescue authority. It passes the alert into ground infrastructure, where Local User Terminals and Mission Control Centres process and route the message toward the responsible search-and-rescue organisation based on the beacon identity and location information available.

Registration adds information rescuers cannot obtain from radio alone

A beacon's unique identity can be tied to vessel and emergency-contact information through the appropriate national registration system. That lets rescue coordinators distinguish a real emergency from some accidental activations and gives them useful context about the yacht, ownership contacts and people who may know the vessel's intended route.

For a superyacht, registration should be treated as a living record rather than a one-time commissioning task. Flag changes, ownership transfers, replacement beacons and changed emergency contacts can all leave a technically functioning EPIRB associated with stale information if the registration is not updated.

Accessibility matters when an incident develops quickly

Ocean Signal's guidance also reinforces a practical point: emergency equipment has to be reachable and understood by the people expected to use it. A beacon that is correctly registered but poorly located, out of service date or unfamiliar to the watchkeeper may not provide its intended benefit when an abandonment or flooding event develops rapidly.

Large yachts often carry several types of distress beacon, including float-free EPIRBs and personal devices. Crew training should therefore cover which beacon is associated with the vessel, which devices are personally assigned, how each is activated and what information should be passed by other communications channels when time permits.

The satellite system does not replace normal distress procedures

EPIRBs are designed to provide an independent distress path, particularly when conventional communications fail or the crew has to abandon the yacht. They do not remove the value of DSC distress alerts, satellite voice or data communications, VHF, AIS safety equipment or direct contact with rescue authorities when those systems remain available.

The strongest safety arrangement uses those systems together rather than relying on a single device. Ocean Signal's guide is therefore a useful reminder for captains and safety officers to verify the small administrative and maintenance details around 406MHz beacons before an emergency turns them into one of the yacht's most important pieces of equipment.