Emergency position-indicating radio beacons (EPIRBs) and search and rescue radar transponders (SARTs)
This domain tests the different jobs of the 406 MHz EPIRB and the SART: one alerts the rescue services, the other helps a rescuing radar find the survival craft. The exam often asks which device does what, how each is activated, and what to do after a false activation.
406 MHz EPIRB
The EPIRB transmits a digital distress alert on 406 MHz to the COSPAS-SARSAT system, often with GNSS position, and provides a 121.5 MHz homing signal for aircraft. It can be activated manually or by water, and a float-free bracket allows it to float and transmit if the vessel sinks. The beacon identity must be registered with the national authority, in the United States through NOAA, with the vessel and emergency contact details. Test only with the built-in self-test, never by live transmission.
SART
The Search and Rescue Radar Transponder operates in the 9 GHz marine radar band. When interrogated by a nearby radar, it replies with a series of twelve dots on the radar display, helping the rescuer see the survival craft. It does not send a satellite alert and does not replace the EPIRB. It is switched on in the survival craft and left on while rescue units are near; its battery supports standby and operating periods.
Worked example
A vessel sinks quickly. The float-free EPIRB activates and sends a 406 MHz alert with position to the RCC. In the liferaft, the crew switch on the SART. A rescue vessel's 9 GHz radar later shows the twelve-dot response, and the rescue vessel homes visually. If the EPIRB had been accidentally activated in port, the operator would switch it off and immediately inform the coast guard or RCC so the false alert can be cancelled.
Traps that cost marks
Do not say the SART alerts satellites; it is a locating device. Do not test the EPIRB by pressing the live transmit button. Do not assume an unregistered EPIRB still provides full identification. Do not leave a SART on in a locker during a routine passage; it should be stowed ready for the survival craft, not transmitting.