Emergency Position Indicating Radio Beacons (EPIRB) and Search and Rescue Transponders (SART)
The exam separates two devices that candidates constantly mix up: the EPIRB alerts the shore, the SART helps the rescue unit find the survival craft on radar.
406 MHz EPIRB
- Cospas-Sarsat system; transmits in the 406.0–406.1 MHz band with a 121.5 MHz homing signal; 48-hour operation; float-free with a hydrostatic release unit; strobe light.
- GNSS-enabled beacons include the position in the alert, cutting detection and location time.
- Must be registered with the national administration (in India, through DG Shipping) with ship name, MMSI, owner and emergency contacts.
- Cospas-Sarsat no longer processes 121.5 MHz-only alerts (ended 2009); 121.5 is for homing.
SART
- 9 GHz (3.2 cm) X-band radar transponder; when triggered by a radar pulse it displays 12 dots on the radar screen, giving range and bearing.
- Standby life about 96 hours, transmit about 8 hours; mounted about 1 m above sea level in the craft.
- Detection range typically 5–10 nm, depending on radar antenna height.
- AIS-SART transmits on the AIS frequencies (161.975/162.025 MHz) and appears as a target on AIS, not as radar dots.
Worked example
An EPIRB is accidentally activated during heavy weather. Switch it off immediately, inform the nearest RCC by Inmarsat-C or radiotelephony with the beacon's identity and time of activation, and log the event. Do not wait for a shore call: an unexplained 406 MHz transmission starts a SAR response.
Traps
- Believing 121.5 MHz alone still alerts satellites.
- Testing a SART on the open X-band near other ships; use the test function or short-range radar check.
- Quoting 96 hours as SART transmit time (it is standby time).
- Failing to update EPIRB registration after a change of ship name or MMSI.