Distress Beacons

What is a distress beacon?

A distress beacon is a small electronic device that, when activated in a life-threatening situation, assists rescue authorities in their search to locate those in distress.

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What types of distress beacons are there?

There are 3 types:

• Emergency Position Indicating Radio Beacons (EPIRB) used in ships and boats;
• Emergency Locator Transmitters (ELT) used in aircraft; and
• Personal Locator Beacons (PLB) for personal use by bushwalkers, four-wheel drivers, other adventurers on land, employees working in remote areas, crew in boats and aircrew.

EPIRBs are designed to float in the water to optimise the signal to the satellite. An EPIRB is required to operate for a minimum of 48 hours continuously once activated. An EPIRB has a lanyard that is used to secure it to something that is not going to sink so that it can float free. There have been a number of incidents where vessels have sunk quickly and crew have not been able to deploy an EPIRB. In such incidents, float-free EPIRBs may have reduced response times and saved lives. Float-free EPIRBs are held in a bracket and fitted with a hydrostatic release that is water activated deploying the beacon automatically if the vessel sinks. If the vessel continues to float then the EPIRB can be manually deployed where a distress situation exists.

ELTs are usually fixed in the aircraft and are designed to activate on impact. ELTs are required to operate continuously for 24 hours once activated. Civil Aviation Safety Authority (CASA) regulations require most aircraft to carry an ELT. CASA regulations allow for PLBs or EPIRBs to be carried in General Aviation aircraft as an alternative to an ELT.

PLBs are designed for personal use in both the land and marine environment. This type of beacon is becoming a multi-environment beacon. PLBs are required to operate for a minimum of 24 hours once activated.

EPIRBs, PLBs and ELTs currently operate on two frequencies - 406 MHz and 121.5 MHz. Because of the digital technology used in 406 MHz beacons, they are far more capable than the analogue 121.5 MHz beacons.

406 MHz beacons come in two basic types: those that provide an encoded (GPS) location and those that do not. The satellite system can calculate a beacon's location, but locating a distress site is usually much faster if the beacon signal provides a GPS location.

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How does a distress beacon work?

When a distress beacon is activated, it transmits a signal that is detectable by satellites and overflying aircraft. As the satellites orbit the Earth they 'listen' for any active beacons and report their position to rescue authorities.

Beacons developed for the Cospas-Sarsat satellite system operate on 406 MHz and use digital technology that allows the beacon to transmit a unique code (HexID or UIN) that identifies the beacon. The satellite system can also receive signals from and locate beacons that operate on 121.5 MHz. These use analogue technology and cannot be identified. Satellite processing of 121.5 MHz signals will cease on 1 February 2009.

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What is the HexID or UIN?

The HexID or Unique Identity Number (UIN) is the unique code programmed into each 406 MHz distress beacon and transmitted when the beacon is activated. When registering a distress beacon, this code must be included on the registration form as it is the only code that links the individual distress beacon to the registration database. Without the HexID the beacon cannot be registered.

The HexID is 15 characters long and is made up of hexadecimal numbers (0-9) and letters (A-F). The code can be found on the label of all 406 MHz distress beacons.

How do I decode a programmed HexID?

406 MHz distress beacons are coded to reflect the beacon type and use. The coding carried out by the supplier results in a unique identifier for your beacon called the HexID. When the HexID is decoded it reveals the country code (503 is Australia) and, depending on the protocol used, a vessel or aircraft radio callsign, MMSI or registration, or a serial number linked to the registration database and, in the case of beacons with input, a GPS position.

If a beacon is coded with an MMSI, radio callsign or aircraft registration, it is tied to that vessel or aircraft and if it is transferred to another vehicle it would have to be recoded. Beacons coded using either the manufacturers' serial numbers or national serial numbers available from AMSA can be transferred more easily.

To decode your programmed HexID, click here

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