EPIRB: What is the Emergency Position Indicating Radio Beacon?

EPIRB What is the Emergency Position Indicating Radio Beacon - Merchant Navy Info - Blog

An Emergency Position-Indicating Radio Beacon (EPIRB) is a device that alerts search and rescue services (SAR) in instances of an emergency out at sea. Tracking equipment transmits a signal on a specified band to find a lifeboat, life raft, ship, or distressed people.

They are placed on ships and other kinds of vessels after being registered with the national search and rescue forces for that boat. The registration verifies false alerts and, in some instances, faster and faster rescue operations.

An EPIRB is a SECONDARY means of SOS alerting. This means it comes later in the scale of alerting SAR authorities in instances of distress.

It is compulsory to carry one EPIRB on every ship. Two EPIRBS are mandatory for all Registered ships (and other vessels).

Different Types Of EPIRBS

  1. COSPAS-SARSAT– EPIRBS under the COSPAS-SARSAT mechanism work on the 406.025 MHz. Also, 121.5 MHz bands are applicable for every sea area.
  2. INMARSAT E– This EPIRB is great on a 1.6 GHz band. These work well for sea areas A1, A2 and A3.
  3. VHF CH 70– This works great in the 156.525 MHz band and is good for sea area A1 only

How Does An EPIRB Work?

The device contains two radio transmitters

1) a 5-watt one 

2)a 0.25-watt one

Each works at 406 MHz, the standard international frequency typically signalling trouble, 406MHz.

It Uses A 5-watt Radio Transmitter With A Goes Weather Satellite

The COSPAS-SARSAT is an international satellite-based search. It is a rescue system founded by the U.S., Russia, Canada and France to catch emergency radio signals.

Due to the many upsides of 406 MHz beacons and the problems of 121.5 MHz beacons, the International Cospas-Sarsat Program ended the satellite processing of 121.5 MHz using satellites on February 1st, 2024. The National Oceanic and Atmospheric Administration/ NOAA. The FAA encouraged switching to 406 for serious reasons.

However, aircraft may still use the Emergency Locator Transmitter, and alerts from these devices would only be acted upon if confirmed by two independent non-satellite sources or devices.

An EPIRB transmits signals to the satellite. The signal consists of an encoded identification number (all in digital code) containing information such as the ship’s identification, event date, details of the issue, emergency contact details, and position.

A UIN is a Unique Identifier Number programmed into each and every beacon at the factory. It comprises a 15-digit series of letters and numbers that make up the beacon’s unique identity. The UIN is on a white label on the beacon’s exterior. The UIN is also known as the Hex ID.

The Local User Terminal (satellite getting units or ground stations) calculates the place of the casualty using Doppler Shift (this is the change in frequency or wavelength of any wave (or other periodic events) for an observer moving in comparison to its source).

The work of the LUT

The LUT conveys the digital message to the MRCC (Mission Rescue Co-Ordination Centre), which is responsible for SAR operations and the execution of the rescue mission.

If the EPIRB does not work well with a GPS receiver, the international satellite orbiting the planet can pick up only the radio signals emitted by the radio. The transmitter’s location or the owner’s identity cannot be deduced in this case.

These satellites can pick up trace elements of such signals. They can only give a vague idea of the area of the EPIRB. Per international standards, a beam of 406MHz is taken as an emergency signal.

Suppose an emitter sends signals of 121.5 MHz. The rescuer or relevant party can reach the lost individual even if they are 15 miles away. The precision of reaching the target could be stretched if an EPIRB also contains a GPS receiver.

Using an EPIRB

The beacon owner needs to activate the EPIRB to emit signals in the case of category II EPIRBs. This could be accomplished by pushing a button on the unit. It could also occur automatically if and when it comes in proximity to water through hydrostatic release.

The latter is called a hydrostatic EPIRB. Its worth makes it the best choice for sailors because it can be automatically activated if the ship or vessel faces an accident and sees itself in deep waters.

The EPIRB needs activation to be operative, and this can happen only when it emerges from the bracket it is placed in. As said earlier, this can be done manually or automatically. The device is battery-operated, which helps because power is the first entity to be hit in case of a calamity.


  • 12 Volt battery
  • 48 hours of transmitting capacity
  • Normally replaced every 2 to 5 years.
  • Use a proper replacement battery.

False Alerting from a radio beacon

A person onboard might mistakenly activate the EPIRB radio beacon and send false alarms. If this occurs, the closest coast station or RCC (Rescue Co-Ordination Center) must be notified immediately, and the alarm must be canceled.

The cancellation intimation must also be sent to the relevant authority (for instance, DG Shipping for Indian-registered boats or ships moving in Indian waters at the time the false alert is transmitted). The shipowner and the agent need to be informed.

Testing of EPIRB radio beacon

The EPIRB should be tested once every 30 days to ensure operational integrity. The process to do so is as follows:

  1. Hit and release the test button on the EPIRB
  2. The red lamp on the EPIRB needs to flash once
  3. Within 30 seconds of hitting the button, the strobe, as well as the red light, needs to flash several times
  4. After 60 seconds of work, the EPIRB will switch off

Maintenance of EPIRB radio beacon

  1. The EPIRB has to be inspected visually for any defects, such as cracks
  2. It is advisable to clear the EPIRB once in a while with a dry cloth
  3. While cleaning, thus switches must be properly checked
  4. The lanyard of the EPIRB needs to be neatly packaged into the container of the EPIRB without any loose ends hanging about
  5. The expiry time of the battery has to be checked to cover the immediate as well as the upcoming voyage at the least
  6. Transmit the EPIRB back to the service agent or the supplier if the EPIRB flops the monthly checks
  7. Change the battery on it if the facilities are available or send it to the right agent if there is not
  8. If the EPIRB radio beacon has been utilized in an emergency, it has to be returned to an authorized service agent for a battery change.
  9. If the HRU has met its expiration date, the HRU ought to be replaced on the ship, and the HRU must be marked with an expiration date many years into the future.

PLBs (Personal Locator Beacons)

PLBs are radio beacon EPIRBs for individual enterprises. They indicate distress for an individual not within the close proximity of emergency services. PLBs work like EPIRBS and beam on the COSPAS SARSAT satellite system at 406.025 MHz. They are much smaller in size compared to the EPIRBs.

They should be kept in a secure place on the vessel or in an easily approachable spot. Some have strobe lights that can be manually or automatically turned on.

Once activated, PLBs transmit for at least 24 hours. In comparison, the battery life on an EPIRB is doubled(a minimum of 48 hours). An EPIRB is registered to a vessel. However, a PLB is registered to an individual.

The EPIRB is an important emergency equipment that is available onboard in case of distress. It must be given notable time to care for, test, and maintain optimally when the situation arises.

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