Celebrating #406Day18

406Day is an awareness day with a play on the date 4th June. The number 406 is significant because it represents 406 MHz signals which are known to be lifesaving emergency communications that have assisted search and rescue teams from all around the world to save thousands of lives. 

406Day aims to raise beacon awareness across the world by reminding boaters about the importance of life-saving 406 MHz technology and by providing advice about the benefits and responsibilities of owning a 406 MHz beacon such as a PLB (Personal Locator Beacon) or EPIRB (Emergency Position Indicating Radio Beacon).



406MHz is the frequency transmitted by distress beacons known as EPIRBs and PLBs via the dedicated satellite network COSPAS-SARSAT. The signal contains unique identification data and GPS positioning* used by Search And Rescue (SAR) teams to locate the vessel or person in distress.


*GPS positioning only on GPS versions.



  1. EPIRB is activated and a distress signal is broadcasted
  2. COSPAS-SARSAT satellite system directs an alert to a Local User Terminal (nearest to distress scene)
  3. The Local User Terminal directs rescue coordination to a Rescue Coordination Centre (RCC) via a Mission Control Centre
  4. The Home RCC validates the alert and launches SAR services if needed
  5. SAR Services home in on the last transmitted location



The International COSPAS-SARSAT programme maintains a network of satellites and ground facilities built solely to receive distress signals from 406MHz beacons, and relay the alerts to relevant authorities in more than 200 countries and territories. All COSPAS-SARSAT type approved 406MHz beacons work on this satellite system no matter the brand.

As of 2015, COSPAS-SARSAT has aided in the rescue of over 41,000 people in over 11,788 SAR events. 


For marine users, there are two options to choose between, an EPIRB or a PLB. Each work on the same frequency, and they send the same signal, but there are differences between the two that will help you make your decision about whether you need an EPIRB, a PLB, or both.



EPIRBs are the biggest of the two options and normally have the option of having a manual, or an automatic bracket. With a manual bracket, the beacon must be removed by hand. The other option is an automatic bracket which has a HRU (Hydrostatic Release Unit) which will release the EPIRB upon reaching a certain depth and the water switch will automatically activate the beacon.

EPIRBs are registered with the information of a vessel, not a person. They are generally bulkier than a PLB, and they will transmit for longer periods due to their larger battery.



The location of your EPIRB is vital, and must be carefully thought through. As mentioned, an automatic bracket will release the EPIRB at a certain depth, this means that it must be in a position that enables the beacon to freely float to the surface if the vessel was to sink. You must also consider the chances of the beacon being damaged during day to day activities, or even being stolen when the vessel is unattended.

A manual bracket should be in a position that is easily accessible in an emergency such as the bulkhead or in a grab bag. Think about a certain scenario such as a fire…could you easily get to your beacon? Will it take considerable risk? Will you remember exactly where it is? Will you even be able to see it clearly through smoke? Once you have considered all scenarios, you can make an educated choice on where to store your EPIRB to give you the best chance of rescue.



PLBs are essentially personal EPIRBs. They are smaller, registered to a person, and will transmit for a shorter period due to their smaller battery. One of the main differences between a PLB and an EPIRB is that 406MHz PLBs can only ever be manually activated. Another big difference is that PLBs can be used both on the water, and on land so are used by a large variety of people from sailors, to kayakers, to mountaineers. They are especially important for solo activities in remote places where mobile phones and other modes of contact cannot be relied upon.

Once activated, a PLB sends exactly the same distress signal as an EPIRB, using COSPAS-SARSAT.



  • The type of boating/activity you do e.g. offshore sailing, kayaking, fishing, mountaineering or flying etc.
  • Size of your crew – do you have a large crew, or do you travel solo?
  • Size of your vessel – there are certain regulations to follow depending on the size
  • How far you travel from shore – the further you are, the longer battery life you will need
  • The operational temperature change
  • Do you require manual or automatic activation?



As mentioned previously, they have saved thousands of lives over the years, and heres a few reason why:

  1. Fast, accurate positioning
  2. Long battery life
  3. They transmit a distress signal for a minimum of 24 hours
  4. They will transmit a signal from anywhere on earth, so long as the antenna has a clear line of sight to the sky (for example, satellites will not receive a signal from a beacon in a cave)
  5. There is no charge for activating your beacon in a genuine distress situation

All of the above relates to beacons that have been properly serviced and registered.



It is vital that all beacon owners register their device with the relative authorities such as the Transport Malta for Maltease owners. If a beacon’s registration is up to date, it greatly speeds up the rescue process by providing information about you, your vessel (EPIRBs), and your activities. So what does a SAR team learn from a properly registered beacon? Here are a few examples:

  • Your contact details – One of the first steps is to try and make contact to gather more information, and to ensure it isn’t a false alarm
  • Contact details of next of kin, or persons who know details about your activities such as a business partner
  • Size of vessel
  • Likely number of people on the vessel, allowing the SAR team to make an informed decision on what resources may be needed
  • Details of your journey – your planned route, departure date, and arrival date etc.



Every beacon comes with an expiration date to ensure it will function properly if used in an emergency. Generally the main effect of activating a beacon past its expiry date is that it will not transmit for as long, which can be disastrous in a time when every minute counts. For most beacons, before the expiry date is reached, you must send your beacon to a certified servicing station like Camilleri Marine in Malta to have the battery changed and the beacon thoroughly tested, at which point the beacon will be given a new expiry date. There are some EPIRBs that come with a user replaceable battery, such as the Ocean Signal SafeSea E100/E100G which allows the battery to be changed by the user every five years.

You can contact Camilleri Marine in case of any questions.


Camilleri Marine 

264, Ta’ Xbiex Seafront Gzira, GZR 1020 – MALTA 




You should test your beacon regularly using the ‘self-test mode’ which will be different for each beacon, so ensure you carefully read the manual to ensure you don’t accidentally activate the beacon. The recommended interval between tests is one month, and these tests are always factored in the advertised battery life of the beacon. The test monitors the 406MHz RF power, 121.5MHz homer RF power, synthesiser lock, and battery voltage under load. It is also recommended to regularly visually inspect your beacon for signs of damage, especially on the most important features such as the antenna, bracket, and HRU (Hydrostatic Release Unit) if applicable.

We recommend you do not test the GPS receiver more than once a year as it expends significant amounts of battery energy.



Q. Are 406MHz beacons limited to on water activities?

A. No. EPIRBs can only be used on water, however PLBs can be used both on water and on land.

Q. Can 406MHz PLBs be automatic?

A. No. Only EPIRBs can be automatic. The main reason for this is to avoid accidental activation.

Q. Why not just have a 121.5Mhz beacon?

A. This is an obsolete technology that is now only used for homing purposes by SAR teams when they get closer to the beacon’s location. As of 2009, satellites no longer process 121.5MHz due to problems with false alerts. 406MHz is now the main signal used for SAR operations, and for decades it has been tried and tested thousands of times.

Q. How do I choose the correct EPIRB?

A. You need to carefully check approvals. Certain vessels require certain EPIRBs due to their size and location etc. Camilleri Marine will be able to advise you on which EPIRB is best for your boat.

Q. How accurate is the location transmitted by the 406MHz signal?

A. The majority of EPIRBs and PLBs transmit a GPS location and generally are accurate to within 100 metres, often even closer, at which point SAR teams home in using the 121.5MHz signal. Estimates indicate that when using the next-gen MEOSAR (Medium-Earth Orbit Search and Rescue) network, anyone activating a GPS-enabled EPIRB or PLB can expect their beacon to be located within 100 metres (328 feet), 95% of the time, within 5 minutes of the distress signal.



  • Is your EPIRB registered?
  • When was your EPIRB last tested/serviced?
  • Is your EPIRB programmed?
  • What is the battery life of your EPIRB and when does it need to be replaced?
  • Do you know how to self-test your EPIRB to ensure it is working correctly?


If you have any more questions, please contact Camilleri Marine at info@camillerimarine.com  or call (+356)2134 6320

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