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MEOSAR – What is it and what will it mean for sailors?

Post by: Dee White
27 September 2017

By NASA [Public domain], via Wikimedia Commons

Did you know that the way your EPIRB’s distress signal is managed is changing?

How do EPIRBs work?

The existing EPIRB (406MHz EPIB) system was implemented in the 1980s and is run by an organisation called COSPAS/SARSAT, a non-profit collaboration of 40 countries. In simple terms these emergency transmitters send a signal that is picked up by one of the geostationary satellites (GEOSAR) which record the identity of the beacon and its position using the beacon’s built-in GPS, or by one of the polar-orbiting satellites (LEOSAR). The signal is relayed to a ground station which in turn is connected to professional search and rescue services. The satellites are not dedicated for this particular task, as the radio-repeaters used to re-transmit the emergency signals are quite small, so they share space on other spacecraft.

The COSPAS/SARSAT programme has helped save over 40,000 lives since its launch in 1982, with aviation, marine and outdoor enthusiasts relying on their beacons to help with their detection and location in emergencies around the world.

One drawback of the present system is that the person who has activated their emergency beacon has no confirmation that their signal has been received. It would obviously be a great comfort to that person to receive some sort of feedback and know that help was on its way.

What is MEOSAR? 

It stands for Medium Earth Orbit Search and Rescue and its purpose is to improve on time delays in the current system and to provide instant pinpoint positioning without having to rely on GPS. MEOSAR radio-repeaters and transponders are being carried by new satellites in a number of different networks; Galileo, the European navigation satellites, Glonass, the Russian network and GPS DASS belonging to the USA. They move over the earth’s surface (unlike GEOSAR) and are at a lower altitude.

How does the MEOSAR system find you without using GPS?

The MEOSAR constellation is much bigger than the LEO and GEO systems. A beacon in the MEOSAR system can be located by lots of satellites at once who can then measure its transmission and triangulate the location. They will then be able to relay it to several ground antennas. This will improve the likelihood of detection and the accuracy of location determination. One example of how much quicker this system is; in Australia MEO satellites were able to calculate the position of a non-GPS-equipped EPIRB in just 10 minutes, compared with 2-4 hours for the LEO system. The MEOSAR system benefits other too; for the SAR teams less time will be spent searching and more time rescuing, with the highly accurate search area coordinates.

Do I have to throw away my present EPIRB or PLB?

No! Both will work with the new system. There is no update necessary to existing devices; just ensure that you are 406MHz – equipped.

However if you want to take advantage of a return link transmission, so you receive confirmation that your message has been received and help is on its way, then that will require a new beacon. There are none of these on the market at the present time and availability will be a few years down the line, but it is something to look out for in the future. The return-link beacons will be more expensive and significantly larger, with more complex circuits; but what price would you put on peace of mind?

MEOSAR should be fully functional by 2019. In the meantime the LEO and GEO systems are filling in any gaps. At that time the LEO system will be switched off, while the GEO system will remain as a back-up. From the users point of view the transition is seamless.

So – look after your emergency devices, be aware of how they work and where they work best, remembering that they could well save your life and those of your crew.  Never take the risk of going to sea without the emergency protection you need. With current cuts to coastguard services, there are fewer people looking out for you, so don’t rely on being spotted by someone on the coast or a passing vessel.