We have been working up to this date since the turn of the century largely because the reliability of the 121.5MHz units have been questioned on many occasions and generally these units have not been recognised since January 2007.
The following is an extract from an article published by the US Coast Guard:
Following this termination date, only the 406 MHz beacons will be detected by the International Cospas-Sarsat Satellite System which provides distress alert and location data for search and rescue operations around the world.
The regulation applies to all Class A, B, and S 121.5/243 MHz EPIRBs. It does not affect 121.5/243 MHz man overboard devices which are designed to work directly with a base alerting unit only and not with the satellite system.
This change, in large part, was brought about by the unreliability of the 121.5/243 MHz beacons in an emergency situation. Data reveals that with a 121.5 MHz beacon, only one alert out of every 50 is a genuine distress situation. This has a significant effect on expending the limited resources of search and rescue personnel and platforms. With 406 MHz beacons, false alerts have been reduced significantly, and, when properly registered, can usually be resolved with a telephone call to the beacon owner. Consequently, real alerts can receive the attention they require.
When a 406 MHz beacon signal is received, search and rescue personnel can retrieve information from a registration database.
The signal is fifty times more powerful than the 121.5MHz units and pin point accuracy of the search area is down to a hundred square metres instead of twenty plus square miles.
The signal includes the beacon owner's contact information, emergency contact information, and vessel/aircraft identifying characteristics. Having this information allows the appropriate rescue organisation to respond far more quickly and effectively.
In the U.S., users are required by law to directly register their beacon in the U.S. 406 MHz Beacon Registration Database at: http://www.beaconregistration.noaa.gov/ or by calling 1-888-212-SAVE. Worldwide users can register their beacon in their country's national beacon registration database or, if no national database is available, in the International Beacon Registration Database at https://www.406registration.com/.
Reproduced courtesy of the US Coast Guard
Note that this does not affect in any way 'on board' personal EPIRBS which respond to an on board/base not connected to the satellite system.
For NSW Australia Boaties it is compulsory to carry a 406MHz EPIRB when planning on sailing beyond two nautical miles offshore. There is a short video you can watch on http://www.beacons.amsa.gov.au/ click on 'Essential distress beacon information', which also shows you how to register your 406MHz beacons.
There is a wide range of 406MHz units to select from your faourite marine supplier but be warned that there may be shortages at present due to the normal human foible of leaving these important things to the last minute.
You can read more about safety at sea in my ebook 'Voyage of the Little Ship 'Tere Moana' downloadable from my website http://www.sailboat2adventure.com