ACR EPIRB Selection Guide
FAQ on EPIRB
Q: What do EPIRBs do?
Emergency Position Indicating Radio Beacons (EPIRBs) are distress radio beacons
which transmit location information about ships directly to Search and Rescue
forces letting them know that the owner is in grave and imminent danger.
SEARCH AND RESCUE PROCESS
1. Distressed mariner/outdoor adventurer/pilot activates beacon (EPIRB, PLB, ELT).
2. Beacon transmits a 406 MHz emergency message containing your Unique
Identifier Number (UIN) to the LEOSAR (polar orbiting) and GEOSAR*
(geostationary) satellite systems.
3. The satellites relay the 406 MHz emergency message to a ground station
called the Local User Terminal (LUT). The LUT calculates the location of the
signal by measuring the Doppler shift caused by the relative movement between
the satellite and the beacon and forwards the location to the Mission Control
4. The MCC continues to receive information from additional satellite passes
and further refines the beacon position (2.3 nm search radius). An alert message
is generated that is combined with the registration information
from the database and is forwarded to the appropriate Rescue Coordination Center
5. The RCC makes contact with the persons listed in the database to verify the
existence of an emergency and gathers additional information about the beacon
users. The RCC will dispatch the closest, capable Search and Rescue (SAR)
6. Local SAR forces launch a rescue mission and use the 121.5 MHz homing signal
to pinpoint the beacon.
* On average, worldwide, this notification (steps 2 through 5) take up to one
hour for non-GPS beacons. For self-locating beacons that provide GPS position
data in their first transmissions, the search radius is reduced to .05 nm (100
m) and the notification can take as little as three minutes. (Data provided by
ABOUT THE COSPAS-SARSAT SEARCH AND RESCUE SYSTEM
Orbiting high overhead every minute of the day is a worldwide network of
polar-orbiting and geostationary satellites. Together with Russia's Cospas
spacecraft, they make up the high-tech international Search and Rescue
Satellite-Aided Tracking System known as Cospas-Sarsat.
Cospas-Sarsat has been credited with nearly 30,000 rescues worldwide. The system
relies on signals received on the 406 MHz frequency to pinpoint position and
speed rescuers to the scene of an emergency on land or at sea.
In fact, the more reliable, digital 406 MHz frequency has become the de facto
internationally recognized distress frequency. Using the 406 MHz frequency,
modern signaling devices can quickly beam GPS LAT/LON coordinates to orbiting
satellites. This frequency also allows a position fix through Doppler shift to
acquire a location even when GPS can't.
As of February 1, 2009, satellite processing of distress signals from the older
121.5 and 243 MHz emergency beacons was terminated worldwide due to
unreliability and false alarms. When a 406 MHz beacon signal is received, search
and rescue personnel can retrieve information from a registration database.
This includes the beacon owner's contact information, emergency contact
information and details regarding the specific trip plan and any medical
conditions of the owner or members in the party. Having this information allows
the Coast Guard, or other rescue personnel, to respond appropriately. NOAA,
along with the U.S. Coast Guard, is strongly advising all mariners, aviators and
individuals using 121.5/243 MHz emergency beacons to make the switch to 406 MHz
in order to take full advantage of the Sarsat system.
Cospas-Sarsat is maintained and operated by governments all over the world, thus
there is no subscription fee required for owning a 406 MHz EPIRB, ELT or Personal
Tags: Cospas Sarsat, 406 MHz Rescue, Search and Rescue Process, Coast Guard
Rescue, How a rescue works, Anatomy of a rescue, EPIRB, Emergency Position
Indicating Radio Beacon, Personal Locator Beacon, PLB, Emergency Locator
Q: Will 406 MHz beacons work anywhere in the world?
Yes, 406 MHz beacons can be used anywhere in the world, including at both poles,
just remember that you need a clear view of the sky (they will not work in
buildings or caves, etc.)
Q: Is there a subscription fee for beacon registration or rescue service?
Beacon registration is
free, should you ever have to activate your beacon, rescue is free in most parts
of the world.
Q: What is the difference between a Category I and a Category II EPIRB? -
The difference is in how the EPIRB is deployed.
A Category I beacon automatically deploys when a vessel sinks. The beacon floats
free at a depth of 1.5 to 3.0m (4.9 to 13.1ft). The EPIRB can be manually
activated while in its bracket or manually removed and activated.
A Category II beacon is manually deployed. The EPIRB will automatically activate
when removed from its bracket and comes in contact with water, or when it is
still in its bracket but a person has lifted the switch to the activation