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As of February 1st 2009, Cospas-Sarsat, the international satellite system for search and rescue, no longer listens for 121.5/243.0 MHz emergency beacons. Search and rescue satellites around the world only process signals from 406 MHz emergency beacons.
A timely response by search and rescue authorities is crucial in the event of a distress situation. As of February 1st 2009, having a 406 MHz emergency beacon is the best way to ensure that authorities are promptly alerted of the occurrence and location of an incident. Whether on water, in the air or on land, 406 MHz emergency beacons offer many benefits over 121.5/243.0 MHz.
Switching to 406 MHz and registering your emergency beacon with the Canadian Beacon Registry will ensure that search and rescue personnel receive crucial information that will help them to locate you in a distress situation.
As of February 1st 2009, the 121.5 MHz frequency is used as a homing frequency on 406 MHz emergency beacons and other homing devices.
Why switch to 406
The 406 MHz emergency beacons were designed specifically for satellite detection using geostationary (GEO) and low-earth orbit (LEO) search and rescue satellites. They have a signal power 50 times stronger than the 121.5/243.0 MHz and also provide:
- improved location accuracy using LEOSAR satellites and ambiguity resolution;
- increased system capacity;
- near instantaneous alerting in the GEOSAR coverage area;
- global coverage; and
- transmit a digitally encoded message with the emergency beacons unique identification.
On second generation 406 MHz emergency beacons that are connected to or have an onboard GPS device, position data can be included in the emergency beacon's encoded message. This feature is of particular interest for GEOSAR alerts because the location of the distress signal can be determined without the need to wait for a LEOSAR satellite pass over and is crucial in the event of a distress situation when every minute counts.
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| Digital: unique identification, registration
data provides information on the owner/vessel or aircraft |
Analog: no data encoded, higher false alert rate |
| 5 Watts pulse |
0.1 Watts continuous |
| Global |
Regional |
| Within 5 km (Doppler), 100m if GNSS
(GPS) position is encoded in message |
Within 20 km (Doppler only) |
| GEO alert within 5 minutes |
Waiting time for LEO satellite pass 45 minutes
average |
| Resolved at first satellite pass |
Two passes required to resolve position ambiguity |
With 406 MHz emergency beacons, false alerts are considerably reduced. According to Cospas-Sarsat, only one out of every 50 alert from 121.5 MHz is a genuine distress situation. This significantly affects search and rescue resources. With 406 MHz emergency beacons, one of out every 17 is genuine. When registered accurately, most 406 MHz false alerts can normally be resolved with a telephone call to the emergency beacon owner using the encoded identification. Consequently, real alerts can receive the attention they deserve.
406 MHz emergency beacons also have a 50 second delay in the event of an inadvertent activation to allow people the time to turn it off. However, if an emergency beacon is accidentally activated, it should be reported to Canadian Mission Control Centre by calling 1-800-211-8107.
Background
Cospas-Sarsat made the decision to cease satellite processing of 121.5/243 MHz as a result of limitations to the 121.5/243 MHz system, and due to the availability of the newer and better performance 406 MHz emergency beacons. Supported by the International Civil Aviation Organization (ICAO), the decision was also made based on the request of the International Maritime Organization (IMO) and a number of national Administrations responsible for search and rescue These United Nations organizations, which mandate safety requirements for aircraft and maritime vessels, recognized the limitations of the 121.5/243 MHz alerting system and the superior capabilities of the 406 MHz system.
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