International Satellite System For Search and Rescue, COSPAS – SARSAT – an Overview

by OldSailor on October 24, 2007


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SARSAT(Search and Rescue Satellite-Aided Tracking) system was developed in a joint effort by the United States, Canada, and France. In the United States, the SARSAT system was developed by NASA. Once the system was functional, its operation was turned over to NOAA where it remains today.


A similar system, COSPAS(Space System for Search of Distress Vessels – a Russian acronym), was developed by the Soviet Union. The four nations, United States, Canada, France and the Soviet Union banded together in 1979 to form Cospas-Sarsat. In 1982, the first satellite was launched, and by 1984 the system was declared fully operational. The system initiates rescue activities by locating emergency radio beacons transmitting on the frequencies 121.5, 243 and 406 MHZ.

3.Cospas-Sarsat Mission Statement:

The Cospas-Sarsat Programme assists search and rescue (SAR) activities on a worldwide basis by providing accurate, timely, and reliable distress alert and location data to the international community on a non-discriminatory basis.


The objective of the Cospas-Sarsat system is to reduce, as far as possible, delays in the provision of distress alerts to SAR services, and the time required to locate a distress and provide assistance, which have a direct impact on the probability of survival of the person in distress at sea or on land.


To achieve this objective, Cospas-Sarsat Participants implement, maintain, co-ordinate and operate a satellite system capable of detecting distress alert transmissions from radiobeacons that comply with Cospas-Sarsat specifications and performance standards, and of determining their position anywhere on the globe. The distress alert and location data is provided by Cospas-Sarsat Participants to the responsible SAR services.

Cospas-Sarsat co-operates with the International Civil Aviation Organization, the International Maritime Organization, the International Telecommunication Union and other international organisations to ensure the compatibility of the Cospas-Sarsat distress alerting services with the needs, the standards and the applicable recommendations of the international community.

6.System Concept:


The System is composed of:

  • distress radiobeacons (ELTs for aviation use, EPIRBs for maritime use, and PLBs for personal use) which transmit signals during distress situations;
  • instruments on board SAR satellites in geostationary and low-altitude Earth orbits which detect the signals transmitted by distress radiobeacons;
  • ground receiving stations, referred to as Local Users Terminals (LUTs), which receive and process the satellite downlink signal to generate distress alerts; and
  • Mission Control Centers (MCCs) which receive alerts produced by LUTs and forward them to Rescue Coordination Centers (RCCs), Search and Rescue Points Of Contacts (SPOCs) or other MCCs.

7.Distress radiobeacons (ELTs, EPIRBs, PLBs):

ELTs for aviation use, EPIRBs for maritime use, and PLBs for personal use. These radio beacons operate on 121.5 MHz and 406 MHz. Processing of 121.5 MHz beacons will terminate on 1 February 2009


8.SAR Satellites:

The Cospas-Sarsat System includes two types of satellites:

  • satellites in low-altitude Earth orbit (LEO) which form the LEOSAR System
  • satellites in geostationary Earth orbit (GEO) which form the GEOSAR System


9.Local User Terminals (LUTs):

Cospas-Sarsat ground stations are called Local User Terminals (LUTs). These satellite receiving units are the ground stations that receive emergency beacon distress alerts. There are two-types of LUTs. The Low Earth Orbiting LUTs (LEOLUTs) and the Geostationary LUTs (GEOLUTs).

LEOLUTs are designed to track the Cospas-Sarsat satellites as they pass across the sky and receive the distress signals relayed by them. The LEOLUT usually consists of a tracking-enabled antenna, a processor, and communications equipment.

A GEOLUT is fixed on one of the Cospas-Sarsat Geostationary satellites and receives the distress signals detected by the Geostationary satellite. This process occurs within a matter of seconds of beacon activation.

Once a signal is received and processed at the LUT it is transmitted to the mission control center (MCC) that operates that particular LUT. The LUTs are fully automated and completely unmanned at all times. In the U.S., NOAA operates twelve LEOLUTs in six locations and operates two GEOLUTs with a third for use in various testing and engineering activities. These multiple LUTs provide total system redundancy and allows for a maximization of satellite tracking.

The map below depicts the location of GEOLUTs in the Cospas-Sarsat System. (click to enlarge the image below)


LEOLUT and GEOLUT operators are expected to provide the SAR community with reliable alert and location data, without restriction on use and distribution. The Cospas-Sarsat Parties providing the space segment supply LEOLUT and GEOLUT operators with System data required to operate their LUTs. To ensure that data provided by LUTs are reliable and can be used by the SAR community on an operational basis, Cospas-Sarsat has developed LUT performance specifications and procedures. Copies of the LEOLUT and GEOLUT specifications and commissioning standards are available for downloading from Cospas-Sarsat web site.


10.Mission Control Center (MCC):

A mission control center (MCC) serves as the hub of information sent by the Cospas-Sarsat system. MCCs have been set up in most countries operating at least one LUT. Their main functions are to:

  • collect, store and sort the data from LUTs and other MCCs;
  • provide data exchange within the Cospas-Sarsat System; and
  • distribute alert and location data to associated RCCs or SPOCs.

The main function of an MCC is to collect, store, and sort alert data from LUTs and other MCCs, and to distribute alert data to RCCs, SPOCS, and other MCCs. All Cospas-Sarsat MCCs are interconnected through nodal MCCs that handle data distribution in a particular region of the world. Currently, there are four data distribution regions served by the United States, France, Russia and Australia. The system utilizes several communication modes to ensure the reliable distribution of alert data and system information.


11.Rescue Coordination Centers (RCC):

Rescue Coordination Centers (RCCs) in the United States are operated by the U.S. Coast Guard and the U.S. Air Force. RCCs receive Cospas-Sarsat distress alerts sent by the USMCC and are responsible for coordinating the rescue response to the distress. Each service takes a slightly different approach to Search and Rescue…


12.COSPAS-SARSAT Rescues carried out as of: September 07, 2007:

  • Number of Persons Rescued (To Date) in the United States: 268
    • Rescues at sea: 194 people rescued in 54 incidents
    • Aviation rescues: 26 people rescued in 16 incidents
    • PLB rescues: 48 people rescued in 22 incidents
  • Worldwide – Over 22,058 People Rescued (since 1982)
  • United States – 5,664 People Rescued (since 1982)

OldSailor is confidant that we are safe in the world with operational COSPAS-SARSAT system.

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