Hubbry Logo
International Cospas-Sarsat ProgrammeInternational Cospas-Sarsat ProgrammeMain
Open search
International Cospas-Sarsat Programme
Community hub
International Cospas-Sarsat Programme
logo
8 pages, 0 posts
0 subscribers
Be the first to start a discussion here.
Be the first to start a discussion here.
International Cospas-Sarsat Programme
International Cospas-Sarsat Programme
International Cospas-Sarsat Programme
View on Wikipedia
from Wikipedia

Logo as used until 1992

Key Information

The International Cospas-Sarsat Programme is a satellite-aided search and rescue (SAR) initiative. It is organized as a treaty-based, nonprofit, intergovernmental, humanitarian cooperative of 45 nations and agencies (see infobox).[2] It is dedicated to detecting and locating emergency locator radio beacons activated by persons, aircraft or vessels in distress, and forwarding this alert information to authorities that can take action for rescue.[3][4][5] Member countries support the distribution of distress alerts using a constellation of around 65 satellites orbiting the Earth which carry transponders and signal processors capable of locating an emergency beacon anywhere on Earth transmitting on the Cospas-Sarsat frequency of 406 MHz.

Distress alerts are detected, located and forwarded to over 200 countries and territories at no cost to beacon owners or the receiving government agencies.[6] Cospas-Sarsat was conceived and initiated by Canada, France, the United States, and the former Soviet Union in 1979.[7] The first rescue using the technology of Cospas-Sarsat occurred on 10 September 1982; 43 years ago (1982-09-10).[8][9] The definitive agreement of the organization was signed by those four States as the "Parties" to the agreement on 1 July 1988.

The term Cospas-Sarsat derives from COSPAS (КОСПАС), an acronym from the transliterated Russian "Космическая Система Поиска Аварийных Судов" (Latin script: "Cosmicheskaya Sistema Poiska Avariynyh Sudov"), meaning "Space System for the Search of Vessels in Distress", and SARSAT, an acronym for "Search And Rescue Satellite-Aided Tracking".[10]

Background

[edit]

Cospas-Sarsat is best known as the system that detects and locates emergency beacons activated by aircraft, ships and people engaged in recreational activities in remote areas, and then sends these distress alerts to search-and-rescue (SAR) authorities. Distress beacons capable of being detected by the Cospas-Sarsat System (currently 406-MHz beacons) are available from several manufacturers and vendor chains. Cospas-Sarsat does not make or sell beacons.

Between September 1982 and December 2023 the Cospas-Sarsat System provided assistance in rescuing at least 63,745 people in 19,883 SAR events. In 2023 Cospas-Sarsat on average assisted in the rescue of almost nine persons each day. In 2021, 2022 and 2023 (the latest year for which statistics have been compiled), Cospas-Sarsat assistance included the following:[11]

Year People Rescued SAR Events → Aviation Land Maritime
2023 3,109 1,076 20% 44% 36%
2022 3,223 1,144 20% 39% 41%
2021 3,623 1,149 18% 45% 37%

These statistics under-count the number of events where Cospas-Sarsat assisted, because they only include cases when an accurate report from SAR personnel is provided back through reporting channels to the Cospas-Sarsat Secretariat.

Cospas-Sarsat does not undertake search-and-rescue operations. This is the responsibility of national administrations that have accepted responsibility for SAR in various geographic regions of the world (typically the same geographic area as their flight information region). Cospas-Sarsat provides alert data to those authorities.

Cospas-Sarsat cooperates with United Nations-affiliated agencies, such as the International Civil Aviation Organization (ICAO), the International Maritime Organization (IMO), and the International Telecommunication Union (ITU), among other international organizations, to ensure the compatibility of the Cospas-Sarsat distress alerting services with the needs, the standards and the applicable recommendations of the global community.[12] Cospas-Sarsat is an element of the IMO's Global Maritime Distress Safety System (GMDSS), and is a component of ICAO's Global Aeronautical Distress and Safety System (GADSS). The IMO requires automatic-activating Cospas-Sarsat beacons (EPIRBs, see below) on all vessels subject to requirements of the International Convention for the Safety of Life at Sea (so-called SOLAS-class vessels), commercial fishing vessels, and all passenger ships in international waters. Similarly, ICAO requires Cospas-Sarsat beacons aboard aircraft on international flights, as well as the ability to track such aircraft when in distress (see "Beacons" under "System architecture" below).[13] National administrations often impose requirements in addition to the international requirements of those agencies.

Cospas-Sarsat only monitors for alerts from digital distress beacons that transmit on 406 MHz (so-called 406 beacons). Older beacons that transmit using the legacy analog signal on 121.5 MHz or 243 MHz rely on being received only by nearby aircraft or rescue personnel. For satellite reception of alerts by Cospas-Sarsat the beacon must be a model that transmits at 406 MHz.[6]

Cospas-Sarsat has received many honors for its humanitarian work, including induction into the Space Foundation's Space Technology Hall of Fame for space technologies improving the quality of life for all humanity.[14][15]

System operation

[edit]
The components and operation of the Cospas-Sarsat system

The system consists of a ground segment and a space segment that include:

Beacons

[edit]

A Cospas-Sarsat distress beacon is a digital 406-MHz radio transmitter that can be activated in a life-threatening emergency to summon assistance from government authorities. Beacons are manufactured and sold by dozens of vendors. They are classified in three main types. A beacon designed for use aboard an aircraft is known as an emergency locator transmitter (ELT). One designed for use aboard a marine vessel is called an emergency position-indicating radio beacon (EPIRB). And one that is designed to be carried by an individual is known as a personal locator beacon (PLB). Sometimes PLBs are carried aboard aircraft or vessels, but whether this satisfies safety requirements depends on local regulations.[6] A Cospas-Sarsat beacon does not transmit until it is activated in an emergency (or when certain testing features are activated by the user). Some beacons are designed to be manually activated by a person pressing a button, and some others are designed for automatic activation in certain circumstances (e.g., ELTs may be automatically activated by a physical shock, such as in a crash, and EPIRBs may be automatically activated by contact with water). There are no subscription or other costs imposed by Cospas-Sarsat for beacon ownership or use. (Some countries may impose licensing and/or registration charges for beacon ownership, and some jurisdictions may assess costs for rescue operations.)[16] See below for recent beacon innovations.

Space segment

[edit]

The Cospas-Sarsat system operational space segment consists of SARR and/or SARP instruments aboard:[17]

  • Five satellites in polar low-altitude Earth orbit with LEOSAR (low-altitude Earth orbit search-and-rescue) payloads (one other in preparation for use),
  • Twelve satellites in geostationary Earth orbit with GEOSAR (geostationary Earth orbit search-and-rescue) payloads (two others in preparation for use),
  • 48 satellites in medium-altitude Earth orbit with MEOSAR (medium-altitude Earth orbit search-and-rescue) payloads (seven others in preparation for use).

A SARR or SARP instrument is a secondary payload and associated antennas attached to those satellites as an adjunct to the primary satellite mission. A SARR instrument retransmits a beacon distress signal to a satellite ground station in real time. A SARP instrument records the data from the distress signal so that the information can later be gathered by a ground station when the satellite passes overhead.

Ground segment

[edit]

The satellites are monitored by receiving ground stations (LUTs) equipped to track (point at and follow) the satellites using satellite dishes or phased antenna arrays. LUTs are installed by individual national administrations or agencies. The distress messages received by a LUT are transferred to an associated mission control centre which uses a detailed set of computer algorithms to route the messages to rescue coordination centres worldwide.

System architecture

[edit]

When a distress beacon is activated, the Cospas-Sarsat system:

  • decodes the binary coded message of the beacon, which contains information such as the identity of the vessel/aircraft and, for beacons equipped with the feature, the location of the beacon derived from a local navigation source (such as a GPS receiver incorporated into the beacon's design), and
  • performs a mathematical analysis of the signal to calculate the location of the beacon, even if the beacon's location is not reported in the distress message.

The Cospas-Sarsat system is the only satellite distress alerting system that is capable of this dual, redundant means of locating an activated distress beacon.

The SARR and/or SARP instrument typically is attached to a satellite that is being launched primarily for another purpose. The primary mission of all of the LEOSAR and GEOSAR satellites is meteorological (gathering of weather data). The primary mission of all of the MEOSAR satellites is navigation.

LEOSAR

[edit]
Example of LEOSAR signal footprint.

LEOSAR was the original Cospas-Sarsat space segment architecture. The complementary LEOSAR-satellite orbits provide periodic coverage of the entire Earth. Because of their relatively low altitude (and therefore, relatively small "footprint" of visibility of any particular part of the Earth at any given time), there are intervals of time when a LEOSAR satellite may not be over a particular geographic location. So there can be a delay in receiving an alert signal, and a delay in relaying that signal to the ground. For this reason, LEOSAR satellites are equipped with the "store-and-forward" SARP modules in addition to "real-time" SARR modules. The satellite can pass over a remote area of the Earth and receive a distress message, and then forward that data later when it passes into view of a ground station (that typically are located in less remote areas). The five satellites in the LEOSAR constellation have approximately 100 minute orbits. Because of their polar orbits the latency between satellite passes overhead is smallest at the poles and higher at the equator.

The Cospas-Sarsat LEOSAR system was made possible by Doppler processing. LUTs detecting distress signals relayed by LEOSAR satellites perform mathematical calculations based on the Doppler-induced frequency shift received by the satellites as they pass over a beacon transmitting at a fixed frequency. From the mathematical calculations, it is possible to determine both bearing and range with respect to the satellite. The range and bearing are measured from the rate of change of the received frequency, which varies both according to the path of the satellite in space and the rotation of the Earth. This allows a computer algorithm to trilaterate the position of the beacon. A faster change in the received frequency indicates that the beacon is closer to the satellite's ground track. When the beacon is moving toward or away from the satellite track due to the Earth's rotation, the Doppler shift induced by that motion also can be used in the calculation.

GEOSAR

[edit]

Because their geostationary orbit does not provide a relative motion between a distress beacon and a GEOSAR satellite, there is no opportunity to use the Doppler effect to calculate the location of a beacon. Therefore, the GEOSAR satellites only can relay a beacon's distress message. If the beacon is a model with a feature to report its location (e.g., from an on-board GPS receiver) then that location is relayed to SAR authorities. While the inability to independently locate a beacon is a drawback of GEOSAR satellites, those satellites have an advantage in that the present constellation well covers the entire Earth in real time, except for the polar regions.

MEOSAR

[edit]

The most recent space segment augmentation for Cospas-Sarsat is MEOSAR. MEOSAR blends the advantages of the LEOSAR and GEOSAR systems, while avoiding their drawbacks. The MEOSAR system is becoming the dominant capability of Cospas-Sarsat. In addition to the large number of satellites, the MEOSAR system benefits from relatively large satellite footprints and sufficient satellite motion relative to a point on the ground to allow the use of Doppler measurements as part of the method of calculating a distress beacon's location. MEOSAR consists of SARR transponders aboard the following navigation-satellite constellations: the European Union's Galileo, Russia's Glonass, and the United States' Global Positioning System (GPS).[18][19][20][21] In November 2022, China became the newest MEOSAR space-segment provider, with Cospas-Sarsat SAR payloads aboard six of its BeiDou (BDS) navigation spacecraft. The first SAR-equipped BDS spacecraft was launched on 19 September 2018, and the last on 23 November 2019.

Operational distribution of MEOSAR alert data began at 1300 UTC on 13 December 2016. Following continued testing and adjustment, a declaration of initial operational capability (IOC) was made by the Cospas-Sarsat Council effective from 25 April 2023. The MEOSAR system advances the ability to provide near-instantaneous detection, identification, and location-determination of 406-MHz beacons. Prior to the operational introduction of MEOSAR, MEOSAR data was successfully used to assist in determining the crash location of EgyptAir flight 804 in the Mediterranean Sea.[22] The location of a distress beacon is calculated by the receiving LUT by analyzing the frequency-difference-of-arrival (related to Doppler-induced variations), and/or the time-difference-of-arrival of a beacon's radio signal due to the differences in distance between the beacon and each MEOSAR satellite that may be in view.

With respect to GPS-hosted payloads, experimental S-band payloads aboard 18 GPS Block IIR and GPS Block IIF satellites, and four payloads aboard GPS Block IIIA satellites are used operationally by the Cospas-Sarsat System. GPS Block IIIF satellites are planned to have dedicated, operational L-band SAR payloads provided by Canada, with launches beginning around 2026. The GPS SAR system is known as the Distress Alerting Satellite System (DASS) by NASA.[23][24][25]

Additionally, the Galileo component of the MEOSAR system is able to download information back to the distress radio-beacon by encoding "Return Link Service" messages into the Galileo navigation data stream. It can be used to activate an indicator on the beacon to confirm receipt of the distress message.[26][27][28]

Ground segment

[edit]

As of December 2022 the LEOSAR satellites are tracked and monitored by 55 commissioned LEOLUT (low-altitude Earth-orbit local user terminals) antennas, the GEOSAR satellites by 27 commissioned GEOLUT antennas [1] and the MEOSAR satellites by 26 commissioned MEOLUT stations, each having multiple antennas. The data from these earth stations is transferred to and distributed by 32 MCCs established globally, 14 of which are commissioned to process data from all three constellation types.[29][30] (See infobox for the countries and agencies that are ground-segment providers.)

Beacons

[edit]

Current Beacon Technologies

[edit]

Most Cospas-Sarsat-compatible 406-MHz beacons also transmit distress or tracking signals on additional frequencies. Most commonly, Cospas-Sarsat beacons have a 121.5-MHz transmitter to provide a signal that can be received by local search crews (airborne, on ground or at sea) using direction-finding equipment. Additionally, the latest EPIRBs include an automatic identification system (AIS) transmitter in the marine VHF band that allows the beacon to be easily tracked from nearby vessels. Recent PLB models designed for attachment to marine life vests transmit an AIS signal to act as a maritime survivor locating system, also known as a man overboard (MOB) system, that activates alarms on nearby vessels and allows the beacon to be tracked by properly equipped vessels.

Beacons with such combinations of signals simultaneously allow for global alerting through the 406-MHz transmission to satellites and the swiftest local response from the 121.5-MHz and AIS transmissions (particularly in the maritime environment by nearby vessels).

In response to recent commercial aviation disasters and subsequent ICAO requirements for autonomous tracking of aircraft in distress,[31][32] Cospas-Sarsat established specifications for ELTs for distress tracking (ELT(DT)s) to meet the ICAO requirements (amended Annex 6, Part I of the Convention on International Civil Aviation). Whereas conventional ELTs are designed to activate on impact or by manual activation by the flight crew, ELT(DT)s activate autonomously when an aircraft enters threatening flight configurations that have been predetermined by expert agencies. In this way, ELT(DT)s allow a plane in distress to be tracked in-flight, prior to any crash, without human intervention aboard the aircraft. ELT(DT)s have been specified using both the existing beacon transmission method (narrowband BPSK) and the second-generation (spread-spectrum QPSK) modulation schemes (see transmission technologies below). Cospas-Sarsat capability for receiving and processing distress messages from ELT(DT)s using the narrowband BPSK transmission method was declared operational effective 1 January 2023. In October 2023 capability for receiving and processing distress messages from ELT(DT)s using the spread-spectrum QPSK modulation method was declared with an effective date of 1 January 2024.

Beacon Transmission Technologies

[edit]

There has been one transmission modulation method used by Cospas-Sarsat 406-MHz digital beacons since their inception more than 30 years ago, binary phase-shift keying (BPSK), with two allowed bit-string lengths: 112 (with 87 bits of message information) and 144 (with 119 bits of message information). Several message protocols are allowed in the available message-bit string to accommodate different kinds of beacons (ELTs, EPIRBs and PLBs), different vessel/aircraft identifiers, and different national requirements. The time length of these transmissions is approximately one-half second. These narrowband transmissions occupy approximately 3 kHz of bandwidth in a channelized scheme across the assigned 406.0 to 406.1 MHz band.[33]

Cospas-Sarsat has recently specified a new, additional beacon modulation and message scheme based on spread-spectrum technology with quadrature phase-shift keying (QPSK). Presently beacons that use this scheme are termed "second generation" beacons. It allows the use of battery-saving lower-power transmissions, improves the accuracy of the determination of the beacon location by the Cospas-Sarsat System, and avoids the need for discrete channelization in the assigned 406.0 to 406.1 MHz band (e.g., avoiding the need for periodic closing and opening of channels by Cospas-Sarsat for use by beacon manufacturers based on narrowband channel loading). Second-generation beacons have a longer transmission period of one second, with 250 transmitted bits, 202 of those being message bits. Additionally, the information sent in the message bits from one transmission to the next can be changed on a rotating transmission schedule ("rotating message fields") to allow significantly more information to be communicated over the course of a series of transmission bursts.[34] Deployment of this technology in ELT(DT)s may begin in January 2024. Cospas-Sarsat readiness for deployment of the technology in other types of beacons is expected later in 2024.

History

[edit]
COSPAS-SARSAT international satellite system, search for ships and aircraft in distress. Stamp of USSR, 1987.

Conception and demonstration

[edit]

In the early 1970s, the Space System Group at Communications Research Centre Canada (CRC) began investigating whether an ELT could be detected and located from space. They realized that this could be accomplished through the Doppler shift of an ELT signal received by an orbiting satellite. CRC contacted AMSAT and was granted use of an OSCAR amateur radio satellite, through which they located an ELT modified to the satellite's uplink frequency. NASA contacted CRC over its success and the United States later agreed to a joint project.[35]

[edit]

On 23 November 1979, a "memorandum of understanding concerning cooperation in a joint experimental satellite-aided search and rescue project" was signed in Leningrad, USSR, among the U.S. National Aeronautics and Space Administration, the USSR Ministry of Merchant Marine, the Centre National d'Etudes Spatiales of France, and the Department of Communications of Canada. Under Article 3 of the memorandum, it was stated that:[36]

"Cooperation will be achieved through effecting interoperability between the SARSAT project and the COSPAS project at 121.5MHz, 243MHz and in the 406.0 – 406.1 MHz band and conducting of tests, mutual exchange of test results and preparation of a joint report. The objective of this cooperation is to demonstrate that equipment carried on low-altitude, near polar-orbiting satellites can facilitate the detection and location of distress signals by relaying information from aircraft and ships in distress to ground stations, where the information processing is completed and passed to rescue services."

"This joint Project will permit the Parties to make recommendations on follow-on global applications."

Development

[edit]

The first system satellite, "COSPAS-1" (Kosmos 1383), was launched from Plesetsk Cosmodrome on June 29, 1982.[37][38][39] Cospas-Sarsat began tracking the two original types of distress beacons, EPIRBs and ELTs, in September 1982. While the satellite's operation was being verified on September 9, COSPAS-1 detected an ELT signal in British Columbia and relayed the information to a then-experimental ground station at Defence Research Establishment Ottawa (DREO). The Canadians calculated the position of the small aircraft, which was 90 km (56 mi) off course, and within hours the crash survivors were rescued via airlift. These were the first persons rescued with the assistance of Cospas-Sarsat, and authorities judged that pilot Jonathan Ziegelheim would likely have died of his injuries if not for the swift rescue made possible by satellite detection.[40][41][42][35]

Prior to the founding of Cospas-Sarsat, the civilian aviation community had already been using the 121.5 MHz frequency for distress, while the military aviation community utilized 243.0 MHz as the primary distress frequency with the 121.5 MHz frequency as an alternate. In each case, detection of the distress signal relied on reception by aircraft passing nearby, and localization of the signal was done with Earth-based direction finding equipment. Satellites made it possible to expand this "local" search paradigm into a global capability.

Each of the four founding Party States took responsibility for one of the major tasks in the project. The United States (with project leadership from NASA's Goddard Space Flight Center in Greenbelt, MD, USA) directed Datron Systems in Chatsworth, CA, USA to design and build LUT ground stations to receive the downlink from the satellites. At Datron, a team designed a LUT with five horn antennas, and Jeffrey Pawlan designed the downconverter and the specialized monopulse receiver capable of locking onto the downlink from the satellites. France and Canada were responsible for the data generation and decoding. They designed the computer that determined the approximate position of the beacon from the Doppler shift of the beacon's signal caused by the relative motion of the beacon and the receiving satellite. The former Soviet Union was responsible for the design and construction of the first satellite to be launched. Engineers from all four countries met in Moscow in February 1982 to successfully test the operational functionality of all of the equipment together in the same laboratory.

The Party States led development of the 406-MHz marine EPIRB, that used a digital messaging scheme, for detection by the system. The EPIRB was seen as a key advancement in SAR technology in the perilous maritime environment. The digital message allowed the beacon and its associated vessel to be uniquely identified. Early in its history, the Cospas-Sarsat system was engineered to detect beacon-alerts transmitted at 406 MHz, 121.5 MHz and 243.0 MHz. Because of a large number of false alerts, and the inability to uniquely identify such beacons because of their old, analogue technology (that provided no message, only a tone indicating distress), the Cospas-Sarsat system beginning in 2009 stopped receiving alerts from beacons operating at 121.5 MHz and 243.0 MHz, and now only receives and processes alerts from modern, digital 406-MHz beacons.

In the early 2000s (in 2003 in the USA) a new type of distress beacon, the personal locator beacon (PLB), became available[43] for use by individuals who cannot contact emergency services through normal telephone-originated services, such as 1-1-2 or 9-1-1. Typically PLBs are used by people engaged in recreational activities in remote areas, and by small-aircraft pilots and mariners as an adjunct to (or, when permitted, a substitute for) an ELT or EPIRB.

The design of distress beacons as a whole has evolved significantly since 1982. The newest 406-MHz beacons often incorporate global navigation satellite system (GNSS) receivers (such as those using GPS). Such beacons determine their location using the internal GNSS receiver (or a connection to an external navigation source) and transmit in their distress message highly accurate position reports. This provides a second method for Cospas-Sarsat to know the location of the distress, in addition to the calculations independently done by Cospas-Sarsat LUTs to determine the location. The distress alert received by the satellites and the beacon location contained in the message and/or calculated from the distress signal are forwarded almost instantly to SAR agencies by Cospas-Sarsat's extensive international data-distribution network. This two-tiered reliability and global coverage of the system has inspired the current motto of SAR agencies: "Taking the 'Search' out of Search and Rescue."[44]

References

[edit]
[edit]
Revisions and contributorsEdit on WikipediaRead on Wikipedia

International Cospas-Sarsat Programme

View on Grokipedia
from Grokipedia
The International Cospas-Sarsat Programme is a satellite-based (SAR) distress alert detection and information distribution system designed to detect beacons transmitting on 406 MHz and their locations to rescue coordination centers worldwide, enabling rapid response to distress situations in , maritime, and land environments. Established in 1979 through an intergovernmental agreement among , , the , and the , the programme became operational in 1982 with the launch of its first satellites and has since expanded to involve 45 participating nations, operating a constellation of 62 satellites across low-Earth (LEOSAR), (GEOSAR), and medium-Earth (MEOSAR) configurations. The system functions by having emergency position-indicating radio beacons (EPIRBs for maritime use), emergency locator transmitters (ELTs for aviation), and personal locator beacons (PLBs for land) emit digital distress signals that are intercepted by orbiting satellites equipped with transponders. These signals are then relayed to local user terminals (LUTs) on the ground for processing, including location determination via Doppler shift analysis for LEOSAR satellites or integrated GPS data for modern beacons, before being forwarded to mission control centers (MCCs) and rescue coordination centers (RCCs) for action. The programme provides global coverage, with GEOSAR satellites offering near-instantaneous detection and MEOSAR enhancing accuracy and speed through integration with global navigation satellite systems like GPS and Galileo, while older 121.5 MHz and 243 MHz analog beacons were phased out in 2009 to focus on the more reliable 406 MHz digital standard. Since its inception, the Cospas-Sarsat Programme—named after the acronyms COSPAS (from Russian "Kosmicheskaya sistema poiska avariynyh sudov", meaning "Space System for the Search of Distressed Vessels") and SARSAT ("Search and Rescue Satellite-Aided Tracking")—has facilitated the rescue of over 63,000 lives (as of 2025) through more than 500,000 distress alerts (as of 2023), demonstrating its critical role in humanitarian efforts despite challenges like beacon registration requirements and environmental signal interference. Ongoing developments include the full deployment of MEOSAR for real-time alerting and expanded international cooperation to improve system resilience and integration with emerging technologies.

Overview

Purpose and Objectives

The International Cospas-Sarsat Programme's primary objectives are to detect and locate distress signals from emergency beacons and to deliver accurate, timely, and reliable alert and position information to (SAR) authorities worldwide, thereby facilitating faster response times and saving lives in maritime, , and terrestrial emergencies. This humanitarian effort focuses on reducing the uncertainties in SAR operations by providing critical data on the location and identity of distressed individuals, , or vessels, ultimately aiming to eliminate the "search" phase in missions. The programme integrates seamlessly with established international SAR frameworks, including the 1979 International Convention on Maritime Search and Rescue (SAR Convention) and standards from the International Civil Aviation Organization (ICAO), by supplying satellite-detected distress information that supports coordinated global SAR responses. Through this alignment, Cospas-Sarsat enhances compliance with these conventions, enabling harmonized procedures for maritime and aeronautical distress situations as outlined in the International Aeronautical and Maritime Search and Rescue (IAMSAR) Manual. In terms of scope, the programme covers distress alerting services for personal locator beacons (PLBs) used in general outdoor emergencies, emergency position-indicating radio beacons (EPIRBs) for maritime incidents, and emergency locator transmitters (ELTs) for aviation distress, all operating primarily on the 406 MHz frequency to ensure international compatibility. It also incorporates a return link service (RLS) capability, which transmits confirmation messages back to compatible beacons, assuring users that their alert has been received and processed by SAR systems. Funded entirely through contributions from its member states, the Cospas-Sarsat Programme operates on a non-commercial basis, imposing no fees or subscription costs for core distress detection, location, and alerting services to promote equitable and universal access for all users regardless of nationality or location. This funding model underscores the programme's commitment to humanitarian goals, with participating nations covering their own contributions to satellites, ground infrastructure, and operations without financial exchanges between parties.

Membership and Governance

The International Cospas-Sarsat Programme operates as an intergovernmental organization with 45 participating states and organizations as of 2025, including full members such as , , the Russian Federation, and the , along with associate members, ground segment providers, user states, and international entities. Other notable participants include , , , , , , and the , contributing through provision of space or ground infrastructure, operational support, or beacon registration services. The programme's International Beacon Registration Database (IBRD) supports global access for beacon owners and authorities, enabling efficient distress response by providing critical registration details to (SAR) operations worldwide. Governance is led by the Council of Participating States (CPS), the primary policy-making body that oversees strategic direction, approves system enhancements, and coordinates international . The CPS is supported by the permanent Cospas-Sarsat Secretariat, located in , , which handles administrative, technical, financial, and conference services while implementing council decisions. Technical oversight is provided through specialized bodies, including the System Technical Group (STG) for system performance and standards, and various working groups addressing specific advancements, such as two-way communication capabilities. National SAR points of contact (SPOCs) in participating administrations interface with the secretariat to manage alert distribution and operational coordination. Funding for the programme's operations is derived from assessed annual contributions by member states and organizations, with parties contributing approximately CAD 190,000 and other participants CAD 42,000, as determined periodically by the council to cover secretariat and system maintenance costs. The legal foundation rests on the International Cospas-Sarsat Programme Agreement, signed on 1 July 1988 by the four founding parties and entering into force on 30 August 1988, which formalized the structure following initial memoranda of understanding from 1984 and 1985 that enabled early operational phases. This agreement ensures cooperative management of the satellite-aided SAR system without profit motives, emphasizing humanitarian objectives.

History

Conception and Demonstration

The International Cospas-Sarsat Programme originated in 1979 when , , the , and the signed a (MOU) to develop a satellite-based (SAR) system, marking a rare instance of technological cooperation during the period. This initiative was spurred by the need for a global SAR capability following high-profile air and maritime disasters, such as the 1972 disappearance of a U.S. aircraft carrying congressmen over , which highlighted the limitations of ground-based detection in remote areas. The program, named COSPAS (from the Russian for "space system for search of vessels in distress") and SARSAT ( Satellite-Aided Tracking), aimed to leverage existing polar-orbiting satellites to detect and locate distress signals worldwide. Between 1979 and 1982, the participating nations conducted proof-of-concept demonstrations to validate the system's feasibility, utilizing U.S. NOAA polar-orbiting satellites and Soviet Kosmos satellites equipped with transponders to receive and relay signals. These tests successfully detected analog signals transmitted at 121.5 MHz, the international aeronautical frequency, from simulated distress s during ground and airborne exercises. A primary technical challenge addressed was the Doppler shift effect caused by the relative motion of (LEO) satellites passing over s at speeds up to 7 km/s, which allowed for position calculation by measuring variations in the received signal; this method achieved location accuracies of approximately 5-10 km for 121.5 MHz s, sufficient for initial SAR response in vast oceanic and polar regions. The system's first operational demonstration occurred on September 10, 1982, when a Soviet COSPAS-1 detected a 121.5 MHz signal from a downed in northern , , enabling rescuers to locate and save all three survivors within hours. This event confirmed the viability of satellite-aided SAR and paved the way for formal international agreements to operationalize the programme. The International Cospas-Sarsat Programme was initially formalized through a (MoU) signed on 23 November 1979 by the four founding states—, , the , and the —establishing a cooperative framework for the development and operation of a satellite-based system. This agreement built on earlier collaborative efforts and focused on joint provision of the space, ground, and user segments to detect and locate distress signals globally. By 1984, participation had expanded to include 15 states, primarily through contributions to the ground segment, which enhanced the system's international scope during its demonstration and evaluation phase. The legal framework further evolved with the signing of the International Cospas-Sarsat Programme Agreement on 1 July 1984, which entered into force on 8 July 1985 and outlined operational responsibilities among the founding parties, including the Soviet Union's Ministry of Merchant Marine, the United States' National Oceanic and Atmospheric Administration, Canada's Department of Communications, and France's Centre National d'Etudes Spatiales. This agreement marked the transition to full operational status, emphasizing the free provision of distress alert data to rescue authorities worldwide. In 1988, the Convention on the International Cospas-Sarsat Programme, signed in Paris on 1 July 1988 and entering into force on 30 August 1988, elevated the programme to full intergovernmental status, ensuring sustained coordination and expansion under a treaty-based structure with defined party obligations. Early infrastructure development accompanied these agreements, with the deployment of the first Local User Terminals (LUTs) in 1984 to receive and process satellite-downlinked signals, followed by the establishment of Mission Control Centres (MCCs) in 1985 for alert validation and distribution to rescue coordination centres. These initial LUTs and MCCs, operated primarily by the founding states, formed the core of the ground segment and enabled the system's declaration as operational in September 1985. The programme's frequencies were designated by the (ITU) under the Radio Regulations, allocating the 406.0–406.1 MHz band exclusively for digital distress beacons in the mobile-satellite service to support position determination and alerting, while 121.5 MHz served as a secondary VHF homing frequency. To prioritize the more reliable 406 MHz beacons, the Cospas-Sarsat Programme phased out satellite processing of 121.5 MHz alerts effective 1 February 2009, reducing false alarms and improving overall efficiency.

Major Developments and Milestones

In the , the Cospas-Sarsat Programme expanded its capabilities by integrating geostationary Earth (GEOSAR) satellites, which provided near-real-time global coverage for 406 MHz distress signals, complementing the existing (LEOSAR) system. The first GEOSAR payloads were deployed in the mid-to-late , with formal integration of the 406 MHz GEOSAR system occurring in 1998 following several years of testing. This development addressed gaps in polar-orbiting satellite coverage and enabled faster alert dissemination. Concurrently, the ground infrastructure grew with the addition of more User Terminals (LUTs) worldwide as additional nations joined the programme, enhancing and location accuracy across diverse regions. The 2000s marked a transition to more reliable and precise beacon technology, with 406 MHz becoming the mandatory frequency for satellite-aided distress alerting after the termination of 121.5 MHz analog signal monitoring on February 1, 2009. This shift, planned since the early 2000s, reduced false alarms and improved detection reliability, as 406 MHz beacons transmit digital data including unique identification codes. Starting in 2003, many 406 MHz beacons incorporated GPS receivers, allowing them to self-locate and transmit positions accurate to within 100 meters, a vast improvement over Doppler-based calculations that could span several kilometers. These enhancements significantly boosted the system's effectiveness in time-sensitive rescues. Advancements in the 2010s focused on the development of the Search and Rescue (MEOSAR) system, initiated formally in 2009 to provide near-instantaneous global coverage and return link messaging for beacon confirmation. The first MEOSAR payloads became operational on Galileo satellites in 2016, followed by integrations on GPS III satellites in 2018, enabling burst transmissions and reduced latency compared to LEOSAR and GEOSAR architectures. This phase represented a major evolution toward a fully interoperable, multi-constellation network involving partners like the , , and others. Key milestones in the 2020s included the operational deployment of Emergency Locator Transmitter (Distress Tracking) or ELT(DT) beacons, declared fully capable for first-generation technology in January 2023 to meet aviation distress tracking requirements under ICAO standards. By 2023, the international beacon registration database had expanded to over 3 million entries, reflecting widespread adoption and improved user compliance for faster response coordination. On September 10, 2025, the programme declared the inaugural Global Day, commemorating the system's first rescue in 1982 and honoring ongoing international efforts to save lives in distress.

System Components

Distress Beacons

Distress beacons, also known as 406 MHz beacons, are portable or fixed emergency transmitters designed to alert (SAR) authorities when activated by individuals, , or vessels in distress. These devices form the user-end component of the Cospas-Sarsat Programme, initiating digital distress signals that satellites detect and relay for location and response. The primary types of distress beacons include Emergency Position Indicating Radio Beacons (EPIRBs) for maritime applications, Emergency Locator Transmitters (ELTs) for , and Personal Locator Beacons (PLBs) for personal or land-based use. EPIRBs are typically installed on ships and activate automatically upon water immersion or manually, complying with international maritime standards. ELTs, mounted on , trigger via impact sensors or manual , with the ELT(DT) variant—part of the second-generation beacons (SGBs)—introduced for enhanced distress tracking since achieving full operational capability in 2023. PLBs are compact, handheld devices suited for hikers, climbers, or remote workers, offering portability without installation requirements. SGBs, mandatory for new ELT(DT) models from 2024 onward, incorporate advanced features like capabilities for improved SAR coordination. Technically, all beacons transmit on the 406 MHz frequency using digital messaging that encodes a unique 24-bit identifier (Hex ID), which distinguishes the device and links to the owner's registration data. This ID includes encoded such as the beacon's of registration and type, enabling rapid identification by SAR teams. Many models also emit an optional 121.5 MHz for local homing by rescue or vessels once in proximity. Second-generation beacons integrate Global Navigation System (GNSS) receivers, providing position accuracy better than 5 meters, which significantly reduces location uncertainty compared to Doppler-based positioning in older models. Battery life specifications ensure reliability: EPIRBs maintain at least 48 hours of continuous transmission at -40°C, while PLBs sustain 24 hours; shelf life typically ranges from 5 to 10 years depending on the model. Registration of beacons is mandatory through the International Beacon Registration Database (IBRD), a centralized system managed by the Cospas-Sarsat Programme that stores owner contact details, emergency contacts, and vessel or aircraft information. As of May 1, 2025, the IBRD contained 112,500 registered beacons, up from 110,600 in March 2024, facilitating faster SAR responses by allowing authorities to contact owners directly and suppress false alarms. Unregistered beacons risk delayed rescues, as SAR teams must otherwise trace identities through national databases. Globally, more than three million Cospas-Sarsat-compatible beacons were deployed by late 2023, reflecting widespread adoption across maritime, , and recreational sectors. Of these, over 75% were equipped with GNSS receivers, enabling near-real-time positioning that enhances system efficiency. Annual production exceeds 200,000 units, with projections for continued growth driven by regulatory mandates for GNSS integration in new devices. Beacons undergo rigorous through the Cospas-Sarsat type approval , which verifies compliance with technical standards outlined in documents like C/S T.001 for first-generation beacons and C/S T.018 for SGBs. Testing includes evaluations of signal modulation, power output, and environmental resilience (e.g., temperature extremes and vibration), conducted by accredited facilities such as those under the (IEC). Manufacturers must submit prototypes for approval, ensuring beacons meet minimum performance thresholds before market release; self-testing modes allow users to verify functionality without alerting SAR authorities.

Space Segment

The space segment of the International Cospas-Sarsat Programme consists of satellite constellations in low-Earth orbit (LEOSAR), geostationary orbit (GEOSAR), and medium-Earth orbit (MEOSAR) that detect and relay 406 MHz distress signals from beacons to ground stations. As of July 2025, the system includes approximately 3 active LEOSAR satellites with 2 under test, 13 active GEOSAR satellites with 2 under test, and around 56 active MEOSAR satellites across providers, including 27 from Galileo, 21 from GPS, 2 from GLONASS (with 2 under test), and 6 from BeiDou. These satellites host specialized search and rescue (SAR) payloads integrated into existing meteorological and global navigation satellite systems (GNSS) operated by international partners such as NOAA (United States), EUMETSAT (Europe), Roscosmos (Russia via GLONASS and legacy COSMOS contributions), the European Union (Galileo), and the U.S. Space Force (GPS), with additional GEOSAR support from India (INSAT/GSAT) and others. Detection occurs through ultra-high frequency (UHF) receivers on the satellites that capture short bursts of 406 MHz signals transmitted by distress beacons, which include identification codes and, in modern beacons, GPS-encoded location data. In the LEOSAR component, satellites equipped with SAR processors perform onboard Doppler shift analysis of multiple signal bursts received during a single pass to estimate the beacon's location, achieving an accuracy of better than 5 km in over 95% of cases. GEOSAR satellites, lacking Doppler capability due to their fixed position relative to , relay signals in real-time but rely on beacon-encoded positions for location, while MEOSAR satellites use advanced digital transponders for time-difference-of-arrival (TDOA) and frequency-difference-of-arrival (FDOA) processing across multiple GNSS satellites, enabling near-real-time detection with sub-kilometer accuracy when combined with beacon GNSS data. Coverage is achieved through complementary orbital principles tailored to each constellation. LEOSAR satellites, orbiting at approximately 850 km in near-polar paths with a 99° inclination, provide global coverage during periodic passes every 102 minutes, ensuring detection even in polar regions but with delays of up to several hours between passes. GEOSAR satellites, positioned at 36,000 km in equatorial geostationary orbits, offer instantaneous, continuous coverage over about 40% of Earth's surface up to 70° , ideal for equatorial and mid-latitude regions with footprints spanning thousands of kilometers. MEOSAR, leveraging GNSS constellations at 19,000–24,000 km altitudes, delivers hybrid near-real-time global coverage with at least four satellites visible per location, minimizing latency to 2–3 minutes in most cases and supporting worldwide redundancy. The system's maintenance relies on hosted payloads—compact SAR repeaters and processors integrated into primary mission satellites—to minimize costs and leverage existing launch and operational infrastructure, with redundancy ensured through diverse international providers and overlapping coverage from multiple constellations. Ongoing transitions to fully digital payloads, particularly in MEOSAR via second-generation GNSS satellites like Galileo, enhance efficiency, reduce false alarms, and support advanced features such as return link service for beacon confirmation, with full operational capability for MEOSAR expected in 2025 following initial rollout in 2023.

Ground Segment

The ground segment of the International Cospas-Sarsat Programme forms the terrestrial essential for detecting, , and disseminating distress alerts relayed from the space segment to (SAR) authorities globally. It enables the rapid transformation of satellite-captured signals into actionable intelligence for operations, ensuring coverage across , maritime, and aeronautical domains. This segment comprises three primary components: Local User Terminals (LUTs), Mission Control Centres (MCCs), and Rescue Coordination Centres (RCCs). LUTs serve as the initial reception points, equipped with specialized antennas and receivers to capture downlinked signals from orbiting satellites in the 406 MHz band. These terminals demodulate the raw signals, extract embedded data such as identification codes and encoded messages, and typically compute the distress using Doppler shift measurements derived from the satellite's pass. Once processed, LUTs forward the alert data to affiliated MCCs for further validation. MCCs authenticate the alerts by cross-referencing beacon details against the International Beacon Registration Database (IBRD), which stores registration information including owner contacts and vessel/ particulars to minimize false alarms. MCCs also perform quality checks, refine location estimates if required, and determine the responsible SAR region before routing the validated alert to the nearest RCC. RCCs, operated by national or regional SAR authorities, receive these alerts and coordinate response efforts, mobilizing resources such as , vessels, or ground teams. The global network supporting this flow includes over 100 LUTs distributed worldwide to ensure redundant coverage, with 33 MCCs handling validation and distribution as of September 2025. Specialized MEOLUTs for (MEO) processing number 36 operational units as of May 2025, enabling near-real-time location tracking for the MEOSAR architecture. This infrastructure maintains a common signaling format for alert messages, standardized under Cospas-Sarsat specifications to facilitate among diverse national systems. Integration with existing SAR frameworks occurs via secure data links, allowing alerts to interface directly with RCC operations in over 40 participating countries.

Operational Architectures

LEOSAR System

The LEOSAR (Low Earth Orbit Search and Rescue) system forms the foundational architecture of the International Cospas-Sarsat Programme, utilizing polar-orbiting satellites to detect and locate distress signals from 406 MHz beacons. These satellites, operating at altitudes of approximately 850 km, include platforms such as Metop-B, Metop-C, and Meteor-M N2-2, provided by contributing space agencies including the U.S. (NOAA), the European Organisation for the Exploitation of Meteorological Satellites (), and . In 2025, the three NOAA satellites (NOAA-15, NOAA-18, and NOAA-19) were decommissioned, reducing the constellation to European and Russian platforms. The enables multiple daily passes over any point on , achieving global coverage through near-polar orbits that complete about 14 revolutions per day, with each satellite covering roughly 6% of the 's surface at a time. In operation, the LEOSAR system relies on Doppler shift measurements to determine beacon locations, requiring signals from at least three beacon bursts captured during two separate satellite passes for effective . This process, performed by ground-based Local User Terminals (LEOLUTs), typically yields a distress location within 1-2 hours, though delays can extend to 3 hours depending on orbital geometry and availability. The system's polar orbits make it particularly effective for high-latitude regions, including polar areas beyond 70 degrees where geostationary systems offer limited coverage, ensuring reliable detection in remote maritime, aeronautical, and terrestrial environments. LEOSAR provides high location accuracy of approximately 5 km through Doppler processing, serving as the programme's backbone since its operational in and enabling the first satellite-aided rescues. However, its limitations include delayed alerting due to non-continuous coverage and the need for multiple passes, which can hinder rapid response in time-sensitive scenarios. As of November 2025, the system remains operational with three active satellites (Metop-B, Metop-C, and Meteor-M N2-2), all exceeding their original design lives of 2-5 years, but it is gradually phasing down in favor of more advanced capabilities.

GEOSAR System

The GEOSAR (Geostationary Earth Orbit Search and Rescue) system forms a critical component of the Cospas-Sarsat Programme, utilizing satellites in at an altitude of approximately 36,000 km above the to provide continuous monitoring for distress signals. These , such as the U.S. GOES series, Europe's Meteosat Second Generation (MSG), and Russia's Electro-L, remain fixed relative to the 's surface, enabling persistent line-of-sight coverage over vast equatorial and mid-latitude regions, encompassing about 70% of the planet's surface between 70°N and 70°S latitudes. This design ensures that a single can oversee nearly one-third of the 's visible disk, with multiple units spaced longitudinally to achieve overlapping non-polar coverage without the need for orbital passes. In operation, GEOSAR satellites detect 406 MHz signals from distress s using onboard transponders that relay the data directly to ground stations known as GEOLUTs (Geostationary Local User Terminals), bypassing Doppler processing due to the absence of relative motion between the satellite and the beacon. Location determination relies on Global Navigation Satellite System (GNSS) data encoded in the beacon's transmission, achieving positional accuracy typically under 1 km—comparable to the size of a football field—provided the beacon is equipped with a compatible receiver. This enables near-instantaneous alerting, with distress signals forwarded to Mission Control Centers (MCCs) for rapid dissemination to rescue coordination centers, often providing alerts up to 46 minutes ahead of low Earth orbit (LEO) satellite detections. The system's primary advantages include its capacity for immediate detection and alerting in mid-latitude areas, facilitating swift response times for maritime, , and land-based emergencies where continuous coverage is essential. However, limitations arise from the lack of polar coverage beyond 70° and potential signal vulnerabilities, such as reduced detection if the beacon's antenna is not optimally oriented toward the equatorial sky for line-of-sight transmission to the geostationary satellites. As of 2025, the GEOSAR constellation includes 12 operational satellites contributing to the Cospas-Sarsat space segment, with the 406 MHz GEOSAR capability formally integrated into the programme in 1999 following successful demonstrations. This architecture complements the periodic passes of LEO satellites by offering reliable, real-time detection in equatorial and temperate zones.

MEOSAR System

The MEOSAR (Medium Earth Orbit Search and Rescue) system represents the latest evolution in the Cospas-Sarsat Programme's satellite architecture, utilizing transponders hosted on global navigation satellite systems (GNSS) such as GPS, Galileo, , and . These satellites operate in at altitudes of approximately 20,000 km, with orbital periods of about 12 hours that enable multiple satellites to be visible from any point on simultaneously, facilitating overlapping coverage footprints each spanning roughly one-third of the planet's surface. In operation, the MEOSAR system detects distress signals from 406 MHz beacons and determines their location through multi-satellite measurements, including frequency difference of arrival (FDOA) and time difference of arrival (TDOA) techniques applied to the beacon's signal bursts relayed via the satellite transponders to ground stations. This GNSS-integrated approach allows for rapid positioning, often achieving accuracy within 5 km for 95% of alerts after initial bursts, enhanced further by burst timing synchronization for precise time-of-arrival calculations. The system also incorporates a return link service (RLS), enabling satellites to transmit confirmation messages back to compatible beacons, providing for alert verification. Global alerting occurs in under one minute in most cases, delivering near-real-time data to coordination centers worldwide. Key advantages of MEOSAR include comprehensive global coverage, encompassing polar regions where earlier architectures like LEOSAR and GEOSAR exhibit gaps, along with high redundancy from approximately 47 operational satellites as of 2025, ensuring continuous visibility and reduced latency compared to prior systems. Limitations primarily involve dependence on host GNSS constellations for payload availability, though this is mitigated by the large number of planned transponders exceeding 75 in full deployment. The system achieved initial operational capability (IOC) in April 2023 and is expected to reach full operational capability (FOC) by the end of 2025, marking a significant enhancement in distress response reliability. Implementation features 36 medium Earth orbit local user terminals (MEOLUTs) operational by May 2025, distributed globally to process relayed signals and compute locations in real time, supporting burst timing protocols that align transmissions with passes for optimized detection and positioning accuracy. These ground stations collectively track multiple satellites, enabling seamless integration with the broader Cospas-Sarsat network for enhanced efficiency.

Performance and Impact

Rescue Statistics and Effectiveness

The International Cospas-Sarsat Programme has demonstrated significant impact in (SAR) operations worldwide. Since its inception in 1982, the system has contributed to 19,883 SAR events, resulting in the rescue of over 63,000 lives as of September 2025. In the United States alone, the programme supported the rescue of approximately 10,871 individuals as of January 2025. Recent annual performance highlights the programme's ongoing effectiveness. In 2023, Cospas-Sarsat alert data assisted in 1,076 distress incidents globally, leading to the rescue of 3,109 persons, compared to 1,144 incidents and 3,223 rescues in 2022. In the U.S., the system facilitated 411 rescues across 159 incidents in 2024, with maritime emergencies accounting for the majority (318 rescues at sea). As of November 2025, the U.S. has recorded 239 rescues in the current year, including 142 at sea, 42 from aviation, and 55 on land.
YearGlobal IncidentsGlobal RescuesU.S. IncidentsU.S. Rescues
20221,1443,223--
20231,0763,109--
2024--159411
2025---239 (as of Nov 2025)
A breakdown of 2023 SAR events by sector reveals the diverse applications: aviation accounted for 20%, land-based incidents for 44%, and maritime for 36%. The programme's operational architectures, including the MEOSAR system, have enabled average response time reductions from hours to minutes by providing near-real-time global coverage and precise location data. The system's effectiveness is underscored by an alert detection rate exceeding 95%, ensuring reliable distress signal processing. This high reliability, combined with efficient SAR coordination, has yielded substantial cost-benefits, with estimates indicating billions of dollars saved globally in operational costs over the programme's lifetime through faster interventions and minimized resource deployment.

Notable Rescue Operations

The International Cospas-Sarsat Programme demonstrated its effectiveness early in its operational history with the first successful in September 1982, when a small crashed near , , ; the system's satellites detected the 121.5 MHz from the survivors' locator transmitter, enabling rescuers to locate and save all three people on board within hours. Another early milestone came in August 1985, when plane crash survivor Mike Ryan activated his beacon; COSPAS-SARSAT satellites relayed the signal to ground stations, facilitating his by U.S. authorities just three years after the system's launch. In the United States, the programme has supported numerous terrestrial rescues. A key lesson from these operations is the critical importance of beacon registration with national databases like NOAA's, which provides rescuers with owner details, medical information, and contacts; unregistered beacons delay responses, whereas registered ones allow over 80% of alerts to be quickly traced to owners, reducing false alarms and speeding effective interventions.

Recent and Future Developments

Current Enhancements and Transitions

In 2025, the International Cospas-Sarsat Programme is expected to achieve full operational capability (FOC) for its Medium Earth Orbit Search and Rescue (MEOSAR) system, marking a significant milestone in global distress signal detection and location accuracy. This transition builds on the initial operational capability established in April 2023, enhancing near-real-time alerting through transponders on GNSS constellations. As part of this rollout, 47 Medium Earth Orbit Local User Terminals (MEOLUTs) are planned for commissioning by 2026, including 11 additional units to expand global coverage and processing capacity. The deployment of Emergency Locator Transmitter with Distress Tracking (ELT(DT)) capabilities has advanced rapidly, with first-generation beacon (FGB) ELT(DT) transponders reaching operational status in January 2023, enabling autonomous aircraft distress tracking and location transmission via the 406 MHz band. Second-generation beacon (SGB) ELT(DT) support followed in January 2024, incorporating improved modulation for faster and more reliable data processing within the Cospas-Sarsat network. These deployable transponders facilitate real-time position updates, reducing search times in aviation incidents. Global initiatives in 2025 have further strengthened the programme's outreach and coordination. The inaugural Global Day was observed on , commemorating the system's first successful rescue in 1982 and highlighting its role in saving over 63,000 lives worldwide. Concurrently, the U.S. assumed management of the U.S. SARSAT operations effective October 1, 2025, transitioning responsibilities from NOAA to enhance integration with national SAR efforts. Infrastructure enhancements include the implementation of a (QMS) for MEOSAR operations, aimed at standardizing processes, improving reliability, and ensuring compliance across participant states. This system supports ongoing upgrades to ground segment equipment, contributing to the programme's sustained performance in distress alerting.

Planned Technological Advancements

The International Cospas-Sarsat Programme is advancing (TWC) capabilities to enable distress s to receive feedback from (SAR) authorities, enhancing response coordination. This feature, designed for second-generation beacons (SGBs), is currently in the design and development phase, with dedicated working groups convened in February 2024 and March 2025 to define requirements and protocols. A correspondence group led by the is coordinating further progress, focusing on bi-directional exchange of predefined codes to confirm signal receipt, improve for responders, provide guidance to beacon users in distress, and minimize false alarms through interactive verification. Efforts to enhance beacon technology include the integration of second-generation models featuring modulation, which became operational in January 2024 and offer improved signal reliability and reduced interference for hybrid alerting scenarios. These advancements build on existing battery technologies, with some s now supporting extended operational lifespans of up to 10 years under proper maintenance, to ensure longer deployment in remote environments without compromising performance. System expansions emphasize the Medium Earth Orbit (MEO) component, with 36 Medium Earth Orbit Local User Terminals (MEOLUTs) commissioned by May 2025, enabling the tracking of up to 400 satellites for near-global, near-real-time coverage. An additional 11 MEOLUTs are planned for deployment by 2026 to achieve full operational capability across the MEOSAR architecture. Broader integration of the International Beacon Registration Database (IBRD) with global registries continues, following its 2022 update to a unified interface at www.406registration.com, which has facilitated over 112,500 registrations by May 2025 and supports seamless data sharing for faster alert validation. Addressing key challenges, the programme is prioritizing cybersecurity enhancements amid identified vulnerabilities in beacon transmission and ground systems, including potential spoofing and jamming exploits, with ongoing research advocating for robust and protocols to safeguard alert integrity. Sustainable funding remains a focus, as participants self-finance their contributions without fund exchanges, while initiatives aim to extend benefits to non-member states through cooperative agreements and shared infrastructure. With approximately 3.17 million in service by the end of 2023 and steady growth driven by mandatory adoption in and maritime sectors, the is positioned for expanded reach into the next decade.

References

  1. https://www.sarsat.noaa.gov/cospas-sarsat-system-overview/
  2. https://www.eoportal.org/satellite-missions/cospas-sarsat
  3. https://storymaps.arcgis.com/stories/a0de188ba1bc412eae533b8f2a8799bf
  4. https://www.marketresearchfuture.com/reports/emergency-beacon-transmitter-market/companies
  5. https://www.sarsat.noaa.gov/mission_statement/
  6. https://www.navcen.uscg.gov/sites/default/files/pdf/imo/comsar/COMSAR_14_17.pdf
  7. https://www.sarsat.noaa.gov/faqs/
  8. https://www.sarsat.noaa.gov/wp-content/uploads/System-Overview-for-UN-USA-no-notes.pdf
  9. https://www.cospas-sarsat.int/en/about-us/participants
  10. https://www.sarsat.noaa.gov/wp-content/uploads/IBRD-for-UN-USA.pdf
  11. https://publications.gc.ca/collections/collection_2021/sp-ps/PS9-17-2021-eng.pdf
  12. https://www.publicsafety.gc.ca/cnt/rsrcs/fndng-prgrms/cospas-sarsat/trms-cndtns-en.aspx
  13. https://www.icao.int/sites/default/files/secretariat/legal/CurrentListofParties/Cospas_EN.pdf
  14. https://laws-lois.justice.gc.ca/eng/regulations/SOR-2005-112/FullText.html
  15. https://www.publicsafety.gc.ca/cnt/rsrcs/fndng-prgrms/cospas-sarsat/index-en.aspx
  16. https://www.mwrf.com/markets/article/21843417/cold-war-cooperation-birthed-search-and-rescue-system
  17. https://www.sarsat.noaa.gov/history-of-the-sarsat-program/
  18. https://www.princeton.edu/~ota/disk2/1985/8533/853311.PDF
  19. https://ntrs.nasa.gov/api/citations/20130009017/downloads/20130009017.pdf
  20. https://www.ndss-symposium.org/wp-content/uploads/spacesec2024-70-paper.pdf
  21. https://thecanadianencyclopedia.ca/en/article/international-search-and-rescue-satellite-system
  22. https://www.cospas-sarsat.int/en/
  23. https://repository.library.noaa.gov/view/noaa/13374/noaa_13374_DS1.pdf
  24. https://www.i-law.com/ilaw/doc/view.htm?id=131660
  25. https://www.itu.int/dms_pub/itu-r/oth/0C/0A/R0C0A00000F0066PDFE.pdf
  26. https://www.federalregister.gov/documents/2001/07/02/01-16575/termination-of-1215243-mhz-satellite-alerting
  27. https://www.sarsat.noaa.gov/wp-content/uploads/2021/08/2020_BMW_Cospas-Sarsat-Updates-and-ELT-DT-Related-Developments_St-Pierre.pdf
  28. https://spacedevice.ru/wp-content/uploads/2020/04/2_p14_0317en.pdf
  29. http://www.equipped.org/406_beacon_test_background.htm
  30. https://www.unoosa.org/pdf/reports/ac105/AC105_827E.pdf
  31. https://skybrary.aero/articles/cospas-sarsat
  32. https://wst.ca/cospas-sarsat-system-declares-full-operational-capability-for-eltdts/
  33. https://www.sarsat.noaa.gov/statistics/
  34. https://www.nesdis.noaa.gov/news/global-search-and-rescue-day-will-recognize-international-effort-save-people-distress
  35. https://www.sarsat.noaa.gov/emergency-406-beacons/
  36. https://www.dco.uscg.mil/Our-Organization/Assistant-Commandant-for-Response-Policy-CG-5R/Office-of-Incident-Management-Preparedness-CG-5RI/US-Coast-Guard-Office-of-Search-and-Rescue-CG-SAR/CG-SAR-2/Emergency-Beacons/
  37. https://beacons.amsa.gov.au/about/beacon-types.asp
  38. https://www.icao.int/sites/default/files/APAC/Meetings/2025/2025%2520APSARWG10/3-Working%2520Papers/WP14-Status-of-the-Cospas-Sarsat-Programme.pdf
  39. https://www.beaconregistration.noaa.gov/
  40. https://cnes.fr/en/projects/cospas-sarsat
  41. https://www.sarsat.noaa.gov/wp-content/uploads/2024-BMW_Results-of-the-2024-B-Mans-Survey.pdf
  42. https://www.sarsat.noaa.gov/wp-content/uploads/2021/08/Beacon-Type-Approval-Process.pdf
  43. https://www.sarsat.noaa.gov/emergency_beacon-testing/
  44. https://navisp.esa.int/uploads/files/documents/AMTBS_Navisp_presentation%20-%20EL1-070.pdf
  45. https://www.sarsat.noaa.gov/search-and-rescue-satellites/
  46. https://moodle.406.org/mod/page/view.php?id=748
  47. https://www.gsc-europa.eu/sites/default/files/sites/all/files/Galileo-SAR-SDD.pdf
  48. https://www.copernicus.eu/en/news/news/observer-how-eu-space-programme-supports-search-and-rescue-galileo-sar-meet-2025
  49. https://www.sarsat.noaa.gov/ground-stations/
  50. https://hmcoastguard.blogspot.com/2025/09/celebrating-first-cospas-sarsat-global.html
  51. https://www.sarsat.noaa.gov/wp-content/uploads/2022-BMW_Cospas-Sarsat_Final-V4_St-Pierre.pdf
  52. https://www.nesdis.noaa.gov/news/legacy-orbit-noaa-decommissions-the-poes-satellite-constellation
  53. https://www.sarsat.noaa.gov/wp-content/uploads/2024-SAR-WKSHOP_SARSAT-Overview.pdf
  54. https://www.sarsat.noaa.gov/wp-content/uploads/2021/08/SAR_2017_SARSAT-Overview_Feb28.pdf
  55. https://www.egmdss.com/gmdss-courses/mod/page/view.php?id=74&lang=hu
  56. http://nauticalfree.free.fr/nautical/Doc_INT_SARSAT_Introduction2014.pdf
  57. https://www.icao.int/sites/default/files/APAC/Meetings/2025/2025%20APSARWG10/5-Presentations/SP01-Status-of-the-Cospas-Sarsat-Programme-WP14.pdf
  58. https://www.yahoo.com/news/articles/global-search-rescue-system-gets-225808929.html
  59. https://www.nesdis.noaa.gov/news/noaa-satellites-were-pivotal-the-rescue-of-411-lives-2024
  60. https://www.noaa.gov/news-release/noaa-satellites-were-pivotal-in-rescue-of-411-lives-in-2024
  61. https://www.mycg.uscg.mil/News/Article/4318183/coast-guard-takes-charge-of-the-search-and-rescue-satellite-aided-tracking-sars/
  62. https://www.sarsat.noaa.gov/sarsat-us-rescues/
  63. https://www.icao.int/sites/default/files/APAC/Meetings/2025/2025%20APSARWG10/3-Working%20Papers/WP14-Status-of-the-Cospas-Sarsat-Programme.pdf
  64. https://www.gpsworld.com/innovation-the-distress-alerting-satellite-system-10883/
  65. https://www.asc-csa.gc.ca/eng/publications/2018-socio-economic-benefits-spce-utilization.asp
  66. https://www.sarsat.noaa.gov/video/sarsat-a-life-saved-the-rescue-of-mike-ryan/
  67. https://www.sarsat.noaa.gov/wp-content/uploads/2023-BMW_RGDB.pdf
  68. https://www.sarsat.noaa.gov/wp-content/uploads/2024_SAR_WKSHOP_ELTDT-LADR.pdf
  69. https://www.euspa.europa.eu/newsroom-events/news/406mhz-emergency-distress-beacons-extended-galileo-return-link-features
  70. https://star.spaceops.org/2025/user_manudownload.php?doc=215__lr14idfe.pdf
  71. https://www.eurosul.com/en/products/radio-baliza-epirb-406-g8-ais-auto-smartfind-com-bateria-de-10-anos/
  72. https://www.406registration.com/
  73. https://arxiv.org/pdf/2302.08361
Add your contribution
Related Hubs
User Avatar
No comments yet.