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Radiocommunications for keeping ships and people safe at sea

​​​​​​ ​Maritime Backgrounder


Challenges and solutions


When ships are at sea or aircraft cross the oceans, they are out of reach of terrestrial networks. The Titanic is one of the best-known examples of what can happen when ships in hazardous situations are unable to contact other ships or appeal effectively for help. Over 1,500 people lost their lives when radio calls for help to ships in the vicinity went unanswered. Multiple smaller scale incidents happen every day across the globe.

Serious accidents may also have a huge economic impact, as demonstrated by the six-day obstruction of the Suez Canal by the Ever-Given container ship in March 2021. This event led to the delay in the delivery of approximately US$9.6 billion of goods per day, according to Lloyd's List.

Shipping lanes are becoming ever more crowded, as global exports increase. It is important for mariners to have reliable communications and accurately determine the position of their vessel and other nearby vessels to maintain the safety of navigation of ships. Precise positioning and access to emergency services prevent accidents and save lives.

ITU’s contribution


The development of global maritime radiocommunications and radionavigation has been an area of work for ITU for more than 110 years. Invented in 1896, wireless telegraphy, as the first type of radiocommunications, was brought into use over a very short period, firstly for maritime safety.

In radionavigation, ITU has contributed to key developments in terrestrial radio navigation systems, including maritime radio beacons and terrestrial positioning systems in the medium frequency (MF) bands.

The ITU Radiocommunication Sector (ITU-R) manages radio-frequency spectrum for all radiocommunication services worldwide, including maritime radiocommunication and radionavigation. The protection of maritime radiocommunication and navigation frequencies is ensured through special provisions in the Radio Regulations (RR). The RR allocates the radio-frequency resource and determines the regulations based on compatibility studies between maritime and other radiocommunication services. The worldwide usage of maritime equipment and its global interoperability are supported by ITU recommendations, serving as technical standards, and reports.

About 25% of the articles in the Radio Regulations govern the use of maritime radio, contributing to safety at sea. For example, by international agreement, Cospas-Sarsat distress transmissions from emergency radio beacons take place on a globally recognized frequency that is protected from any interference. In addition, ITU's special radio monitoring programme of this band is aimed at ensuring the availability of this important frequency for use by Emergency Position Indicating Radio Beacons (EPIRB) to transmit distress alerts.

Global Automatic Identification System (AIS)

ITU and the International Maritime Organization (IMO) introduced the global automatic identification system (AIS). It improves the safety of navigation and monitoring of shipping worldwide. AIS radio equipment is mandatory onboard all commercial ships on international voyages and contributes daily to the safety and monitoring of ships worldwide. ITU-R developed the basic technical document for the AIS system worldwide

Global Maritime Distress and Safety System (GMDSS)

The Global Maritime Distress and Safety System (GMDSS) is an internationally agreed set of safety procedures, frequencies, types of equipment, and communication protocols, developed through cooperation between IMO and ITU since the mid-1970s. It operates using terrestrial and satellite radio technologies onboard ships and onshore, making it easier to rescue distressed persons, ships, boats, and aircraft. The system alerts shore-based rescue and communication personnel via the coast radio station or Rescue Coordination Centres (RCC) in cases of distress and emergency and makes calls to vessels in the vicinity to provide assistance.

There is a continuing enhancement of the GMDSS on a global basis, including in the ITU. The modernization of GMDSS and implementation of e-navigation are on the agenda of ITU's 2023 World Radiocommunication Conference (WRC-23), and ITU-R Study Groups are already carrying out the preparatory work. to examine the introduction of advanced maritime terrestrial systems and a new satellite service provider to the GMDSS to ensure better maritime safety communications. 

Maritime Service Publications and the MARS database

ITU helps improve ships' operational safety through several key publications and the database. The ITU Maritime mobile Access and Retrieval System (MARS) is an online maritime database system used by ships to access to detailed information about onboard radio communication systems, including emergency contacts, 24-hour emergency phone numbers and onboard satellite terminal numbers, radio call signs and access codes, including the Maritime Mobile Service Identity (MMSI), call signs and telex identities. 

This database and website lists registered ships, coast and other stations, including Search and Rescue (SAR) Aircraft or Automatic Identification System AIS Aid to Navigation (AtoN) for shipping and shore authorities worldwide. For coastal stations and Rescue Coordination Centres, it is easy to find information such as watch frequencies, services offered such as medical advice and hours of watch.

International technical standards

ITU issues international technical standards, developed by experts from administrations, operators, the industry and other organizations dealing with radiocommunication matters from all over the world. For example, several key standards relate to the digital switchover of maritime communication (Rec. ITU-R M.2010M.2058,  M.2092 and M.1371). 

Learn more about ITU's role here.​ 

Last update: Sept 2021