The Usage of Automatic Identification System (AIS)

In accordance with the International IMO Convention on Safety of Life at Sea (SOLAS), all ships of 300 gross tonnes and over engaged in international navigation together with cargo ships of 500 gross tonnes and over not engaged in international navigation and all passenger ships, regardless of their size, are required to be equipped with an AIS system. The AIS system is essential for ensuring safe navigation. That is why disabling this system is only permitted in exceptional situations. This information sheet addresses the possible consequences that may occur if the AIS system is deactivated.

What is the AIS system?

The AIS technology was developed by the IMO technical committees to prevent collisions between ships at sea. When at sea, information about a ship's movement and the identity of other ships in the vicinity are critical for navigators to make decisions to avoid collisions with other ships and hazardous circumstances (sandbanks or rocks). This is where the AIS technology comes to the fore, allowing to get a virtual picture by identifying each ship separately, together with its specific position and movements, and generates a table in real time. Although AIS is necessary to display very basic textual information only, the data acquired can be integrated with a graphic electronic chart or a radar display and provide consolidated navigational information on a single screen.


How does AIS work?

AIS sends and receives information automatically to and from depot stations with appropriate equipment, other ships and aircrafts while monitoring and tracking ships. AIS operates by transmitting VHF radio waves that carry this data. The horizontal range of VHF radio waves is limited to about 24 nautical miles or about 44 kilometres from ship to ship due to the curvature of the Earth. In more distant or dense areas, a ground station can be used to amplify signals in the vicinity. Vertical signals can be received by low earth orbit satellites, which in turn transmit the data to ground stations, making satellite coverage available for almost all areas.

Regulations related to AIS system

The transmission of AIS signals is regulated by the International IMO Convention on Safety of Life at Sea (SOLAS). As part of the revised Chapter V, IMO made it mandatory in 2000 for all ships to be equipped with automatic identification systems (AIS), which can automatically provide information about a ship to other ships and coastal authorities.

According to this regulation, all ships of 300 gross tonnes and above engaged in international navigation, cargo ships of 500 gross tonnes and above not engaged in international navigation and all passenger ships regardless of their size are required to have an AIS system.

Deactivation of the AIS system

The AIS system must be in working order at all times when ships are underway or at anchor. The Master may switch off the system when he/she believes that the continuous operation of the AIS may jeopardise the safety or security of his/her ships or when safety incidents are imminent. The master must notify the competent authority of this shutdown action and its reason. Such action must always be recorded in the ship's logbook together with its reason.

If the system is deliberately switched off in order to stop transmitting the ship's position and other ship-related details, this constitutes a so-called 'darkening'.

Reasons for deactivation of the AIS system

 Switching off the AIS system is possible in exceptional circumstances, as explained in the previous section, and the detailed regulation on this issue is made within the scope of the revised guidelines for the operational use of the AIS on-board of the IMO Resolution A. 1106 (29). These guidelines authorise the master to switch off the AIS in certain circumstances where safety and security are at stake.  Within the scope of these principles, valid reasons for the shutdown of the AIS system can be listed as follows:

  • The system can be switched off to conceal the location, position or identity of the vessel in regions where sea bandits are active. This increases the safety of persons on board and reduces the risks where bandits may embark and capture the vessel.

  • To avoid detention by sanctioning authorities;

  • It may be shut down if a ship is involved in operations related to secret projects, such as laying important secret data cables or military operations.

However, AIS can also be switched off to conceal a vessel's illegal activities. Examples of such illegal activities may be as follows:

  • Trading with sanctioned countries: Ships can deactivate their AIS systems to conceal their visits to the ports of sanctioned countries.

  • Illegal cargoes, containing drugs, weapons and human trafficking, are often not loaded and unloaded in quite obvious ports. Intermediate stoppages to load and unload these illegal cargoes and people are often concealed by deactivating AIS systems.

  • The system can also be switched off to conceal ship-to-ship transfers by vessels or cargoes linked to sanctioned countries, including for oil trade.

  • The AIS may also be deactivated for the purpose of illegal fishing. This may be particularly the case where illegal fishing is taking place in the territorial waters of another country.

Consequences in terms of Insurance Policy and Charter Party

Darkening a ship, unless it is necessary to protect the safety or security of the ship, constitutes a breach of the SOLAS Convention and violates the requirements of the ship's Flag State. Furthermore, as the AIS system is important for the navigation of the ship, disabling the AIS system increases the risk of collision, damage to other ships or floating objects, pollution and loss of life at sea.

Switching off the AIS system may cause problems for the ship's insurance coverage. For example, disabling the AIS system may invalidate the insurance coverage. Moreover, most insurance policies contain liability clause(s) stating that shipowners must act in accordance with the law and not act in a reckless manner. Therefore, non-compliance with SOLAS regulations may cause damage to the insurance coverage. In addition, an insurer may refuse to provide insurance cover on the grounds of imprudent or illegal trading where a shipowner uses his vessel to trade in breach of sanctions, concealing his position by manipulating or hiding the transmission of AIS data.

In terms of contracts by sea, it is recommended to include a clause in the charter party stipulating that the AIS should not be deactivated, as a preventive measure to eliminate the above-mentioned negative situations and to protect any and all rights. Among the type clauses in this regard, the BIMCO AIS switch-off clause 2021 may be mentioned first. Such type clauses generally give the charterers the right to terminate the contract in the event of deactivation, regardless of the circumstances in which the AIS can be legitimately deactivated.

You can always contact us if you have any questions on the subject.

Selçuk Esenyel

Managing Partner

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Deha Aydın

Consultant / Captain

Aydıncan Devrik

Legal Intern

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