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04 Feb, 2025

According to the IMO International Convention for the Safety of Life at Sea (SOLAS), all ships of 300 gross tons and over navigating internationally, cargo ships of 500 gross tons and over not navigating internationally, and all passenger ships, regardless of size, must be equipped with an AIS system. The AIS system is very important for safe navigation. For this reason, deactivation of this system is only permitted in exceptional circumstances. This information note discusses the possible consequences of disabling the AIS system.

What is the AIS system?

AIS technology was developed by IMO technical committees to prevent collisions between ships at sea. When a ship is at sea, information about its movement and the identity of other ships in the vicinity is critical for navigators to make decisions to avoid collisions with other ships and hazards (shoals or rocks). AIS technology identifies each ship individually, along with its specific position and movements, to create a virtual picture and chart in real time. While AIS is only required to display very basic textual information, the resulting data can be integrated with a graphic electronic chart or a radar display, providing consolidated navigational information on a single screen.

How does AIS work?

When tracking and monitoring ships, AIS automatically sends and receives information to and from suitably equipped depot stations, other ships and aircraft. AIS works by transmitting VHF radio waves that carry this data. Due to the curvature of the Earth, the horizontal range of VHF radio waves is limited to about 24 nautical miles or about 44 kilometers from ship to ship. In more remote or dense areas, a ground station can be used to amplify signals in the vicinity. Vertical signals can be received by lower orbiting satellites, which in turn relay the data to ground stations, making satellite coverage available in almost all areas.

Regulations related to the AIS system

The transmission of AIS signals is regulated by the IMO International Convention for the Safety of Life at Sea (SOLAS). In 2000, as part of the revised Chapter V, IMO required all ships to carry automatic identification systems (AIS) that can automatically provide information about a ship to other ships and coastal authorities.

This regulation requires all ships of 300 gross tons or more on international voyages, cargo ships of 500 gross tons or more not on international voyages, and all passenger ships, regardless of size, to have AIS.

Disabling the AIS system

The AIS system must be operational at all times when ships are underway or at anchor. If the master believes that the continuous operation of the AIS may jeopardize the safety or security of his ships or in the event of imminent safety incidents, he may shut down the system. The master must notify the competent authority of this shutdown action and the reason for it. Such actions should always be recorded in the ship’s log with the reason.

Where there is a deliberate shutdown of the system to stop transmitting the ship’s position and other details about the ship, this is called a ‘blackout’.

Reasons for deactivation of the AIS system

The deactivation of the AIS system, as explained in the previous section, is possible only in exceptional circumstances. Detailed regulations regarding this matter are provided under the revised guidelines on the operational use of AIS on board vessels, as per IMO Resolution A. 1106 (29). These guidelines grant the captain the authority to deactivate the AIS in specific situations involving safety and security. The legitimate reasons for deactivating the AIS system under these guidelines are as follows:

  • The system can be turned off to conceal the vessel’s location, position, or identity in areas where piracy is active. This enhances the safety of those on board and reduces the risk of pirates boarding and hijacking the vessel.
  • To avoid being detained by sanctioning authorities;
  • If a vessel is involved in secret operations, such as the laying of important classified data cables or military operations, the system may be deactivated.

However, AIS can also be deactivated to conceal a vessel’s illegal activities. Examples of such illegal activities include:

  • Trade with sanctioned countries: Vessels may deactivate their AIS systems to conceal their visits to ports of sanctioned countries.
  • Illegal cargoes such as drugs, weapons, and human trafficking are typically not loaded or unloaded at well-known ports. Intermediate stops for loading and unloading these illegal cargoes and people are often concealed by deactivating the AIS system.
  • The system can also be deactivated to conceal ship-to-ship transfers involving vessels or cargoes connected to sanctioned countries, such as in the case of oil trade.
  • AIS may be deactivated for illegal fishing activities. This could especially apply in cases where illegal fishing occurs in another country’s territorial waters.

Consequences for Insurance Policy and Charter Party

Unless necessary to protect the safety or security of a ship, blacking out 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.

Disabling the AIS system may cause problems with the ship’s insurance coverage. For example, disabling the AIS system may invalidate the insurance coverage. Furthermore, 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, failure to comply with SOLAS regulations may prejudice the insurance cover. In addition, where a shipowner uses his/her vessel to trade in violation of sanctions or conceals his/her position by manipulating or hiding the transmission of AIS data, the insurer may refuse to provide insurance cover on the grounds of reckless or illegal trading.

In terms of contracts by sea, it is recommended to include a clause in the charter party regulating the non-deactivation of AIS as a preventive measure to eliminate the negative situations described above and to protect all rights. Among the type clauses in this regard, the BIMCO AIS deactivation clause 2021 can be mentioned first. Such clauses generally give the charterers the right to terminate the contract in case 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.

Esenyel Partners | AIS Usage
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