What is the Automatic Identification System (AIS)?

Although it is now used for security and commercial tracking of ships, the Automatic identification system (AIS) was initially developed and mandated as a complement to radar for collision avoidance. There is now an additional intention to expand the concept and make it a key element of e-navigation.

Before the advent of AIS, identifying a ship — or more importantly its intended movements — from a blip on a radar screen or by sight when its name could not be seen was an impossibility that had implications for the safety of both vessels. AIS was initially developed purely as a response to that problem and to aid shore-based VTS operators as well as navigators on ships to properly identify radar targets.

In practical terms, AIS consists of a transponder system in which ships continually transmit their ID, position, course, speed and other data over VHF. The data transmitted is derived from ships equipment as regards position, course and speed, from initial input for the ID which comprises ship’s name and call sign and from direct manual input for other details such as port of destination and type of cargo.

Updated information is transmitted at regular intervals of very short duration. When received on the other ships, the data is decoded and displayed for the officer of the watch, who can view AIS reports from all other AIS-equipped ships within range in graphic and text format.

The AIS data may optionally be fed to the ship’s integrated navigation systems and radar plotting systems to provide AIS “tags” for radar targets. The AIS data can also be logged to the ship’s Voyage Data Recorder (VDR) for playback and future analysis.

By the late 1990s the concept had been developed to a point where it was considered by the IMO as a desirable aid to navigation and, despite attempts by proponents of rival systems was being marked down for mandatory carriage on ships. In 2000, IMO adopted a new requirement (as part of a revised new chapter V) for all ships to carry AIS capable of providing information about the ship to other ships and to coastal authorities automatically.

What does the regulation require?

The regulation requires AIS to be fitted aboard all ships of 300gt and upwards engaged on international voyages, cargo ships of 500gt and upwards not engaged on international voyages and all passenger ships irrespective of size. The requirement became effective for all ships by 31 December 2004.

In between the regulation being adopted and the coming into force and as a result of terrorist attacks on New York in September 2001, the role of AIS as a pure aid to navigation was ‘hijacked’ and instead it became a first but poorly considered attempt at imposing official surveillance on the world fleet. Later LRIT was to take on that role but once again even that system proved it is adequate for surveillance of ‘honest’ ships but easily by-passed by ships with nefarious intent.

The IMO regulation requires ships fitted with AIS to maintain AIS in operation at all times except where international agreements, rules or standards provide for the protection of navigational information. Because of its intended purpose as a safety tool, AIS is one of the systems required to feed data to the VDR.

AIS transceivers are categorised into one of two classes AIS A or AIS B. The former is the standard required by the SOLAS regulations whereas the class B equipment is intended for non-commercial and leisure vessels. The class B systems are less powerful and slightly limited in function but they do permit SOLAS vessels to identify radar targets that would otherwise remain unidentifiable.

The SOLAS regulation requires that AIS shall:

  • provide information – including the ship’s identity, type, position, course, speed, navigational status and other safety-related information automatically to appropriately equipped shore stations, other ships and aircraft;
  • receive automatically such information from similarly fitted ships; monitor and track ships; exchange data with shore-based facilities.

The regulation applies to ships built on or after 1 July 2002 and to ships engaged on international voyages constructed before 1 July 2002. All of the deadline dates connected to the roll-out of AIS are historic so a working AIS is now required on all vessels above 300gt.

Within a very short period of time after the introduction of AIS, a number of organisations and individuals were disseminating AIS data by way subscription and free to view services on the internet. This caused great concern to operators not just because it might be seen as compromising safety but also because commercial information could easily be accessed by competitors.

At its 79th session in December 2004, the IMO’s Maritime Safety Committee agreed that, in relation to the issue of freely available AIS-generated ship data on the world-wide web, the publication on the world-wide web or elsewhere of AIS data transmitted by ships could be detrimental to the safety and security of ships and port facilities and was undermining the efforts of the Organization and its Member States to enhance the safety of navigation and security in the international maritime transport sector.

The Committee condemned the regrettable publication on the worldwide web, or elsewhere, of AIS data transmitted by ships and urged Member Governments, subject to the provisions of their national laws, to discourage those who make available AIS data to others for publication on the world-wide web, or elsewhere from doing so. In addition, the Committee condemned those who irresponsibly publish AIS data transmitted by ships on the worldwide web, or elsewhere, particularly if they offer services to the shipping and port industries.

Despite the IMO’s condemnation, the number of web sites and services has continued to grow and it is possible for anyone with an internet connection to carry out surveillance on all ships that have their AIS switched on.

A more recent development in AIS monitoring is the growing number of satellite AIS services. Early monitoring of AIS data was done by shore stations connected to ports and VTS authorities that had a limited range of around 50 nautical miles. As a consequence, the monitoring activity was of little more consequence to commercial activity than was the case when all ship arrivals were reported in the shipping press.

This has been changed by the advent of the commercial services that have fitted AIS receivers to satellites meaning that ships can be monitored at any time if their AIS is operational. The satellite AIS (S-AIS) services are viewed as desirable by some and a major threat by others. Proponents include some government bodies which see them as useful tools for defence, security, SAR and environmental protection and also some ship owners and commodity traders that see them as sources of commercial information. There are ship operators that are prepared to provide their clients with position data but not all see this transparency as desirable.

With S-AIS availability those in the latter category will no longer have any control if shippers and receivers are prepared to subscribe to a service provider. Those less enamoured with the idea of continuous monitoring perhaps have a justifiable argument that such monitoring of data contravenes privacy laws and could be construed as commercial espionage.

They also point out that there are flaws in the idea that S-AIS is a good security tool as the AIS can be switched off at will and it is also possible to make use of a cloned system that would make a ship appear to be other than it was. Regardless of the rights and wrongs of S-AIS or any of the more basic tracking services, its existence is a fact and operators and others will eventually learn to live with it. Whether flag states will allow ships to switch off AIS when not in an area where a port state requires it to be operational is a matter for those flag states.