The long-range identification and tracking (LRIT) of ships was established as an international system on 19 May 2006 by the International Maritime Organization (IMO) as resolution MSC.202 (81). This resolution amends Chapter V of the International Convention for the Safety of Life at Sea (SOLAS), regulation 19-1 and binds all governments which have contracted to the IMO.

The LRIT regulation will apply to the following ship types engaged on international voyages:

• All passenger ships including high-speed craft,
• Cargo ships, including high-speed craft of 300 gross tonnage and above, and
• Mobile offshore drilling units.

These ships must report their position to their flag administration at least four times a day. Most vessels set their existing satellite communications systems to automatically make these reports. Other contracting governments may request information about vessels in which they have a legitimate interest under the regulation.

The LRIT system consists of the already installed (generally) shipborne satellite communications equipment, communications service providers (CSPs), application service providers (ASPs), LRIT data centres, the LRIT data distribution plan and the International LRIT data exchange. Certain aspects of the performance of the LRIT system are reviewed or audited by the LRIT coordinator acting on behalf of the IMO and its contracting governments.

Some confuse the functions of LRIT with that of AIS (Automatic Identification System), a collision avoidance system also mandated by the IMO, which operates in the VHF radio band, with a range only slightly greater than line-of-sight. While AIS was originally designed for short-range operation as a collision avoidance and navigational aid, it has now been shown to be possible to receive AIS signals by satellite in many, but not all, parts of the world. This is becoming known as S-AIS and is completely different from LRIT. The only similarity is that AIS is also collected from space for determining location of vessels, but requires no action from the vessels themselves except they must have their AIS system turned on. LRIT requires the active, willing participation of the vessel involved, which is, in and of itself, a very useful indication as to whether the vessel in question is a lawful actor. Thus the information collected from the two systems, S-AIS and LRIT, are mutually complementary, and S-AIS clearly does not make LRIT superfluous in any manner. Indeed, because of co-channel interference near densely populated or congested sea areas satellites are having a difficult time in detecting AIS from space in those areas. Fixes are under development by several organizations, but how effective they will be remains to be seen.