The SOLAS Chapter V (Revision 2002) has required that Automatic Identification Systems (AISs) is to be fitted onboard international seagoing ships of 300 gross tonnages (GT) and upwards, domestic cargo ships of at least 500 GT as well as passenger ships irrespective of sizes. Class A transponder fulfills the IMO AIS carriage requirement for these ships and provides the functionalities such as the full provision for all three regulated types of AIS information (Static, Dynamic, and Voyage-related).
The AIS data is autonomously sent on different update rates. The static and voyage-related data are transmitted every 6 minutes or on request. The transmission rate of dynamic data over class A transponder depends on the ship's speed and its maneuver status. The transmission frequency ranges from every 2 seconds to 3 minutes. With a transmission power of up to 12.5 W, class A transponder can transmit and receive data more frequently as well as over longer distances than Class B devices.