A vessel’s personnel use AIS to ensure the safety of the ship, and maritime authorities use AIS to track ships and monitor where they are and where they are going.
AIS is a communications system based on radio frequency (RF), which is a form of wireless communications that uses the transmission and reception (sending and receiving) of electromagnetic waves. These waves work very much the same as do wireless transmissions from and to cellular telephones.
A ship’s AIS transponder (the device that sends and receives signals) uses a very high frequency (VHF) RF transmitter to broadcast important information to receiver devices on other ships or land-based systems. By sending and receiving regular communications about their identity and course, vessels can avoid collision and navigate safely, even when they can’t see each other.
Today, AIS transponders are so prevalent that the data they transmit and receive has become increasingly valuable, and not just to the vessels themselves. Naval forces, port authorities, coast guards, and other marine authorities use AIS data to improve their awareness of the current maritime situation.
What is the legal framework behind AIS?
Since 2004, the International Maritime Organization (IMO) has required AIS transponders to be aboard most vessels. The Safety of Life at Sea (SOLAS) Convention, Chapter V, states: “All ships of 300 gross tonnage and upwards engaged on international voyages and cargo ships of 500 gross tonnage and upwards not engaged on international voyages and passenger ships irrespective of size shall be fitted with an automatic identification system (AIS).”
More than 60,000 ships worldwide have installed these transponders at a combined cost of several hundred million dollars, making AIS one of the most successful maritime technology deployments of all time. Equipment that uses AIS technology is increasingly being deployed in smaller vessels, as well as radio/AIS-enabled aids to navigation (AtoNs), and it is also being installed on search and rescue (SAR) vessels and aircraft.