The London P&I Club – Dangers of Overreliance on AIS
Automatic Identification System (AIS) appeared in the early part of the millennium and found its way rapidly onto the bridges of ships of all sizes worldwide. In the earliest days, AIS took the form of a standalone AIS unit sited on the bridge for the reference of the watch keeping officer. At that time, most ships operated paper charts and most existing radar systems did not have a facility to integrate AIS data to their displays.
The main advantage of the system was the ability for vessel traffic monitoring systems to actively identify vessels within monitored zones. A major benefit to the bridge user was the ability to cross-reference a radar target by range and bearing to an AIS signal displayed on a separate unit.
Two decades later and much has changed, with the rapid growth in the number of ships operating integrated bridge systems. Bridge systems today permit AIS data to be overlaid onto radar screens and in many cases electronic chart displays. Successful operators use their Management of Change Policies to manage the potential for importation of risk with new technologies, but it is becoming apparent that AIS-assisted collisions are on the rise.
The Club refers to a high-value collision case in which a ship proceeding along a Traffic Separation Scheme (TSS) was involved in a collision with another ship which altered course to cross the TSS under the apparent direction of the local Vessel Traffic Services (VTS). At the time visibility was very poor.
Neither the VTS Controller nor the ship crossing the TSS would appear to have detected the presence of the ship proceeding in the TSS. While the ship within the TSS was broadcasting an AIS signal, it may not have been displayed accurately on the navigational devices upon which the bridge team of the ship crossing the TSS were relying. If the crew of the ship crossing the TSS had used the radar set in its intended role, the detection of the other ship involved in the collision was entirely possible despite the unreliable AIS data.
A lesson from this incident is to use good seamanship and “lookout” under Rule 5 of the COLREGS: