USCG: Automatic identification system (AIS) inaccuracies led to fatalities

The United States Coastguard (USCG) has published Safety Alert 04-20 relating to an incident where a causal factor in a number of fatalities was incorrect information entered into vessel AIS (Automatic Identification Systems). Accurate AIS data entry and display is essential to safe navigation.

What happened?

During the hours of darkness, two towing vessels were approaching a bend on the Mississippi River. Neither vessel was broadcasting the total length overall of their tow to other AIS users.

  • The first vessel’s AIS broadcast showed its length at 72 feet, but the overall length of the vessel and its two-barge tow was 672 feet.
  • The second vessel’s AIS broadcast showed the length at 200 feet, but the overall length of the vessel and its 40-barge tow was 1,600 feet.

Without the information regarding the total length of the other vessel and its tow, the operators did not have a full understanding of the pending passing situation. As the vessels rounded the bend and completed their turns, they collided, causing the down bound towing vessel to capsize and sink with several fatalities.

The US Coast Guard notes:

The AIS is a valuable tool which broadcasts critical vessel information to other vessels. However, proper function of the AIS is dependent on accurate vessel data entry, including entering the proper ship type code and the full length of a vessel and its tow. The accurate display of a vessel’s full length becomes particularly important in situations that prevent vessels from seeing each other until they are in very close proximity.