Specifically, the USG notes that improper AIS may have been the cause of a recent collision between two towboats on the Mississippi.
Despite the fact that the investigation about the incident is still ongoing, the USCG issued an interim warning for the towboat community about the risks created by having inaccurate AIS data.
Concerning the incident, two towing vessels were approaching a bend on the Mississippi River before sunrise. Neither vessel was broadcasting the total overall length of their tow to other AIS users, according to the USCG. As the vessels rounded the bend and completed their turns, they collided, causing one to capsize and sink with multiple fatalities.
The first vessel's AIS broadcast showed its length at 72 feet (the size of the RC Creppel), but the overall length of the vessel and its two-barge tow was more than 670 feet. The second vessel’s AIS broadcast showed its length at 200 feet (the size of the Cooperative Spirit), but the overall length of the vessel and its 40-barge tow was 1,600 feet. Without 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, the Coast Guard assessed.
USCG highlights that
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.
It is added that accurate AIS is crucial to an operator's ability to make informed navigational decisions.
Therefore, the agency's Directorate of Inspection and Compliance issued recommendations to minimize the risks and assis operators. Specifically they advise to:
- Use the Coast Guard's AIS Encoding Guide to ensure that accurate and up to date information is entered into the AIS.
- For vessels towing ahead or alongside, use Ship Type 57 (not Ship Type 31) within the static data fields in order to broadcast the overall dimensions of the vessel and its tow.
- Ensure towing vessel officers have the training and resources to update AIS data when tow sizes change.