What happened?
At 1247 on January 21, 2016, the towing vessel Amy Frances was pushing a flotilla of six barges downbound on the Lower Mississippi River near Natchez, Mississippi, when the port lead barge allided with the center pier of the Natchez–Vidalia Highway 84 Bridge. The allision breached a forward cargo tank on the barge, resulting in the release of 24,654 gallons of catalytic cracked clarified oil into the river. The estimated damage exceeded $542,000. No one was injured in the accident.
The evening before the accident, the vessel’s owner/ operator instructed the Amy Frances’ captain to moor for the night because high-water conditions present at that time was restricting nighttime transits. The next morning the Amy Frances got under way about 1136 with a credentialed crewmember (also called “pilot” on inland waterways) operating the vessel. The pilot told investigators that, during the approach toward the bridge, he found that the tow was setting to the left, so he decided to take the left channel under the bridge rather than the right channel as originally planned.
However, when the Amy Frances was about 0.5 mile from the bridge, the tow was setting toward the center pier. The pilot tried to back the vessel at full astern, but, about 1247, barge MM46 at the head of the flotilla struck the right side of the center pier at a speed of about 9.4 mph. Five of the six barges broke away from the Amy Frances; they were later recovered with the assistance of other towing vessels in the area.
Extreme High-Water
At the time of the allision, a Coast Guard safety advisory warning mariners about the “extreme high-water” conditions on the Lower Mississippi River was in effect. The advisory noted “hazardous conditions associated with strong currents” with the river above flood stage (Vicksburg gauge at 49.6 feet; flood stage for this gauge was 43 feet). It advised that downbound wheelman should have recent experience in handling current conditions. The accident pilot later told investigators that he had never transited through the accident area downbound when the river was above flood stage.
The owner/operator’s navigation program did not account for the pilot’s experience during “high-river” stages nor did it mention the use of an additional pilot to assist. Investigators believe that if the captain or another pilot had been in the wheelhouse together with the accident pilot to observe the vessel’s electronic charting system, they would have noticed that the vessel’s earlier set toward the left had decreased and that the tow would no longer pass safely through the left channel.
Probable Cause
The NTSB determined that the probable cause of the allision of the Amy Frances tow with the Natchez–Vidalia Highway 84 Bridge was the pilot’s failure to properly compensate for the current in the vicinity of the bridge while proceeding downbound under high-water conditions, and the captain’s failure to recognize the pilot’s inexperience with these conditions and assist the pilot with the maneuver.
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Source: NTSB
