Report: Severe Winds Caused Ship Breakaway

Severe, unforecasted winds caused a containership to break away from a pier and damaged equipment at the Napoleon Avenue Container Terminal in New Orleans on August 2, 2020, according to the National Transportation Safety Board’s Marine Accident Brief 21/18, which was issued September 16.

As longshoremen loaded and unloaded cargo from the containership CMA CGM Bianca, a sudden, localized thunderstorm passed through the area. Ten of the vessel’s 16 mooring lines parted in the high winds, and the ship moved away from the pier. Containers lifted by shoreside gantry cranes struck the ship. One damaged container dropped in the water, spilling a cargo of plastic pellets, known as nurdles. A crane operator suffered a minor injury. Damages totaled about $15.1 million.

The Malta-flagged, 1,099-foot-long CMA CGM Bianca was built in 2010 and had a maximum container capacity of 8,533 twenty-foot-equivalent units. 

The ship was equipped with self-tensioning-capable mooring winches that, when engaged, heaved in or paid out line to maintain line tension between a set range. The auto-tensioning devices on the mooring line winches were not engaged because, according to the master, the river current in the Mississippi River and wash from passing vessels could trigger unwanted payout, resulting in slack lines. Instead, the mooring winches were secured by their brakes, and the lines were inspected by the crew during regular rounds to ensure adequate tension.

At 1:50 p.m., security cameras at the terminal recorded rain beginning to fall. Ten minutes later, “gale force winds and strong rain” hit the CMA CGM Bianca, according to the vessel’s deck log. The master described the conditions as “in the form of a tornado,” and both crane operators stated that the winds developed “in seconds.” At 14:02, seven forward mooring lines and three aft mooring lines on the CMA CGM Bianca parted, and the ship moved away from the pier. 

At about the same time, Cranes 5 and 6, both with containers suspended from their spreaders, began moving along their rails (forward to aft, in relation to the CMA CGM Bianca) as they were buffeted by the wind. The container suspended from Crane 5 hit other containers stowed on the ship and then fell from the ship, still connected to the spreader, hitting the pier and breaking open before falling in the water. Part of the container’s cargo of very small (less than 5 millimeters) plastic pellets, known as “nurdles” and used for producing plastic products, was discharged into the river. Millions of the pellets floated downriver, washing up on the river banks or out into the Gulf of Mexico. 

Investigators determined the probable cause of the accident to be the sudden onset of unforecasted severe winds likely originating from the outflow of a thunderstorm-generated downburst.

Marine Accident Brief 21/18 is available online at