The US Coast Guard has released the Report of Investigation (ROI) into the loss of 33 mariners and the cargo ship El Faro on October 1, 2015 in the North Atlantic off the Bahamas during Hurricane Joaquin.

The USCG Marine Board of Investigation (MBI) concluded that the primary cause of the casualty was the decision of the master to navigate the vessel too close to the path of the hurricane. Secondary factors included an ineffective safety management system within the operating company and failures by both the Coast Guard designated representative and the Coast Guard itself to provide effective oversight of the vessel’s compliance with safety regulations.

The loss of the U.S. flagged El Faro, along with its crew, ranks as one of the worst maritime disasters in U.S. history, and resulted in the highest death toll from a U.S. commercial vessel sinking in 40 years. At the time of the sinking, El Faro was on a U.S. domestic voyage with a full load of containers and roll-on roll-off cargo bound from Jacksonville, Florida, to San Juan, Puerto Rico.

The Coast Guard found that Hurricane Joaquin defied weather forecasts and standard behavior for Atlantic hurricanes by traveling southwest. The ship’s master directed the ship on its normal route southward direct San Juan. That move steered the ship “almost directly towards the strengthening hurricane,” the report concluded.

On the morning of October 1, 2015, after flooding was identified in one of the vessel’s cargo holds and as engineers were struggling to right the listing ship, El Faro lost propulsion and began drifting subject to hurricane force winds and seas. Later that morning, without propulsion and with uncontrolled flooding, the master signaled distress using a satellite communication and ordered to abandon ship.

“The vessel, at the time, was near the eye of Hurricane Joaquin,” the report found, “which had strengthened to a Category 3 storm.”

The Report of Investigation is not yet final and is being forwarded to Coast Guard headquarters for consideration.