12/04/2017 21:37 EST | Updated 12/04/2017 21:37 EST

Bella Bella, B.C. Oil Spill Likely Caused By Sleeping Crew On Tugboat: Report

The second mate fell asleep before the barge crashed.

Heiltsuk First Nation via CANADIAN PRESS
Oil is seen on the water in Seaforth Channel following an oil spill near Bella Bella, B.C., in this undated handout photo.

BELLA BELLA, B.C. — The U.S. National Transportation Safety Board says the second mate of a tugboat fell asleep before it ran aground off the coast of British Columbia last year and spilled thousands of litres of fuel.

The American safety agency says records show the second mate relieved the captain of watch duty and missed a scheduled change of course for the Nathan E. Stewart before the articulated tug and barge crashed near Bella Bella on Oct. 13, 2016.

The board's report dated Nov. 21 says the second mate told investigators he missed the change of course because he had fallen asleep, which it says is the probable cause of the vessel running aground.

The vessel owned by Houston-based Kirby Offshore Marine was en route to the Port of Vancouver with an empty barge when it ran aground and partially sank in the Seaforth Channel.

107,000 litres of diesel spilled

More than 107,000 litres of diesel and 2,240 litres of lubricants, including gear, hydraulic and lube oils, were released into the Pacific Ocean from the 30-metre vessel.

The safety board says a contributing factor to the crash was also the ineffective implementation of Kirby's safety management procedures.

Based on statements from the crew, the board says there was a lack of documentation on safety rounds and no evidence that safety management procedures were implemented on board the Nathan E. Stewart.

"Although the company's (safety management system) addressed the identified risks associated with the potential incapacitation of the navigating officer, those procedures were not adhered to by the captain and crew on board," it says.

Second mate said he had 'adequate' rest

"The second mate stated that at the time of the accident he was not taking any prescription medications and had only brought on board a bottle of ibuprofen in case he experienced any back pain or a headache. He claimed that he had never been diagnosed with any sleep-related disorders and felt that he had 'adequate' rest during the three days preceding the accident."

Since the accident, the board says the company has implemented a wheelhouse assessment program to provide "direct oversight" of the captain and crew of towing vessels.

"Under the program, a senior qualified captain rides along on each vessel for 10 consecutive days evaluating navigation procedures, change of watch routines, and bridge-layout ergonomics, in addition to conducting an overall internal audit of the vessel and crew performance," the report says.

The company has also installed a system on its offshore vessels that requires someone to regularly interact with it to prevent an alarm from sounding. Captains and mates must also attend a five-day simulator training program in Houston on navigation techniques and navigational decision-making.

"Besides these changes, port captains for each Kirby operational region now conduct random vessel ride-alongs and evaluations of the captain and crew," it says, adding the company has also implemented an external audit of its navigation watch procedures.

Previously On HuffPost: