Mate asleep at helm when ATB grounded off British ColumbiaJan 31, 2018 01:27 PM
Courtesy NTSB/Kirby Offshore Marine
The extent of the damage to Nathan E. Stewart was revealed when the tug was lifted from the seafloor by the heavy-lift floating crane D.B. General. The $6.4 million vessel was declared a total loss.
The crewman steering a U.S.-flagged articulated tug-barge through British Columbia’s Inside Passage fell asleep sometime before the vessels ran aground near Bella Bella, resulting in a 29,000-gallon fuel and oil spill.
National Transportation Safety Board (NTSB) investigators said the mate acknowledged nodding off before the Kirby Offshore Marine vessels Nathan E. Stewart and DBL 55 slammed into a reef off Athlone Island at 0108 on Oct. 13, 2016.
Although the sleeping crewman was the leading factor, the NTSB determined the crew’s “ineffective implementation of the company’s safety management system procedures for watch-standing” contributed to the incident. Kirby has since implemented new safety and oversight measures for its offshore crews.
The 95-foot, 3,400-hp Nathan E. Stewart was returning to Vancouver, B.C., with the empty DBL 55 after delivering jet fuel and gasoline to two southeast Alaska ports. The second mate woke up at 2230 on Oct. 12 and relieved the captain an hour ahead of schedule at 2300.
The mate’s last autopilot course change occurred at 0024. He missed the next waypoint 29 minutes later, when he should have made a 98-degree turn to port to avoid hitting rocks off Athlone Island. DBL 55’s bow and Nathan E. Stewart’s starboard prop or prop shaft hit the reef at 9 knots almost 15 minutes after the missed turn.
Initially, the crew could not find any damage to the tug or barge. But the falling tide and wind-driven swells from an approaching storm began battering the tug’s underside. By 0200 the crew began moving personal and safety gear to DBL 55, and 40 minutes later they started pumping diesel into a barge tank. At about 0400, diesel appeared in the water around the tug.
“The falling tide, wave action and repeated contact with the rocky bottom subjected the hull and structure of Nathan E. Stewart/DBL 55 to significant static and dynamic forces,” the NTSB said. “Racking, hogging, sagging and torsional moments caused deformation of the hull and the structure of both vessels.”
Pumps could not keep up with the flooding in the tug and its stern went under at 0927, tossing three crewmembers into the sea. All three made it to safety and none of the seven crew reported injuries. At least three Canadian Coast Guard vessels assisted the stricken tug.
Canadian regulations typically require a local pilot to guide most commercial vessels through the Inside Passage. Some Kirby vessels, including Nathan E. Stewart, earned a waiver based on the experience of the captain and mate in navigating the waterway. The second mate was not covered by the exemption, and the captain was not aware of the pilotage rules or the waiver requirements, the NTSB report said.
Separately, Kirby’s safety management system required a second licensed crewmember on watch in waterways where pilots are normally used. The NTSB found no evidence that a second person was on watch with the second mate when he fell asleep.
Nathan E. Stewart’s electronic chart reader had a track error alarm that sounds when the vessel leaves the trackline programmed for the route. However, the second mate did not activate this feature, which he said was rarely used.
Nathan E. Stewart initially remained connected to DBL 55 by its ATB coupler system. The pins let go at about 1840 and the tug sank in 28 feet of water, leaving its upper wheelhouse partially exposed. Salvage teams raised it a month later and Kirby Offshore declared the 15-year-old vessel a total loss with a value of $6.4 million. The 287-foot DBL 55 sustained $5.6 million in damage but its tanks did not breach.
Nathan E. Stewart’s crew tried to lay containment boom but strong winds and rough seas hampered the effort. Authorities believe 29,000 gallons of diesel and lube oil escaped from the tug. Multiple rings of boom ultimately were laid around the vessels, and skimmers removed some fuel from the water.
The spill occurred near Heiltsuk First Nation fishing grounds and rainforest. The Heiltsuk oppose oil transits through tribal areas, and the nation released a report in March criticizing the initial spill response. The report cited a lack of communication, not enough oil spill containment materials and lack of safety gear for responders.
A tribal representative did not respond to inquiries about the NTSB report.
Following the accident, Kirby installed pilothouse alert systems in its offshore vessels that meet Subchapter M standards. These units, which were not present on Nathan E. Stewart before the accident, require manual crew inputs at set intervals to prevent an alarm.
Kirby also has established new safety and oversight protocols. They include mandatory navigation software and systems training for wheelhouse crew, and more intensive programs for senior crew in Houston. Kirby port captains now conduct random vessel ride-alongs to monitor crews, and the company has hired an outside firm to lead regular safety summits.
In the days leading up to the incident, the second mate worked 12, 10, 12 and 11 hours, respectively, including six-hour shifts starting at 2200. He told investigators he had sufficient rest over the preceding three days.
“It is unknown whether the frequent variation between the two watch-rotation schedules, or other factors that could have impacted his circadian rhythm, influenced his sleep/wake cycles,” the NTSB said.
Canadian authorities are conducting a separate investigation of the accident. A spokesman for the Transportation Safety Board of Canada said that process is still under way.