EXECUTIVE SUMMARY
The ice-class mobile offshore drilling unit (MODU) Kulluk,
owned by Shell Offshore, Inc., and operated by Noble Drilling, grounded in
heavy weather near Ocean Bay on the eastern coast of Sitkalidak Island off
Kodiak Island, Alaska, about 2040 local time on December 31, 2012. The Kulluk,
under tow by the ice-class anchor-handling tow supply vessel Aiviq, departed
Captains Bay near Unalaska, Alaska, 10 days earlier for the Seattle,
Washington, area for maintenance and repairs. Four crewmembers on the Aiviq sustained minor
injuries as a result of the accident.
PROBABLE CAUSE
The National Transportation Safety Board determines that the
probable cause of the grounding of the mobile offshore drilling unit Kulluk was
Shell’s inadequate assessment of the risk for its planned tow of the Kulluk,
resulting in implementation of a tow plan insufficient to mitigate that risk.
DISCUSSION
No single error or mechanical failure led to this accident.
Rather, shortcomings in the design of a plan with an insufficient margin of
safety allowed this accident to take place. The plan was created to move the
MODU at a time of year with a known likelihood of severe weather conditions for
reasons unrelated to operational safety.
Shell had retained warranty surveys on all five previous
tows of the Kulluk. No regulatory requirement existed for a warranty surveyor
to review and approve, or suggest modifications to, the tow plan and its
components. The surveyor that Shell retained for the accident voyage approved
the tow plan in its entirety. This was the only external review of the tow plan
and the equipment that was to be used in the planned tow.
The Coast Guard was not required to oversee the tow. Rather,
the Coast Guard’s role, a critical one given the circumstances, was limited to
its response to this accident―delivering the needed engine components to the Aiviq,
unsuccessfully attempting to tow the Kulluk, and, most important, rescuing Kulluk
personnel when their lives were endangered, an operation that itself risked the
lives of the Coast Guard rescuers.
Many maritime regulators in countries with operations in
environments with the potential for severe weather actively oversee tow
operations. For example, Norway addresses many of the shortcomings in the
oversight of tow gear and severe weather avoidance that were evident in this
accident.6 Canada similarly addresses safe towing operations, including
specifying parameters for tow gear strength, by recommending that operators
adhere to IMO towing guidelines (IMO MSC Circ. 884, 21 December 1998).7 IMO and
the Norwegian Maritime Authority provide guidance for oceangoing tows with
margins of safety for encounters with adverse weather.
The Aiviq lost engine power at a critical point in the Kulluk’s
tow. Coast Guard investigators believe that the design of the fuel oil storage
tanks’ common vent and overflow system was flawed and that these flaws led to
the seawater contamination of the fuel tanks during the Aiviq’s transit during
rough sea conditions. Offshore Service Vessels contends that fuel contaminants
were present in the fuel taken on by the Aiviq in Dutch Harbor and that this
contamination, rather than seawater that entered the system later, led to the
engine power loss. Regardless, the source of the fuel contamination was outside
the scope of the NTSB’s investigation of this accident and, therefore, was not
determined.
Given the risks associated with this transit, including the
likelihood of the tow encountering severe weather, Shell and its contractors,
particularly Offshore Service Vessels, the operator of the Aiviq, who reviewed
and approved the tow plan should have either mitigated those risks or departed
at a time of year when severe weather was less likely.
For example, Shell and
its contractors could have included additional tow vessels to the entire
transit to reduce the likelihood of catastrophic results from a failure of the Aiviq
or its tow gear. Redundancy is a necessary element of safety-critical
transportation systems, and given the hazards of operations in Alaskan waters,
those involved in the tow plan should have recognized and addressed the lack of
redundancy.
The series of failures that led to this accident began when
Shell failed to fully address the risks associated with a late December tow in
Alaskan waters, and ended with the grounding of the Kulluk. Although multiple
parties were involved in the review and approval of the tow plan, the ultimate
decision to approve and implement the tow was Shell’s.
The dynamics of a single
entity approving a go/no-go decision in the face of risks, with multiple
parties involved, have been addressed in studies of previous catastrophic
events.8 This research demonstrates that, even with formal review processes
involving multiple entities, the ability of parties involved in a decision to
articulate and draw attention to risks is limited when a single entity bears
ultimate decision-making responsibility and at the same time favors a
particular outcome of the decision. For this reason, Shell, as the organization
responsible for designing, approving, and implementing the tow plan, is
considered to be ultimately responsible for this accident.
Probable Cause
The National Transportation Safety Board determines that the
probable cause of the grounding of the mobile offshore drilling unit Kulluk was
Shell’s inadequate assessment of the risk for its planned tow of the Kulluk,
resulting in implementation of a tow plan insufficient to mitigate that risk.
NTSB: Shell Blamed for Poor planning in botched tow of 2012
Arctic drilling rig
Posted on May 28, 2015
U.S. Coast Guard image showing the Royal Dutch Shell
drilling rig Kulluk aground off a small island near Kodiak Island on Jan. 2,
2013. (AP Photo/U.S. Coast Guard)
WASHINGTON — The National Transportation Safety Board on
Thursday blamed the grounding of Shell’s Kulluk drilling rig on the company’s
failure to adequately assess the risks of towing the vessel across predictably
stormy Alaska seas in 2012.
The independent federal agency’s findings, released
Thursday, represent the third major government report on what went wrong when
Shell Oil Co. and its contractors tried towing the Kulluk across Gulf of Alaska
waters in December 2012 — only to have the rig run aground on Sitkalidak Island following a failed
five-day fight to get control of it.
“No single error or mechanical failure led to this
accident,” the NTSB said. “Rather, shortcomings in the design of a plan with an
insufficient margin of safety allowed this accident to take place. The plan was
created to move the (mobile offshore drilling unit) at a time of year with a
known likelihood of severe weather conditions for reasons unrelated to
operational safety.”
The NTSB report comes at a pivotal time for Shell, which has
asked federal regulators for permission to resume exploratory oil drilling in
the Chukchi Sea as soon as July.
The Interior Department’s Bureau of Ocean Energy Management
has already approved Shell’s broad plans to bore up to six wells in those
Arctic waters during ice-free drilling seasons this summer and next. But the
company is waiting on a handful of other authorizations, including drilling
permits from the Bureau of Safety and Environmental Enforcement, before it can
launch the work.
The botched Kulluk tow job came months after Shell had
finished drilling the top portions of one well each in the Beaufort and Chukchi
seas, when the company began moving the non-propelled drilling rig from Dutch
Harbor, Alaska to a Seattle shipyard.
Shell contractor Edison Chouest began towing the Kulluk with
its anchor handling vessel, the Aiviq on Dec. 21, 2012. But six days later,
when the vessels ran into a series of storms near Kodiak Island, the tow line
broke and on Dec. 28, 2012, Aiviq’s four engines failed. The Coast Guard tried
but failed to connect a new tow line to the Kulluk, evacuated most of the Kulluk’s crew and delivered spare
parts to the Aiviq, allowing partial engine power to be restored on the ship.
Although towlines were briefly reconnected between the
Kulluk and the Aiviq as well as another tugboat, the Alert, on Dec. 31, once
the connection to the Aiviq failed, officials instructed the struggling Alert
to release its line for safety reasons.
That sealed the Kulluk’s fate.
Roughly a half hour later, at 8:48 p.m. on Dec. 31, the rig
plowed into the rocky seabed on Alaska’s uninhabited Sitkalidak Island.
A Coast Guard probe, completed last year, blasted Shell and
its contractors for deciding to tow the drilling rig across the “notoriously
treacherous” Gulf of Alaska, asserting that financial considerations —
including a potential multi-million dollar tax bill from the state of
Alaska — played a role in the timing.
A separate Interior Department analysis also faulted Shell’s oversight
of contractors, saying the company appeared to be focused “on compliance with
prescriptive safety and environmental regulations . . . rather than on a
holistic approach to managing and monitoring risks.”
Shell’s executive vice president for the Arctic, Ann
Pickard, has stressed the company has radically improved its approach to
overseeing contractors involved in its Alaska operations, with daily phone
calls to share lessons learned among them, a detailed, down-to-the-minute
operations plan outlining planned vessel movements and more Shell managers
overseeing individual contractors.
Where one of those Shell managers was handling seven
contracts in 2012, now they are parceled among 49 different employees. One of
them is in charge of just one: Shell’s contract with Edison Chouest.
Pickard said “you can’t compare” the level of planning in
2012 “to where we are today,” because there have been so many changes, some
directed by a deep internal audit Shell conducted after the Kulluk incident.
At the time, Pickard noted, with key permits and approvals
coming far later than expected, the focus was on getting in to the Chukchi and
Beaufort seas to drill during what remained of the brief ice-free window. As a
result, Pickard said, the company planned “decently” going forward into the
drilling operations, but “it wasn’t decently planned coming out.”
Shell spokesman Curtis Smith said Thursday that the company
was reviewing the National Transportation Safety Board report.
“We have already implemented lessons learned from our 2012
season and have engaged extensively with the regulators,” Smith said. “As we
prepare for a 2015 exploration season, we will continue to test and prepare our
personnel, assets and contingency plans against the high bar stakeholders and
regulators expect of an Arctic operator.”
Environmentalists who argue the entire endeavor is too risky
say they have no way to independently assess Shell’s operations — including how
much the company learned from mishaps in 2012. An independent audit of the
company’s management systems — ordered by the Interior Department in 2013 — has
not been publicly released to Greenpeace and other groups that have requested
it under a Freedom of Information Act request.
“Why should we take Shell’s word for it that the company has
learned its lesson from the wreck of the Kulluk?” said Greenpeace USA spokesman
Travis Nichols. “The Department of Interior needs to make the results from the
third-party audit available publicly, so we all can have some kind of proof
that this summer won’t just be the sequel to 2012’s epic dud.”
Accident Location: Ocean Bay, Sitkalidak Island, AK USA
Accident Date: 12/31/2012
Accident ID: DCA13NM012
Date Adopted: 5/22/2015
NTSB Number: MAB1510
NTIS Number:
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