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Investigation findings (M16P0378) 2016 grounding and sinking of the Nathan E. Stewart

Findings as to causes and contributing factors

  1. The second mate, who was working alone on the bridge, was fatigued.
  2. The second mate fell asleep and did not make the planned course alteration, and the articulated tug-barge struck and grounded on a reef.
  3. The navigational alarms were not used and a bridge navigational watch alarm system was not available; the use of these could have prevented the second mate from falling asleep and provided a warning to other crew members.
  4. The other crew member on watch was not on the bridge and did not reach the wheelhouse prior to the grounding.
  5. Following the grounding, and after several hours of continuous interaction between the tug's hull and the reef, the hull breached and released diesel oil into the environment.
  6. The pollution boom around the tug did not contain the diesel oil; approximately 110 000 L of diesel oil were not recoverable and were left in the environment.

Findings as to risk

  1. If a 1-person bridge watch is in use without mitigating measures, particularly during the hours of darkness, a single point of failure may occur, increasing the risk of an accident.
  2. If a 6-on, 6-off shift schedule is used without fatigue-mitigating measures, there is a risk that crew members will be impaired by fatigue while on duty.
  3. If there is no requirement for crews to receive fatigue-awareness or -management training, there is a continued risk that fatigue will not be identified, prevented, or mitigated.
  4. If a coordinated and comprehensive evaluation of the response to an environmental spill is not conducted, there is a risk that shortfalls will go unidentified by the response groups as a whole, resulting in a missed opportunity to improve Canada's spill response regime.

Other findings

  1. There was no delay in the agencies' reaction to the incident and the oil spill response, and the recovery efforts of both the Western Canada Marine Response Corporation and the Canadian Coast Guard met the prescribed time standards.
  2. Other responding agencies, and some Canadian Coast Guard personnel, were not familiar with the incident command system, which created confusion about the roles and responsibilities of all responding agencies and about who had final authority.