The UK MAIB recently published an investigation report focusing on a near miss between ro-ro ferry Stena Superfast VII and Royal Navy submarine.
The incident
At 1256 on 6 November 2018, Stena Superfast VII’s officer of the watch took action to avoid collision with a submerged submarine that had been spotted at close range ahead of the ferry.
Post-event analysis showed that, prior to the ferry’s course alteration, there had been a serious risk of collision.
In fact, this near miss happened because the submarine’s control room team had underestimated the ferry’s speed and overestimated its range, resulting in an unsafe situation developing.
However, the submarine’s control room electronic tactical display presented a picture of a safer situation than reality, this meant that safety-critical decisions made on board the submarine may have appeared rational at the time.
Findings:
- safety-critical decisions need to be made based on accurate information
- passage planning should identify all potential hazards and effective mitigations
- maintaining a good lookout is vital for the safety of all vessels
Although there was no collision, this was the third accident or incident between a dived Royal Navy submarine and a surface vessel in 4 years, which is a matter of significant concern. The Royal Navy co-operated with the MAIB’s investigation into this near miss and has taken a series of actions, intended to prevent recurrence, in response to this, and the other similar incidents.
… Chief Inspector of Marine Accidents stated.
Conclusions
- Until avoiding action was taken by Stena Superfast VII’s OOW, there was a serious risk of collision between a laden ferry and a submerged Royal Navy submarine.
- It was extremely fortunate that Stena Superfast VII’s bridge AB spotted the submarine’s periscope, though there was no reasonable expectation he would do so.
- Overestimation of the ferry’s range and underestimation of its speed resulted in the submarine’s command system presenting an inaccurate surface picture. However, this situation meant that the unsafe decisions might have seemed rational at the time.
- Safety-critical decisions on board the submarine, specifically to turn towards the ferry and remaining at periscope depth, were taken based on inaccurate information.
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