Marine Accident Investigation Branch
Accident Investigation Report 13/2020
Investigation report into marine accident including what happened, safety lessons learned and recommendations made:
Submarine periscope as seen from ferry (photo: Stena Line)
At 1256 on 6 November 2018, Stena Superfast VIIs officer of the watch took urgent action to avoid a submerged submarine after its periscope had been spotted close ahead of the ferry. Post-event analysis showed that, prior to the ferrys course alteration, there had been a serious risk of collision. This near miss happened because the submarines control room team had underestimated the ferrys speed and overestimated its range, resulting in an unsafe situation developing. However, the submarines 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.
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
The Royal Navy has taken a series of actions in response to this and similar previous accidents. As a result, a safety recommendation (2020/124) has been made to the Royal Navy to undertake an independent review to ensure that the actions taken have been effective in reducing the risk of further collision.
MAIB Report 20/2016 collision between a dived Royal Navy submarine and the fishing vessel Karen.