British accident investigators have urged the Royal Navy to launch a review after a series of near misses involving submarines and merchant vessels.
In a report into a close call between the unnamed navy vessel and Stena Line's 30,300-gt ro-pax Stena Superfast VII (built 2001) in 2018, the Marine Accident Investigation Branch (MAIB) revealed that there have been three such incidents in the past four years.
The UK's chief inspector of marine accidents, Steve Clinch, said the matter was 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," he added.
"However, I have today recommended that the Royal Navy undertakes an independent review of the actions that have been taken, in order to ensure that the risk of similar collisions has been reduced to as low as possible."
'Serious risk'
On 6 November 2018, Stena's watch officer had to take urgent action to avoid a submerged submarine after its periscope was spotted close ahead of the ferry.
Post-event analysis showed that, before the ferry altered course, there had been a serious risk of collision, MAIB said.
"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," the report found.
"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."
The MAIB said passage planning should identify all potential hazards, as well as measures to mitigate them.
It reiterated that maintaining a good lookout is vital for the safety of all vessels.
