A Royal Navy nuclear submarine had a near miss after a gauge malfunctioned and left it sinking towards an unsafe depth, it has been reported.
A depth gauge failed on one of the Vanguard class submarines, which have been in service for 30 years, the Sun reported.
The submarines carry around 140 crew, as well as Trident ballistic missiles.
The vessel was preparing to go on patrol when a depth gauge malfunctioned, leading crew to believe it was level when it was in fact still diving, according to the Sun.
It was about to enter the “danger zone” of depth that the submarine can withstand, before disaster was averted, the paper reported.
Engineers are said to have spotted a second gauge and raised the alarm.
A source told The Sun: “It’s not the engineers’ job to control the sub’s depth but they saw how deep they were and realised something was wrong.
“Technically the sub was still at a depth where we know it can operate, but if it ever has to go that deep the whole crew is piped to action-stations.
“That hadn’t happened. The sub wasn’t supposed to be there, and it was still diving. And if it had carried on going, it doesn’t really bear thinking about.”
A submarine carrying nuclear weapons has been on patrol at all times since 1969 as part of the UK’s continuous at sea deterrent.
The Royal Navy has four Vanguard class vessels which fulfil this role on rotation.
The ageing vessels are set to be replaced by the Dreadnought class, which are currently being built, in the 2030s.
A Royal Navy spokesperson said: “Our submarines continue to meet their commitments, deploying globally on operations, protecting national interests, and keeping us and our allies safe. While we do not comment on specific details regarding submarine operations, safety of our personnel is always the highest priority.”
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