HMS Vanguard and Le Triomphant submarine collision

The submarines HMS Vanguard and Triomphant collided in the Atlantic Ocean in the night between 3–4 February 2009. Both are nuclear-powered ballistic missile submarines. The Royal Navy's HMS Vanguard and the French Navy's Triomphant both sustained damage, but no injuries or radioactivity releases were reported. At the time of the collision, both vessels were submerged and, according to the UK Ministry of Defence, moving "at very low speed"; both are equipped with active and passive sonar, although only the latter is used on an operational patrol.

HMS Vanguard was on a routine patrol in the Eastern Atlantic Ocean with a crew of 135, and can carry a maximum load of 16 Trident 2 D5 ballistic missiles, with a standard patrol load of 48 warheads.Triomphant was returning from a tour of duty when the incident occurred; it was carrying a crew of 111, and capable of being equipped with 16 M45 ballistic missile, with a standard patrol load of 48 warheads.

On the night between 3–4 February 2009, the two submarines collided in the Atlantic Ocean. On 6 February 2009, the French Ministry of Defence reported that Triomphant "collided with an immersed object (probably a container)" The UK Ministry of Defence initially would not comment that the incident took place. On 16 February 2009, the incident was confirmed by First Sea Lord Sir Jonathon Band, in response to a question at an unrelated event. Band said that the collision occurred at low speed, and that there had been no injuries. The French Ministry of Defence also stated that a collision "at a very low speed" had occurred, with no casualties.

Both vessels were damaged. Vanguard received damage to the outer casing in the area of the missile compartment on the starboard (right) side.Triomphant was initially said to have received damage to the active sonar dome under her bow, indicating that Triomphant ran into Vanguard from above and amidship, but was later reported as having received impacts to three parts of her structure, with her conning tower and the starboard sail plane attached to the conning tower visibly deformed by the incident. According to the Daily Telegraph, the cost of repairing the damage to both boats was expected to amount to up to £50 million. Both vessels returned to home bases under their own power, Vanguard to Her Majesty's Naval Base Clyde in the Firth of Clyde, on 14 February 2009 and Triomphant to Île Longue in Brittany, escorted by a frigate as a normal procedure, although it is unclear whether this was an unplanned return following the incident.

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