The UK Royal Navy (RN) Trafalgar Class nuclear-powered hunter-killer submarine (SSN), HMS Trenchant, has returned to the operational fleet after undergoing a major refit programme.

The submarine has been fitted with the Thales Sonar 2076 stage 5 system along with additional upgrades to the Tomahawk cruise missile capability.

The upgrade to the new stage 5 system supports the UK MoD’s vision for a common sonar and combat system across the submarine flotilla.

The Trafalgar Class submarines are used for high-intensity missile strikes, anti-submarine and surface unit warfare, surveillance, and inshore and beach reconnaissance missions.

Thales UK was awarded a contract by BAE Systems to upgrade three additional Trafalgar Class and three Astute Class submarines with the stage 5 system in February 2010.