Stirling has been involved with the Royal Navy Astute submarine programme since 1996, initially providing the algorithm designs for both the depth and course autopilot and the hover system for Boats 1 to 3. For Boat 4, in addition to the algorithm design, Stirling are supplying the PMS (Platform Management System) central computer software. In 2009, BAE Systems re-bid the PMS System for Boat 4 and awarded us the contract to supply the PMS central computer software. Our safety-critical software incorporates the course, depth autopilot and hover control algorithms and all associated logic and fault cascading, and is compliant with DEF STAN 00-56. We are also responsible for delivering the whole-boat simulation model, which has been developed across boats 1-4. We are currently progressing towards the delivery of this system.