Safety cases for legacy warships: a systematic approach

Although a Maritime Safety Case regime has existed since 1993, there are very few papers within the academic literature. There is considerably more interest across the defence and wider maritime sector in Safety Assessment (e.g. Safedore 2007), than when the UK MOD embarked on its systems safety journey in the early 1990's. Capital Ships Directorate (ex. Major Warships Integrated Project Team (IPT)) manages the new Carriers (HMS QUEEN ELIZABETH & PRINCE OF WALES) and the in- service material state of the current Aircraft Carriers, Type 42 Destroyers, and Amphibious ships ALBION, BULWARK and OCEAN. It is considered that a widely applicable methodology has been generated and indeed a similar approach is now being adopted by other Ship-IPTs. Our methodology accommodates reviews of ship operating history and drives our risk management programme, integrating Ships Staff, Platform IPT and relevant Equipment IPTs risk assessments. The main results have helped us confirm: residual safety and environmental claims are justifiable and the risks tolerable and ALARP; prioritise maintenance and obsolescence management, given the remaining years of operations; Consider the lessons from significant accidents. The approach is based upon "claims-argument-evidence" (Kelly, McDermid, 1997 [6]), and our own adapted concept of a "hazard footprint". This high-level doctrine offers just as flexible a framework for legacy analysis (such as our own) as has been historically applied to new risk-based designs. The resources expended have proven to be minimal, whilst the analysis process itself has enhanced the IPT's safety culture and is beginning to influence wider Asset Management Planning and Environmental work, up to the end of the ship service lives. The Safety Case Reports generated from the work demonstrate for the first time, our 'responsibility on a page', whilst being flexible enough to allow for management of inherently hazardous operations. The wide range of hazard logs have been rationalised using the hazard-footprint to encomas typical warship evolutions (with typically include a number of potentially catastrophic and disastrous accident sequences), during: a) Specified wartime operations; b) Peacetime operations; c) Whole ship training exercises; The management system allows identification of the additional controls needed to retain elderly ships and systems within their design intent. This drives maintenance levels to ensure that intent, what additional constraints and operational controls are required as well as informing senior management of safety and environmental performance. (6 pages)