Safety analysis breakthrough

Aircraft Engineering and Aerospace Technology

ISSN: 0002-2667

Article publication date: 1 February 2000




(2000), "Safety analysis breakthrough", Aircraft Engineering and Aerospace Technology, Vol. 72 No. 1.



Emerald Group Publishing Limited

Copyright © 2000, MCB UP Limited

Safety analysis breakthrough

Keywords York Software Engineering, Safety, Aerospace, Engineering, Software

A new approach to safety analysis and controlling project risk in aviation and aerospace engineering was recently launched by York Software Engineering.

SAM 2000 has been developed by YSE Ltd, the software development subsidiary of CSE International Ltd, a software management and critical systems consultancy company in conjunction with the University of York.

YSE reports that the system combines a new and rigorous way of ensuring completeness in project safety arguments with an integrated customisable package of safety analysis tools and editors.

This system is said to be an easy to use PC based tool, which has been several years in development and has already been widely and successfully used by a number of leading companies and organisations including British Aerospace, DERA, Rolls-Royce, GEC Marconi and GKN Westland.

SAM 2000's CD-ROM based package helps users to develop analyses to meet the requirements of major standards, including IEC 61508, Def Stan 00-42, 00-43, and 00-56, RCTA/DO 178B and CENELEC, EN50128 and EN50129.

It uses as its core the goal-structuring notation (GSN) technique developed by the University of York.

GSN provides a logical graphically-based means of expressing arguments linked to supporting evidence. It examines the underlying objectives, strategies, rationales, assumptions, justifications and contextual information in a safety case and brings them all to the fore, thereby improving communication and traceability.

GSN is also said to enable weak arguments and missing or irrelevant evidence to be identified and corrected. This, it is thought, has the potential not only to produce much better quality safety arguments but also to improve overall safety management processes and ultimately to minimise the possibility that flaws in a project's safety analysis will not be spotted.

SAM 2000's rigorous analysis techniques are not thought to be confined to safety applications and can be used also to greatly ease the management of a wide range of complex processes - from the construction of legal cases to the planning and implementation of corporate change and the control of project risk.

Development of SAM 2000 began in late 1993, as a collaborative research project under the DTI/EPSRC SafeIT programme; the partners were The University of York, British Aerospace, Rolls-Royce, Lloyd's Register of Shipping and York Software Engineering Ltd.

A fully functioning Beta version was released at the end of 1996 and a SAM Users Club, of up to 25 member companies, was established in order to bring the product to the market. The plan was that ideas for improving the tool, based on realistic usage, could be fed back into the development programme. The companies made clear that, given the growing complexity of safety analysis, there was a real need for such a comprehensive and totally logical tool to be developed.

Traditionally, safety legislation or best practice has been addressed by presenting the regulatory body or department with a large collection of test result, safety analysis outputs and other data in the hope that the weight (quite literally) of such evidence will be accepted as an overwhelming argument that the system has been adequately demonstrated.

The short-sightedness of that approach is deemed to be obvious and it also undermines the basis for approval of such safety critical systems - hence the need for GSN.

Said Derek Fowler, Air Transport Group Manager, CSE International Ltd:

It was recognised that safety analysis demanded a software tool that would bring a high degree of rigour to the safety management process by combining a structured argument technique with the best of all existing safety analysis tools in one flexible package. SAM 2000 does just that, going well beyond any other product in the area.

The SAM 2000 Toolset includes: Model Editor, Risk Calculator, Hazard Log Editor, Preliminary Hazard Identification, HAZOP Editor, FFA Editor, FMEA Editor, FTA Editor, ETA Editor and RBD Editor.

It is also thought to be novel in allowing users to customise product tools or produce their own to meet their requirements.

All its editors have a common "look and feel", but with notation specific operations. Diagrams can span many pages with full navigation provided between them. The integrity of cases modelled and analysed within SAM 2000 can be checked in a number of ways using the multiple tools integrated into the SAM 2000 editors.

According to YSE, goal structure, system models and analyses can be built using the various notation editors, and linked into Microsoft Word or other documents for presentation in a textual safety case. Tables can be filtered to include or exclude columns and rows according to user-defined selection criteria, and diagrams sized, thus giving control over what data are put into the delivered safety case. Diagrams automatically fit onto multiple A4 pages but can be scaled to fit smaller areas. Facilities are also provided for producing reports directly in SAM.

A comprehensive set of documentation is provided giving instruction on how to operate each of the tools within the SAM 2000 toolset, SAM 2000 runs under Windows 95/98 and Windows NT. A Pentium processor is recommended with at least 32MB of RAM, and at least 40MB of disk space.

Details available from: York Software Engineering Ltd. Tel: + 44 (0)1724 977520; Fax: + 44 (0)1724 846256; e-mail:

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