Developments in Risk-based Approaches to Safety.,,,, i

Transcription

1 Developments in Risk-based Approaches to Safety,,,, i

2 Related titles: Towards System Safety Proceedings of the Seventh Safety-critical Systems Symposium, Huntingdon, UK, Lessons in System Safety Proceedings of the Eighth Safety-critical Systems Symposium, Southampton, UK, Aspects of Safety Management Proceedings of the Ninth Safety-critical Systems Symposium, Bristol, UK, Components of System Safety Proceedings of the Tenth Safety-critical Systems Symposium, Southampton, UK, Current Issues in Safety-critical Systems Proceedings of the Eleventh Safety-critical Systems Symposium, Bristol, UK, 2003 RedmiU and Anderson (Eds) X Practical Elements of Safety Proceedings of the Twelfth Safety-critical Systems Symposium, Birmingham, UK, Constituents of Modern System-safety Thinking Proceedings of the Thirteenth Safety-critical Systems Symposium, Southampton, UK, 2005 gedmill and Anderson (Eds)

3 Felix Redmill and Tom Anderson (Eds),,,,,, Developments in Risk-based Approaches to Safety Proceedings of the Fourteenth Safety-critical Systems Symposium, Bristol, UK, 7-9 February 2006 Safety-Critical Systems Club Springer

4 Felix RedmiU RedmiU Consultancy, 22 Onslow Gardens, London, N 10 3JU Tom Anderson Centre for Software Reliability, University of Newcastle, Newcastle upon Tyne, NE1 7RU British Library Cataloguing in Publication Data A catalogue record for this book is available from the British Library ISBN- 10: ISBN-13: Printed on acid-flee paper Springer-Verlag London Limited 2006 Apart from any fair dealing for the purposes of research or private study, or criticism or review, as permitted under the Copyright, Designs and Patents Act 1988, this publication may only be reproduced, stored or transmitted, in any form or by any means, with the prior permission in writing of the publishers, or in the case of reprographic reproduction in accordance with the terms of licences issued by the Copyright Licensing Agency. Enquiries concerning reproduction outside those terms should be sent to the publishers. The use of registered names, trademarks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant laws and regulations and therefore free for general use. The publisher makes no representation, express or implied, with regard to the accuracy of the information contained in this book and cannot accept any legal responsibility or liability for any errors or omissions that may be made. Printed in the United Kingdom Springer Science+Business Media springer.corn

5 PREFACE Each February, the Safety-critical Systems Symposium (SSS) hosts a oneday tutorial followed by two days of paper presentations. Annually, the papers provide a mix of industrial experience and research results, and address the most critical topics in the field of safety-critical systems. This year, the focus is on recent developments in risk-based approaches, and the papers report on these in a number of areas. A topic of continuing interest and increasing importance is that of the safety case, and in recent years papers at the Symposium have highlighted its principles and the nature of its contents. This year there are two sessions on the subject. The papers in the first report on experience of developing safety cases, and they offer advice on the process; those in the second give suggestions on the safety case's evolutionary requirements and directions. Other perennial subjects are risk and software safety. Three papers report on directions that risk analysis have taken or could take, and two provide interesting insights into language development and the creation of systems for complex control functions. On the academic side, three papers address the use of new software technologies. They raise questions as to when such technologies are ready for application in the field of safety-critical systems. The need to consider them in the context of safety principles, taking a risk-based approach, is emphasised. Finally, there is a section on management risk, a subject that is both important and neglected. It is hoped that both practitioners and academics in our field will carry out further work on this subject. Each year, the organisation of SSS depends heavily on the authors who prepare and present their papers. Without them, there would be no Symposium, and without useful content in the papers, there would be no successful Symposium. We therefore extend our thanks to the authors and their companies for their time and intellectual application, and for responding to our editing demands with grace and good will. We also (and again) thank Joan Atkinson for being a continuing mainstay of the event. FR & TA November 2005

6 THE SAFETY-CRITICAL SYSTEMS CLUB organiser of the Safety-critical Systems Symposium What is the Club? The Safety-Critical Systems Club exists to raise awareness of safety issues in the field of safety-critical systems and to facilitate the transfer of safety technology from wherever it exists. It is an independent, non-profit organisation that co-operates with all bodies involved with safety-critical systems. History The Club was inaugurated in 1991 under the sponsorship of the UK's Department of Trade and Industry (DTI) and the Engineering and Physical Sciences Research Council (EPSRC). Its secretariat is at the Centre for Software Reliability (CSR) in the University of Newcastle upon Tyne, and its Co-ordinator is Felix Redmill of Redmill Consultancy. Since 1994 the Club has been self-sufficient, but it retains the active support of the DTI and EPSRC, as well as that of the Health and Safety Executive, the Institution of Electrical Engineers, and the British Computer Society. All of these bodies are represented on the Club's Steering Group. What does the Club do? The Club achieves its goals of awareness-raising and technology transfer by focusing on current and emerging practices in safety engineering, software engineering, and standards that relate to safety in processes and products. Its activities include: Running the annual Safety-critical Systems Symposium each February (the first was in 1993), with Proceedings published by Springer-Verlag; Organising a number of 1- and 2-day seminars each year; Providing tutorials on relevant subjects; Publishing a newsletter, Safety Systems, three times each year (since 1991), in January, May and September. How does the Club help? The Club brings together technical and managerial personnel within all sectors of the safety-critical community. Its events provide education and training in principles and techniques, and it facilitates the dispersion of lessons within and between industry sectors. It promotes an interdisciplinary approach to safety engineering and management and provides

7 VIII a forum for experienced practitioners to meet each other and for the exposure of newcomers to the safety-critical systems industry. The Club facilitates communication among researchers, the transfer of technology from researchers to users, feedback from users, and the communication of experience between users. It provides a meeting point for industry and academia, a forum for the presentation of the results of relevant projects, and a means of learning and keeping up-to-date in the field. The Club thus helps to achieve more effective research, a more rapid and effective transfer and use of technology, the identification of best practice, the definition of requirements for education and training, and the dissemination of information. Importantly, it does this within a 'club' atmosphere rather than a commercial environment. Membership Members pay a reduced fee (well below a commercial level) for events and receive the newsletter and other mailed information. Without sponsorship, the Club depends on members' subscriptions, which can be paid at the first meeting attended. To join, please contact Mrs Joan Atkinson at: Centre for Software Reliability, University of Newcastle upon Tyne, NE1 7RU; Telephone: ; Fax: ; cs~ewcastle.ac.uk

8 CONTENTS LIST TUTORIAL People and Systems: Striking a Safe Balance between Human and Machine Carl Sandom and Derek Fowler... NEW APPROACHES TO RISK ASSESSMENT Risk Assessment for M42 Active Traffic Management Max Halbert and Steve Tucker... Safety Risk Assessment by Monte Carlo Simulation of Complex Safety Critical Operations Henk A P Blom, Sybert H Stroeve and Hans H de Jong... So How Do You Make a Full ALARP Justification? Introducing the Accident Tetrahedron As A Guide for Approaching Completeness Richard Maguire EXPERIENCE OF DEVELOPING SAFETY CASES Safety Case Practice - Meet the Challenge Werner Winkelbauer, Gabriele Schedl and Andreas Gerstinger Safety Case Development- A Practical Guide Derek Fowler and Bernd Tiemeyer MANAGEMENT INFLUENCE ON SAFETY Governing Safety Management Andrew Vickers Understanding the Risks Posed by Management Felix Redmill I

9 Common Law Safety Case Approaches to Safety Critical Systems Assurance Kevin Anderson SOFTWARE SAFETY Ada 2005 for High-Integrity Systems Josd F Ruiz Safety Aspects of a Landing Gear System Dewi Daniels NEW TECHNOLOGIES IN SAFETY-CRITICAL SYSTEMS Optimising Data-Driven Safety Related Systems Richard Everson, Jonathan Fieldsend, Trevor Bailey, Wojtek Krzanowski, Derek Partridge, Adolfo Hernandez and Vitaly Schetinin Classification with Confidence for Critical Systems D Partridge, T C Bailey, R M Everson, J E Fieldsend, A Hernandez, W J Krzanowski and V Schetinin Use of Graphical Probabilistic Models to Build SIL Claims Based on Software Safety Standards such as IEC Mario Brito, John May, Julio Gallardo and Ed Fergus ADDING DIMENSIONS TO SAFETY CASES Safety Arguments for Use with Data-driven Safety Systems Alastair Faulkner Gaining Confidence in Goal-based Safety Cases Rob Weaver, Tim Kelly and Paul Mayo Author Index