SAFEWARE: SYSTEM SAFETY AND COMPUTERS

                   Nancy G. Leveson

              University of Washington

(leveson@cs.washington.edu)

Publisher:  Addison-Wesley
ISBN: 0-201-11972-2
Price: $49.50

Contents: This book examines past accidents and what is currently known 
about building safe electromechanical systems to see what lessons can be 
applied to new computer-controlled systems.  One lesson is that most 
accidents are not the result of unknown scientific principles but rather 
of a failure to apply well-known, standard engineering practices.  A 
second lesson is that accidents will not be prevented by technological
fixes alone, but will require control of all aspects of the development 
and operation of the system.  The features of a methodology for building
safety-critical systems are outlined.

PART 1: The Nature of Risk (126 pages) 

   Is there a problem? 
   How safe is safe enough?
   The role of computers in accidents
   Software myths 
   Why software engineering is hard
   Problems in ascribing causality 
   A hierarchical model of causality
   Root causes of accidents 
   Do humans cause most accidents? 
   The need for and role of humans in automated systems

PART 2: Introduction to System Safety  (50 pages)

   Foundations of system safety (systems theory and systems engineering)
   Historical development
   Basic concepts (hazard analysis, design for safety, management),
   Software system safety 
   Cost and effectiveness of system safety
   Other approaches to safety (industrial engineering, reliability
       engineering).

PART 3: Definitions and Models  (75 pages) 

   Terminology 
   Accident models
   Human task and error models

PART 4: Elements of a Safeware Program  (290 pages) 

   Managing safety (the role of management, setting policy, communication
       channels, setting up a system safety organization, place in the 
       organizational structure, documentation) 
   The system and software safety process (general tasks, real examples) 
   Hazard analysis (what it is, how to do it, types of models, types of 
       analysis, current models and techniques, limitations, evaluations) 
   Software hazard analysis and requirements analysis
   Designing for safety 
   Design of the human--machine interface 
   Verification of safety (testing, software fault tree analysis).

APPENDICES:  (132 pages) 
 
 Detailed descriptions of well-researched accidents along 
 with brief descriptions of industry-specific approaches to safety 
   
Appendix A
 Medical Devices:  The Therac-25 story
   
Appendix B
  Aerospace:  The civil aviation approach to safety, Apollo 13, DC-10,
   and Challenger
   
Appendix C
  The Chemical Industry: The chemical process industry approach to 
   safety, Seveso, Flixborough, and Bhopal
   
Appendix D
  Nuclear Power: How a nuclear power plant works, The nuclear power
   approach to safety, Windscale, Three Mile Island, and Chernobyl

References (20 pages)