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Using IEC 61508 to Guide the Investigation of Computer-Related Incidents and Accidents. Chris Johnson University of Glasgow, Scotland. http://www.dcs.gla.ac.uk/~johnson SAFECOMP: 26 th September 2003. Acknowledgements. HSE: Mark Bowell, Ray Ward.
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Using IEC 61508 to Guide the Investigation of Computer-Related Incidents and Accidents Chris Johnson University of Glasgow, Scotland. http://www.dcs.gla.ac.uk/~johnson SAFECOMP: 26th September 2003
Acknowledgements • HSE: Mark Bowell, Ray Ward. • Adelard: George Clelland, Peter Bishop, Sofia Guerra, Robin Bloomfield, Luke Emmett. • Blacksafe Consulting: Bill Black. • Glasgow University: Chris Johnson. Look, I’m not blaming you, I’m just suing you…
HSE Investigatory Process
Not Prosecute HSE Investigatory Process Prosecute
Key Design Objectives • Proportionate effort: • simple technique for ‘simple incident’; • more complex technique if appropriate. • Links to development standard (61508): • help identify processes that ‘failed’; • provide feedback if standard is failing? • Support different potential users: • end-users may know little about architecture; • suppliers are not integrators are not developers…
PARCEL: Programmable Electronic Systems Analysis of Root Causes
PARCEL: Programmable Electronic Systems Analysis of Root Causes As opposed to Leveson’s STAMP…
Key Issues with Flow Chart • Need several passes for multiple causes. • Protocol can increase consistency: • ‘are you sure’, ‘can you justify selection’. • Insufficient information for some areas: • End-users only look at subset of chart; • End-users lack development information.
Decision to Open Valve C Would the incident have been prevented if:
Conclusions - PARCEL • Program. Electronic Systems Analysis of Root Causes • Uses 2 existing techniques (ECF & Flowcharts). • Design objectives: • Proportionate effort; • Links to development standard (61508); • Support user/supplier/integrator/developer… • Being validated for HSE technical report.
Concerns 1:Flow Chart Validation • The flow chart is very simplistic. • Will people be able to use it consistently? • How much must we change for each industry? • Can it really be used by: • developers, vendors, integrators and end-users?
Concerns 2: Human Factors • PARCEL is narrowly based on IEC61508. • IEC61508 is poor on human factors issues. • But HSE and others are addressing this?
Concerns 3: IEC61508? • PARCEL embodies IEC61508: • Can we use it with other standards? • Will it really help spot problems in 61508? • PARCEL embodies flowcharts and ECF: • We could use flowcharts and STAMP? • Must match tool complexity to industry need.
Medical Example • End-user frustrated by device unreliability and manufacturers’ response: SEVERAL UNITS RETURNED FOR REPAIR HAD FAN UPGRADES TO ALLEVIATE TEMP PROBLEMS. HOWEVER, THEY FAILED IN USE AGAIN AND WERE RETURNED FOR REPAIR… AGAIN SALESMAN STATED ITS NOT A THERMAL PROBLEM ITS A PROBLEM WITH X’s Circuit Board. X ENGINEER STATED Device HAS ALWAYS BEEN HOT INSIDE, RUNNING AT 68⁰C AND THEIR product ONLY RATED AT 70⁰C…. ANOTHER TRANSPONDER STARTED TO BURN…SENT FOR REPAIR. SHORTLY AFTER MONITOR BEGAN RESETTING FOR NO REASON…(MDR TEXT KEY: 1370547) • Manufacturers felt reports not safety-related: • “reports relate to end-user frustration regarding product reliability (not safety)”.
Da Vinci, 1st robotic aid approved by the FDA: • New York Presbyterian Hospital uses it on atrial septal defects. • ‘Fly-by-wire’ technology, enhanced 3D ‘virtual’ display of site. • Ave. hospital stay 7-10 days (traditional) now 3 days (N=17).
Questions? http://www.dcs.gla.ac.uk/~johnson Acknowledgements: Mark Bowell (HSE); Bill Black (Blacksafe Consulting); Peter Bishop (Adelard); Luke Emmett (Adelard); George Clelland (Adelard); …