fragmented than the maritime sector, such as nuclear power generation. Fishbone diagrams may be more suitable but also bring with them some inappropriate conceptual background.
The dymamics of the interactions between regulatory system elements have been discussed (Refs 10, 13, 14) but are considered a second order issue here and not discussed further. The portrayal of such interactions would require a different format, such as an influence diagram.
Annex B
Systems, causation, and creating safety
Incidents have large numbers of 'causes'. Wagenaar (Ref 15) has shown 'The number of causes in the 100 accidents ranged from 7 to 58 with a median of 23. The median number of 12 gates per network indicates that the number of steps between the remotest causes and the final consequence was fairly large- much bigger than even a very experienced chess player would consider in deciding about the next move. The analysis of 100 accidents at sea has brought us to the conclusion that the acts which lead to an accident are part of a complex causal network that cannot be overseen by the actors. Errors do not look like errors at the time they are perpetrated, and the accidents that are caused by them look impossible beforehand'. The number of causes identified was considered to be conservative because of the source data used.
Complex systems are not inherently safe (Cook, Ref 2); people continually create safe systems by local adaptations. With hindsight, some of these adaptations can look like errors. Taking a limited view of 'cause' may do something to prevent a re-occurrence of the identical incident but may do little to prevent the next one. Even this may be optimistic. ‘Views of 'cause' limit the effectiveness of defenses against future events. Post-accident remedies for 'human error' are usually predicated on obstructing activities that can 'cause' accidents. These end-of-the-chain measures do little to reduce the likelihood of further accidents.
In fact that likelihood of an identical accident is already extraordinarily low because the pattern of latent failures changes constantly. Instead of increasing safety, post- accident remedies usually increase the coupling and complexity of the system. This increases the potential number of latent failures and also makes the detection and blocking of accident trajectories more difficult.’ (Cook, Ref 2)
The mechanistic analysis of the coupling shaft in Fig 1 is appropriate; such a process could conceivably be described by equations. However, such an analysis is not appropriate to the bridge, the design office or a fitting shop. Weinberg (Ref 16) points out the limits of mechanistic analysis and statistical analysis and the use of system to fill 'the yawning gap in the middle'. The idea of strict causality and the treatment of counterfactuals then changes.
THE NAVALARCHITECT FEBRUARY 2006 Annex D. Assessment of the incident involving the loss of Jambo(Ref 18).
The authors propose that active failures (and hence incidents) occur when the demands of earlier shortfalls exceed the resources available to create safety; 'an accident waiting to happen' is a fair summary of the build up to many incidents. The systems approach gives philosophical support to 'learning from incidents'. The specific causal path attributed to an incident assumes less importance, and the shortfalls identified that were not deemed directly causal become worthy of consideration.
References
1. Harremoes, P et al, Late Lessons from early Warnings: the Precautionary Principle 1896-2000, European Environment Agency, (2001). 2. Cook, R I, How Complex Systems Fail, Cognitive Technologies Laboratory.
http://www.ctlab.org/publications.cfm (2000) 3. Dekker, S, The Field Guide to Human Error Investigations, Ashgate (2002). 4. Johnson, C W, 'Why Human Error Analysis Fails to Help Systems Development', Interacting With Computers 5, 517-524 (1999) 5. Open University, Systems Thinking and Practice: Diagramming, T552,
http://systems.open.ac.uk/materials/t552/inde x.htm 6. Hudson, P, Reason, J, Wagenaar, W, Bentley, P, Primrose, M, and Visser, J, TRIPOD Delta: 'Pro-active approach to enhanced safety'. Journal of Petroleum Technology, 1994 46: (1994). 7. National Transportation Safety Board (USA), 'Grounding of the Panamanian Passenger Ship Royal Majesty on Rose and Crown Shoal near Nantucket, Massachusetts, June 10, 1995'. NTSB PB97-916401, Marine Accident Report NTSB/MAR-97/01, (1997). 8. Pomeroy, R V and Sherwood Jones, B M, 'Managing the Human Element in Modern Ship Design and Operation', International
Conference on Human Factors in Ship Design & Operation, The Royal Institution of Naval Architects, (2002). 9. Johnson, C W, 'Reasons for the failure of incident reporting in the healthcare and rail industries', Redmill, F,
Anderson, T,
Tenth Safety-Critical Systems Symposium, Southampton, UK, Springer- Verlag, (2002). 10. Rasmussen, J, 'Risk Management in a Dynamic Society: A Modelling Problem', Safety Science, Vol. 27, No. 2/3, pp. 183-213, (1997). 11. Moray, N, Error Reduction as a Systems Problem in Bogner MS, ed., Human Error in Medicine. Erlbaum, L, pp. 255-310. [ISBN 0- 8058-1385-3] (1994) 12. Reason, J, Managing the Risks of Organizational Accidents, Ashgate, (1997) 13. Andrew, M, Hampshire, E, Webb, J, 'A "system-of-systems" risk approach', XVII Annual Conference of the International Society for Occupational Ergonomics and Safety; Munich (2003). 14. Andrew, M, 'Reframing Risk using Systems Thinking', Proceedings of the Annual Ergonomics Society Conference; Edinburgh (2003). 15. Wagenaar, W A and Groeneweg, J, ‘Accidents at sea: Multiple causes and impossible consequences’, International Journal of Man-Machine Studies 27, 587-598 (1987) 16. Weinberg, G M, An Introduction to General Systems Thinking, Dorset House (1975). 17. MAIB, Report on the investigation of the impact with the quay by the passenger ro-ro ferry P&OSL Aquitaine at Calais on 27 April, 2000, Report No 27/2001 (July 2001). 18. MAIB, Report on the investigation of the grounding and loss of the Cypriot-registered general cargo ship Jambo, Report No. 27/2003.
'Components of System Safety'. Proceedings of the
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