'Swiss Cheese' safety model

From - "Survive ! – Remarkable tales from the New Zealand outdoors." Who lives, who dies and why. By Carl Walrond, 2008 613.69 WAL http://image.slidesharecdn.com/elizabethtosti-140325193525-phpapp01/95/elizabeth-tosti-director-health-safety-and-environment-goodman-fielder-developing-a-safety-strategy-to-achieve-your-company-goals-11-638.jpg The ‘Swiss Cheese' model of human error - from ‘Human Error’ by James Reason There are 4 levels of human failure, each influencing the next. The levels, that are barriers that deflect hazards, are like slices of Swiss cheese. For the accident to occur, the hazard must pass through one hole in each slice and the holes must line up. Many different factors (each slice) must synchronise. No two slices have holes in the same place, so that when they align, the combination of where holes occur is unique. Accidents follow a unique set of circumstances. In real life the ‘holes’ are not static, but are constantly opening and closing with time. - Organisational influences. - Pre-conditions for unsafe acts. - Unsafe supervision. - Unsafe acts. The first 3 are ‘Latent Failures’ as they are insidious factors, lurking in the background. ‘Unsafe Acts’ is an ‘Active Failure’ as it involves decisions made on the ground. The balance has shifted in accident investigations, from finding scapegoats and single causes, to accepting that in many cases there is no real underlying cause, but that many factors may contribute. Instead of dismissing an accident by saying “ Someone made an error, so they died”, the finding nowadays is more likely to be “Most people, in this situation, who made this error, would die”.

That’s jolly interesting, and makes a lot of sense. I must admit that when Yessica Asmin was swept to her death recently I think we could all see that there were a number of pre-conditions that disposed themselves to an accident but the decision to cross was entirely of their own doing. It was a terribly sad end for all involved but Sebastian Keilholz ranting in the media and blaming DOC was, while an entirely natural human reaction, entirely without substance because the “active failure” was theirs alone. Nobody forced them to cross! Very interesting article, thankyou

Ta. The book "Survive" has been mentioned before on the forum. I believe it's out of print, but Christchurch library has a copy. Other libraries as well, maybe ?. The chapters are stories of incidents, that illustrate principles of how to stay alive. Easy reading. If you watch First Crossings/Intrepid NZ, then you'll motor through it. The 'Swiss Cheese Safety Model' came from the summary in the appendix, I think.

It's a good book. Carl Walrond, the author, also has an ongoing series of shows on Radio Live, archived at http://www.radiolive.co.nz/WeekendHosts/WeekendVarietyWirelesswithGraemeHill/TalesOfTheLostwithCarlWalrond.aspx

For what it's worth, another excellent book of a comparable type, which considers a bunch of historic scenarios is High Misadventure, by Paul Hersey. One example scenario is the guide who, as recently as 1988, had a client swept away to their death on a trip, and was ordered by his employer to continue running more trips for more clients with no stand-down or counselling, only to have another near-fatal accident immediately after. Also the 1990 army cadets' AIC tragedy on Ruapehu, 1977 Three Johns Hut, the Mt Tasman slab avalanche of 2003, and others.

I agree that is an excellent book, it doesnt go into a lot of analysis about the particular cases but the mistakes slap you in the face as you are reading it. The swiss cheese model is taught on NOL's courses, it is a very elegant way to explain how accidents happen. Everyone who spends time in the outdoors should have a passing interest in this type of material. Even if it is only reading accident reports in old FMC bulletins, there is a wealth of learning to be had.