What’s wrong with Swiss Cheese model?

Not far from my home, there are two trees with one leaning on another. As a forest walker, I’ve been watching these trees for over three years. It has now come to the point that the tree on the left (taking the weight of the leaning tree) has also begun uprooting. On a windy day, one can hear the screeching sound from the tree on the left as if it is screaming out for help. In the beginning, all that came to mind was a simple, straightforward, and linear explanation just like the one supplied by the Swiss Cheese model.

When I asked people walking past what they made of the two trees, their answer was ‘The Domino Effect’ in action or how ‘one thing leads to another’. And it sounds so appealing.

Observe their metaphor. Weak roots, heavy bottom, poor foundations and a cascading effect. The origin of the problem is down there. It makes for a simple, straightforward story.

But here’s an alternative narrative. We’ve experienced exceptional weather in Scotland for the last few years. Trees around here adapt to withstand wind and weather from the Southwest direction. (In fact, the UK infrastructure in general is designed based on the traditional S/SW wind direction). In the last quarter of 2021, Scotland has experienced two intense and consecutive storms (Arwen and Corrie) that have caused havoc across the country. In both the cases, the gust came from the North and, as a result, tens of thousands of trees were felled throughout the country. The problem was not with the roots ‘down there’ but the abrupt change in the weather that came into opposition with the ecological design.

We love simple stories and models like Swiss-Cheese and Bow-Ties provide instant gratification. But as Oscar Wilde once said, ‘the truth is rarely pure and never simple.’

I have been warned on many occasions that both Bow-Ties and Swiss Cheese are only helpful to trigger conversations. But such lame explanations dismiss the importance of metaphors and how one metaphor of reality becomes dominant over another. The problem is not with the Swiss Cheese model (or for that matter, FRAM, STAMP, RCA, 5 why’s and RCA). The real issue is in over-identifying with either of these and losing the ability to think critically.

In our forthcoming book, Robert Long and I will share the limitations of all the dominant models and metaphors of risk and safety and how they can prove misleading in learning from accidents and beyond.

Good investigation models do not begin with pointing at the problem up, down, or sideways. They start with putting a mirror on the investigators to help them realise the limits of their worldview.

If you are genuinely interested in unlearning and learning from accidents, the starting point is to question your metaphors, models and ethics.