Swiss Cheese Model

In the Swiss cheese model, an organisation’s defenses against failure are modeled as a series of imperfect barriers, represented as slices of cheese, speci cally Swiss cheese with holes known as “eyes”. The holes in the slices represent weaknesses in individual parts of the system and are continually varying in size and position across the slices. The system produces failures when a hole in each slice momentarily aligns, permitting “a trajectory of accident opportunity”, so that a hazard passes through holes in all of the slices, leading to a failure.