The Swiss cheese model of accident causation is a model used in risk analysis and risk management, including aviation safety, engineering, healthcare, emergency service organizations, and as the principle behind layered security, as used in computer security and defense in depth.
It likens human systems to multiple slices of Swiss cheese, stacked side by side, in which the risk of a threat becoming a reality is mitigated by the differing layers and types of defenses which are "layered" behind each other. Therefore, in theory, lapses and weaknesses in one defense do not allow a risk to materialize, since other defenses also exist, to prevent a single point of failure.
The model was originally formally propounded by James T. Reason of the University of Manchester, and has since gained widespread acceptance. It is sometimes called the "cumulative act effect".
Holes and slices
In the Swiss cheese model, an organisation's defenses against failure are modeled as a series of barriers, represented as slices of cheese, specifically Swiss cheese with holes known as "eyes", such as Emmental cheese. 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 (in Reason's words) "a trajectory of accident opportunity", so that a hazard passes through holes in all of the slices, leading to a failure
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It likens human systems to multiple slices of Swiss cheese, stacked side by side, in which the risk of a threat becoming a reality is mitigated by the differing layers and types of defenses which are "layered" behind each other. Therefore, in theory, lapses and weaknesses in one defense do not allow a risk to materialize, since other defenses also exist, to prevent a single point of failure.
The model was originally formally propounded by James T. Reason of the University of Manchester, and has since gained widespread acceptance. It is sometimes called the "cumulative act effect".
Holes and slices
In the Swiss cheese model, an organisation's defenses against failure are modeled as a series of barriers, represented as slices of cheese, specifically Swiss cheese with holes known as "eyes", such as Emmental cheese. 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 (in Reason's words) "a trajectory of accident opportunity", so that a hazard passes through holes in all of the slices, leading to a failure
Link