Swiss cheese safety model

Figure 4.1 also illustrates the additive nature of a job s safety risks. That is, added safety risks associated with each factor cumulatively increase the job s overall safety risk. The additive nature of risk is well captured by Reason s (1990) Swiss cheese safety model. Each factor represents a risk layer, and the probability of an accident increases as the number of risk layers increases. Where possible a job which a new employee is entering should be striped of as many risk layers as possible. As will be discussed below, more senior employees, who are experienced, are likely to be better able to cope with job risks which are difficult or impossible to remove. 

The Swiss Cheese Model of Accident Causation is a prerequisite for understanding the dynamics of the emerging risk and organizational defenses that are necessary to improve safety. Figure 4.2 illustrates the model, using its metaphor, a wedge of Swiss cheese. The model was described in detail in Chapter Three here, a metaphorical exploration of the model amplifies its implications for accepting leadership responsibility. 

Gradually the evidence accumulated to indicate that crashes have multiple, interactive causes, and that a systems approach was likely to prove a more fruitful approach to prevention. The notion of a causal chain spanning an extended timeline, with injurious events being the result of the coincidence of causal circumstances—the Swiss cheese conceptual model—became an accepted conceptual approach in industrial safety long before its widespread acceptance in the field of traffic safety. ... 

James Reason offered another useful model, often referred to as the Swiss cheese model, that explains how the many factors can converge, resulting in an incident (Figure 6-5). A company tries to promote safety and prevent catastrophic incidents hy putting into place layers of system defenses, depicted in Figure 6-5 as slices of Swiss cheese. Essentially, the term system defenses refers to the safety-related decisions and actions of the entire company top management, the line supervisors, and the workers. This model recognizes that each defense layer has weaknesses or holes. 

Process safety incidents are rarely caused by a single catastrophic failure, but rather by multiple events or failures that coincide and collectively result in an incident. This relationship between simultaneous or sequential failures of multiple systems is illustrated by the Swiss cheese model, as shown in Figure 1.1, where hazards are contained by multiple protective barriers that may have weaknesses or holes. ... 

The Swiss cheese model of accident causation was originally proposed by British psychologist James T. Reason and has since gained widespread acceptance in many risk-analysis and management fields including process safety. 

Figure 1.1 Swiss Cheese Process Safety Model (CCPS, 2007b)...

The Swiss cheese model (see Figure 1.3 in Chapter I and Figure 3.2) offers another useful way to envision how failure to contain a hazard could result in a serious consequence if the process safety barriers and controls have weaknesses— the holes in the slices of Swiss cheese. For example, in order to prevent the risk of an accident, such as hydrocarbon release, a number of barriers (i.e., risk reduction... 

Regardless of whether one uses the process safety pyramid, the Swiss cheese model, or something else (for example, the anatomy of an incident model discussed in HEP 3), the concepts of... 

Perneger, T.V. 2005. The Swiss cheese model of safety incidents Are there holes in the metaphor BMC Health Services Research. 5 71. 

The study of patient safety is the study of complexity. The study of complexity invites us to understand key concepts that can be applied to patient safety. Basic concepts from the fleld of patient safety are sharp and blunt end active and latent failure the Swiss Cheese Model of Accident Causation slips, lapses, and mistakes and hindsight bias and the fundamental attribution error. Key concepts from organizational analysis, such as normalization of deviance, diffusion of responsibility, tightly coupled work processes, and sensemaking, introduce practical lessons from high-reliability organizations. Application of specific lessons to health care are explored in Chapter Five. 

An important component of the Swiss Cheese Model depicted in Figure 3.3 is the individual plane. This plane represents the protective defenses put up by workers at the sharp end to deflect failure and vulnerability from becoming transformed into harm. Individual workers create safety at the sharp end aU the time as they encounter hazards and opportunities for failure and continually stop them before they reach patients. It is when worlqjlace stresses erode the coping resources... 

Concept to Action Using the Swiss Cheese Model to Deconstruct Risk-Prone Conditions and Improve Safety... 

As a participant in his hospital s patient safety initiative, pediatric emergency physician Tom Hellmich attended several educational sessions where he learned about basic concepts in safety, such as hindsight bias and the Swiss Cheese Model. The lessons proved useful during a particularly busy week at work. In one day, two children, one in the hospital s emergency department and the other in an inpatient unit, suffered a cardiac arrest, requiring a code to be called. 

New students of patient safety quickly discover that the Swiss Cheese Model can alter perceptions. 

The systems approach seeks to identify situations or factors likely to contribute to human error. James Reason s analysis of industrial accidents revealed that catastrophic safety failures almost never result from isolated errors conunitted by individuals. Most incidents result from smaller and multiple errors in components and environments with underlying system flaws. Reason s Swiss Cheese Model describes this phenomenon. Errors made by individuals can result in disastrous consequences due to flawed systans that are represented by the holes in the cheese. Reason believed human error would happen in complex systems. Striving for perfection or punishing individuals who make errors does not appreciably improve safety. A systems approach stresses efforts to catch or anticipate human errors before they occur. Reason used the terms active errors and latent errors to distinguish individual errors from system errors. Active errors almost always involve frontline personnel. They occur at the point of contact between a human and some element of a larger system. Latent errors occur due to failures of the organization or designs that allow inevitable active errors to cause harm. The terms sharp end and blunt end correspond to active error and latent error. The systems approach provides a framework for analysis of errors and efforts to improve safety. 

Schwartz (2010) have presented a method for the identification of barriers on the basis of a fault tree. The method is based on the so-called Swiss Cheese model, in which holes must overlap so that the arrow may go through (so that safety fallibility occurs). The situation of risk, which is the peak event, is modeled by a classic fault tree with AND and OR gates. 

As mentioned in the background section, barrier management has been highly focused in the Norwegian petroleum industry lately. Safety barriers are implemented to avoid hazards or accidents. When several barriers are in place to prevent an undesirable event or accident, this is often referred to as defence in depth . The principles apply to safety in rig move operations as well. Severd barriers must fail simultaneously in order for an accident to occur. This is often illustrated by the Swiss cheese model (Reason, 1997). The following barrier definitions are based on the memo Principles for barrier management in the petroleum industry (PSA, 2013) ... 

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