Jun

22

Aviation Safety experts talk a lot about "The Swiss Cheese Model" of human error as described by Dr. James Reason of the University of Manchester Dept. of Psychology.

From wikipedia:: ( http://tiny.cc/ysg88 )

"James Reason hypothesizes that most accidents can be traced to one or more of four levels of failure: Organizational influences, unsafe supervision, preconditions for unsafe acts, and the unsafe acts themselves. In this model, an organization's defences against failure are modelled as a series of barriers, with individual weaknesses in individual parts of the system, and are continually varying in size and position. The system as a whole produces failures when all individual barrier weaknesses align, permitting "a trajectory of accident opportunity", so that a hazard passes through all of the holes in all of the defenses, leading to a failure."

In "Human error models and management" ( http://tiny.cc/xl25n ) James Reason criticizes the "person approach" to human error and suggests a "Systems approach": "The long-standing and widespread tradition of the person approach focuses on the unsafe acts—errors and procedural violations—of people on the front line …" ~ " It views these unsafe acts as arising primarily from aberrant mental processes such as forgetfulness, inattention, poor motivation, carelessness, negligence, and recklessness. The associated countermeasures are directed mainly at reducing unwanted variability in human behavior."

… "Another serious weakness of the person approach is that by focusing on the individual origins of error, it isolates unsafe acts from their system context. As a result, 2 important features of human error tend to be overlooked. First, it is often the best people who make the worst mistakes—error is not the monopoly of an unfortunate few. Second, far from being random, mishaps tend to fall into recurrent patterns. The same set of circumstances can provoke similar errors, regardless of the people involved. The pursuit of greater safety is seriously impeded by an approach that does not seek out and remove the error-provoking properties within the system at large."

"The basic premise in the system approach is that humans are fallible and errors are to be expected, even in the best organizations. Errors are seen as consequences rather than causes, having their origins not so much in the perversity of human nature as in “upstream” systemic factors. These include recurrent error traps in the workplace and the organizational processes that give rise to them.

Countermeasures are based on the assumption that although we cannot change the human condition, we can change the conditions under which humans work. A central idea is that of system defenses. All hazardous technologies possess barriers and safeguards. When an adverse event occurs, the important issue is not who blundered, but how and why the defenses failed."

His seminal work : "Human Error", James Reason, 1990 ( http://tiny.cc/i1q5a )


 Peter Grieve comments:

This is very similar to Nigel's chess teaching - when someone makes a blunder, usually it's been set up by a position that has been deteriorating for several moves.


 

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