Human Performance Fundamentals A New Way of Thinking
ANATOMY OF AN EVENT
Events are caused. Typically, they are triggered by human action. In most cases, the human action causing the event was in error. However, the action could have been directed by a procedure; or it could have resulted from a violation -- a short cut to get the job. In any case, an act initiates the undesired consequences. The Anatomy of an Event graphic below provides an illustration of the elements that exist before a typical event occurs. Breaking the linkages will prevent events.
Anatomy of an Event
An event is an unwanted, undesirable change in the state of facility structures, systems, or components or human/organizational conditions (health, behavior, administrative controls, environment, and so on) that exceeds established significance criteria. Events involve serious degradation or termination of the equipment's ability to perform its required function. Other definitions include: an outcome that must be undone; any facility condition that does not achieve its goals; any undesirable consequence; a difference between what is and what ought to be. The following paragraphs describe in some detail how events come about.
The initiating action is an action by an individual, either correct, in error, or in violation, that results in a facility event.ivSenders and Moray. Human Error: Cause, Prediction, and Reduction. 1991, p. 20. Active errors are those errors that have immediate, observable, undesirable outcomes in the physical facility. They can be either acts of commission or omission. The majority of initiating actions are active errors. Therefore, a strategic approach to preventing events should be the anticipation and prevention of active errors.
Flawed defenses are defects under the right circumstances that may inhibit the ability of defensive measures to protect facility equipment or people against hazards or fail to prevent the occurrence of active errors. Defenses or barriers are methods that
- protect against various hazards (such as radiation, chemical, heat)
- mitigate the consequences of the hazard (for example, reduced operating safety margin, personal injury, equipment damage, environmental contamination, cost)
- promote consistent behavior. When an event occurs, there is either a flaw with existing defenses or appropriate defenses are not in place.
Error Precursors are unfavorable prior conditions at the job site that increase the probability for error during a specific action, that is, error-likely situations. An error-likely situation — an error about to happen — typically exists when the demands of the task exceed the capabilities of the individual or when work conditions aggravate the limitations of human nature. vReason. Managing the Risks of Organizational Accidents. 1998, p. 142. Error-likely situations are also known as error traps.
Latent Organizational Weaknesses The decisions and activities of managers and supervisors determine what is done, how well it is done, and when it is done, either contributing to the health of the organization or further weakening its resistance to error and events. Consequently, managers and supervisors should perform their duties with the same uneasy respect for error-prone work environments as workers are expected to at a job site. Understanding the major role the organization plays in the facility's performance — a second strategic thrust to preventing events — should be the identification and elimination of latent organizational weaknesses.
Latent organizational weaknesses are hidden deficiencies in management control processes (for example, strategy, policies, work control, training, and resource allocation) or values (shared beliefs, attitudes, norms, and assumptions) create workplace conditions that can provoke error (precursors) and degrade the integrity of defenses (flawed defenses). viReason. Managing the Risks of Organizational Accidents. 1998, p, 10-18.
Strategic Approach for Human Performance
The strategic approach to improving human performance within the DOE community embraces two primary challenges:
- Anticipate, prevent, catch, and recover from active errors at the job site.
- Identify and eliminate latent organizational weaknesses that provoke human error and degrade defenses against error and the consequences of error.
If opportunities to err are not methodically identified, preventable errors will not be eliminated. Even if opportunities to err are systematically identified and prevented, people still err in unanticipated and creative ways. Consequently, additional means are necessary to protect facility equipment from errors that are not prevented or anticipated. Reducing the error rate minimizes the frequency, but not the severity of events. Only defenses prevent an event, which is the severity of the outcome of error. Defense-in-depth-defenses, barriers, controls, or safeguards arranged in a layered fashion — provides assurance such that if one fails, remaining defenses will function as needed to reduce the impact on the physical facility.
To improve human performance and facility performance, efforts should be made to 1) reduce the occurrence of errors at all levels of the organization and 2) enhance the integrity of defenses, barriers, controls, or safeguards discovered to be weak or missing. Reducing errors (Re) and managing defenses (Md) will lead to no significant events (OE). Eliminating significant facility events will result in performance improvement within the organization.
Principles of Human Performance
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