2) Error type or violation
The second sub-step is the selection of the error type or violation that best describes the failure, keeping in mind the decision regarding internationality. There are four potential error/violation categories, i. e., slip, lapse, mistake and violation. A slip is an unintentional action where the failure involves attention. These are errors in execution. A lapse is an unintentional action where the failure involves memory. These are also errors in execution. A mistake is an intentional action, but there is no deliberate decision to act against a rule or plan. These are errors in planning. A violation is a planning failure where a deliberate decision to act against a rule or plan has been made. Routine violations occur everyday as people regularly modify or do not strictly comply with work procedures, often because of poorly designed or defined work practices. In contrast, an exceptional violation tends to be a one-time breach of a work practice, such as where safety regulations are deliberately ignored to carry out a task. Even so, the intention was not to commit a malevolent act but just to get the job done.
Step 5-Identify underlying factors
The designation of separate activities implied by steps 4 and 5 may be somewhat arbitrary in terms of what actually occurs when an investigator attempts to reveal the relationship between the occurrence errors/violations and the behaviour that lead to them. In simplest terms, behaviour consists of a decision and an action or movement. In step 3, the action or decision (i. e., unsafe act or decision) was identified. In step 4, what was erroneous regarding that action or decision was revealed. In step 5, the focus is on uncovering the underlying causes behind the act or decision of an individual or group. To do so it is important to determine whether there were any factors in the work system that may have facilitated the expression of the given failure mode (and hence the error/violation and the unsafe act). These factors have been termed underlying factors. They can be found by examining the work system information collected and organized using the SHEL or Reason frameworks in steps 1 and 2. The re-examination of these data emphasizes the iterative nature of this investigative process in that it may even be deemed necessary to conduct further investigations into the occurrence.
Step 6-Identify potential safety problems and develop safety actions
The identification of potential safety problems is based extensively on what factors were identified as underlying factors. Once again this underscores the importance of the application of a systematic approach to steps 1 and 2 of the process, which lays the foundation for the subsequent analysis steps. Where appropriate, potential safety problems can be further analysed to identify the associated risk to the system and to develop safety actions.
References
Edwards, E (1972). Man and machine: Systems for safety. In Proceedings of the BALPA Technical Symposium, London.
Hawkins, F.H. (1987). Human factors in flight. Aldershot, UK: Gower Technical Press.
Nagel, D.C. (1988). Human error in aviation operations. In E. L. Weiner and D. C. Nagel (Eds.), Human factors in aviation (pp. 263-303). San Diego, CA: Academic Press.
Norman. D.A. (1981). Categorization of action slips, Psychological Review, 88 (1), 1-15.
Norman D.A. (1988). The psychology of everyday things. New York: Basic Books.
Rasmussen, J. (1987). The definition of human error and a taxonomy for technical system design. In J. Rasmussen. K. Duncan, and J. Leplat (Eds.), New technology and human error. Toronto: John Wiley & Sons.
Reason, J. (1990). Human error. New York: Cambridge University Press.
