(b)With reference to practical examples or actual incidents, explain how EACH of these types of operating behaviour can give rise to human error AND, in EACH case, explain how human error can be prevented.

In the case of ‘skill-based’ behaviour, errors may arise if a similar routine is incorrectly selected, if there is interruption or inattention causing a stage in the operation to be omitted or repeated or if checks are not carried out to verify that the correct routine has been selected. Preventive measures would be directed at designing routines and controls so that they are distinct from each other, using feedback signals to warn when the wrong course of action is being taken, allowing adequate work breaks or job rotation to maintain attention and introducing training, competence assessment and a high level of supervision. Signals passed at danger on the railway may be a result of skill-based errors.

‘rule-based’ behaviour, errors may occur where, for example, the diagnosis is based only on previous experience or where sufficient training has not been given to enable employees to make an accurate diagnosis, where there is a tendency to apply the usual rule or solution even if it is inappropriate or where simply there is a failure to remember the rule that should be applied. Preventive measures include clear presentation of information, logical and easy to follow rule sets, systems designed to highlight infrequent or unusual events and the provision of training and competence assessment.

Examples (if properly explained) could have included the Kegworth air crash, Piper Alpha or Three Mile Island In the case of ‘knowledge-based’ behaviour errors will occur if there is a lack of knowledge or inadequate understanding of the system, if there is insufficient time to carry out a proper diagnosis and if the problem is not properly thought through or evidence is ignored. Preventive measures would again involve training particularly in risk and hazard assessment, the provision of adequate resources in terms of information and time and the use of supervision and checking systems such as group or peer review.
Flixborough and Port Ramsgate provide examples of this type of error. There were candidates who had difficulty in matching errors with the correct type of behaviour whilst others were unable to explain how human error might be prevented.