Analysis Techniques For Man-Machine Systems Design

NATO UNCLASSIFIED115 - AC 243(Panel-8)TR/ 7i 15 Volume 25.8 ANALYSIS OF HUMAN ERRORS AS CAUSAL FACTORS INACCIDENTSWhat the technique doesThe analysis of how an accident happened can be represented by a network. Events leading to an accident are connectedby logical AND/OR gates, revealing the causal factors. In the case of AND-gates. the related deviations fromnormative performance all need to be present for the occurrence of the accidenL In the case of OR-gates, there is onlyone factor deviating from the normative approach needed. The transmission from the accident description to theschematized network of AND/OR gates is dependent on the interpretation of the described data. The approach isprimarily relevant if a number of accidents, for instance more than 100, are reported. The analysis of factors, after theprocess of indicating the chain of events leading to an accident, will show factors to remedy accidents byimprovement of hardware and software design, operational procedures, and selection and training procedures.Inputs to the techniqueDescriptions of a number of accidents (at least 100)suitable for interpretation to provide data to generate acausal network.Outputs of the techniqueThe approach produces a set of causal factors.When to useBecause of the need to develop the data base over a long period, the technique should not be restricted to applicationwithin any one project development cycle. The technique should be used early in the design phases of a specificsystem to identify possible human factors leading to accidents.Related techniquesFault tree analysis techniques.Resources requiredThe technique can be used with only a paper and pencil. It requires access to a collection of consistently reportedaccident and incident data. Analysts may develop their own networks of causal factors, or use an established taxonomyof human errors (e.g., Feggetter, 1982; Rasmussen, 1982).AdvantagesDisadvantagesThe technique provides a set of causal factors suitable for The interpretation of accidents is subjective. Theremedying design-induced error.descriptions of the accidents may suffer frominsufficiencies in data collection and recording. The use ofan established causal network may influence the collectionand reporting of data. Retrospective reviews of accidentreports do not incorporate the knowledge of the personsinvolved.NATO UNCLASSIFIED1 IC%