System audits, human factors

In the case of root cause analysis systems, more comprehensive evaluations of PIFs will normally be carried out as part of a full-scale human factors audit. This could make use of the types of comprehensive PIF evaluation methods described in Chapter 2 (see Section 2.7.7 and Figure 2.12). 

The case study described here concerns a human factors audit of a computer controlled process system which was being introduced in a distillation imit of a chemical plant. The unit was in transition from replacing its pneumatic panel instrumentation with the new system. However, control had not yet been transferred and the staff were still using the panel instrumentation. The role of the project was to evaluate a preliminary design of the computer-based display system and provide recommendations for future development. 

The human factors audit was part of a hazard analysis which was used to recommend the degree of automation required in blowdown situations. The results of the human factors audit were mainly in terms of major errors which could affect blowdown success likelihood, and causal factors such as procedures, training, control room design, team communications, and aspects of hardware equipment. The major emphasis of the study was on improving the human interaction with the blowdown system, whether manual or automatic. Two specific platform scenarios were investigated. One was a significant gas release in the molecular sieve module (MSM) on a relatively new platform, and the other a release in the separator module (SM) on an older generation platform. 

Such a procedure can also form a logical basis for human factors audits. The first step chooses the areas of study, the second samples the system, the third analyzes these samples, and the final step produces an audit report. These define the broad issues in human factors audit design ... 

Usability refers to the auditor s ease of use of the audit system. Good human factors principles should be followed, such as document design guideUnes in constructing checklists (Patel et al 1993 Wright and Barnard 1975). If the instrument does not have good usabiUty, it will be used less often and may even show reduced reliability due to auditors errors. 

In any sampling, we must define the unit of sampling, the sampling frame, and the sample choice technique. For a human factors audit the unit of sampling is not as self-evident as it appears. From a job-evaluation viewpoint (e.g., McCormick 1979), the natural unit is the job that is composed of a number of tasks. From a medical viewpoint the unit would be the individual. Human factors studies focus on the task/operator/machine/environment (TOME) system (Drury 1992) or equivalently the software/hardware/environment/Uveware (SHEL) system (ICAO 1989). Thus, from a strictly human factors viewpoint, the specific combination of TOME can become the sampling unit for an audit program. 

The ERNAP audits have been included here to provide examples of a checklist embedded in an audit system where the workplace is not the sampling unit. They show that non-repetitive tasks can be audited in a valid and reliable manner. In addition, they demonstrate how domain-specific audits can be designed to take advantage of human factors analyses already made in the domain. 

Besides outcome measures, interviews represent a possible data-collection method. Whether directed or not (e.g., Sinclair 1990) they can produce critical incidents, human factors examples, or networks of communication (e.g., Drury 1990a), which have vrilue as part of an audit procedure. Interviews are routinely used as part of design audit procedures in large-scale operations such as nuclear power plants (Kirwan 1989) or naval systems (Mrilone et al. 1988). 

SAMMIE, see System for Aiding Man-Machine Interaction Evaluation Sampling. See also Work sampling in health care systems, 745-746 in human factors audits, 1135-1136 when using control charts, 1840 Sanden Corporation, 555 SAP AG, 87, 95, 96, 304, 306, 492, 1002,... 

Retain a firm with comprehensive PSM expertise. This firm should be an expert in pressure relief systems, safety instrumented systems, human factor analysis, etc. The firm must perform process safety audits, to conduct a refinery-wide comprehensive audit and analysis of the company s PSM systems [22]. 

In a two-year project, reported by Simpson (1994) and Fox (1992), the human error audit described in Section 3.2 was applied to two colliery haulage systems. The results of the first study will be presented here. In both systems, data collection focused on potential errors and the performanceshaping factors (PSFs) that can influence these errors. Data was collected by observation, discussion and measurement within the firamework of the broader man-machine systems and checklist of PSFs, taking some 30-40 shifts at each site. The whole haulage system from surface operations to delivery at the coal face was covered. 

The data collected from accidents, injury-producing or not, can be examined to identify the contributing factors which led to the accident. It is possible to find out which part of the controls in the system broke down. For example, despite good and well documented maintenance, a part failed. This requires an engineering solution. Or perhaps a part has failed and it is clear from the documentation (or lack of it) on repairs and maintenance that the human control (management) system was sloppy. This may indicate poor policies, failure to develop procedures or failure to train people in procedures, and then audit observance of those procedures. 

JHEDI is derived from the human reliability management system (HMRS) and is a quick form of human reliability analysis that requires little training to apply. The tool consists of a scenario description, task analysis, human error identification, a quantification process, and performance shaping factors and assumptions. JEDHI is a moderate, flexible and auditable tool for use in human reliability analysis. Some expert knowledge of the system under scrutiny is required. 

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