Error management discussion

Following the implementation of the error management program, evaluations of its effectiveness must be made on a continuing basis. Measures of effectiveness can be gained partly by direct discussions with individuals at all levels of the plant, using a predesigned evaluation checklist to ensure that all the evaluation dimensions are assessed in a systematic way. Examples of evaluation questions follow. 

In his book, Kletz reviewed several accidents that at first sight were due to human error and discussed how, in reality, they could have been prevented through (a) improved design, construction, and maintenance, (b) improved design of work methods, and (c) better management. 

The interview data provided a range of insights into the processes of error management employed by expert pilots. The scope of this chapter allows only for abrief discussion of the major categories of error management competencies identified by the expert pilots in the interview data A more detailed exploration of each of these categories is provided in the full report (Thomas and Petrilli, 2004). 

The book begins with a discussion of the theories of error causation and then goes on to describe the various ways in which data can be collected, analyzed, and used to reduce the potential for error. Case studies are used to teach the methodology of error reduction in specific industry operations. Finally, the book concludes with a plan for a plant error reduction program and a discussion of how human factors principles impact on the process safety management system. 

Chapter 1, The Role of Human Error in Chemical Process Safety, discusses the importance of reducing human error to an effective process safety effort at the plant. The engineers, managers, and process plant personnel in the CPI need to replace a perspective that has a blame and punishment view of error with a systems viewpoint that sees error as a mismatch between human capabilities and demands. 

Human error has often been used as an excuse for deficiencies in the overall management of a plant. It may be convenient for an organization to attribute the blame for a major disaster to a single error made by a faUible process worker. As will be discussed in subsequent sections of this book, the individual who makes the final error leading to an accident may simply be the final straw that breaks a system already made vulnerable by poor management. 

The last area addressed by the systems approach is concerned with global issues involving the influence of organizational factors on human error. The major issues in this area are discussed in Chapter 2, Section 7. The two major perspectives that need to be considered as part of an error reduction program are the creation of an appropriate safety culture and the inclusion of human error reduction within safety management policies. 

As discussed earlier in this chapter, the main requirements to ensure an appropriate safety culture are similar to those which are advocated in quality management systems. These include active participation by the workforce in error and safety management initiatives, a blame-free culture which fosters the free flow of information, and an explicit policy which ensures that safety considerations will always be primary. In addition both operations and management staff need feedback which indicates that participation in error reduction programs has a real impact on the way in which the plant is operated and systems are designed. 

Management policies are the source of many of the preconditions that give rise to systems failures. For example, if no explicit policy exists or if resources are not made available for safety critical areas such as procedures design, the effective presentation of process information, or for ensuring that effective communication systems exist, then human error leading to an accident is, at some stage, inevitable. Such policy failures can be regarded as another form of latent human error, and will be discussed in more detail in Section 2.7. 

The various PIFs discussed so far provide a basis for the control of human error at the level of the individual. This section will consider various factors related to the performance of the team and the management practices related to safety. 

From a human reliability perspective, a number of interesting points arise from this example. A simple calculation shows that the frequency of a major release (3.2 x lO"" per year) is dominated by human errors. The major contribution to this frequency is the frequency of a spill during truck unloading (3 X10" per year). An examination of the fault tree for this event shows that this frequency is dominated by event B15 Insufficient volume in tank to imload truck, and B16 Failure of, or ignoring LIA-1. Of these events, B15 could be due to a prior human error, and B16 would be a combination of instrument failure and human error. (Note however, that we are not necessarily assigning the causes of the errors solely to the operator. The role of management influences on error will be discussed later.) Apart from the dominant sequence discussed above, human-caused failures are likely to occur throughout the fault tree. It is usually the case that human error dominates a risk assessment, if it is properly considered in the analysis. This is illustrated in Bellamy et al. (1986) with an example from the analysis of an offshore lifeboat system. 

The type of data collected on human error and the ways in which these data are used for accident prevention will vary depending upon the model of error and accident causation held by the management of an organization. This model will also influence the culture in the plant and the willingness of personnel to participate in data collection activities. In Chapters 1 and 2 a number of alternative viewpoints or models of human error were described. These models will now be briefly reviewed and their implications for the treatment of human error in the process industry will be discussed. 

Table II demonstrates how NPV would be calculated for a hypothetical LIMS, purchased as a package with negligible site preparation and with installation costs included in the purchase. It is to be acquired for a service laboratory primarily supporting R D activities but with some minimal process monitoring responsibilities. The IRR for this project could be found by trial and error determination of the yearly discount rate which results in a zero NPV. A succinct discussion of these financial management analysis tools can be found in two works by Weston and Brigham. The first (9) presents theoretical and detailed analytical expositions the second OO) is a more practical, applications oriented presentation.

These two errors have been duly discussed under the chapter on Pharmaceutical Chemicals Purity and Management (Section 1.3.2.2). 

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