Human error nature

The main thrust of the HF/E approach is to provide the conditions that will optimize human performance and implicitly minimize human error. However, there is rarely any attempt to predict the nature and likelihood of specific human errors and their consequences. By contrast, the study of human error in the context of systems reliability is concerned almost exclusively with these latter issues. It is appropriate to introduce the systems reliability assessment approach to human error at this stage because, until recently, it was largely... 

Several examples have already been provided of the use of cognitive models of error to evaluate the possible causes of accidents that have already occurred. This form of retrospective analysis performs a vital role in providing information on the recurring underlying causes of accidents in which human error is implicated. The advantage of an analytical framework driven by a model of human error is that it specifies the nature of the questions that need... 

The classification structure for PIFs used in this chapter is based on the model of human error as arising from a mismatch between demands and resources which was described in Chapter 1, Section 1.6 (Figure 1.6). In this model demands were seen as requirements for human performance which arise from the characteristics of the process environment (e.g., the need to monitor a panel or to be able to fix a seal in a flange) and the nature of the human capabilities to satisfy these demands (e.g., skills of perception, thinking, and physical action). These demands are met by the individual and group resources of personnel and the extent to which the design of the task allows these resources to be effectively deployed. Where demands exceeded resources, errors could be expected to occur. 

Checks of critical process parameters and warnings about hazardous conditions that can cause injury or equipment damage are important factors which determine the occurrence and recovery of human error. The purpose of these checks is to emphasize critical process information. Because of the critical nature of this information, checks and warning should be highlighted in a way that distinguishes them from other notes, and should be located where process workers will not overlook them. 

The objective of consequence analysis is to evaluate the safety (or quality) consequences to the system of any human errors that may occur. Consequence Analysis obviously impacts on the overall risk assessment within which the human reliability analysis is embedded. In order to address this issue, it is necessary to consider the nature of the consequences of human error in more detail. 

Task Analysis and Error Analysis of the Blowdown Operation Task analysis was carried out in order to organize all the performance data about the way that workers process information, the nature of the emergency and the way that decisions are made. Figure 7.20 shows a tabular task analysis of the workers response to a significant unignited gas leak in MSM. The analysis was a combination of a tabular HTA and a CADET analysis (see Chapter 4). Human error analysis identified the major human failure modes which could affect time to blowdown (see Table 7.2). 

It is desirable for the record to have an objective statement of the nature and degree of color deterioration. The simplest, but least desirable, method is comparison of sample color with color charts or plates such as those used in the Munsell system, Ridgeway s color standards, or the Maerz and Paul dictionary of color. Such a method is limited in value because of the difficulty of obtaining true color matches, and because of variations due to human error. The use of color charts or plates may be much improved in the Munsell system by employing a disk colorimeter (29). Kramer and Smith (21) have pointed out that the results obtained in its application to foods are sometimes difficult to explain and compare, and that the method requires special training of the operator and is tedious and cumbersome. 

Piping failure can be caused in several ways. A study by U.S. EPA16 has shown that piping failure accounted for a substantial portion of releases at USTs. Spills and overfills are usually caused by human error. Repeated spill can also increase the corrosive nature of soils. 

Human error is frequently used to describe a cause of losses. Almost all accidents, except those caused by natural hazards, can be attributed to human error. For instance, mechanical failures could all be due to human error as a result of improper maintenance or inspection. The... 

Advances in information technology and the necessity of improved efficiency have resulted in increasingly automated and interlinked infrastructures, and have created new vulnerabilities due to equipment failure, human error, weather and other natural... 

A slightly more structured approach uses AVhat-If Analysis,(i) which involves the team asking What if questions that usually concern equipment failures, human errors, or external occurrences. Some examples are What if the procedure was wrong What if the steps were performed out of order The questions can be generic in nature or highly specific to the process or activity where the incident occurred. Sometimes these questions are preprepared by one or two individuals, which may also potentially bias the discussion. 

A failure that may be of technical origin or stem from human error, either during the operation or during process design. External events, such as weather conditions or natural catastrophe may also be at the origin of a failure. 

The preparation of prefractionated natural product libraries for drug discovery can be made more efficient by automation. Automation reduces manpower requirements, improves efficiency and increases productivity. In addition, human errors are reduced and reproducibility is improved. Overall, automation increases throughput and can produce larger and more diverse screening libraries. 

There are many methods of safety analysis reviews that are available and can be applied to a facility or project design to overcome human errors and the various failures of the process system. The methods may be either qualitative or quantitative in nature. 

Some examples of human error of a plant nature are ... 

Detection of contamination levels (dust, food and drink, production materials) that can accumulate in equipment and lead to system malfunction Monitor hours worked by individuals and/or mundane nature of work that might result in loss of concentration and hence introduchon of human errors (data errors and user operahon errors)... 

Feasibility of implementation. Are the methods for sampling and measuring the environmental variables technically feasible, appropriate, and efficient for use in a monitoring program Response variability. Are human errors of measurements and natural variability over time and space sufficiently understood and documented ... 

Recently, few topics in analytical chemistry have occupied the scientific community more than the ability of chemical laboratories to reliably determine at the low parts-per-billion level the presence of Fusarium trichothecenes in environmental and toxicological samples. This paper provides a systematic approach for developing and implementing a quality assurance and quality control program for a complex analytical method in which human error and system failure can occur. The application of this approach to the problem of determining the presence of nine naturally... 

Such a task description invites task analysis, which would lead naturally to human reliability analysis (HRA). Indeed, perhaps the earliest work in this field applied HRA techniques to construct fault trees for aircraft structural inspection (Lock and Strutt 1985). The HRA tradition lists task steps, such as expanded versions of the generic functions above, lists possible errors for each step, then compiles performance shaping factors for each error. Such an approach was tried early in the FAA s human factors initiative (Drury et al. 1990) but was ultimately seen as difficult to use because of the sheer number of possible errors and PSFs. It is occasionally revised, such as in the current FRANCIE project (Haney 1999), using a much expanded framework that incorporates inspection as one of a number of possible maintenance tasks. Other attempts have been made to apply some of the richer human error models (e.g.. Reason 1990 Hollnagel 1997 Rouse 1985) to inspection activities (La-toreUa and Drury 1992 Prabhu and Drury 1992 Latorella and Prabhu 2000) to inspection tasks. These have given a broader understanding of the possible errors but have not helped better define the PoD curve needed to ensure continuing airworthiness of the civil air fleet. 

This gateman has associated zero with practice, and in doing so has positioned zero firmly within his own site reality in which people are the cause of unsafety, and the reason zero cannot be achieved. But this is not blame as prescribed in the simplistic causal thinking of human error and accidents, rather more systemic causes are naturally identified, long hours and fatigue, creating a close relationship between zero-people-work. For this worker, zero in its tangible form is simply unachievable the current reality will dominate and injuries can never be eliminated. 

The second important difference between human and automated controllers is that, as noted by Thomas [199], while automated systems have basically static control algorithms (although they may be updated periodically), humans employ dynamic control algorithms that they change as a result of feedback and changes in goals. Human error is best modeled and understood using feedback loops, not as a chain of directly related events or errors as found in traditional accident causality models. Less successful actions are a natural part of the search by operators for optimal performance [164]. 

Errors of omission are related to the change of human roles in systems from direct controllers to monitors, exception handlers, and supervisors of automated controllers. As their roles change, the cognitive demands may not be reduced but instead may change in their basic nature. The changes tend to be more prevalent at high-tempo and high-criticality periods. So while some types of human errors have declined, new types of errors have been introduced. 

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