Operator errors, types

The whole range of error types that could occur at each task step are described in Figure 4.16. The terms action errors and checking errors are self-explanatory. Retrieval errors refer to the retrieval of infonnation either from an external source (e.g., a chart recorder or a procedure) or from memory. Transmission/ communication errors refer to communications among individuals either directly or via written communications. Selection/choice errors refer to making incorrect choices among alternative operations, for example, manual instead of automatic. 

This analysis is applied to each operation at the particular level of the HTA being evaluated. In most cases the analysis is performed at the level of a step, for example. Open valve 27B. For each operation, the analyst considers the likelihood that one or more of the error types set out in classification in Figure 5.7 could occur. This decision is made on the basis of the information supplied by the PIF analysis, and the analyst s knowledge concerning the types of error likely to arise given the nature of the mental and physical demands of the task and the particular configuration of PIFs that exist in the situation. The different error categories are described in more detail below ... 

Figure 1-7 presents the causes of losses for the largest chemical accidents. By far the largest cause of loss in a chemical plant is due to mechanical failure. Failures of this type are usually due to a problem with maintenance. Pumps, valves, and control equipment will fail if not properly maintained. The second largest cause is operator error. For example, valves are not opened or closed in the proper sequence or reactants are not charged to a reactor in the correct order. Process upsets caused by, for example, power or cooling water failures account for 11 % of the losses. 

The most frequent type of operational error was a valve being left in an improper position, either open or closed. 

In this chapter we explore some of the problems that you may encounter when running what are meant to be routine spectra. The increasing computer control found in modem spectrometers is a great benefit to the user, but can also lead to some subtle types of operator error. The problems discussed in this chapter are not the sort one encounters as a result of a failure in the system. Many of them appear when a parameter is wrongly set through forgetfulness or ignorance, or when a command is mistyped or misused. 

The distribution of steric defects along the polymer chain may be indicative of which kind of stereocontrol is operative. The type and amount of stereomistakes (enantioface insertion errors) is measured by solution 13C NMR spectroscopy, a sensitive technique that is able to see the steric environment of a given propylene unit up to undecads (five propylene units on each side of the observed monomeric unit). Routine analysis is usually performed at the pentad level (two propylene units on each side of the observed monomeric unit).162,179 The microstructures which result from stereomistakes are shown in Scheme 7. 

When analysis is needed of a small portion of a large process or of an item of equipment, such as a reactor, the Failure Mode and Effect method can be used (2). While this method may not evaluate operating procedure errors or omissions, or the possibility or probability of operator error, it does assess the consequences of component failures on the process. This type of analysis has been used infrequently at the Experimental Station, and then most often in a somewhat modified form. 

It should also be noted that for most, if not all, of the models presented in the literature using this approach, the concentrations used to estimate AUC are the sole variable types used in model development. It is entirely possible that other patient characteristics, such as age or sex, may be useful predictor variables in the model, as well. Further, using drug concentration as an independent variable violates the assumption that the independent variables are known with certainty. Drug concentrations are not known with certainty—they are measurements subject to assay variability, operating error, etc. A more technically correct approach to the problem would be an error-in-variables approach to the problem, although this is never done in practice. Once the model is developed, an independent validation data set is used to characterize the model. 

Operator error it means that the person who actual contacted with objects, including the frontline workers, all machine operators, maintenance persons have mistake. It includes 6 kinds of types. That is, thought is not correct unskilled unhappy family or work trusting to luck illegal operation psychological is not well. 

Fire and explosion accidents are of major concern to the owners and operators of refineries and petrochemical, gas processing, terminal, and offshore facilities. Statistics have shown that the majority of monetary loss in these types of complexes is due to fire and explosion. According to statistics (www.ohsonline.com, December 2010), 77 percent of the monetary loss in refinery and petrochemical complexes is due to fire and explosion. The breakout of accidents due to fire and explosion is 65 percent vessel (container) and vapor cloud explosion and 35 percent fire. The causes of these accidents are mostly attributed to mechanical issues, process upset, and operator error. 

The rotary sample divider, or spinning riffle, is less prone to operator error than is the static riffle. Basically it consists of a hopper which allows particulate material to flow on to a vibrating chute which then discharges into a number of sample boxes located in a rotating ring. Several units of this type are available commercially. 

In summary, many accidents are blamed, at least in part, on operator error. In many cases, the errors made by the operators were the result of poor human factors engineering in design. The designer set up the error-prone situation, and the operator was simply the victim, performing very consistently with the way any other human would have operated under the same conditions. This is not to say that operators do not make accident-causing errors or that all errors made by operators were the result of poor engineering or design. Some common types of operator errors are... 

Some common types of designer errors that contribute to operator errors are that they require operators to... 

A type of safety identification review that methodically analyzes the interactions between individuals and machines. It reviews the operation phase to operational phase, while considering the consequences of operator-system faults at each operating step within each phase. This analysis allows for the recognition of threats from equipment faults that may coexist with operator errors. It is considered similar to a Failure Mode and Effects Analysis (FMEA), but with increased emphasis on the steps in human procedures rather than viewing hardware exclusively. See also Failure Mode and Effects Anafysis (FMEA) Job Safety Analysis (JSA). 

This chapter presents an exploratoiy study of the interaction between error type and error detection mechanism in the context of normal flight operations within the commercial airline environment. 

With respect to the interaction between error type and error detection mechanism, a number of operationally relevant findings were obtained. Overall, there was a significant difference in error detection, as a function of error type X2(12, 677) = 173.882, p <. 001. Analysis of the adjusted standardized residues indicated significant interaction between specifie types of errors, and patterns of error detection. The differences in error detection mechanism as a function of error type is presented in Figure 8.2, below. 

The reactors were equipped with interlocks to prevent opening the reactor drain valve if the reactor was pressurized. The CSB theorized that the blaster operator believed he was at the correct reactor and the bottom valve on Reactor D310 was not properly functioning. The CSB established that bottom valve actuator air hoses were found disconnected. Furthermore the emergency air hose to bypass the interlock was comiected [8]. This is obvious part of a Human Error type incident. 

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