Читать книгу Root Cause Failure Analysis - Trinath Sahoo - Страница 74

There are 3 types of active human error:

 Slips and lapses – made inadvertently by experienced operators during routine tasks

 Mistakes – decisions subsequently found to be wrong, though the maker believed them to be correct at the time

 Violations – deliberate deviations from rules for safe operation of equipment

Familiar tasks carried out without much conscious attention are vulnerable to slips and lapses if the worker's attention is diverted: for example, missing a step in a sequence because of an interruption.

Mistakes occur where a worker is doing too many or complex tasks at the same time or is under time pressure: for example, misjudging the time and space needed to complete an overtaking maneuvre.

Violations, though deliberate, usually stem from a desire to perform work satisfactorily given particular constraints and expectations.

Factors that are most closely tied to the failure and can be described as active failures or actions committed by the operator that result in human error. We have identified these active failures or actions as Errors and Violations.

1 Errors: Errors are factors in a mishap when mental or physical activities of the operator fail to achieve their intended outcome as a result of skill‐based, perceptual, or judgment and decision‐making errors, leading to an unsafe situation. Errors are unintended. We classified Errors into two types:Skill‐based Errors: When people are performing familiar work under normal conditions, they know by heart what to do. They react almost automatically to the situation and do not really have to think about what to do next. For instance, when a skilled automobile driver is proceeding along a road, little conscious effort is required to stay in the lane and control the car. The driver is able to perform other tasks such as adjusting the radio or engaging in conversation without sacrificing control. Errors committed at this level of performance are called slips or lapses.System based: are a more complex type of human error where we do the wrong thing believing it to be right. The failure involves our mental processes which control how we plan, assess information, make intentions and judge consequences. These errors are judgment and decision‐making errors. Misperception of an object, threat or situation (such as visual, auditory, proprioceptive, or vestibular illusions, cognitive or attention failures).

1 Violations: Violations are any deliberate deviations from rules, procedures, instructions, and regulations. The breaching or violating of rules or maintenance procedures is a significant cause of many failures. Removing the guard on dangerous machinery or driving too fast will clearly increase the risk. Our knowledge of why people break rules can help us to assess the potential risks from violations and to develop control strategies to manage these risks effectively.

Figure 4.1 Contributing factors to human error.