Introduction to Human Factors

Human Factors is a scientific discipline concerned with understanding the interactions between people and technology.  The goal of human factors is to reduce human error, increase quality and productivity, and enhance safety. There are many factors beyond the engineered system that non-destructive evaluation (NDE) personnel inspect, including the elements shown in Figure 1, that combine to result in safe, effective, and error-free examinations.

Figure 1. Categories of factors that influence human performance in non-destructive evaluation.

The general categories of human factors that influence human performance in NDE are reflected in Figure 1.  Research studies have shown that these factors exert considerable influence on the quality of NDE evaluations and need to be considered in how work is performed.

Task Characteristics refer to what is done and the tools used to perform the job.  Task performance is affected by how well the examiner prepares beforehand, the type of equipment used and how easy it is to use, the degree of detail in a written procedure and the examiner’s familiarity with it.  Examinations can vary in complexity – some may be quite straightforward, such as dye penetrant inspection, whereas others such as phased array ultrasound involve much more equipment and many steps to set up, acquire and interpret data.  More complex examinations can create more opportunities for errors. The amount of time pressure on an examiner also affects performance. How much time is available to inspect a component may be limited in a hazardous setting like a radioactive area, or examiners may feel pressure to complete a job quickly due to other competing demands.   Tasks performed under time pressure can increase stress on the examiner and lead to errors.

People differ from one another, which is the basic idea of the Individual Differences category of factors.  Examiners have varying levels of knowledge and experience on the job, as well as a diverse set of personalities, motivations and attitudes.  Certain physical abilities – such as being able to fit into small spaces, and cognitive abilities – such as good capability to navigate in complex factories and plants, can help performance.  Different examiners may use different processes to accomplish the same inspection, which may affect reliability and probability of detection. Increases in workload, stress and fatigue due to long shifts can increase the risk of errors.

Although NDE can often be done by a single individual, there are many instances where more than one examiner is involved – sometimes with a single partner, or in more complex examinations a team of several individuals.  The Group Characteristics category encompasses the human factors associated with teams, including the coordination of individual member roles and responsibilities and how well the team works together.  Team cohesion involves individuals working together in a smooth and efficient manner, sometimes anticipating other team member requirements, and generally getting along well.  In addition to clear roles and responsibilities, team coordination involves ensuring that everyone has the information and equipment needed to do their job. Teams that work well together tend to perform more efficiently and effectively.

The Physical Environment is another category of factors that can affect NDE performance. NDE is often performed in locations that are difficult to reach (see Figure 2), and which may expose the examiner to hazardous circumstances or make the examination more difficult.  Poor accessibility may require examiners to arrange themselves in uncomfortable positions for extended periods of time and limit the ability to see the component being inspected or the equipment being used. High levels of heat and noise can increase stress, affect the ability to see or hear equipment signals, and make communication with team members more difficult. Poor lighting can be particularly challenging for visual examinations, impacting the ability to distinguish cracks from surface scratches.  

Figure 2.  NDE examiner conducting ultrasonic inspection of pipe weld in a nuclear power plant.  Access to weld requires removal of insulation and awkward positioning in order to obtain full coverage examination.

Organizational Factors are concerned with the overall system in which NDE is conducted – like a power plant run by an electric utility or a pipeline managed by an oil producer.  The ability of individual examiners to conduct effective NDE is influenced by how well organizations support and plan for NDE. The culture of an organization sets the tone for the work environment – it can affect how well people work together or how much time pressure examiners experience. Training examiners, providing supervision, and planning inspection schedules often involves coordination among multiple units to ensure a successful outcome, including interactions between inspection vendors and end users.  Challenges to the overall NDE industry, such as an aging workforce or reductions in job opportunities, can affect an organization’s ability to recruit, hire, and retain qualified examiners.  The organizations and systems that support NDE can help set examiners up for success or increase opportunities for error.