Nuts & Volts - February 2004

The Health and Safety Executive has estimated that 80% of accidents are caused by human error in some form. Loss of production and profitability due to human error is probably incalculable, but is likely to run to many hundreds of millions of pounds per year. There is a common misconception that human error is unavoidable and usually arises from carelessness or neglect. From this, there follows a general belief that human error can only be prevented by identifying, blaming, and correcting the individual who made the error. In reality, nearly all instances of human error are the consequence of badly designed systems. The systems may be technological, such as the design of the human machine interface (e.g., an aircraft cockpit display) or the work environment (e.g., how an item of industrial machinery is operated). Alternatively, the systems may be organizational, varying from an operating or maintenance procedure to a management system, or indeed, the culture of a whole company.

& VOLTS n i c s

In all cases, the systems which influence the way work is carried out are the main cause of human error. If a system

will be increased. Errors caused by system deficiencies are known as systemic errors and it follows from this that, by careful attention to design, their incidence can be limited. Once it is accepted that most errors are caused by defective systems rather than neglect, then human error is no longer seen as inevitable. Indeed, if the system faults can be identified and corrected, then there is a possibility for error reduction and blame can be virtually eliminated from the equation. However, it also means that the remedy for human error often lies in the hands of the mechanical and electrical engineers who designed the system in the first place.

There are two basic approaches to the design of equipment from an operability point of view. The sys-tem-centered approach has tended to be the traditional method adopted in the design process. Here, the attention of the design engineer is almost totally directed towards the

RESOURCES

system to the exclusion of the human beings who will have to operate or maintain it. Today, many designers are still tempted to adopt this old-fashioned approach. Their natural inclination is to focus upon the system rather than the human being because of the perception that it is the system that delivers the specified requirements. However, it needs to be seen that the system comprises both human and machine. The end result of such an approach is that the operator or maintainer must adapt to a system that is not designed to take account of their needs. Quite often the discovery that the human being cannot easily adapt to the system is not realized until the product is brought into operation. By this time, it is often too late or very expensive to make the required changes.

It is sometimes argued that designers do not have the required knowledge of ergonomics (see resources) to be able to take into account human factors in their designs. However, in many cases, all that is required is an ability to understand how the system will eventually be operated or maintained. This may involve no more than the

1. Ergonomics is "an approach which puts human needs and capabilities at the focus of designing technological systems. The aim is to ensure that humans and technology work in complete harmony, with the equipment and tasks aligned to human characteristics." The Ergonomics Society, 2003, www.ergonomics. org.uk/ergon omics/ definition.htm