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.
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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
2. The Blame Machine — Why Human Error Causes Accidents,
Elsevier Science and Technology Books, Oxford, R.B. Whittingham,
2003, ISBN 0750655100
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is badly designed from a
human operability perspective, then the probability of errors occurring
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application of simple common sense. The result of
designing equipment without the application of such
FEBRUARY 2004