Page 7 - Module 9 Look Inside

The need to take human factors into account

Without the intervention of maintenance personnel, equipment used in complex technological
systems such as aviation, rail and marine transport, and medicine would drift towards a level of
unreliability that would rapidly threaten efficiency and safety.

Despite the essential contribution of maintenance to system reliability, maintenance is also a
major cause of system failure. The rate of power station outages increases shortly after
maintenance, maintenance quality is a major concern in the chemical industry, and in aviation
there is evidence that maintenance is contributing to an increasing proportion of accidents. As
automated systems become increasingly common, humans are performing less direct manual
control of equipment and systems. As a result, maintenance is becoming a major remaining
point of direct interaction between people and technology, where human capabilities and
limitations can have a significant impact on system safety and reliability.

Understanding the human factors in maintenance is more necessary than ever if we are to
improve safety and reliability in aviation.

Modern technological systems in industries such as manufacturing, transport and healthcare
comprise equipment, procedures, and of course people.

In most cases, we have a fairly good understanding of the performance characteristics of the
engineered equipment that form parts of these systems.

Aircraft come with manuals that specify their performance envelopes and capabilities.
Procedures too, have been created by people and can be documented and understood.

But when it comes to people, we are faced with a system element that comes with no operating
manual and no performance specifications, and that occasionally performs in ways not
anticipated by the system designers. Some of these failures can be easily explained, an
arithmetic error for example, while others are harder to predict.

Although individuals differ, researchers have discovered general principles of human
performance that can help us to create safer and more efficient systems. The focus of this
paper is on the functioning of people as elements of maintenance systems in aviation.

The cost of maintenance error

Since the end of World War II, human factors researchers have studied pilots and the tasks they
perform, as well as air traffic control and cabin safety issues. Yet until recently, maintenance
personnel were overlooked by the human factors profession. Whatever the reason for this, it is
not because maintenance is insignificant. Maintenance is one of the largest costs facing
airlines. It has been estimated that for every hour of flight, 12 man-hours of maintenance occur.
Most significantly, maintenance errors can have grave implications for flight safety.

Accident statistics for the worldwide commercial jet transport industry show maintenance as the
‘primary cause factor’ in a relatively low four percent of hull loss accidents, compared with flight
crew actions that are implicated as a primary cause factor in more than 60 per cent of accidents.
Yet primary cause statistics may tend to understate the significance of maintenance as a
contributing factor in accidents.

Total Training Support Ltd 1-7 Issue 2 – September 2016
© Copyright 2016 Module 9.1 General