1. HUMAN FACTORS
TOPIC 1
Introduction

2. The need to take Human Factors into account
"Human factors" is the study of human capabilities and limitations in the workplace.
In aviation maintenance, the aim is towards improving personnel well-being, safety
and efficiency.
There is no question that human error in aircraft maintenance has been a major
cause of several air carrier accidents. 2

3. The need to take Human Factors into account
Human Factors researchers study system performance. That is, they study the
interaction of maintenance personnel, the equipment they use, the written and verbal
procedures and rules they follow, and the environmental conditions of any system.
The aim of human factors is to optimise the relationship between maintenance
personnel and systems with a view to improving safety, efficiency and well-being.
It is also beyond question that unless the aviation industry learns from these
occurrences, maintenance-related safety breakdowns will continue to occur.
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4. The need to take Human Factors into account
Human factors include such attributes as:
 Physiology - the mechanical, physical, and biochemical functions of living
organisms
 Psychology - including perception, cognition, memory, social interaction, error
 Work place design
 Environmental conditions
 Human - machine interface
 Anthropometrics - the scientific study of measurements of the human body
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5. Issues associated with Human Factors
The SHEL model can be used as an aid to understanding human factors.
 S - software
 H - hardware
 E - environment
 L - liveware
Human factors concentrates on the interfaces between the human (the ‘L’ at the centre
of the model) and the other elements of the SHEL model.
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6. Issues associated with Human Factors
“Liveware” (human being) , can perform a wide range of activities.
Even though modern aircraft are now designed with the latest self-test and diagnostic
routines that modern computing power can provide, one aspect of aviation
maintenance has not changed: maintenance tasks are still being done by human
beings.
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7. Issues associated with Human Factors
With modern technology, aircraft are becoming more and more reliable.
However, it is not possible to re-design the human being.
To overcome humans being unreliable it is important to provide:
 Good Training;
 Procedures;
 Tools and;
 Duplicate Inspections.
And we can improve aircraft design. For example, making it impossible to reconnect
something the wrong way.
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8. Human Error
In 1940, it was calculated that approximately 70% of all aircraft accidents were
attributable to human error.
In 1975 IATA reviewed the situation and there had been no reduction in human error.
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9. Human Error
In 1986 a study was carried looking at significant accident causes in 93 aircraft
accidents. These causes were as follows:
 Pilot deviated from basic operational procedures - 33%
 Inadequate cross-check by second crew member - 26%
 Design faults -13%
 Maintenance and inspection deficiencies - 12%
 Absence of approach guidance - 10%
As can be seen from the list, maintenance and inspection deficiencies are a major
contributing factor to accidents.
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10. Human Error
Aircraft maintenance and inspection duty can
be very complex and varied in an
environment where opportunities for error
abound.
Maintenance personnel frequently work
under considerable time pressures.
Personnel at the maintenance base and at
the flight line stations realize the importance
of meeting scheduled departure times.
Operators have increased aircraft utilization
in order to counteract the economic problems
that plague the industry.
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11. Human Error contributing factors
Aircraft maintenance related incidents are characterised by:
 Staff shortages
 Time pressures
 Shift or Task handovers
 An element of a “can do” attitude
 Errors occurred at night
 Interruptions occurred
 Some failure to use approved data or company procedures
 Confusion using technical manuals
 Inadequate pre-planning, equipment or spares
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12. A breakdown in Human Factors
All accidents or incidents are avoidable if any of the number of steps could have been
done differently.
Incidents and accidents can be prevented.
By breaking any one of the links in the Error Chain.
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13. Murphy’s Law
“Murphy’s Law” can be regarded as the
notion: “If something can go wrong, it will.”
There is a tendency amongst human beings
towards complacency.
It is a belief that an accident will never
happen to me or my company.
It is important to convince individuals and
organisations of the importance of human
factor issues and how to:
 Recognise risks and;
 Implement Improvements
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14. Human Performance
Just as certain mechanical components
used in aircraft have limitations,
engineers themselves have certain
capabilities and limitations.
Failures by aircraft maintenance
engineers can also be to the detriment of
aircraft safety.
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