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This lesson will help the students’
understanding towards the importance and
function of Human Factors towards
maintaining Safety in the workplace. This
lesson shall primarily focus on the common
human error preconditions, or conditions
that can leads to accidents or incidents
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The Dirty Dozen refers to twelve of the most common human error
preconditions, or conditions that can act as precursors,
to accidents or incidents. These twelve elements influence people to make
mistakes. 3
The Dirty Dozen is a concept developed
by Gordon Dupont, in 1993, whilst he
was working for Transport Canada, and
formed part of an elementary training
program for Human Performance in
Maintenance.
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Countermeasures
• Whilst The Dirty Dozen list of human factors has increased awareness
of how humans can contribute towards accidents and incidents, the
aim of the concept was to focus attention and resources towards
reducing and capturing human error. Therefore, for each element on
The Dirty Dozen list there are examples of typical countermeasures
designed to reduce the possibility of any human error from causing a
problem.
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1. Lack of communication
• Poor communication often appears at the top of
contributing and causal factors in accident
reports and is therefore one of the most critical
human factor elements. Communication refers
to the transmitter and the receiver, as well as the
method of transmission.
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2. Complacency
• Complacency can be described as a feeling of
self-satisfaction accompanied by a loss of
awareness of potential dangers. Such feeling
often arises when conducting routine activities
that have become habitual and which may be
“considered”, by an individual as easy and safe.
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3. Lack of knowledge
• The regulatory requirements for training and
qualification can be comprehensive, and
organizations are forced to strictly enforce
these requirements. However, lack of on-the-
job experience and specific knowledge can
lead workers into misjudging situations and
making unsafe decisions.
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4. Distraction
• Distraction could be anything that draws a
person’s attention away from the task on
which they are employed. Some distractions
in the workplace are unavoidable, such as
loud noises, requests for assistance or
advice, and day-to-day safety problems that
require immediate solving.
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5. Lack of teamwork
• In aviation many tasks and operations
are team affairs; no single person or
organization can be responsible for the
safe outcomes of all tasks. However, if
someone is not contributing to the team
effort, this can lead to unsafe outcomes.
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6. Fatigue
• Fatigue is a natural physiological reaction to
prolonged physical and/or mental stress. We
can become fatigued following long periods of
work following periods of hard work.
Therefore, we are more easily distracted, and
we lose situational awareness.
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7. Lack of resources
• If all the parts are not available to
complete a maintenance task, then there
may be pressure on a technician to
complete the task using old, or
inappropriate parts. Regardless of the task,
resources also include personnel, time,
data, tools, skill, experience and
knowledge etc.
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8. Pressure
• Pressure is to be expected when working in a
dynamic environment. However, when the
pressure to meet a deadline interferes with
our ability to complete tasks correctly, then it
has become too much. It is the old argument
of Quantity versus Quality; and in aviation
we should never knowingly reduce the
quality of our work.
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9. Lack of assertiveness
• Being both unable to express our concerns
and not allowing other to express their
concerns creates ineffective communications
and damages teamwork. Unassertive team
members can be forced to go with a majority
decision, even when they believe it is wrong
and dangerous to do so.
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10. Stress
There are many types of stress. Typically in the aviation environment there are two
distinct types - acute and chronic:
• Acute stress arises from real-time demands placed on our senses, mental
processing and physical body; such as dealing with an emergency or working under
time pressure with inadequate resources.
• Chronic stress is accumulated and results from long-term demands placed on the
physiology by life’s demands, such as family relations, finances, illness,
bereavement, divorce, or even winning the lottery.
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11. Lack of awareness
• Working in isolation and only considering one’s
own responsibilities can lead to tunnel vision; a
partial view, and a lack of awareness of the
affect our actions can have on others and the
wider task. Such lack of awareness may also
result from other human factors, such
as stress, fatigue, pressure and distraction.
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12. Norms
• Workplace practices develop over time, through experience, and often
under the influence of a specific workplace culture. These practices can
be both, good and bad, safe and unsafe; they are referred to as “the
way we do things round here” and become Norms.
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