Posted 5 years 51 days ago ago by jhadmin
Maintenance engineers and mechanics have known about ‘The Dirty
Dozen’ for years. They are the 12 most common human error preconditions
or conditions that act as precursors to accidents or incidents for
I first learned about The Dirty Dozen when I put together a crew
resource management course for helicopter engineers and mechanics. I
instantly realized that pilots would be safer if they knew about these
dozen error traps too.
The Dirty Dozen is a concept developed in 1993 by Gordon DuPont, when
he worked for Transport Canada. They have since become a cornerstone in
maintenance training courses worldwide.
The Dirty Dozen:
1) Lack of Communication
3) Lack of Knowledge
5) Lack of Teamwork
7) Lack of Resources
9) Lack of Assertiveness
11) Lack of Awareness
The Dirty Dozen can affect our performance and should be remembered
by anyone working in and around aircraft, whether pilot or mechanic.
Let’s dissect these dozen culprits more closely.
Lack of Communication
Studies have shown that generally only 30 percent of verbal
communication is received and understood by either person in a
conversation. People normally remember what was said first and last in
an exchange; consequently it is important to put the most important part
of our message first and then repeat it at the end. Depending on the
complexity of the message, it might be more effective to provide some
form of written instruction, such as a checklist.
Complacency is defined as “self-satisfaction accompanied by a loss of
awareness of the danger.” If an activity has become routine and we’re
feeling fat dumb, and happy, we may be missing important signals because
we tend to see what we expect to see.
Lack of Knowledge
Air operators have a regulatory responsibility to ensure that their
personnel have required training. A pilot or mechanic should always keep
up to date on relevant information to perform their job safely.
Distraction is anything that draws our attention away from the task
at hand. Psychologists say distraction is the number one cause of
forgetting things. We are always thinking ahead, thus we have a natural
tendency when we are distracted before returning to a job to think we
are further ahead than we actually are.
Lack of Teamwork
An effective team will:
- Maintain a clear mission
- Maintain team expectations
- Communicate to all team members
- Maintain trust
- Pitch in
Scientific studies have shown that, similar to being under the
influence of alcohol, when fatigued we tend to underestimate the problem
and overestimate our ability to cope with it. It’s been proven that
after 17 hours of wakefulness we are functioning as if we had an
equivalent blood alcohol level of 0.05 percent. After 24 hours, the
level increases to 0.1 percent. It is also noteworthy that the more
fatigued we are, the more easily we become distracted.
Lack of Resources
A lack of resources can interfere with our ability to complete a task
because there is a lack of supply and support. Low-quality products
also affect our ability to complete a task.
Urgent demands that can influence our performance include:
1) Company demands
2) Client demands
3) Peer demands
4) Self-induced demands
Interestingly, of these four demands, we put the most pressure on
ourselves. Self-induced pressures are those occasions where we take
ownership of a situation not of our doing. The “monkey on our back” is
ours because we accepted and took ownership of it. Being assertive and
not accepting said monkey will help distance us from the assumed
“urgency” of the induced pressure to perform.
Lack of Assertiveness
Assertiveness is the ability to express our feelings, opinions, beliefs, and needs in a positive, productive manner. It is not
the same as being aggressive.
The following are examples of how a lack of assertiveness can be offset.
- Get the persons attention and state the problem:
- “John, I have a concern with…”
- “If we continue… this will be the result…”
- “We could… You may want to try… I’d like to…”
In all of the above scenarios, remember to deal with one issue at a
time (not multiple issues), do not embellish or exaggerate, stick to the
facts, and remain calm.
There are two types of stress: acute and chronic. Acute stress
relates to the demands placed on the body because of current issues like
time constraints for readying an aircraft for flight. Chronic stress
results from long-term demands placed on the body by negative major life
events such as divorce and financial worries, or positive events like
having a child. Chronic stress can exaggerate the effects of acute
stress. To handle acute stress, take a short break and relax by deep
breathing. Dealing with chronic stress is more difficult and usually
involves a lifestyle change.
Lack of Awareness
This is defined as “a failure to recognize all the consequences of an
action, or lack of foresight.” To combat lack of awareness, try asking
yourself these questions: What if…? Do I see the complete picture? What
have I forgotten?
Norms are unwritten rules or behaviors in an organization that are
dictated, followed, and supported by the majority of the group. With
norms, they have become part of the company’s culture, often referred to
as “the way we do things around here.”
Unfortunately, norms follow unwritten rules or behaviors that can
deviate from well-proven rules, procedures, instructions, or SOPs. Norms
can be enforced through peer pressure and force of habit. It is
important to understand that most norms have not been designed to meet
all circumstances, and therefore are not adequately tested against
Keep The Dirty Dozen in mind while on the job. Just as awareness of them
helps keep mechanics from making mistakes on the ground, they will help
keep you safe in the air.
About Randy: Randy Mains is an author, public speaker, and a
CRM/AMRM consultant who works in the helicopter industry after a long
career of aviation adventure. He currently serves as chief CRM/AMRM
instructor for Oregon Aero. He may be contacted at