This document outlines 12 common causes of human error in aircraft maintenance, called "The Dirty Dozen". It describes each of the 12 factors, including lack of communication, complacency, lack of knowledge, distraction, lack of teamwork, fatigue, lack of resources, pressure, lack of assertiveness, stress, lack of awareness, and norms. For each factor, examples of accidents are presented and recommendations are provided for how to reduce errors by improving safety nets like checklists, inspections, and communication between maintenance technicians. The goal is to raise awareness of the types of human errors that can occur and how following best practices in maintenance can help prevent accidents.

1. Presented to:
By:
Date:
Federal Aviation
Administration
Airworthiness
Human Factors
R1
Maintenance Error- Dirty Dozen

2. 2Federal Aviation
Administration
Dirty Dozen- Human Error in Aircraft Maintenance
Objectives
• Illustrate that human error in
maintenance causes death and
destruction
• Identify 12 causes of
maintenance error, “The Dirty
Dozen”
• Suggest how to reduce
maintenance error

3. 3Federal Aviation
Administration
Dirty Dozen- Human Error in Aircraft Maintenance
The Best People Make
the Worst Mistakes

4. 4Federal Aviation
Administration
Dirty Dozen- Human Error in Aircraft Maintenance

5. 5Federal Aviation
Administration
Dirty Dozen- Human Error in Aircraft Maintenance
Delta Flight 1288 MD-88

6. 6Federal Aviation
Administration
Dirty Dozen- Human Error in Aircraft Maintenance
The Dirty Dozen
• Communication
• Complacency
• Lack of Knowledge
• Distraction
• Teamwork
• Fatigue
• Lack of Resources
• Pressure
• Assertiveness
• Stress
• Lack of Awareness
• Norms

7. 7Federal Aviation
Administration
Dirty Dozen- Human Error in Aircraft Maintenance
“The Dirty Dozen”
1. Lack of Communication
2. Complacency
3. Lack of Knowledge
4. Distraction
5. Lack of Teamwork
6. Fatigue
7. Lack of Resources
8. Pressure
9. Lack of Assertiveness
10. Stress
11. Lack of Awareness
12. Norms
Safety Nets
Use logbooks, worksheets etc. to
communicate and remove doubt.
Discuss work to be done or what has been completed.
Never assume anything.

8. 8Federal Aviation
Administration
Dirty Dozen- Human Error in Aircraft Maintenance

9. 9Federal Aviation
Administration
Dirty Dozen- Human Error in Aircraft Maintenance
Safety Nets
Use logbooks, worksheets etc. to communicate and remove doubt.
Discuss work to be done or what has been completed.
Never assume anything.
Continental Express, 14 Fatalities, 9-11-91

10. 10Federal Aviation
Administration
Dirty Dozen- Human Error in Aircraft Maintenance
“The Dirty Dozen”
1. Lack of Communication
2. Complacency
3. Lack of Knowledge
4. Distraction
5. Lack of Teamwork
6. Fatigue
7. Lack of Resources
8. Pressure
9. Lack of Assertiveness
10. Stress
11. Lack of Awareness
12. Norms
Safety Nets
Train yourself to expect to find a fault.
Never sign for anything you didn‟t do.

11. 11Federal Aviation
Administration
Dirty Dozen- Human Error in Aircraft Maintenance
Italian Air Force, Keflavik
• No lineman present for start-up
• Crew asked LM to verify battery door
closed (near left landing gear) after
engines were started
• LM walked thru prop, killing him instantly
• First such case in Italian AF in over 50
years

12. 12Federal Aviation
Administration
Dirty Dozen- Human Error in Aircraft Maintenance
Italian Air Force, Keflavik
CREW DOOR
BATT. DOOR
Loadmaster exits crew door to check battery door.
Engines were running

13. 13Federal Aviation
Administration
Dirty Dozen- Human Error in Aircraft Maintenance
Loadmaster killed as he walks into prop.
Body and remains scattered over 100 feet.

14. 14Federal Aviation
Administration
Dirty Dozen- Human Error in Aircraft Maintenance
Accident cleanup by “Fire Department”
Carelessness and overconfidence are more dangerous than
deliberately accepted risk.
- Wilbur Wright, 1901.

15. 15Federal Aviation
Administration
Dirty Dozen- Human Error in Aircraft Maintenance
Therefore the Safety Board concludes
that a low expectation of finding a
crack in a –219 series fan hub might
have caused the inspector to overlook
or minimize the significance of an
indication.

16. 16Federal Aviation
Administration
Dirty Dozen- Human Error in Aircraft Maintenance
Face Reality
Physical Fitness
Create Challenges for yourself
Train yourself to expect to find a fault.
Never sign for anything you didn‟t do
Safety Nets

17. 17Federal Aviation
Administration
Dirty Dozen- Human Error in Aircraft Maintenance
“The Dirty Dozen”
1. Lack of Communication
2. Complacency
3. Lack of Knowledge
4. Distraction
5. Lack of Teamwork
6. Fatigue
7. Lack of Resources
8. Pressure
9. Lack of Assertiveness
10. Stress
11. Lack of Awareness
12. Norms
Safety Nets
Get training on type.
Use up to date manuals.
Ask a Tech. Rep. or someone who knows.

18. 18Federal Aviation
Administration
Dirty Dozen- Human Error in Aircraft Maintenance

19. 19Federal Aviation
Administration
Dirty Dozen- Human Error in Aircraft Maintenance

20. 20Federal Aviation
Administration
Dirty Dozen- Human Error in Aircraft Maintenance

21. 21Federal Aviation
Administration
Dirty Dozen- Human Error in Aircraft Maintenance
Lack Of Knowledge
Get training on type.
Stay Current
-Read, Read, Read
Use up to date manuals.
Ask a Tech. Rep.
-or someone who knows
Communicate
No Pride!
Safety Nets
September 2, 1998
Douglas MD-11 in the sea
9KM Off Nova Scotia

22. 22Federal Aviation
Administration
Dirty Dozen- Human Error in Aircraft Maintenance
“The Dirty Dozen”
1. Lack of Communication
2. Complacency
3. Lack of Knowledge
4. Distraction
5. Lack of Teamwork
6. Fatigue
7. Lack of Resources
8. Pressure
9. Lack of Assertiveness
10. Stress
11. Lack of Awareness
12. Norms
Safety Nets
Always finish the job or unfasten the connection
Mark the uncompleted work.
Lock wire where possible or use torque seal.
Double inspect by another or self.
When you return to the job always go back three steps.
Use a detailed check sheet.

23. 23Federal Aviation
Administration
Dirty Dozen- Human Error in Aircraft Maintenance
Always finish the job or unfasten the connection.
Mark the uncompleted work.
Lock wire where possible or use torque seal.
Double inspect by another or self.
When you return to the job always go back three steps.
Use a detailed check sheet.
Safety Nets

24. 24Federal Aviation
Administration
Dirty Dozen- Human Error in Aircraft Maintenance
“The Dirty Dozen”
1. Lack of Communication
2. Complacency
3. Lack of Knowledge
4. Distraction
5. Lack of Teamwork
6. Fatigue
7. Lack of Resources
8. Pressure
9. Lack of Assertiveness
10. Stress
11. Lack of Awareness
12. Norms
Safety Nets
“Reconfirm duties among team members.”
“Team tasks require a full team.”
“Communicate!”
“FOLLOW THE CORRECT PROCEDURES.”

25. 25Federal Aviation
Administration
Dirty Dozen- Human Error in Aircraft Maintenance

26. 26Federal Aviation
Administration
Dirty Dozen- Human Error in Aircraft Maintenance

27. 27Federal Aviation
Administration
Dirty Dozen- Human Error in Aircraft Maintenance
“Communicate!”
“Team tasks require
a full team.”
“Reconfirm duties
among team members.”
“FOLLOW THE CORRECT PROCEDURES.”
Safety Nets
Lack of Teamwork

28. 28Federal Aviation
Administration
Dirty Dozen- Human Error in Aircraft Maintenance
“The Dirty Dozen”
1. Lack of Communication
2. Complacency
3. Lack of Knowledge
4. Distraction
5. Lack of Teamwork
6. Fatigue
7. Lack of Resources
8. Pressure
9. Lack of Assertiveness
10. Stress
11. Lack of Awareness
12. Norms
Safety Nets
Be aware of the symptoms and
look for them in yourself and
others.
Plan to avoid complex tasks at
the bottom of your circadian
rhythm.
Sleep and exercise
regularly.
Ask others to
check your work

29. 29Federal Aviation
Administration
Dirty Dozen- Human Error in Aircraft Maintenance
ACUTE FATIGUE
Produced by physical exertion or sleep loss
Alleviated by a single rest period
CHRONIC FATIGUE
Medical or psychological problem
Depression or “chronic fatigue syndrome”
OPERATIONAL FATIGUE
Most commonly seen after 3-4 days of heavy tasking
Not relieved by a single sleep period
Fatigue

30. 30Federal Aviation
Administration
Dirty Dozen- Human Error in Aircraft Maintenance
Attention reduced
Memory diminished
Mood becomes withdrawn
Low situational awareness
Long hours of labor (any type).
High intensity stress.
SYMPTOMS OF FATIGUE

31. 31Federal Aviation
Administration
Dirty Dozen- Human Error in Aircraft Maintenance
CIRCADIAN RHYTHMS

32. 32Federal Aviation
Administration
Dirty Dozen- Human Error in Aircraft Maintenance
Be aware of the symptoms and look for
them in yourself and others.
Plan to avoid complex tasks at the bottom
of your circadian rhythm.
Sleep and exercise regularly.
Ask others to check your work.
Safety Nets
Fatigue

33. 33Federal Aviation
Administration
Dirty Dozen- Human Error in Aircraft Maintenance
“The Dirty Dozen”
1. Lack of Communication
2. Complacency
3. Lack of Knowledge
4. Distraction
5. Lack of Teamwork
6. Fatigue
7. Lack of Resources
8. Pressure
9. Lack of Assertiveness
10. Stress
11. Lack of Awareness
12. Norms
Safety Nets
Check suspect areas at the beginning of the inspection
and AOG the required parts.
Order and stock anticipated parts before they are
required.
Know all available parts sources and arrange for
pooling or loaning.
Maintain a standard and if in doubt ground the aircraft.

34. 34Federal Aviation
Administration
Dirty Dozen- Human Error in Aircraft Maintenance
Jackscrew
88

35. 35Federal Aviation
Administration
Dirty Dozen- Human Error in Aircraft Maintenance
Check suspect areas at the beginning of the
inspection and AOG the required parts.
Order and stock anticipated parts before they are
required.
Know all available parts sources and arrange for
pooling or loaning.
Maintain a standard and if in doubt ground the
aircraft.
Safety Nets
Lack of Resources

36. 36Federal Aviation
Administration
Dirty Dozen- Human Error in Aircraft Maintenance
“The Dirty Dozen”
1. Lack of Communication
2. Complacency
3. Lack of Knowledge
4. Distraction
5. Lack of Teamwork
6. Fatigue
7. Lack of Resources
8. Pressure
9. Lack of Assertiveness
10. Stress
11. Lack of Awareness
12. Norms
Safety Nets
Be sure the pressure is not self- induced.
Communicate your concerns.
Ask for extra help.
Just say NO.

37. 37Federal Aviation
Administration
Dirty Dozen- Human Error in Aircraft Maintenance
Jessica Dubroff 1988- 1996

38. 38Federal Aviation
Administration
Dirty Dozen- Human Error in Aircraft Maintenance
Chiang Kai-Shek Airport Taiwan
June 6, 2005

39. 39Federal Aviation
Administration
Dirty Dozen- Human Error in Aircraft Maintenance
Be sure the pressure is not self- induced.
Communicate your concerns.
Ask for extra help.
Just say NO.
Safety Nets
Pressure

40. 40Federal Aviation
Administration
Dirty Dozen- Human Error in Aircraft Maintenance
“The Dirty Dozen”
1. Lack of Communication
2. Complacency
3. Lack of Knowledge
4. Distraction
5. Lack of Teamwork
6. Fatigue
7. Lack of Resources
8. Pressure
9. Lack of Assertiveness
10. Stress
11. Lack of Awareness
12. Norms
Safety Nets
If it‟s not critical, record it in the journey log book &
only sign for what is serviceable.
Refuse to compromise your standards.

41. 41Federal Aviation
Administration
Dirty Dozen- Human Error in Aircraft Maintenance
AggressivePassive
Assertive
Performance
Assertiveness
Anger
Offense
Acquiesce
Compromise
Others
Rights
Your
Rights
Both Party‟s Rights
Team Work
Synergy
High
Low

42. 42Federal Aviation
Administration
Dirty Dozen- Human Error in Aircraft Maintenance

43. 43Federal Aviation
Administration
Dirty Dozen- Human Error in Aircraft Maintenance

44. 44Federal Aviation
Administration
Dirty Dozen- Human Error in Aircraft Maintenance
If it‟s not critical, record it in the journey log book
& only sign for what is serviceable.
Refuse to compromise your standards.
Safety Nets
Lack of Assertiveness

45. 45Federal Aviation
Administration
Dirty Dozen- Human Error in Aircraft Maintenance
“The Dirty Dozen”
1. Lack of Communication
2. Complacency
3. Lack of Knowledge
4. Distraction
5. Lack of Teamwork
6. Fatigue
7. Lack of Resources
8. Pressure
9. Lack of Assertiveness
10. Stress
11. Lack of Awareness
12. Norms
Safety Nets
Be aware of how stress
can effect your work.
Stop and look rationally
at the problem.
Determine a rational
course of action and
follow it.
Take time off or at least
have a short break.
Discuss it with
someone.
Ask fellow workers to
monitor your work.
Exercise your body.

46. 46Federal Aviation
Administration
Dirty Dozen- Human Error in Aircraft Maintenance
STRESS

47. 47Federal Aviation
Administration
Dirty Dozen- Human Error in Aircraft Maintenance
Be aware of how stress can effect your work.
Stop and look rationally at the problem.
Determine a rational course of action and
follow it.
Take time off or at least have a short break.
Discuss it with someone.
Ask fellow workers to monitor your work.
Exercise your body.
Safety Nets
Stress

48. 48Federal Aviation
Administration
Dirty Dozen- Human Error in Aircraft Maintenance
“The Dirty Dozen”
1. Lack of Communication
2. Complacency
3. Lack of Knowledge
4. Distraction
5. Lack of Teamwork
6. Fatigue
7. Lack of Resources
8. Pressure
9. Lack of Assertiveness
10. Stress
11. Lack of Awareness
12. Norms
Safety Nets
Think of what may occur in the event of
an accident.
Check to see if your work will conflict
with an existing modification
or repair.
Ask others if they can see any
problem with the work done.

49. 49Federal Aviation
Administration
Dirty Dozen- Human Error in Aircraft Maintenance

50. 50Federal Aviation
Administration
Dirty Dozen- Human Error in Aircraft Maintenance

51. 51Federal Aviation
Administration
Dirty Dozen- Human Error in Aircraft Maintenance

52. 52Federal Aviation
Administration
Dirty Dozen- Human Error in Aircraft Maintenance
Think of what may occur in the event of an
accident.
Check to see if your work will conflict with an
existing modification or repair.
Ask others if they can see any problem with the
work done.
Safety Nets
Lack of Awareness

53. 53Federal Aviation
Administration
Dirty Dozen- Human Error in Aircraft Maintenance
“The Dirty Dozen”
1. Lack of Communication
2. Complacency
3. Lack of Knowledge
4. Distraction
5. Lack of Teamwork
6. Fatigue
7. Lack of Resources
8. Pressure
9. Lack of Assertiveness
10. Stress
11. Lack of Awareness
12. Norms
Safety Nets
Always work as per the instructions or
have the instructions changed.
Be aware that „norms don‟t make it right.

54. 54Federal Aviation
Administration
Dirty Dozen- Human Error in Aircraft Maintenance
This picture was taken by an amateur photographer
seconds before an American Airlines DC-10 crashed at
Chicago O'Hare Airport, after losing an engine during
takeoff. Below is the resulting explosion. Improper
maintenance procedures was to blame. Two-hundred-
seventy-one people aboard were killed as well as 2 on the
ground. (May 25, 1979)

55. 55Federal Aviation
Administration
Dirty Dozen- Human Error in Aircraft Maintenance
Always work as per the instructions or
have the instructions changed.
Be aware that „norms don‟t make it right.
Safety Nets
Norms

56. 56Federal Aviation
Administration
Dirty Dozen- Human Error in Aircraft Maintenance
FATIGUE
STRESS
COMPLACENCY
COMMUNICATION
AWARENESS
DISTRACTION
LACK OF KNOWLEDGE
TEAMWORK
LACK OF RESOURCES
PRESSURE
LACK OF ASSERTIVENESS
NORMS
Lee Marvin, Ernest Borgnine, Jim Brown, Charles Bronson, John Cassavetes, Trini Lopez, Telly Savalas, Donald Sutherland, Clint Walker

57. 57Federal Aviation
Administration
Dirty Dozen- Human Error in Aircraft Maintenance
Face Reality

58. 58Federal Aviation
Administration
Dirty Dozen- Human Error in Aircraft Maintenance
• Information for You
• A Request from Us
• Any Questions???
Before We End