Human Factors In Aircraft Maintenance
Jon Byrd
Director of Aviation
Coosa Valley Technical College
Rome, Georgia
What is Human Factors?
M70-80% of aircraft accidents are due
to human factors – JAA, May 2001
MMaintenance contributed to 15% of
commercial jet accidents – Boeing,
1995
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Maintenance Human Factors
M20-30% of in-flight engine shutdowns
& 50% of delays/cancellations are
caused by human error – Boeing, 1997
M48,800 non-airworthy aircraft are
dispatched each year as a result of
maintenance error – Marx, 1998
MRamp accidents cost over $2 billion
annually – Ramp Safety Vol.11:3
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Dollars & “Sense”
MAvg. cost of an in-flight engine shutdown is
$500,000
MAvg. cost of a flight cancellation is $50,000
MAvg. cost of a return to gate is $15,000
MAvg. ground damage incident costs $70,000
MOne airline estimates $75-$100 million/year
is lost
MAirline Transport Association estimates that
ground damage costs $850 million/yr
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Accidents w/ Maintenance Error
MAmerican Airlines Flight 191 – 1979
MAloha Airlines Flight 243 – 1988
MUnited Flight 232 – 1989
MAtlantic Southeast Airlines (ASA) Flight
532 – 1995
MAir Alaska Flight 261 – 2000
MPaul Wellstone (B100) crash – 2002
MSpectrum Aeronautical LLC - 2006
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General & Corporate Aviation
• Little to no data is available
• Huge industry push yet we get pushed
aside
• With little focus we have to work
harder
• Safety Managers will have to adapt and
adopt
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The Human Element (“Hu”)
M“We’re only human...”
MWe *will* make mistakes...
MThe key is to minimize errors, but
how?
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The “Dirty Dozen”
M Complacency
M Lack of Assertiveness
M Distraction
M Lack of Awareness
M Fatigue
M Lack of Communication
M Norms
M Lack of Knowledge
M Pressure
M Lack of Resources
M Stress
M Lack of Teamwork
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Dirty Dozen - Complacency
M“I don’t need to go get the tech data;
I’ve done this a hundred times...”
M“No need to pull that panel. Last time
I checked that linkage had plenty of
grease...”
MI’ve been an aircraft mechanic for over
25 years; I know what I’m doing...”
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Dirty Dozen - Complacency
MSafety Nets
MAlways follow checklist(s) &/or squawk
cards
MNever work from memory
MBe sure to vary your routine periodically
MBe aware of the dangers of complacency
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Dirty Dozen - Distraction
MPhone calls
MPersonal Issues
MWater Cooler Talk
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Dirty Dozen - Distraction
MSafety Nets
MUse a detailed checklist
MAlways finish the task
MDouble-inspect the work
MUse torque seal &/or safety wire
MRecord or tag uncompleted work
MWhen you return to the task, always go
back three (3) steps
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Dirty Dozen – Fatigue
MWhat is Fatigue?
MThe body’s normal reaction to a physical
or mental stress of a prolonged duration
MThere are two types
MAcute – short duration; cured with good
night’s sleep
MChronic – occurs over a long period of
time; long recovery
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Dirty Dozen – Fatigue
MCauses of Fatigue
MLong hours of labor (any type)
MHigh-intensity stress
MLarge temperature variations
MNoise – above 80db for long duration
MSufficient intensity vibration for long
periods
MSTRONG lighting
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Dirty Dozen – Fatigue
MSymptoms of Fatigue
MEnhanced stimulus required in order to
respond
MAttention reduced
MMemory diminished
M“Withdrawn” mood
MCircadian Rhythm inconsistencies
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Dirty Dozen - Norms
M“I don’t care how you did it there,
we’ve done it this way for years!”
MOutdated/inadequate company policies
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Dirty Dozen – Norms
MWhat are “Norms” exactly?
MThe way of doing business that’s not
approved, but it’s been done locally for so
long that it’s now a “Norm”
MALWAYS work IAW the appropriate tech
data, or if needed, have the manual
revised
MBe aware that “Norms” do not make it
right
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Dirty Dozen – Pressure
M“Get it to the gate!!!”
MToo tightly scheduled deadlines
MFlat-rated Work Orders that maybe
should have been rated
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Dirty Dozen – Pressure
MSafety Nets
MStop! Assess the situation
MLook at the situation rationally
MCan I safely do the job on time?
MHave I voiced my concerns clearly?
MWhat is the worst thing that can happen to
me?
MListen to your rational mind
MHas this happened before?
MAct
MSpeak up – ask for help or more time
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Dirty Dozen - Stress
MPersonal issues
MWeather concerns
MWanting that “atta-boy” for the boss
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Dirty Dozen - Stress
MHow to Manage
MIf you do not manage stress, it will gladly
manage you
MStop burning up emotional energy
MLook rationally at the problem
MCure the cause, not the symptom
MListen to your rational, not your
emotional, mind
MAct – once you have a plan, go for it
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Dirty Dozen - Stress
MOther Stress Helpers
MBe sure the solution starts with “I”
MBe realistic and practical
MTake a break
MTalk to someone who is not emotionally
involved with the situation
MDon’t expect miracles, just keep trying
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Dirty Dozen – Lack of Assertiveness
M“Only do what’s expected of me and
that’s it... Not a movement more.”
MNot researching all applicable technical
data
MNot following technical data to the “t”.
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Dirty Dozen – Lack of Assertiveness
MSafety Nets
MRecord all the work you do in the logbook,
but only sign for that which is serviceable
MRefuse to compromise your standards
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Dirty Dozen – Lack of Awareness
MNot aware of technical data revision
MNot aware of surroundings
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Dirty Dozen – Lack of Awareness
MSafety Nets
MTHINK
MWhat could occur in the event of an accident?
MCHECK
MWill your work conflict with a previous or
existing repair &/or modification?
MASK
MSee if anyone else can spot a problem you
overlooked
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Dirty Dozen – Lack of Communication
MEither technician to technician
MManagement to hangar
MInspection Department to Maintenance
crew(s)
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Dirty Dozen – Lack of Communication
MGood Communication Tips
MYou have:
MTwo ears
MTwo eyes
MOne mouth
MUse them in that order!
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Dirty Dozen – Lack of Communication
MTo Improve Communication
MLearn to Listen
MDo NOT
MDebate
MDetour
MPre-plan
MTune-out
MDo
MAsk questions
MParaphrase
MMake eye contact
MUse positive body language
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Dirty Dozen – Lack of Knowledge
M“Am I experienced for this task?”
M“Do I have all of the appropriate tech
data?”
MAware of FAR’s
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Dirty Dozen – Lack of Knowledge
MSafety Nets
MObtain school training on type, model, etc
MGet supervised on-the-job training
MUse current technical manuals
MTech Reps &/or Manufacturer Reps are
there for a purpose – use them!
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Dirty Dozen – Lack of Resources
MIs the appropriate tech data available?
M“Do I have the proper tools and
equipment to perform the task?”
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Dirty Dozen – Lack of Resources
MSafety Nets
MCheck all suspect areas at the beginning
of all inspections and AOG the required
parts
MOrder & stock parts before they’re
required
MKnow your sources
MArrange for pooling &/or loaning
MMaintain aircraft to highest standard
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Dirty Dozen – Lack of Teamwork
MIs this a task that really two
technicians should do?
M“No, I don’t need any help; I know
what I’m doing!”
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Dirty Dozen – Lack of Teamwork
MSafety Nets
MAlways discuss and plan the Who, What,
When, Where, and How of the task to be
done
MInsure that everyone understands and
agrees
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Accident Model
1
Co
nd
iti
on
sa
fe
Un
Superv
ision/O
rg
anizati
on
The Domino Theory
ct
A
fe
nt
a
e
s
v
pE
a
Un
h
Mis
Damage/Injury
2
3
4
Dominos
5
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Reason’s Swiss Cheese Model
Organizational
Factors
Latent Condition
Unsafe
Supervision
Latent Condition
Unsafe Act
Preconditions
HFACSHuman Factors Analysis
& Classification System
Latent Condition
Unsafe
Acts
Active Failure
Accident
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Human Factors Prevention
• Recap
• We’re all human and we will make
mistakes
• Know your own limits
• Learn to recognize it in others
• Cure the cause and not the symptom
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My Thanks
• FAA
• Lou Lerda – Safety Program Manager,
Seattle, WA FSDO
• Atlanta FSDO-11
• Jim Lumley & GWBAA
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Human Factors in Aviation Maintenance
Questions?
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