46109930-15750363-Human-Factors-for-Aircraft-Maintenance

Prévia do material em texto

Human Factors for Aircraft Maintenance
Compiled by Shahzad Khalil
Aug2007
1
Contents of Course
1. General
2. Human Performance and Limitations 
3. Social Psychology
4. Factors affecting Performance
5. Physical Environment
6. Tasks
7. Communication
8. Human Error
9. Hazards in the Work Place 
2
Foreword
This course will benefit you both:
 professionally – at workplace
& 
 personally – in daily life
3
Goal
 Awareness of personal behaviour
 
 Minimise errors
 Reduce the number of incidents
 Improve Safety – of personnel & aircraft. 
4
E:\human Factors\MPEGAV\AVSEQ01.DAT
Quotation: To err is human.
Quiz
 Do human make mistakes? 
 Are we human? 
 Will we make mistakes?
 Would we like to reduce the possibility of 
mistakes?
5
Introduction
 Aviation: Safest forms of 
travelling.
 Chain of Events/human 
errors
Solution / Safety Net:
 If we break the chain at our 
level, the accidents will not 
happen.
6
The need to consider the human factor 
Most important human factor:
 Ability to learn from experience & mistakes 
committed by others.
 Basic Rules:
If it has gone wrong once, it will probably go 
wrong again.
 Safety Net:
At Design stage – By manufacturer. ( e.g. Cross wires)
At user level – By following written procedures.
7
Error in aircraft maintenance 
Valujet Flight 597:
 5 pax & 2 flight attendants injured.
 7th Stage high compressor disk failed.
Investigated Causes:
 Fatigue crack.
 Poor Record-keeping.
8
Reasons of Safety Improvement
 better aircraft 
 better air traffic control 
 better weather forecasts. 
9
It is difficult to fix a faulty person 
than to fix a faulty component.
Do you agree?
10
Human Error Estimates:
11
Error Iceburg:
 A chain of minor events caused accidents.
 Heinrich Ratio:
 Fatal Accidents 1
 Non Fatal 10
 Reportable accidents 30
 Unsafe Acts (Not reported 600
Safety Net:
 Look below the surface for minor mistakes and 
never leave anything unreported.
 Saying :Take care of your hours and days, 
months and years will take care themselves.
12
In aviation, Extremely Low Tolerance for Errors
 Although we learn through mistakes, yet 
cannot afford to commit mistakes ourselves 
and learn. We have to: 
 learn from the mistakes of others.
 Proactive Approach:
Taking measures, in advance, to avoid the 
occurrence of any event.
13
Causes & Casts of Air Accidents ex: Boeing
14
A Simple Mistake by one Person 
affects an Entire Organsiation
B767 was being brought into Hanger, collided with workstands. 
 Resulting Damage:The following equipment was damaged:
 Left-hand horizontal stabilizer
 Rudder 
 Rear dock stands
 Hangar wall 
 Cost factors: The following cost factors resulted from this one mistake: 
 Material 
 Regular and overtime labour 
 Repairs to dock stands and hangar wall 
 Loss of bay facility during additional repair 
 Delayed or third party maintenance for other aircraft
 Operational complications due to aircraft unavailability 
 Investigation and corrective action 
15
Cost of one Night Stop at Foreign 
Station
Approximately 40,000/- USD
16
Top seven causes of inflight shutdowns :
Boeing analyzed the most common errors behind B767 inflight shutdowns; almost 70% 
were caused by installation problems.
 Incomplete installation (33%) 
 Damage on installation (14.5%)
 Improper installation (11 %) 
 Equipment not installed or missing (11%)
 Foreign object damage (6.5%) 
 Improper troubleshooting, inspection, test (6%)
 Equipment not activated or deactivated (4%) 
17
Top eight common maintenance errors 
 Incorrect installation of components 
 Fitting of wrong parts 
 Wrong electrical wiring of parts (including cross 
connections) 
 Loose objects left in the aircraft 
 Not enough lubrication 
 Cowling and/or access panels not secured 
 Fuel/oil caps and/or refuel panel not secured 
 Landing gear ground lock pins not removed before 
departure 
18
Who is right? 
 Both are right from their 
own positions.
 When you decide 
anything or assign any 
task to someone, place 
yourself on his position 
and see the things as 
he perceives.
19
Aloha Airline’s flight of B737
had 18 feet (5.5m) of fuselage skin ripped off. 
 An AD called for close inspection of 1300 rivets. 
 The inspector had 22 years of experience. 
 The chief inspector had 33 years of experience. 
 In the inspection prior to the incident no cracks were found. 
 A post incident inspection revealed that there were at least 240 cracks 
present at the last inspection prior to the incident. 
20
Comparison of Human Errors to Machine Errors 
21
Murphy’s Law:
“Anything that can go wrong will go wrong.”
 Manufacturers – 
 design changes-make it impossibility to use in 
wrong way. e.g. computer connectors. 
 Procedures misunderstood 
 –Users – improve procedures e.g. Dual 
inspection.
22
Types of Errors
 Active error - immediate effect 
 Height of aircraft not read correctly – crash – immediate 
effect
 Latent error - delayed effect
 Bolt was corroded – not seen so not replaced will 
ultimately break.
 Delay between the mistake and consequence.
 e.g. Smoking.
 
23
Conclusions from brief introduction of human Errors
 Errors affect both lives and profit. 
 Many errors are made, but it usually requires a chain of 
events for a serious incident to occur. 
 Although only a few errors will be the cause of an 
accident, it is impossible to predict which one this will be. 
 AMTs must be aware of the different kinds of mistake 
they make and the possible consequences. 
 AMTs must know the company's procedures for avoiding 
errors and the benefit of following those procedures. 
24
9.2 HUMAN PERFORMANCE AND LIMITATIONS 
 Brain – the CPU of Human body.
 Input devices of human body and their related 
senses.
 Five senses: : smell, taste, sight, hearing 
and touch. 
 Minimum level of stimulation – Threshold 
values.
 Health of our senses.
 Potections.
25
Brain
 Left half of brain thinks 
rationally. Used while 
dealing with problems.
 Right half of brain thinks 
emotionally. Related to 
creativity and clever ideas.
 Which one is correct to use?
 Both should be used.
26
Strategies
27
Information Awareness
 Five senses - the sources of information.
 Smell can warn us of dangers.
 Sense of temperature through touch.
 Extreme of touch is pain. – sense of touch.
 Taste – very rarely used.
 The two most used senses: Sight and 
hearing.
28
Detection & Awareness
 Sight sense – eyes.
 Minimum level of 
stimulation / threshold 
level with naked eye : 
60 micron.
 Inspection involves: 
search and decision 
making.
29
Use of eyes:
 Inspections: 80% of inspections are visual inspection
 Written documents: Different manuals.
 Job-cards
 Writing what you have done.
 Written Communication: 
 Legible
 Accurate
 Complete
 Order of sentences.
30
Hearing
 Use ears.
 AF : 20 Hz – 20 KHz
 Volume / Audio level in decibel 
(dB)
 Awareness threshold: 0 dB
 Deteriorate with age and also 
suffers from non-reversible 
permanent damage when exposed 
to high level of noise.
 50% to 80% waking time spent in 
listening.
 Two ears and one tongue.
31
Ear Protections
 When sound volume > 90 dB
 Even at 85 dB if remain exposed for 
> 4 hours.
 Earmuffs / Earplugs.
 Treatment of ears take years.
32
 What is the difference between 
Hearing & Listening 
 Hearing
 is just the process of taking in sounds.
 not selective.
 Passive.
 Sound of fan, air-conditioner etc.
 Listening
 hearing with selective attention.
 Involves interpreting the sounds.
 Active.
 To each other.
33
Listening
 Interest in topic.
 Distraction tolerance
 Appropriate time & place.
 Listening instead of talking: two ears & one tongue.
 Preparation
 Eye contact
 What is said and what is not said? Sometimes more 
information in what is not said.
 Prejudices: decision already made.
34
Hearing Damage
35
Different Ways of Information Transfer:
 Person to Person:
 Via verbal communication
 Via written communication
 Display / Product to person:
 Job cards
 Manuals
 Displays
 Indicators
 Person to Product:
 Key board of computer
 Controls in aircraft
36
Information That is Hard to See or Hear
 Noisy environment 
 Makes it hard to hear what people say. 
 Poor lighting 
 Can't see cracks, loose tools or parts.
 Poor communication 
 Not speaking clearly 
 Bad handwriting 
37
Information Present but Missed
 Awareness Problem
 Completely focused on one task and miss 
other things around.
 Distractions: e.g. During walk-around, a hole 
on ground is a distractor.
 Conversations
 Interruptions
38
Attention and Awareness
 Selective Attention:
 Monitoring several sources of information to decide 
whether particular event has occurred e.g. deviant 
reading on several indicators in cockpit. 
 Focused Attention:
 Being task focused. Concentrating to one source.
 e.g. Mechanic reading in noisy environment. 
 Divided Attention
 Sustained Attention
 Security Guards viewing a TV monitor.
39
Mental limits: Disassembly and Re-assembly
 There is only one way to disassemble the nuts, but there are 
40, 000 wrong ways to re-assemble them.
 Knowledge and experience will help to prevent mistakes, but 
nobody can know everything (Human limitations)
 Use of Written instructions and Experience of colleagues can 
compensate for these limitations.
40
Claustrophobia and Physical Access
 Claustrophobia: 
 Definition: An irrational fear of being in a 
confined or enclosed space.
 e.g. Maintenance in Fuel Tank.
 Use Life-Line
 Space Availability:
 More space improves performance.
 Controllability:
 Minimum restrictions due to clothes & shoes.
41
9.3 Social Psychology
The area of psychology that deal with how 
groups behave and how individuals are affected 
by the group.
42
Different Ways to Learn & %age Remembered:
 Hear 25%
 See 30-35%
 See & Hear 50%
 Say & Repeat 75%
 Do 90%
 
43
Motivation 
Willingness to put effort into 
achieving a goal.
44
Alfred Adler’s Motivation Theory
 All human behaviour is goal-directed. 
 When given the chance to contribute, they become 
productive, task-oriented employees and in result feel 
significant. 
 People are creative decision-makers. 
 An active role in solving problems and decision making. 
 Humanity is socially embedded. 
 Problems cannot be solved by one person in isolation. 
They are solved by co-operation and contribution. 
 Use is more important than possession. 
 A person's knowledge and skills are of no value if they are 
not used. 
 People (and organisations) function holistically. 
 The whole is greater than the sum of the individual parts. 
 A group effort be encouraged. 
45
Maslow’s Theory of Hierarchy of Needs
46
Culture Issues
 Corporate Culture:
 Develop a desirable corporate culture.
 Pleasant workplace and effective maintenance.
 Philosophy:
 Mission Statement: Clearly worded and communicated.
 Guidelines stating what is and is not acceptable.
 Ceremonies for appropriate recognition.
 Hearfelt concerns for employees.
 Open communication.
47
Teamwork
 Planning, co-ordination and communication.
 Team: a group of inter-dependent individuals 
working together to complete a specific task. 
 Example: Football Team
 In maintenance, working as a team improves 
productivity and reduces injury and equipment 
damage.
48
Characteristics of an Effective Team
n A clear purpose: accepted by all members. 
n Relaxed: no tensions among the members. 
n Participation: in decisions making and/or activities. 
n Listening: listens to the others. 
n Disagreement: Agree to disagree with each other. 
n Openness: full and open communication. 
n Clear expectations: about the roles each member & 
assignments fairly distributed 
n Shared leadership: Delegation of Power. 
n Relations with others: With other teams.
n Team maintenance: focus on their primary goal but also spend 
time recognising and maintaining the functions of the team. 
49
Leadership
 The ability to direct and co-ordinate the 
activities of group members and stimulate / 
inspire them to work together to complete a 
specific task. 
Lead by example.
50
Responsibilities of Leaders
 Direct and co-ordinate team activity 
 Delegate tasks to appropriate team members 
 Make sure team members know what is expected of 
them 
 Focus attention on important aspects of the situation 
 Adapt to internal and external changes to the 
environment 
 Keep team members up to date on work-related 
information 
 Ask team members for work-relevant information
 Provide feedback to team on performance 
 Create and maintain a professional atmosphere 
51
Effective Leader
 Make suggestions 
 Encourage the team to perform 
 Lead by inspiration 
 Provide feedback 
How well you lead depends on how 
well you communicate.
52
Types of Leaders
 Authoritative Leader:
 Runs the show alone. Sole decision maker.
 Controls all the resources.
 Dictates actions with little input from team members.
 Participatory Leader:
 Encourages participation.
 Distributes resources and delegate power.
 Get maximum input from members
 Group decisions.
 
53
 Which type of leadership is better?
 Balance between the two types.
54
When to use Authoritative and when 
Participatory?
Authoritative Participatory
Done quickly. Time available.
Task structured. Clear 
Answers.
Task unstructured. Inputs 
required.
Conflicts Work well together.
Accepts decision taken by 
single person.
Do not accepts decision 
taken by single person.
55
 9.4. Factors Affecting Performance 
Stress
 Definition: 
 Physical or psychological tension caused by dealing 
with difficult situations.
 Stressors
 Personal problems.
 Work related problem.
 Social problems.
 Cost of Stress
 Poor work quality – Public safety jeopardised.
 Heart diseases – Sleeping problem
56
Stress and performance
 Stress in itself is not 
necessarily bad.
 Positive level of stress: 
Best Performance.
 Negative level of stress: 
Poor performance.
57
Time Pressures & Deadlines
 Time pressure sets the pace of work.
 Stressful Situations:
 Overload
 Under-load 
 Fire Fighters: 
 Under-loaded & Overloaded
58
Varying the Task
 Alternate / swap tasks:
 Physical demanding with mentally demanding
 High awareness with low awareness
 Long duration with short duration
 Frequent Breaks
 Break can be a change of work.
59
Components of Situation Awareness
 Be aware of your surroundings.
 Use all the senses.
“ Fire , Fire, Fire”
 Perceiving : e.g. listening of some sound.
 Comprehending: What that sound mean?
 Projecting: Thinking about possible consequences.
60
Models
 Are in diagram form.
 Drawn to understand complex systems.
 For example: model of braking system of bicycle to 
understand aircraft braking system.
 Block Diagrams, wiring diagrams etc.
61
Why we draw models?
 To identify the components of the system.
 To develop the strategies to improve the 
system.
62
SHELL Model
Software
Hardware
Environment 
Liveware (Individual)
Liveware (Group)
63
9.7 Communication
64
Definitions of Communication
 Skill of passing information from on person to 
another.
 Transfer of information from one place to 
another.
 The dynamic and irreversible process by 
which we make contact and interpret 
messages within a given situation or context.
65
The Transactional Analysis Model
 Is an attempt to explain 
human behavior, 
especially 
communication.
 Three minds or ego 
states.
 No good or bad ego 
state.
 A healthy personality 
includes all three.
66
The Transactional Analysis Model (Contd.)
 Parent:
 Orders 
 Claims to know everything 
 Caring, encouraging,supportive & protective.
 Sentences:
 Let me help you.
 Leave it to me, I will do 
this.
67
The Transactional Analysis Model (Contd.)
 Adult:
 Asks for reasons.
 Talk on equal level.
 Sentences:
 What is your opinion?
 I do not agree.
 Child:
 Emotional
 Free & natural.
 Obey, retreat, be polite.
 Not sure of itself.
 Sentences:
 I do not like you.
 I do not know, I want 
leave.
68
Dupont Model
 Emotional Minds:
 Responds faster.
 Decisions made without 
analysis.
 Sentences:
 Hurry up.
 Forget it.
 Rational Minds:
 Takes more time to react.
 Decisions made through 
analysis.
 Balance
69
Results of poor communication 
 Errors 
 Inefficiencies 
 Duplication of effort.
 Conflict 
 Reduced quality
 Cost increases 
70
Results of good communication 
 Reach an understanding with one another. 
 Co-ordinate their efforts.
 Agree who does what. 
 Decide on actions and make decisions 
effectively. 
 Take correct action to reach their goals. 
71
Forms of communication 
 Verbal communication 
 the spoken word.
 face-to-face or through an electronic medium such as a 
telephone, radio, loud speaker etc. 
 Non-verbal communication 
 as body language. 
 Wave, smile or frown. 
 Written communication 
 Manuals, Job-cards, letters, magazines, books, forms, 
e-mail etc. 
72
Communication model 
 Communication in its simplest form involves two people: 
 The Sender : the speaker or writer who is transmitting 
a message. 
 The Receiver : the person who sees, hears or reads 
the message. 
 Feedback
 Messages filtered through feelings, opinions and 
intentions. The message includes body language.
73
Three Cs of Communication
 Be correct
 Standard part names.
 Be complete.
 Enough information.
 Be clear
 Say what you mean to say.
74
The impact of information technology 
 e-mail, voice mail, fax machines, mobile phones and pagers. 
 Information technology (IT) improves communication in 
organisations in the following ways: 
 It cuts across time boundaries. 
 It cuts across geographical boundaries. 
 It allows multiple, simultaneous reception. 
 Bottlenecks can be avoided as electronic information channels 
are typically direct between sender and receiver. 
 It helps reduce paperwork. 
75
9.8 Human Errors 
 General Model of Human Error:
76
E:\human Factors\MPEGAV\AVSEQ02.DAT
Types of Errors
 Example: John drives into water and the car begins to 
hydroplane. 
 Slip - having a good plan, but bad execution: John's plan is to 
pump his brakes, but he misses the brake pedal and steps on 
the accelerator instead. 
 Mistake - a bad plan is selected: John thinks that speeding up 
will give him control over his car so he accelerates. 
 Violation - the wrong procedure is performed intentionally: 
John learned from his driving teacher that he should pump his 
brakes in this situation, but his brother said that acceleration is 
best, so John steps on the accelerator. 
77
Dirty Dozen
 Aviation safety specialist, Gordon Dupont, 
identified 12 most common human factor 
maintenance errors, known as dirty dozen 
that limit people’s ability to perform effectively 
and safely
78
Dirty Dozen ( continued)
 Lack of communication 
 Lack of teamwork 
 Lack of assertiveness (not enough confidence).
 Complacency (too relaxed) 
 Distraction 
 Pressure 
 Lack of resources 
 Lack of knowledge 
 Lack of awareness
 Norms 
 Stress
 Fatigue 
79
1. Lack of Communication
 Communication by:
 the spoken words
 the written words
 gestures and facial 
expressions
 body language
80
Sender-Receiver Model of Communication 
81
Compare two Log-book Entries
82
2. Lack of Team Work
83
3. Lack of Assertiveness
84
4. Complacency (Too relaxed)
85
5. Distraction
86
6. Pressure
87
7. Lack of Resources
88
8. Lack of Knowledge
89
9. Lack of Awareness
90
10. Norms
91
11. Stress
92
12. Fatigue
93
Shift Work
94
95
96
97
13-Feb-05
Thank you for your Attention
97