Table Of ContentMANAGING MAINTENANCE ERROR
We have left undone those thinges whiche we ought to have done, and we
have done those thinges which we ought not to have done.
Book of Common Prayer, 1559
This book is dedicated to
John Goglia, NTSB
Chow Hock Lin, Singapore Airlines Engineering Company
Mike Innes, Cathay Pacific
Maintenance Crew S11
MANAGING MAINTENANCE
ERROR
A Practical Guide
JAMES REASON
ALAN HOBBS
CRC Press
Taylor & Francis Group
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© 2003 by James Reason and Alan Hobbs
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Contents
List of Figures ix
List of Tables xi
Preface xiii
1 Human Performance Problems in Maintenance 1
The bad news 1
The good news 3
Removal versus replacement 4
Commission versus omission errors 6
Summary 7
2 The Human Risks 9
Taking a systems view 9
Systems with human elements 10
Human-related disturbances 11
Each disturbance has a history 12
Systems build defences against foreseeable disturbances 12
System defences can also fail 14
The moral issue 14
Errors are like mosquitoes 16
Looking ahead 17
3 The Fundamentals of Human Performance 19
Psychology meets engineering 19
A ‘blueprint’ of mental functioning 20
Limitations of the conscious workspace 21
Attention 22
The vigilance decrement 24
Attention and habit 24
Control modes and situations 25
Three performance levels 27
v
vi Managing Maintenance Error
Stages in acquiring a skill 30
Fatigue 31
Stressors 32
Arousal 33
Coping with informational overload 33
Personality types 34
Biases in thinking and decision making 35
Summary 36
4 The Varieties of Error 39
What is an error? 39
Skill-based recognition failures, slips and lapses 40
Rule-based mistakes 49
Knowledge-based errors 51
Violations 53
Violation types 55
The consequences of maintenance errors 59
Summary 60
5 Local Error-provoking Factors 63
Documentation 64
Time pressure 65
Housekeeping and tool control 65
Coordination and communication 66
Tools and equipment 67
Fatigue 68
Knowledge and experience 70
Bad procedures 70
Procedure usage 72
Personal beliefs: a factor promoting violations 73
Links between errors and error-provoking conditions 74
Summary 75
6 Three System Failures and a Model of Organizational
Accidents 77
Latent conditions and active failures 77
The Embraer 120 crash: a shift turnover failure 78
The Clapham Junction rail collision: the defences that
faded away 82
The Piper Alpha explosion: Failures of both the permit-to-
work and the shift handover systems 86
Modelling organizational accidents 89
Contents vii
Defences 91
Summary 93
7 Principles of Error Management 95
Nothing new 95
The principles of error management 96
The management of error management 100
Summarizing the EM principles 101
8 Person and Team Measures 103
Person measures 103
Team measures 113
Summary 117
9 Workplace and Task Measures 119
Fatigue management 119
Task frequency 120
Design 122
Housekeeping 124
Spares, tools and equipment 124
Using procedures to manage omissions 125
Summary 132
10 Organizational Measures 133
How accidents happen: a reminder 133
Reactive and proactive measures: working together 134
Reactive outcome measures 135
Proactive process measures 138
Identifying gaps in the defences 141
Summary 143
11 Safety Culture 145
What is a safety culture? 145
Can a safer culture be engineered? 147
Creating a just culture 148
Creating a reporting culture 151
Creating a learning culture 153
Types of safety culture: the good, the bad and the
average 155
Summary 156
viii Managing Maintenance Error
12 Making it Happen: The Management of Error
Management 159
Here comes another one 159
The common features of safety and quality management
systems 162
Why error management is necessary 164
More on mindset 165
In search of resilience 166
Summary 174
Index 177
List of Figures
1.1 The frequency of reoccurence of aircraft maintenance
incidents 4
2.1 A system with human elements 10
2.2 A symbolic representation of a human-related
disturbance 11
2.3 Factors involved in the occurrence of human-related
disturbances 12
2.4 A many-layered defensive arrangement intervenes
between the disturbance and the vulnerable parts of
the system 13
2.5 Defences are never perfect: each one has holes and
gaps 14
3.1 A simplified ‘blueprint’ of mental functioning 20
3.2 The torch beam model of human attention 23
3.3 A continuum of action control 26
3.4 Classifying situations along a continuum 27
3.5 Using the activity space to define the three performance
levels 29
3.6 The principal stages in skill acquisition 30
3.7 Time-of-day effects and fatigue 31
3.8 The relationship between arousal and the quality of
performance 33
3.9 Four personality types based upon the introversion–
extraversion and stable–unstable dimensions 35
4.1 The typical pattern of events involved in an action slip 47
4.2 Aircraft maintenance personnel questioned on whether
they have continued with an unfamiliar job despite
being uncertain how to proceed 53
4.3 The job of the shunter: linking up railway wagons 57
4.4 Comparison of error types resulting in quality incidents
and worker safety incidents 59
5.1 Maintenance errors in the context of local error-
producing factors 63
5.2 Links between errors and contributing factors 74
6.1 The T-tail assembly on an Embraer 120 79
ix
