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The Field Guide to Understanding Human Error, 3rd Edition
Sidney Dekker
In a sentence
A practical guide arguing that 'human error' is never the cause of failure but a symptom of deeper trouble inside organizations, and showing how to investigate, learn, and build safety accordingly.
The Field Guide to Understanding 'Human Error' overturns the intuitive but counterproductive belief that accidents are caused by unreliable people undermining otherwise safe systems. Sidney Dekker contrasts the 'Old View' (Bad Apple Theory), which treats people as the problem to control, with the 'New View,' which treats behavior labeled as error as the systematic by-product of tools, tasks, and organizational conditions. Drawing on decades of human factors and safety science, the book teaches readers to contain their own hindsight-driven reactions to failure, to reconstruct why people's assessments and actions made sense from inside the unfolding situation, and to conduct investigations that leave a verifiable analytic trace rather than pasting large psychological labels over the facts. It explains competing accident models, the pitfalls of behavior-based safety programs and 'zero visions,' the dangers of over-bureaucratized safety departments, and how safety in already-safe systems is best understood as the presence of resilience rather than the mere absence of negatives. Humane and systemic, it offers a durable language and set of methods for learning from failure and improving the conditions in which people work.
The four lenses
- Science
- Statistics
- Systems
- Strategy
The model
A causal framework in which organizational design levers and contextual conditions shape the situation people face, producing psychological states and behavioral patterns commonly labeled 'human error,' which in turn drive safety outcomes; the way an organization frames and reacts to failure moderates learning and long-term safety.
Organizational and Design Conditionsdesign lever
The blunt-end features an organization creates—tool and interface design, procedures, training, staffing, resource allocation, production expectations, and goal conflicts—that shape the situation sharp-end operators face.
Production Pressure and Goal Conflictscontextual condition
The simultaneous, often contradictory demands for safety, efficiency, punctuality, cost control, and customer service that push operators to make efficiency-thoroughness trade-offs in real time.
Local Rationality (Situated Sensemaking)psychological state
The psychological state whereby people's assessments and actions make sense to them given their goals, attentional focus, knowledge, and the cues available inside the unfolding situation without knowledge of outcome.
Cognitive and Behavioral Patternsbehavioral pattern
Patterns of human performance such as cognitive fixation, plan continuation, fatigue effects, buggy or inert knowledge, automation surprises, and procedural adaptations that arise from the interaction of people with their tools, tasks, and situation.
Attributed 'Human Error'behavioral pattern
The after-the-fact judgment or attribution placed on behavior when an outcome is bad, often relabeled as loss of situation awareness, complacency, or non-compliance; a symptom rather than a cause.
Drift into Failurebehavioral pattern
The gradual, incremental normalization of deviance whereby an organization's definition of acceptable risk erodes over time as small departures succeed on other goals like cost, time, and efficiency.
Organizational Reaction and Framing of Failurecontextual condition
How an organization interprets and responds to failure—blame versus learning, Old View versus New View, retributive versus restorative accountability—which moderates whether conditions are surfaced or suppressed.
Organizational Learning and Resiliencebehavioral pattern
The organization's capacity to learn from normal work and near misses, understand how safety is created, and adjust functioning before, during, and after disturbances (Safety II).
Safety Outcomesoutcome metric
The realized safety of the system, including incidents, injuries, accidents, fatalities, and resilient successful operations under varying conditions.
How they connect
- organizational conditions → influences local rationality
- production pressure → influences cognitive behavioral states
- local rationality → predicts cognitive behavioral states
- cognitive behavioral states → predicts labeled human error
- cognitive behavioral states − influences safety outcomes
- production pressure → predicts drift into failure
- drift into failure − influences safety outcomes
- organizational reaction to failure → moderates organizational learning
- labeled human error − influences organizational learning
- organizational learning → predicts safety outcomes
- organizational learning − influences drift into failure
- organizational conditions → influences production pressure
The story
The reader A safety practitioner, manager, investigator, regulator, or student who works with or near safety-critical systems and wants to understand and reduce failure.
External problem
Failures, incidents, and accidents keep being blamed on 'human error' while the same trouble recurs.
Internal problem
They feel frustrated, judgmental, or helpless in the face of failure and unsure how to learn from it without blaming people.
Philosophical problem
Blaming individuals for symptoms of systemic trouble is both ineffective and unjust; people deserve to be understood, not condemned.
The plan
- Distinguish the Old View from the New View and question your assumptions about 'human error'.
- Contain your own retrospective, counterfactual, judgmental, and proximal reactions to failure.
- Conduct investigations that reconstruct the inside perspective and leave an analytic trace.
- Understand your accident model and its implications for what counts as risk.
- Organize an effective safety department and build a safety culture focused on learning.
- Abandon quick fixes and pursue hard, systemic fixes.
Success
- Fewer recurring incidents and genuine organizational learning.
- Practitioners who report honestly and are treated as a resource, not a problem.
- Investigations that explain rather than blame and lead to durable improvements.
- A resilient organization that stays chronically uneasy and understands how normal work creates safety and risk.
At stake
- Continued blame, suppressed reporting, and unlearned lessons.
- Surprising accidents in seemingly safe systems due to undetected drift.
- Wasted resources on quick fixes, posters, and compliance campaigns.
- Second victims and eroded trust throughout the organization.
Questions this book answers
- What are the two fundamental views of 'human error' and why does the choice matter?
- How do hindsight, outcome bias, and judgmental reactions distort our understanding of failure?
- How should a New View 'human error' investigation be conducted so it explains rather than judges?
- What accident models exist and how do they shape what counts as risk and how to manage it?
- How should safety departments and safety culture be organized to actually improve safety?
Glossary
- Organizational and Design Conditions
- The blunt-end features an organization creates that shape the operating environment and the situations sharp-end operators face.
- Production Pressure and Goal Conflicts
- The simultaneous, often contradictory demands placed on operators that force efficiency-thoroughness trade-offs.
- Local Rationality (Situated Sensemaking)
- The state in which people's actions make sense given their goals, knowledge, attention, and cues available inside the situation without knowledge of outcome.
- Cognitive and Behavioral Patterns
- Recognizable patterns of human performance arising from interaction with tools, tasks, and dynamic situations.
- Attributed 'Human Error'
- An after-the-fact judgment placed on behavior once an outcome is known to be bad; a symptom, not a cause.
- Drift into Failure
- The gradual normalization of deviance whereby acceptable-risk definitions erode as small departures succeed on other goals.
- Organizational Reaction and Framing of Failure
- How an organization interprets and responds to failure, ranging from blame and retribution to learning and restorative justice.
- Organizational Learning and Resilience
- The organization's capacity to learn from normal work and near misses and to adjust functioning to sustain operations under varying conditions.