Transcript The Field Guide to Human Error Investigations

The Field Guide to Human Error
Investigations- The Old View
(Chapters 1 – 6)
By Dekker
AST 425
Two Views of Error
• The Old View and the New View
• The Old View– Human error is a cause of accidents- in the past,
accidents used to conclude with “the cause of the
accident was the pilot’s failure to…” (human error)
– To explain failure investigations must seek failure
– They must find people’s inaccurate assessments,
wrong decisions, and bad judgments
The Bad Apple Theory- Ch. 1
• A way of summarizing the old view might be
called the bad apple theory:
– Complex systems (ie. Air carrier) would be fine were it
not for the erratic behavior of some unreliable people
(bad apples)
– Human errors cause accidents; humans are the
dominant contributor to more than two thirds of them
– Failures come as unpleasant surprises- they do not
belong in the system and are caused by the inherent
unreliability of people
Terms
• Sharp end- that part of an organization
where failures play out, the driver’s seat of
a car, the cockpit of an aircraft, or in the
maintenance shop
• Blunt end- that part of an organization that
supports, drives, and shapes activities at
the sharp end (scheduling department,
flight crew training, personnel, etc.)
“Fixes” proposed by the old view
• Tighten procedures
• Introduce more technology
• Get rid of the bad apples- fire them or
move them around
Why then is view prevalent?
• It requires little effort, requires little
thought; i.e. it is easy to fire someone
• The illusion of omnipotence- that people
can simply choose between making or not
making errors independent of their
environment (example p. 10)
How to counter the bad apple
theory
• Understand the concept of local rationalitythat people usually perform their tasks in a
manner that seems logical, reasonable,
and rational at the time- they do not intend
to fly into a mountain or over-run a runway
• The astute investigator needs to attempt to
determine why erroneous actions made
sense at the time.
Chapter- Reactions to Failure
• It is difficult for those on the outside of an
accident to not “react” to a failure- “How could
they not have seen that, etc.”
• We must understand that reactions are:
– Retrospective- we can look back and see the
outcome
– Proximal- it’s easy to focus on those who were closest
to the event
– Counterfactual- it’s easy to lay out in detail what
should have been done differently, but knowing the
outcome destroys our objectivity
– Judgemental- “They SHOULD have done…”
Retrospective
• Looking back you can:
– Know the outcome
– Know which cues were the critical cues
– What could have done to prevent the
occurrence
– *Recognize that events look differently as they
unfold
Chapter 3- Cause
• In any organization, after an accident,
there usually are significant pressures to
find “cause”
– People want to know how avoid the same
trouble
– People want to start investigating
countermeasures
– People may seek retribution, justice
2 myths driving the causal search
• It is thought that there is always “The”
cause- cause is something you construct,
not something you find
• It is often thought that we can make a
distinction between human cause and
mechanical cause- the pathways are
actually quite blurred
Chapter 4- Human Error by any
other name
• Often “Human Error” is given other names
which are almost as useless:
– Loss of CRM
– Loss of Situational Awareness
– Complacency
– Non-compliance
– *These all identify the “what” but not the “why”
Beneath the labels
• Investigators need to understand what’s
behind the labels i.e.:
– How perception shifts based on earlier
assessments or future expectations
– Trade-offs people are forced to make between
operational goals
– How people are forced to deal with complex,
cumbersome technology
Chapter 5- Error in the Head or
World
• Where should investigators begin looking
for the source of the error
– In the head of the person committing the error
– In the situation in which the person was
working
– If we start with the head (i.e. the pilot forgot
to…) what good does that do?
Looking in the Environment
• If we look at the environment, connections
are revealed:
– We see how the evolving situation changed
people’s behavior providing new evidence,
new cues, updates people’s understanding,
presents more difficulties.
– This opens or closes pathways to recovery
Looking in the environment we can:
• Show how the situation changed over time
• Show how people’s assessments and
actions evolved in parallel with their
changing situation
• How features of people’s tools and tasks
and their environment (both organizational
and operational) influenced their
assessments and actions inside that
situation
Ch. 6 Putting data in context
• 2 concepts are important here, micromatching, and cherry picking.
– Micromatching- placing people’s actions
against a world you now know to be true
(after-the-fact world- little related to the actual
world at the time)
– Cherry Picking- lumping selected bits of
information together under one condition you
have identified in hindsight.
Cherry Picking
• Understand that there is a difference between
data availability and data observability
– Data Availability- what can be shown to have been
physically available somewhere in the situation
– Data observability- what would have been observable
given the features of the interface and the multiple
integrated tasks, goals, interests, knowledge and
even the culture of people looking at it.