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 rationality- that 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, micro-matching, 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.