Health and Safety Executive

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Health and SafetyExecutive

• Human Factors
• in Accident
• Investigation
• David Birkbeck
• HID Onshore Human
• Organisational Factors Group

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Human Factors in Accident Investigation

• David Birkbeck
• HID Onshore Human Organisational Factors Group

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Introduction

• To say accidents are due to human failing is
  like saying falls are due to gravity. It is true
  but it does not help us prevent them Trevor
  Kletz
• Aim today is to present methods that are known to
  help identify human failure in accident
  investigation and prevent reoccurrence
• Not a black art, a pragmatic and robust process

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What we expect

• Methodical process for gathering information,
  analysing what went wrong (and right), and
  learning lessons in order to
• Manage risk
• Prevent reoccurrence
• Retrospective tool, but can be powerful in
  promoting change

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Accident reports

• What happened
• Who to
• When
• How it happened
• But not why
• Technical myopia
• Failure to consider human factors

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Significance of human factors

• Up to 90 of accidents attributable to some
  degree to human failures
• ...Texas CityBuncefield... Texaco Milford Haven
  ... Southall and Ladbroke Grove crashes
  ...Zeebruger
• Proportion and significance increasing as
  technical safety measures improve

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Recent news
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But not as simple as we think..

• This accident was the result of human error
• ..pilot error
• Error or rule-breaking put down to
• Lack of competence
• Poor supervision
• Not paying attention
• Its not usually as simple as that!

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Human failure taxonomy
Human failures
Unintended actions
Intended actions
Errors - Unintended consequences
Violation - Intended consequences
Mistakes
Lapses
Slips
When the person decided to act without complying
with a known rule or procedure
When the person forgets to do something
When the person does something, but not what they
meant to do
When the person does what they meant to, but
should have done something else
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Slip, lapse or mistake?
Involuntary or non-intentional action
No
Was there intention in the action?
Was there prior intention to act?
No
Spontaneous or subsidiary action
Yes
Yes
Did the actions proceed as planned?
Unintentional action (slip or lapse)
No
Yes
Did the actions achieve their desired end?
Intentional but mistaken action
No
Yes
Successful action
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How to apply

• Create timeline
• Identify significant behaviours
• Analyse behaviours
• Identify effective measures to prevent
  reoccurrence
• Record

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Errors

• Slip
• When a person does something, but not what they
  meant to do
• Lapse
• When a person forgets to do something
• Both are unintended actions with unintended
  consequences

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Example slip Emirates EK407

• Emirates Flight EK407
• Pre-flight take off calculations were based on an
  incorrect take off weight (262M/t rather than
  362M/t)
• This weight was entered into take off performance
  software on separate laptop
• Captain noticed something was wrong at the end of
  the runway, took manual control and selected
  maximum thrust

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Example slip Emirates EK407
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Example slip Emirates EK407

• After the accident, Captain and First Office were
  asked to resign by Emirates and did so
• ATSB investigation revealed
• Captain had flown 99 hours in last month (1 hour
  below maximum)
• Had slept for 3.5 hours in 24 hour period prior
  to flight (shift rotas)
• Excessively complex system for calculating take
  off speed (manual transfer of information from 2
  automated systems)
• No automated failsafe

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Mistakes

• When a person does something they intended to do,
  but should have done something else
• Rule based choosing a standard solution for a
  known problem the maintenance worker who
  selects the wrong isolation procedures
• Knowledge based working from first principles
  3 Mile Island shift team dismissed a potential
  explanation for the unfolding incident as they
  believed a valve was closed

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Mistakes

• Because the action is intended, mistakes are much
  harder to detect at the individual level
• People believe what they are doing is right and
  often dismiss evidence to the contrary
• Bias
• Tunnel vision

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Violations

• The Texas City technicians who filled the
  raffinate splitter to 90-100 capacity rather
  than 50 as stated in procedures
• The Assistant Boson who was asleep rather than
  checking the bow doors were closed on the Herald
  of Free Enterprise
• The technicians who knowingly maintained the
  Chernobyl reactor in an unsafe state to allow a
  safety study to be conducted

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Violations

• Violation
• When a person decides to act without complying
  with a known rule or procedure
• Note that, in this context, there must be an
  known rule or procedure
• This is not a moral or ethical judgement

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Violations
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Violations

• Note that we all integrate rule violation into
  our day to day lives so the identification of a
  violation should not be regarded as a precursor
  to discipline
• Indeed, we tend to like those who break the rules

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Violations
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Violations

• Types of violations
• Routine
• Exceptional
• Acts of sabotage
• The key to the effective analysis of violations
  is to understand why
• What antecedents were present?
• What behaviour was observed?
• What consequences resulted?

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Performance Influencing Factors

• Defined as the characteristics of the job, the
  individual and the organization that influence
  behaviour
• Considered during behavioural analysis, often at
  the end of the process
• Very broad topic including a range of factors
  e.g. fatigue, group effects, design of equipment,
  mental wellbeing, task knowledge/complexity
• A comprehensive list available on HSE website
• Often have a critical role in error causation but
  equally often overlooked (e.g. fatigue EK407)

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Performance Influencing Factors

• Can profoundly influence potential for error
  (proposed nominal human unreliability). Task is
• Routine, highly practiced, rapid task involving
  relatively low level of skill (0.02)
• Miscellaneous task for which no description can
  be found (0.03)
• Fairly simple task performed rapidly or given
  scant attention (0.09)
• Totally unfamiliar, performed at speed with no
  real idea of consequence (0.55)
• Williams, J.C. HEART Technique

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Common issues

• Failure to correctly specify behaviour
• The individual involved
• The task they were engaged in at the time
• What they did (or did not do)
• What the outcome was
• Making early decisions and sticking to them
• As information becomes available, a mistake can
  become a violation
• Failure to identify the multiple behaviours
  contributing to an accident or incident
• Timeline critical

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Why bother with any of it?

• Each failure type has a different set of
  solutions designed to prevent their reoccurrence.
  For example (not exhaustive)
• Slip/Lapse
• NOT training
• Hardware solutions
• Cross checks
• PIFs
• Error
• Training e.g. scenarios
• Group support
• Challenge
• Violations
• Behaviour modification
• Culture improvement

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What to remember

• Human behaviour can be predicted with reasonable
  accuracy
• Correctly integrating HF into your accident
  investigation process will reap rewards just
  look at the contemporary causation figures
• Separating error, mistake and violation
  represents a highly valuable first step
• Help is out there
• Guidance
• HSE
• Industry working groups e.g. Energy Institute

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A final thought

• The most powerful influence on human behaviour is
  outcome
• Therefore managing human failure requires a high
  degree of corporate honesty
• What behaviour is really rewarded?
• Are we willing to look at organizational factors,
  especially when we see rule breaking?
• Are we willing to make the investments that are
  likely to prevent reoccurrence?
• Are we willing to strive for objectivity and
  pragmatism?

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Sources of guidance

• Reducing Error Influencing Behaviour HSG 48
• Investigating Incidents Accidents HSG 245
• Successful Health Safety management HSG 65
• Human Factors Website pages
• http//www.hse.gov.uk/humanfactors/majorhazard/ind
  ex.htm
• Energy Institute guidance
• http//www.energyinst.org.uk/index.cfm?PageID1268