Human Error

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Human Error

• The James Reason Model
• AST 425
• Dr. Barnhart

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Human Error

• Human Error study is still in its infancy- much
  we still dont understand
• Human error in technology breakdown has increased
  fourfold in 30 years- consequences are
  increasingly dire

3
Definitions

• Accident or Event Trajectory
• Defenses, Barriers, and Safeguards- vary from few
  to many- from heavily defended to lightly
• Unsafe acts- errors and violations
• Latent failure- On the Blunt End
• Active Failure- On the Sharpend
• Local Trigger- Trips the Event
• Event- Complete Penetration of a trajectory- have
  varying natures from all active (possibly Egypt
  Air 990 to all latent Columbia- 1st shuttle
  disaster)

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Error

• The term human error as used herein is composed
  of two components
• -Error Factors- unintended
• - Violations- intentional

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Errors

• True errors occur within the mind of an
  individual and derive mainly from informational
  problems (forgetting, inattention, incomplete
  knowledge).

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Violations

• Violations- occur within a social context and are
  largely motivational problems such as poor
  morale, failure to reward compliance and/or
  sanction Non-compliance

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Individual or Collective errors?

• The issue of whether accidents are individually
  caused or collectively caused revolves around
  three dimensions
• Moral
• Scientific
• Practical

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Moral Issue- much to be gained

• Easier to pin legal responsibility on
  individuals- more direct connection
• Issue compounded by professionals willing to
  accept responsibility- (captain etc.)
• Most people highly value personal autonomy- they
  should have known better
• We assume big failures result from big mistakes
  rather than several small ones
• Emotional satisfaction in blaming someone

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The Scientific Dimension- do we stop with people
directly involved or go on back?

• Why stop at organizational roots? Why not go back
  to the beginning of creation?
• Answer should be practical- go back so far as to
  be able to change organizational behavior
• Peculiar nature of accidents- initially appear to
  be the convergence of many failures but we would
  see the same in any organization frozen in time-
  why then are failures rare?

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What then about the practical?

• Moral issue- favors individual approach
• Scientific issue- undecided
• Answer here depends on two factors
• can latent factors be identified and stopped
  prior to an accident?
• The degree to which improvements can better equip
  the organization to deal with local failures

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Categories of errors and violations

• Errors and violations can be categorized into
  three areas
• Skill based
• Rule based
• Knowledge based

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Errors

• Basically there are three types of skill based
  errors
• Attentional slips- failure to monitor progress of
  routine actions at some critical point
• Memory lapses- forgetfulness (most common)
• Perceptual error- misrecognition of some object
  we see what we expect to see
• Most slips and lapses have minimal consequences
  responding fine to hello etc. but on the
  flight deck they can be dire!

13
Rule Based Mistakes

• Two types
• Misapplication of good rules- braking to avoid a
  deer on an icy road we humans tend to apply
  solutions to familiar problems on the basis of
  largely automatic pattern matching
• Application of bad rules- learning shortcuts and
  cutting corners- usually circumstances are
  forgiving and you get by with it

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Knowledge based mistakes

• Due to Limited capacity of working memory
• Incomplete mental models of the problem
• Thinking on ones feet- confirmation bias-
  bending the facts to fit a hasty conclusion,
  over-confidence, similarity bias, and frequency
  bias

15
Skill-based violations

• Corner cutting promoted by a largely indifferent
  environment

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Rule-based violations

• More deliberate than skill based violations

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Knowledge based violations

• Novel circumstance- no specified procedure
• Trainers and procedure writers can only address
  the foreseeable
• Usually involve the unexpected occurrence of a
  rare but trained for situation or an unlikely
  combination of individually familiar circumstances

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To Finish Defining Error

• Cicero stated- To err is human
• Accidents result from a failure of the risk
  management system to absorb the consequences of
  these errors (unsafe acts)
• Human error is stubborn sophisticated discrete
  solutions to human error will likely lead to more
  sophisticated sources of error- we must be
  prepared to manage it

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The End

• Questions?