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Human Error


Human error in technology breakdown has increased fourfold in 30 years ... Unsafe acts- errors and violations. Latent failure- On the 'Blunt End' ... – PowerPoint PPT presentation

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Title: Human Error

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

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

  • 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

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

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

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

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

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

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?

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

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

  • Basically there are three types of skill based
  • 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!

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

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

Skill-based violations
  • Corner cutting promoted by a largely indifferent

Rule-based violations
  • More deliberate than skill based violations

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

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

The End
  • Questions?