Understanding Human Error Geoff C Simpson

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• Understanding Human ErrorGeoff C Simpson
• December 2008

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Understanding Human ErrorGeoff C Simpson

• Studies by HSEs Accident Prevention Unit and
  others suggest that human error is a major
  contributory cause in 90 of accidents of which
  70 could have been prevented by management
  action.
• We seem to have passed the era where the need was
  for more engineering safeguards... What we need
  now is to capture the human factor.
• John Rimmington

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Understanding Human ErrorGeoff C Simpson

• MYTH 1
• In almost every case the Human Error is
  implicitly (if
• not explicitly) assumed to be an Operator Error

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Understanding Human Error Geoff C Simpson

• MYTH 2
• Accident Proneness
• There is NO substantial evidence to support the
• concept of accident proneness

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Understanding Human Error Geoff C Simpson

• While it is undoubtedly true that many accidents
• and incidents are immediately proceeded by a
• human error of some sort, in the majority of
  cases you
• will learn nothing at all which will help
  accident
• prevention if you fail to understand what caused,
  or
• predisposed, the error.

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Understanding Human Error Geoff C Simpson

• Factors Predisposing Human Error Potential

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Understanding Human Error Geoff C Simpson

• Man-Machine Interface Errors Example 1

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Understanding Human Error Geoff C Simpson

• Man-Machine Interface Error Example 2

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Understanding Human Error Geoff C Simpson

• Man-Machine Interface Error Example 3

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Understanding Human Error Geoff C Simpson

• Man-Machine Interface Error Example 4
• The mine engineer had noticed a considerable
  number of damage only
• accidents to mobile plant on a diamond mine which
  he considered could
• only have occurred from over-speeding.
• He couldnt understand this as a great deal of
  effort had been put into
• Setting limits for gradients and bends
• Erecting reflective signs marking speed limits
• Positioning signs so they could be seen from the
  drivers position
• Training and regular re-training of drivers with
  speed limits as part of the competence test

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Understanding Human Error Geoff C Simpson

• Man-Machine Interface Error Example 4
• REASON
• Not one of over 150 vehicles used underground at
  the mine had a speedometer

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Understanding Human Error Geoff C Simpson

• Workplace Environment Error Example 1
• A man was killed by a reversing fork-lift in a
  fettling shop.
• When examined the fork-lift was found to have a
  reverse warning
• interlocked to reverse gear and that it was fully
  functional.
• As the man killed was fully trained and
  experienced in that workplace the
• initial conclusion was poor personal
  positioning.
• Further analysis to answer the question why
  didnt he hear the warning
• showed that the hearing defenders he was wearing
  had an attenuation so
• high as to be likely to mask the warning signal.
• In this circumstance an inappropriate Occ. Health
  measure had created a
• safety risk.

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Understanding Human Error Geoff C Simpson

• Workplace Environment Error Example 2
• A man was spotted during a safety audit working
  at
• height with his safety harness upside down he
  had his
• arms through the leg holes and his legs through
  the arm
• holes.
• When this was pointed out it was obvious he knew
  what
• he had done but his reason was much more
  interesting

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Understanding Human Error Geoff C Simpson

• Workplace Environment Error Example 2
• Its a lot more comfortable this way

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Understanding Human Error Geoff C Simpson

• Codes, Rules Procedure Errors Example 1
• Message on alarm screen of SCADA system in
  Hydrofluoric Acid
• Plant
• STAND BY PUMP NOT WORKING
• This is a strange alarm as it is in fact a normal
  state for the stand
• by pump to be not working!
• When the operator was asked what does it mean
  .......

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Understanding Human Error Geoff C Simpson

• Codes, Rules Procedure Errors Example 1
• Dont know but it cant be important as its
  always there!

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Understanding Human Error Geoff C Simpson

• Codes, Rules Procedure Errors Example 2
• A UK coal mine introduced a loco drivers defect
  book
• At the end of the shift a driver noted anything
  which concerned
• him about the safety of his train or the rolling
  stock.
• The on coming fitters and electricians would
  check the book and
• check out any entries.
• Nice simple idea to address safety concerns.

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Understanding Human Error Geoff C Simpson

• Codes, Rules Procedure Errors Example 2
• One loco driver had entered a concern at the end
  of the Monday
• morning shift.
• Repeated it on Tuesday, again on Wednesday and
  Thursday ...
• By Friday he had clearly got fed-up and wrote
• Doesnt any fr read this except me?

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Understanding Human Error Geoff C Simpson

• Codes, Rules Procedure Errors Example 3
• NO SMOKING REGULATIONS APPLY HERE

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Understanding Human Error Geoff C Simpson

• Training Competence Errors Example 1
• Much of the UKs manual handling training is
  based on the mantras
• of Kinetic Lifting
• Lift with your legs not your back
• Straight back bent knees

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Understanding Human Error Geoff C Simpson

• Training Competence Errors Example 1

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Understanding Human Error Geoff C Simpson

• Training Competence Errors Example 1

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Understanding Human Error Geoff C Simpson

• Training Competence Errors Example 1

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Understanding Human Error Geoff C Simpson

• Training Competence Errors Example 2
• In August 1994 an explosion occurred underground
  at the Moura No. 2
• mine in Queensland in which 11 men were killed.
• Among many recommendations made by the official
  inquiry was this
• important and salutatory statement
• As demonstrated repeatedly in evidence, it
  should not be taken for
• granted that a statutory certificate of
  competency to practice as a
• mine manager, undermanager or deputy carries an
  assurance that the
• person possessing it is maintaining, and where
  necessary developing,
• the original knowledge base required for the
  appointment.

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Understanding Human Error Geoff C Simpson

• Supervision Management Errors Example 1
• During the investigation into the capsize of the
  Herald of
• Free Enterprise it came to light that several of
  the
• companys highly experienced Ships Masters had
  raised
• concerns about not being able to confirm from
  the bridge
• that the bow doors were closed.
• Some of these predicted exactly what happened to
  the
• Herald.
• The reply of the Operations Director speaks
  legions -

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Understanding Human Error Geoff C Simpson

• Supervision Management Errors Example 1
• Do they need an indicator light to tell them
  whether the deck storekeeper is awake and sober?

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Understanding Human Error Geoff C Simpson

• Supervision Management Errors Example 2
• In a study of compliance with Permit to Work
  systems in
• electrical isolation an assessment was made of
  the attitudes
• of managers, supervisors and electricians to the
  importance
• of the PtW.
• Both managers and electricians considered the PtW
  as
• crucial to safety .
• But over half of the supervisors considered it to
  be either a
• waste of time or impractical.

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Understanding Human Error Geoff C Simpson

• Organisational Structure Errors Example 1
• The conclusions of the Public Inquiry into the
  Kings Cross
• underground station fire included the following
  comment
• ... no one person was charged with overall
  responsibility for safety. Each director believed
  he was responsible for safety in his division,
  but that it covered principally the safety of
  staff. The operations director, who was
  responsible for the safe operation of the system,
  did not believe he was responsible for the safety
  of lifts and escalators which came within the
  engineering directors department. Specialist
  safety staff were mainly in junior positions and
  concerned solely with safety of staff.

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Understanding Human Error Geoff C Simpson

• Organisational Structure Errors Example 2
• In a study of the Safety management System at a
  major NHS
• Trust it emerged that while the HS department
  had the
• responsibility for conducting risk assessments of
  ward based
• activities they had no role in ensuring that they
  were
• implemented and followed.
• When examining who was responsible it became
  apparent that 7
• different functions had responsibility for
  various aspects not
• surprisingly it emerged that there had been a
  number of near
• misses which arose because everyone assumed that
  some one else
• was dealing with it

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Understanding Human Error Geoff C Simpson

• Safety Culture Errors Example 1
• In a study of the Safety management of a surface
  rail
• infrastructure maintenance company they linesmen
  were
• asked
• If there was one thing you would like to be done
  to improve
• safety what would it be?
• The answer was, with out hesitation
• Get rid of the brambles

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Understanding Human Error Geoff C Simpson

• Safety Culture Errors Example 1
• The problem turned out to be contractual
• If the root of the bramble was within a metre of
  the track it
• was Railtracks responsibility if it was beyond
  a metre it
• was the company's responsibility.
• If bramble was considered to be a woody plant it
  was
• Railtracks responsibility whereas if it was a
  green plant it
• was the companys.

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Understanding Human Error Geoff C Simpson

• Safety Culture Errors Example 2
• Following a potential human error audit to
  identify potential accident
• scenarios a colliery in the UK established a
  series of Safety Improvement
• Teams to address each of the potential errors
  identified.
• Following the work of these teams and the
  improvements made, the lost
• time accident rate improved by 80 over the
  following 12 months. In
• addition the self certified sickness absence
  reduced by over 20 although
• nothing had been done to address this.

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Understanding Human Error Geoff C Simpson

• Safety Culture Errors Example 2
• Improvements (albeit not as spectacular)
  continued over the next
• 2 years resulting in the colliery becoming the
  safest in the UK.
• Both the management and the men believed that
  there had been a
• fundamental change in the safety culture.
• 30 months after the study, the Colliery Manager
  changed and
• within a month of being appointed the new manager
  disbanded all the
• Safety improvement teams.
• Within 6 months of his appointment the mine had
  dropped to next
• to bottom in the safety league.

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Understanding Human Error Geoff C Simpson

• HF Solutions has been working with Holistic
  Services to develop a version of
• the Human Error Audit used in mining for
  application in any context .
• The outcome is a process we call HERM
• Human Error Risk Management.