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‘Obvious’ Errors: Anything but Simple
Gareth Lock!!Cognitas Incident Research and Management
Background
Some humour…
Some humour…
OC Rec Case Study - Report"Four divers were diving on a wreck to a maximum depth of approximately 22m. One of the divers entered the wreck. Another diver then went after him and found him unconscious with his regulator in his mouth. He brought him out and recovered him to the surface. He was lifted into the boat and the emergency services were alerted. The diver was airlifted to hospital where he later died. The diver had a 15l main cylinder and a 3l pony cylinder. After the event the main cylinder was found to be full. A press report of the Coroner's inquest suggests that the casualty had 'mixed up his air supply tanks'. The cause of death was drowning."
OC Rec Case Study Introduction❖ Club dive on wreck in 24m!❖ Diver A 19st, 6’2”!❖ BCD, 12L & pony, !❖ 1st dive of the season, not dived for
10 months, 4 dives previous year!❖ Buddy Checks carried out!❖ OOG after 10mins!❖ Separation!❖ ‘Body’ found, CBL, sent up !❖ Problems in recovering onto RHIB
Risk Perception/Acceptance vs Safety❖ Risk is:!
❖ Relative!
❖ Personal (Voluntary)!
❖ Experience/Knowledge!
❖ Environment influenced!
❖ Goal influenced
Risk Perception/Acceptance vs Safety❖ Risk is:!
❖ Relative!
❖ Personal (Voluntary)!
❖ Experience/Knowledge!
❖ Environment influenced!
❖ Goal influenced
Risk Perception/Acceptance vs Safety❖ Risk is:!
❖ Relative!
❖ Personal (Voluntary)!
❖ Experience/Knowledge!
❖ Environment influenced!
❖ Goal influenced
Risk Perception/Acceptance vs Safety❖ Risk is:!
❖ Relative!
❖ Personal (Voluntary)!
❖ Experience/Knowledge!
❖ Environment influenced!
❖ Goal influenced
❖ Is safety absence of risk?!
❖ Can we measure a negative?
Risk Perception/Acceptance vs Safety❖ Risk is:!
❖ Relative!
❖ Personal (Voluntary)!
❖ Experience/Knowledge!
❖ Environment influenced!
❖ Goal influenced
❖ Is safety absence of risk?!
❖ Can we measure a negative?
❖ “Safety” is ability to sustain required operations under both expected and unexpected conditions.
Causality Models❖ Cause and Effect Trees!
❖ Denoble's Triggers!
❖ Systems Approach !
❖ ETTO!
❖ HFACS-D
Small World Problem
How likely is it that any two persons, selected arbitrarily from a large population, can be linked via common acquaintances and how long will the links be on average?
Small World Problem
In risk assessment, the problem is how likely it is that two events are indirectly coupled and how many steps in between are required on average…The small world phenomenon demonstrates the importance of this, namely that things (actions) that seemingly have no relation to each other still may affect each other. - ETTO, Hollnagel, 2009
Cause and Effect Trees❖ Simple, easy to understand!
❖ Bimodal - this happened, caused that!
❖ Biases!
!
!
!
!
Cause and Effect Trees
Cause and Effect Trees
Cause and Effect Trees
Cause and Effect Trees
Cause and Effect Trees
Cause and Effect Trees
Hindsight bias!
Confirmation bias!
Cause and Effect Trees
Cause and Effect Trees
Action
1. Action based on event history and current environment/situation
Cause and Effect Trees
Action
1. Action based on event history and current environment/situation
!!
Difference between the expected !and unexpected outcome is not
clear cut!
3. Unexpected outcome - ‘Error’
2. Expected outcome - ‘Good’
Cause and Effect Trees
Action
Outcome of Previous Action
4. Hindsight provides "feedback of ‘correct’ action
1. Action based on event history and current environment/situation
!!
Difference between the expected !and unexpected outcome is not
clear cut!
3. Unexpected outcome - ‘Error’
2. Expected outcome - ‘Good’
Cause and Effect Trees
Action
Outcome of Previous Action
4. Hindsight provides "feedback of ‘correct’ action
1. Action based on event history and current environment/situation
!!
Difference between the expected !and unexpected outcome is not
clear cut!
3. Unexpected outcome - ‘Error’
2. Expected outcome - ‘Good’
4. Hindsight provides "incorrect feedback of action "if they thought outcome was ‘Good’
or
Denoble's Triggers❖ 947 fatalities analysed
Denoble's Triggers❖ 947 fatalities analysed
❖ Triggers!
❖ OOA (41%)!
❖ Entrapment (20%)!
❖ Equipment Problems (15%)
Denoble, P.J., Caruso, J.L., Dear, G.d.e. .L., Pieper, C.F. & Vann, R.D., 2008, Common causes of open-circuit recreational diving fatalities, Undersea & hyperbaric medicine : journal of the Undersea and Hyperbaric Medical Society, Inc, 35(6), pp. 393-406
Denoble's Triggers❖ 947 fatalities analysed
❖ Triggers!
❖ OOA (41%)!
❖ Entrapment (20%)!
❖ Equipment Problems (15%)
❖ What, not why
Denoble, P.J., Caruso, J.L., Dear, G.d.e. .L., Pieper, C.F. & Vann, R.D., 2008, Common causes of open-circuit recreational diving fatalities, Undersea & hyperbaric medicine : journal of the Undersea and Hyperbaric Medical Society, Inc, 35(6), pp. 393-406
Systems ApproachTechnological Failure Human Failure Organisational Failure
1900 1950 2000
Simple Linear Models!Independent Causes
Complex Linear Models!Active and Latent
Non-Linear Models!Tractable/Intractable Dynamic Complexity
Adapted from Hollnagel, E., 2009, The ETTO Principle:
Efficiency Thoroughness Trade Off (ETTO)
❖ ETTO!
❖ Heuristics!
❖ Shortcuts
Efficiency Thoroughness Trade Off (ETTO)
❖ ETTO!
❖ Heuristics!
❖ Shortcuts
❖ Performance Variability!
❖ Approximations!
❖ Normalisation of Deviance
Efficiency Thoroughness Trade Off (ETTO)Examples of Heuristics• Looks fine"
• Not really important"
• Normally OK, no need to check"
• I’ve done it millions of times before"
• Will be checked by someone else"
• Has been checked by someone else"
• This way is much quicker"
• No time (or resource) to do it now"
• Can’t remember how to do it"
• We always do it this way"
• Looks like X, so must be X
HFACS-Diving
HFACS-Diving❖ Based on HFACS Model
HFACS-Diving❖ Based on HFACS Model❖ Constructed after reviewing 18
pieces of literature - 232 factors!❖ Validated by 13 SMEs
Poor decision to con,nue dive
Incorrect assembly of CCR/scrubber packing
Incorrect maintenance of pO2 (eCCR)
HFACS-Diving❖ Based on HFACS Model❖ Constructed after reviewing 18
pieces of literature - 232 factors!❖ Validated by 13 SMEs
❖ 96 factors!❖ Rules/Violations!❖ 5 equipment based!❖ Fiscal drivers*!❖ Latent Medical*"❖ Direct Contravention of Trg*
Poor decision to con,nue dive
Incorrect assembly of CCR/scrubber packing
Incorrect maintenance of pO2 (eCCR)
OC Rec Review Incident Case Study❖ General Fitness!
❖ Dive and Rescue!
❖ ‘Dived Up’!
❖ Checks and Config!
❖ OOA response!
❖ Separated!
❖ Body recovered
OC Rec Review Incident Case StudySkill Based Errors (Incorrect In Water Skills)!
Failure to Monitor Gauge and end dive when reached mininum gas pressure e.g. surface with 50bar/500psi Incorrect response for Out of Air (OOA) Equipment problems (use of, not failure of)
Knowledge Based Failure to Understand Equipment usage!Failure to Complete Pre-Dive Buddy/Self Checks
Condition of Operator (Physiological State) Drug or Alcohol Intoxication
Personal Readiness (Training/Skills)
Insufficient Training (Lack of currency of skills to ensure that they are upto date, 'Dive Fit')
HFACS-D - Data as at 11/2/14
HFACS-D - Data as at 11/2/14❖ Incidents (n=341)!
❖ 31% physical OOG/below agency minimums!
❖ 9% uncontrolled buoyant ascents!
❖ 23% unplanned separation
HFACS-D - Data as at 11/2/14❖ Incidents (n=341)!
❖ 31% physical OOG/below agency minimums!
❖ 9% uncontrolled buoyant ascents!
❖ 23% unplanned separation
❖ Dive plan deviation - 18%
HFACS-D - Data as at 11/2/14❖ Incidents (n=341)!
❖ 31% physical OOG/below agency minimums!
❖ 9% uncontrolled buoyant ascents!
❖ 23% unplanned separation
❖ Dive plan deviation - 18%
❖ Decision to continue when should have ended - 23%
HFACS-D - Data as at 11/2/14
❖ ETTO!❖ Looks fine to me 10%!❖ Normally worked/Worked before 24%
HFACS-D - Data as at 11/2/14
❖ ETTO!❖ Looks fine to me 10%!❖ Normally worked/Worked before 24%
❖ Attitude!❖ Complacency 41%, Lack of Situational Awareness 32%!❖ Risk Perception/Acceptance 50%!❖ Behaviour 20% not changed
HFACS-D - Data as at 11/2/14
❖ ETTO!❖ Looks fine to me 10%!❖ Normally worked/Worked before 24%
❖ Attitude!❖ Complacency 41%, Lack of Situational Awareness 32%!❖ Risk Perception/Acceptance 50%!❖ Behaviour 20% not changed
❖ Social!❖ 8-12% direct, indirect or fiscal pressures
HFACS-D - Data as at 11/2/14
How to Improve Things❖ Attitudinal Changes Essential!
❖ Stop Throwing Rocks at Those Who Make Mistakes
How to Improve Things❖ Attitudinal Changes Essential!
❖ Stop Throwing Rocks at Those Who Make Mistakes
❖ Promote Personal Responsibility!
❖ We ALL make mistakes, most of them our own doing!
❖ Group Polarisation/Risky Shift
How to Improve Things❖ 'Just Culture'!
❖ 'Who Decides'!
❖ Recreational vs Voluntary Instruction vs Professional Instruction
How to Improve Things❖ 'Just Culture'!
❖ 'Who Decides'!
❖ Recreational vs Voluntary Instruction vs Professional Instruction
How to Improve Things❖ Work Together!
❖ Improved Reporting !
❖ Sharing of Data!
❖ Common Models
All the Information Possible to be Known
Diver’s Knowledge
Friends’s Knowledge
Researcher’s Knowledge
http://www.divingincidents.org.uk
@DISRC #DISMS
Summary❖ Risk and Safety are compromises!
❖ Too many factors to use simple models!
❖ No one ‘root cause’!
❖ Need detailed narratives!
❖ We can improve things…
http://www.cognitas.org.uk
http://www.divingincidents.org.uk
@DISRC #DISMS
“What good is hindsight if we supposedly learn something but don’t apply it to our own/community’s foresight?”
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