Human ErrorHuman Error

The James Reason ModelThe James Reason Model

AST 425AST 425

Dr. BarnhartDr. Barnhart

Human ErrorHuman Error

Human Error study is still in its infancy- Human Error study is still in its infancy- much we still don’t understandmuch we still don’t understand

Human error in technology breakdown has Human error in technology breakdown has increased fourfold in 30 years- increased fourfold in 30 years- consequences are increasingly direconsequences are increasingly dire

DefinitionsDefinitions Accident or Event TrajectoryAccident or Event Trajectory Defenses, Barriers, and Safeguards- vary from few Defenses, Barriers, and Safeguards- vary from few

to many- from heavily defended to lightlyto many- from heavily defended to lightly Unsafe acts- errors and violationsUnsafe acts- errors and violations Latent failure- On the “Blunt End”Latent failure- On the “Blunt End” Active Failure- On the “Sharp”endActive Failure- On the “Sharp”end Local Trigger- Trips the EventLocal Trigger- Trips the Event Event- Complete Penetration of a trajectory- have Event- Complete Penetration of a trajectory- have

varying natures from all active (possibly Egypt Air varying natures from all active (possibly Egypt Air 990 to all latent Columbia- 1990 to all latent Columbia- 1stst shuttle disaster) shuttle disaster)

ErrorError

The term “human error” as used herein is The term “human error” as used herein is composed of two components:composed of two components:

-Error Factors- unintended-Error Factors- unintended

- Violations- intentional- Violations- intentional

ErrorsErrors

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

ViolationsViolations

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

Individual or Collective errors?Individual or Collective errors?

The issue of whether accidents are The issue of whether accidents are individually caused or collectively caused individually caused or collectively caused revolves around three dimensions:revolves around three dimensions:

MoralMoral ScientificScientific PracticalPractical

Moral Issue- much to be gainedMoral Issue- much to be gained

Easier to pin legal responsibility on Easier to pin legal responsibility on individuals- more direct connectionindividuals- more direct connection

Issue compounded by professionals willing Issue compounded by professionals willing to accept responsibility- (captain etc.)to accept responsibility- (captain etc.)

Most people highly value personal Most people highly value personal autonomy- “they should have known better”autonomy- “they should have known better”

We assume big failures result from big We assume big failures result from big mistakes rather than several small onesmistakes rather than several small ones

Emotional satisfaction in blaming someoneEmotional satisfaction in blaming someone

The Scientific Dimension- do we The Scientific Dimension- do we stop with people directly involved or stop with people directly involved or

go on back?go on back? Why stop at organizational roots? Why not Why stop at organizational roots? Why not

go back to the beginning of creation?go back to the beginning of creation? Answer should be practical- go back so far Answer should be practical- go back so far

as to be able to change organizational as to be able to change organizational behaviorbehavior

Peculiar nature of accidents- initially appear Peculiar nature of accidents- initially appear to be the convergence of many failures but to be the convergence of many failures but we would see the same in any organization we would see the same in any organization frozen in time- why then are failures rare?frozen in time- why then are failures rare?

What then about the practical?What then about the practical?

Moral issue- favors individual approachMoral issue- favors individual approach Scientific issue- undecidedScientific issue- undecided Answer here depends on two factors:Answer here depends on two factors:

can latent factors be identified and stopped prior to can latent factors be identified and stopped prior to an accident?an accident?

The degree to which improvements can better The degree to which improvements can better equip the organization to deal with local failuresequip the organization to deal with local failures

Categories of errors and violationsCategories of errors and violations

Errors and violations can be categorized into Errors and violations can be categorized into three areas:three areas:– Skill basedSkill based– Rule basedRule based– Knowledge basedKnowledge based

ErrorsErrors

Basically there are three types of skill based Basically there are three types of skill based errors:errors:– Attentional slips- failure to monitor progress of routine Attentional slips- failure to monitor progress of routine

actions at some critical pointactions at some critical point– Memory lapses- forgetfulness (most common)Memory lapses- forgetfulness (most common)– Perceptual error- misrecognition of some object; we see Perceptual error- misrecognition of some object; we see

what we expect to seewhat we expect to see

– Most slips and lapses have minimal consequences; Most slips and lapses have minimal consequences; responding “fine” to “hello” etc. but on the flight deck responding “fine” to “hello” etc. but on the flight deck they can be dire!they can be dire!

Rule Based MistakesRule Based Mistakes

Two types:Two types:– Misapplication of good rules- braking to avoid a Misapplication of good rules- braking to avoid a

deer on an icy road; we humans tend to apply deer on an icy road; we humans tend to apply solutions to familiar problems on the basis of solutions to familiar problems on the basis of largely automatic pattern matchinglargely automatic pattern matching

– Application of bad rules- learning shortcuts and Application of bad rules- learning shortcuts and cutting corners- usually circumstances are cutting corners- usually circumstances are forgiving and you “get by with it”forgiving and you “get by with it”

Knowledge based mistakesKnowledge based mistakes

Due to Limited capacity of working memoryDue to Limited capacity of working memory Incomplete mental models of the problemIncomplete mental models of the problem Thinking on one’s feet- confirmation bias- Thinking on one’s feet- confirmation bias-

bending the facts to fit a hasty conclusion, bending the facts to fit a hasty conclusion, over-confidence, similarity bias, and over-confidence, similarity bias, and frequency biasfrequency bias

Skill-based violationsSkill-based violations

Corner cutting promoted by a largely Corner cutting promoted by a largely indifferent environmentindifferent environment

Rule-based violationsRule-based violations

More deliberate than skill based violationsMore deliberate than skill based violations

Knowledge based violationsKnowledge based violations

Novel circumstance- no specified procedureNovel circumstance- no specified procedure Trainers and procedure writers can only Trainers and procedure writers can only

address the foreseeableaddress the foreseeable Usually involve the unexpected occurrence Usually involve the unexpected occurrence

of a rare but trained for situation or an of a rare but trained for situation or an unlikely combination of individually familiar unlikely combination of individually familiar circumstancescircumstances

To Finish Defining ErrorTo Finish Defining Error

Cicero stated- “To err is human”Cicero stated- “To err is human” Accidents result from a failure of the risk Accidents result from a failure of the risk

management system to absorb the management system to absorb the consequences of these errors (unsafe acts)consequences of these errors (unsafe acts)

Human error is stubborn; sophisticated Human error is stubborn; sophisticated discrete solutions to human error will likely discrete solutions to human error will likely lead to more sophisticated sources of error- lead to more sophisticated sources of error- we must be prepared to manage itwe must be prepared to manage it

The EndThe End

Questions?Questions?