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Human failure types

A Hearts and Minds resource

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Human failure typesWhat?

- This resource gives an overview of human failure types, and provides a taxonomy and supporting information to help you to better understand the various types of human failure, and the factors that make each type more likely to occur, and remedies to prevent their occurrence.

How?

- It uses a taxonomy flowchart to illustrate human failure types and causes.

- It can be used in conjunction with the Hearts and Minds tools Managing rule breaking, Risk assessment matrix and Improving supervision, but is also a good general resource when exploring and reacting to human failure.

- It is illustrated with examples and includes a simple knowledge test.

Why?

- To be of assistance when exploring the possibility of human failure in risk assessments and in identifying barriers to reduce risks.

- To be of assistance when exploring human failure causation in incident and accident investigations (see EI Guidance on investigating and analysing human and organisational factors aspects of incidents and accidents).

- To help manage rule breaking and identify relevant remedies to address the particular human failure type.

ACKNOWLEDGEMENTS

The resource should be viewed in slide show mode

The human failure taxonomy illustrated in this resource is shown in three stages so that you can focus on specific areas at a time.

The completed taxonomy diagram contains embedded links to additional guidance and examples. If you hover the cursor over the highlighted text boxes a dialogue box will appear that describes the additional material available. Use the ‘Next Slide’ and ‘Go back’ buttons to navigate from screen to screen and to return to the human failure taxonomy chart.

You can refer to the taxonomy when you complete the knowledge test at the end of the resource.

Click Here to Start

How to use this resource

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http://intranet/index.php

This resource provides information about• Different types of errors.• Different types of non-compliances.• Remedies for errors and non-compliances.

Examples are used throughout the resource to illustrate the various types of Error and Non-compliance.

A simple knowledge test is included at the end of the resource which will enable you to assess how well you have understood the material presented.

What this resource provides

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Human Error and Non-ComplianceHuman errors and non-compliances are how people cause accidents.

Errors

Errors are intentional or unintentional actions – or inactions – that deviate from what would have been expected.

Non-Compliances

Non-compliances, also called Violations, are intentional actions or inactions that do not conform with agreed rules or procedures.

• The term non-compliance is used here as a less threatening alternative to Violation and refers specifically to (apparently) deliberate failure to follow known rules or procedures.

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Human failure taxonomy

Mistakes Lapses Slips

Knowledge-based

Rule-based

Attention

Memory

Competition

Attention

Organisational benefit

Personal benefit

Routine non-compliance Routine errors

When rules are broken to get the job done and make the boss happy

Breaking the rules for solely personal gain

When knowingly dangerous and performed without any care or consideration of oneself or others, whether for organisational or personal goals

• Choosing a standardsolution for a known

problem (rule-based behaviour)

Or• Solving a problem from

first principles (knowledge-based behaviour)

And• Getting the wrong

solution; or the right solution for the wrong problem (mistake)

Performing highly skilled and routinised tasks that require: 1) occasional checks on accuracy and progress and 2) remembering what to do next. Will be made more likely by other task demands that take attention or memory, such as being in a hurry, having too many tasks, insufficient information, hard to see.

Strong but wrong - doing what worked last time - is the most common error. If there is a possibility of such a reversion to previous behaviours, this can be predicted when other conditions make errors more likely

Routine non-compliance may be personal (a habitual rule breaker) or common (“everyone does it that way”)

The question that has to be asked is: Did management know this non-compliance was routine? If not, how could they be made more aware of it?

Routine errors by an individual may be due to temporary personal factors (e.g. stress). If many people make the same error there may be a problem with design, workload, training etc. Does management know that errors are being made frequently? If not, why not?

When the person does what they

meant to, but should have

done something else

When the person forgets

to do something

When the person does

something, but not what they meant to do

Human failures

Unintended actionsIntended actions

Errors - Unintended consequences

Non-compliances

When the person decided to act without

complying with a known rule or

procedure

A special case when the rule or procedure is not

known or well understood. A form of

mistake by the individual who didn’t know better

Non-compliances - Intended consequences

Non-compliance

remedies

Error

remedies

Unintentional Non-compliances

Reckless

Situational

The solution to an unworkable situation to get the job done

When official solutions to novel problems are hard to follow, or old habits take over

Exceptional

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Knowledge-based

Rule-based

Attention

Memory

Competition

Attention

Exceptional

Situational


Personal benefit













Performing highly skilled and routinised tasks that require:1) occasional checks on accuracy and progress and 2) remembering what to do next. Will be made more likely by other task demands that take attention or memory, such as being in a hurry, having too many tasks, insufficient information, hard to see.







done something else


to do something



Human failures



Non-compliances



procedure





Non-compliance

remedies

Error

remedies

Unintentional non-compliances

Reckless

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Knowledge-based

Rule-based

Attention

Memory

Competition

Attention

Exceptional

Situational


Personal benefit
















done something else


to do something



Human failures



Non-compliances



procedure





Unintentional Non-compliances

Reckless





Non-compliance

remedies

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Error

remedies


Knowledge-based

Rule-based

Attention

Memory

Competition

Attention

Exceptional

Situational


Personal benefit













Performing highly skilled and routinised tasks that require:1) occasional checks on accuracy and progress and2) remembering what to do next. Will be made more likely by other task demands that take attention or memory, such as being in a hurry, having too many tasks, insufficient information, hard to see.







done something else


to do something



Human failures



Non-compliances



procedure





Non-compliance

remedies

Error

remedies

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Reckless

Human failure taxonomyClick the flashing boxes

for more information

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How dangerous are human failures and why?Slips• Simple slips are usually benign and most people quickly spot that they have made

such an error. Slips can be very dangerous under certain conditions, such as flying at low altitude or heart surgery, but such situations should have been recognised and prepared for in advance.

Lapses• Lapses are more dangerous than slips because they are harder to recognise, and

other people may assume that the necessary action has in fact been taken. Lapses are the main errors in maintenance and can lead to hidden problems.

Mistakes• Mistakes are even more dangerous because people often refuse to believe that they

are wrong, despite evidence to the contrary, and may go beyond the point where safe recovery is possible.

Non-compliance• Non-compliances are usually successful adaptations to real or imagined problems.

When they combine with an error they are suddenly extremely dangerous. People breaking the rules assume everything else will go safely so they will get away with it, but errors are unexpected and the combination can suddenly become lethal.Next SlideGo back


Safety Culture and dealing with errors and non-compliancesThe organisational response to errors and non-compliances is an indicator of the organisational culture. This is determined by what people see as the causes of such behaviours. People often explain their own errors and non-compliances in terms of the situation in which they found themselves, but see the same types of behaviour by others as the result of personal failings of those individuals.

• Pathological and Reactive cultures subscribe to explanations in terms of individual weaknesses and look to identify error-prone individuals. Reporting one’s own errors and non-compliances is seen as personally dangerous – Messengers of bad news are reprimanded.

• Calculative cultures are heavily procedure-based and so may tolerate errors but have difficulty with non-compliances. People find it hard to report their own errors, and non-compliances may still be kept hidden if possible – Messengers of bad news are tolerated.

• Proactive and Generative cultures teach people to recognise errors and how to identify their causes so that they can be prevented. Errors provide information that can be used for improvement – Messengers of bad news are trained and rewarded. Next SlideGo back


PATHOLOGICALwho cares as long as we’re not

caught

REACTIVESafety is important, we do a lot every time we have an accident

Increasing Trust/Accountability

Increasinglyinformed

PROACTIVESafety leadership and values

drive continuous improvement

GENERATIVE (High Reliability Orgs.)

HSE is how we do business round here

CALCULATIVEwe have systems in place to

manage all hazards

The Safety Culture Ladder

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Knowledge quiz

Set out on the next slide are a series of statements which represent different types of human failure. Decide which type of human failure each statement belongs to.

If you are unsure go back to the Human Failure Taxonomy flowchart and review the information presented again.

Click the ‘answer’ button to reveal which type of human failure each statement belongs to.

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Knowledge quizWhich type of human failure?

Because of their lack of knowledge of the procedures, operators are found to have been working without the correct PPE specified for the process.

Unintentional Non-

Compliance

A fuel tanker driver knows that lack of attention can cause an accident but still uses a mobile phone while driving at high speed on a busy highway.

Reckless Non-Compliance

Because of using out of date drawings, a maintenance worker caused a gas release that led to a fire.

Mistake

During a start-up, a refinery operator discovers they have omitted a step in a lengthy procedure.

Lapse

In order not to cause any production losses a maintenance worker decides to fix a broken relay without turning off the electricity supply.

Organisational Benefit

Because they were in a hurry to get home early, instead of asking for a scaffold, a construction worker used his own ladder to tighten a screw at 5 m height.

Personal Benefit

During maintenance a technician discovered that the torque wrench they were supposed to use cannot be used in the space available. They used a drilling wrench instead.

Situational Non-Compliance

While filling out a report, a maintenance worker accidentally marked the wrong checklist item, indicating a check has been done, when it hadn’t.

Slip

Answer

Answer

Answer

Answer

Answer

Answer

Answer

Answer

Human failure taxonomy flowchart

End QuizGo back

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The knowledge gained from this resource can be used in a number of ways:

- It can be used to help managers make better decisions regarding rule breaking behaviour (for more information, please see the Managing rule-breaking tool)

- When should behaviour be punished? - Can we learn from people’s non-compliance?

- It can be used when taking human failure into account when assessing risks (for more information, please see the Risk assessment matrix tool)

- What is the risk of someone making an error/non-compliance?

- It can be used to improve supervision (for more information, please see the Improving supervision tool)

- Why are people making errors or non-compliances? - Can supervisors detect and solve them?

- It can be used when investigating accidents (see EI Guidance on investigating and analysing human and organisational factors aspects of incidents and accidents).

- What was the root cause of human failure? (Non-compliances also have root causes)

What now?


Return to Start

End PresentationReplay Quiz


Errors

Errors are always unintended.

Slips (doing what you didn’t mean to do) and lapses (not doing what you meant to do) are unintended poor actions that are deviations from skilled performance.

Mistakes (doing what you thought you ought to do, but wouldn’t have chosen with hindsight) are unintended poor solutions to problems that individuals think are adequate under the circumstances.

• Skilled performance requires a pre-programmed plan of action that is activated by an intention (1) to act, that itself is defined by the intention (2) to achieve a goal – so there are at least two levels of intention required.

• Slips & lapses = failure to carry out plan of action (1): A good plan that goes wrong – good plan, lousy execution.

• Mistakes = failure to create good plan to achieve goal (2): Not having a good plan to start with, but carrying it out anyway – lousy plan, seemed a good idea at the time.

NB: Perception (Detection) errors are a fourth error type used in other human error taxonomies. They occur when an individual misperceives or fails to perceive something. For example an individual could mishear an instruction from a colleague or read the wrong pressure from a computer screen. Being able to distinguish this fourth error type is important as different solutions are required.

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Errors

Unfamiliarity with task (x17)

Time shortage (x11)

Poor signal:noise ratio (x10)

Poor human-system interface (x8)

Designer-user mismatch (x8)

Irreversibility of errors (x8)

Information overload (x6)

Negative transfer between tasks (x5)

Misperception of risk (x4)

Key: (x1) = probability of error occurring

Poor feedback from system (x4)

Inexperience (not lack of training) (x3)

Poor instructions or procedures (x3)

Inadequate checking (x3)

Educational mismatch (x2)

Disturbed sleep patterns (x1.6)

Hostile environment (x1.2)

Monotony and boredom (x1.1)

Factors both internal and external to an individual make it more or less likely that an error will occur. Such factors are called Performance Influencing (Shaping) Factors (PIFs / PSFs). These can be identified and fixed. These include (from J. Williams) :

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Skill-, rule- and knowledge-based information processing refers to the degree of conscious control exercised by an individual over their tasks.

• In skill-based mode, highly practised largely physical actions are performed smoothly and with little conscious monitoring, e.g. a competent driver can drive from A to B with little conscious thought.

• In rule-based mode an individual applies rules learnt through training or from experience. Here the level of conscious control is intermediate between knowledge- and skill-based mode.

• In knowledge-based mode the individual carries out a task in largely conscious mode, e.g. a learner driver or process operator presented with a novel situation.

Human failure

taxonomy

Skill-based

Automated routines with little conscious attention

Rule-based

IF symptom X THEN cause is Y IF the cause is Y THEN do Z

Knowledge-based

No routines or rules available for handling situation

Automatic

Conscious

Automatic

The skill-, rule-, and knowledge-based classification

Errors

Slips and Lapses are caused mainly by problems with attention, perception and memory.

• Lapses are typically failures of memory that cause us to forget to carry out an action, to lose our place in a task or even forget what we intended to do.

e.g. A busy maintenance worker, even though he meant to do so, forgot to notify the control room about an unusual noise that he heard while inspecting one of the new pumps in the unit.

e.g. A busy operator forgets to re-order a reserved stock of production material.

Human failure

taxonomy

Errors

Slips and Lapses are caused mainly by problems with attention, perception and memory.

• Slips occur when a person does something, but not what they meant to do.

e.g. Instead of isolating Pump 1, a maintenance worker closed the suction and discharge valves on Pump 2. When asked later he said he had no idea why he had done so. He knew that he was supposed to isolate Pump 1 instead of Pump 2 and actually had intended to do so.

Human failure

taxonomy

Errors

Mistakes occur when a solution for a problem is incorrect. They come in two types

• Rule-based - using a rule-of-thumb experience to solve a problem• Knowledge-based - solving a problem from first principles when there is no

standard solution

Rule-based mistakes either involve recognising a situation too quickly, overlooking or not knowing about different situations, or accepting the first rule that promises to achieve the goal.

Knowledge-based mistakes usually result from taking either too little or too much information into account. An individual may not have been given essential information by others. When under time stress or lack of sufficient information

people tend to use assumptions.

Human failure

taxonomy

Remedies for Errors

Errors are unintentional, so just telling people not to make them does not work. The notion of the error-prone individual has always proved very difficult to prove in practice – some people go through periods when they make more errors, but this is temporary. The problem of people making errors is not solved by looking for error-prone individuals and removing them; effective solutions lie in recognising error-provoking environments and fixing them.

• Mistakes are failures to select the correct course of action, often because a diagnosis was wrong. They can be prevented by providing useful information, training in decision making, team support processes (e.g. Crew Resource Management [CRM]) etc. Because people find it hard to accept that they are wrong, recovery is often too late and most attention should be paid to prevention.

• Slips are failures of highly automated human processes, so it is necessary to ensure that attention is not captured elsewhere when it is necessary to perform a check on progress, that the design does not invite the wrong response, that there is sufficient time to perform the task and no competing demands. Warning people of a mismatch between expected and actual outcomes is effective in prompting recovery actions.

• Lapses are typically memory failures but may also be due to working in a hurry, to design, and to competing prompts. Providing effective external memory cues such as checklists works well.

Human failure

taxonomy

Non-Compliance

Non-compliance can only be understood in a social context where rules and procedures are agreed (or imposed) ways of working; these may range from detailed work instructions, procedures and guidelines up to the laws of physics and chemistry.

When a major assumption of the Safety Management System is broken, the chances of bad consequences become significantly greater because other individuals will work with the expectation that the rules and procedures are being followed. Wider experience has shown this may also involve going past the point where the chances of an accident become greater than is acceptable.

Non-compliances are influenced by the social and personal norms - “This is how far we go” – “This is how far I go”.Typical examples (each of which may be any one of the types) are:

• Speeding or not wearing a seatbelt• Not isolating a hazardous system to avoid shutting it down• Giving a manager a task without the appropriate required training (e.g.

Journey management)

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Non-Compliance

Five different types of non-compliance

1. Unintentional non-compliance is a form of mistake. The person either does not know about a rule or procedure or understands it differently.

e.g. Because of a failure to follow a procedure, an incident occurred. After investigation, it turned out that the rule had been changed recently but the workers had not yet been properly informed about the revision.

2. Situational non-compliances occur when it is not possible to get the job done by following the procedures strictly.

e.g. During maintenance a technician discovered that the torque wrench they were supposed to use cannot be used in the space available. They used a drilling wrench instead.

3. Organisational benefit non-compliances occur when people want to meet organisational goals, which they may believe are what their managers and supervisors actually want.

e.g. During the conceptual design evaluation of a project, a number of environmental considerations are dropped in order to reduce costs and speed up the work.

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Non-Compliance

Five different types of non-compliance, continued

4. Personal benefit non-compliances are when individuals achieve purely personal goals.

e.g. A mechanic is working up on the derrick, while there is a crew down on the drill floor. No permit-to-work was raised, the drilling supervisor was not informed and the derrick access procedures were ignored. The mechanic wanted to ‘just quickly’ grease the crown block so he could go home early.

5. Exceptional non-compliances occur when people have to solve problems for the first time and fail to follow good practice.

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Non-Compliance

Non-compliances are made more likely by the dangerous mixture of 4 ingredients:

• The Expectation that rules will need to be bent or broken• The feeling of Powerfulness – one has the skills and experience to get

away with it• The lack of detailed Planning, making short-cuts necessary• The existence of Opportunities to take short-cuts that are recognised,

often by the most highly motivated individuals

Non-compliances may also be Reckless if they are known to be dangerous and are performed without care or consideration of oneself or others.

e.g. To show off in front of his colleagues, a worker is seen working while under the influence of alcohol.

Any non-compliance (except exceptional) may also be Routine.e.g. In a plant there are often large periods (> 30 minutes) with many plant

alarms (more than one per minute). An operator has accepted an alarm and did not take any further action which resulted in a poor quality product run. During the last few weeks this had happened several times to other operators as well.

Human failure

taxonomy

Remedies for Non-CompliancesNon-compliances are usually intentional, but it is necessary to understand which type of non-compliance has been committed because every type has a different remedy. Simply telling people to be compliant is not effective and may result in people mindlessly following poor or inappropriate rules and procedures. Rules and procedures exist to ensure safe work, but may be out of date, hard to follow, or felt to slow the work down. People break the rules if they have had to do it before to get the job done, if they feel they know how to do it, if they recognise an opportunity and there is a poor plan of action.

• Unintentional non-compliances. The solution is to make sure everyone knows exactly what the rules and procedures are (Awareness and Distribution) and that their understanding is correct (Training and Testing).

• Situational non-compliances may be caused by change, with procedures that were previously correct, or were written without consulting users in the field on feasibility. Situations should be recognised and procedures altered accordingly. People should be trained to report such situations without fear of reprisal/negative consequences.

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Remedies for Non-Compliances• Exceptional non-compliances need to be discovered by requiring people to

think the unthinkable and practice what feels difficult or personally dangerous (e.g. H2S rescue).

• Organisational benefit non-compliances: Expectations should be made completely clear by managers and supervisors. This should come from the very top of the organisation. A professional risk-based approach, taking a measured account of the local situation and competences, may allow local variances to be applied.

• Personal benefit non-compliances can often be avoided by supervisors who know their workforce well enough and who make their expectations sufficiently clear.

• Reckless non-compliances require understanding about just how dangerous they are, with a knowledge of sanctions and the belief that they will be applied.

If any type of non-compliance is routine it is necessary to ascertain if only one individual is breaking the rules or if it is common practice. In all cases it is necessary to find out if management knows and condones or even expects and tells people to break the rules (and is creating the problem) or does not know (and is failing in their duty to manage).

Human failure

taxonomy

Routine Errors

All errors may be committed routinely. If this is the case then there is a serious problem for the organisation

• If an error is routine then either there is a systemic problem, independent of the individuals who make the error, or an individual has a specific problem

• Routine errors made by many people may be caused by problems such as instruments that are easily confused, rows of identical switches, complicated sequences and repetitions, stressful conditions inherent in the task, etc.

• The Substitution Test (Would another individual with the same competence, in the same situation, be likely to make the error?) can be used to test if an individual or the task is the problem.

• Individual routine errors may be made because an individual lacks the required level of skill to perform the task or because they were in a particular situation, e.g. personal stress or medical conditions like diabetes leading to poor decision making.

Routine errors are first and foremost a supervisory problem:

• Supervisors and managers who actively go in search of routine issues should be rewarded, those who ignore them should be reminded of their

responsibilities.

Human failure

taxonomy

Routine Non-ComplianceAll non-compliances (apart from exceptional) may be committed routinely. If this is the case then there is a serious problem for the organisation

• Routine non-compliances by many people may be caused by poor or impossible procedures, or poor setting of standards by supervisors

• Two questions should be asked

1. Did supervisors know, and condone?

2. If supervisors did not know, why not?

• Supervisors and managers who actively go in search of routine issues should be rewarded; those who ignore them should be reminded of their responsibilities.

• Routine non-compliance by a single individual requires assessing that individual’s attitudes. They may have a history of disregard for the rules in general.

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Routine Non-ComplianceReckless non-compliances and Sabotage

Individuals who deliberately choose to act in ways that are intended to cause harm or disruption, sabotaging plant or activities, form a distinct group and need to be treated separately.

Individuals who pursue a course of action knowing it to be unacceptably risky, bringing themselves or others into danger, are acting recklessly. While many actions may appear reckless at first sight, careful investigation is necessary. Investigators should be aware of hindsight bias, since the individual may well have failed to see the hazard or assessed the risk completely inappropriately. Road transport non-compliances are more likely to be reckless.

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Routine Non-ComplianceSheep and Wolves

People are to be found along a continuum between extreme Sheep – people who dislike cutting corners or breaking rules – and outright Wolves – people who only see rules and procedures as guidance for others, if they get in the way of achieving their goals. In a major study the majority of offshore workers, and management, were classified as wolves. Wolves’ and Sheep’s clothing can indicate whether individuals have broken the rules recently. The largest single group were Wolves in Sheep’s clothing, individuals predisposed to finding rule-breaking easy to justify, but lacking the opportunity, especially in environments with many alternatives so that often any action could be justified.

Human failure

taxonomy



Knowledge-based

Rule-based

Attention

Memory

Competition

Attention

Exceptional

Situational


Personal benefit




















done something else


to do something



Human failures



Non-compliances



procedure





Non-compliance

remedies

Error

remedies

Return to Quiz


Reckless

Acknowledgeme

ntsThis resource was developed by Patrick Hudson (Consultant) and was commissioned by the Energy Institute’s Human and Organisational Factors Working Group, which comprised during the project:

Fiona Brindley, Health and Safety ExecutiveDr Robin Bryden, Shell International Exploration and Production B.V.Suzanne Croes, Shell International Exploration and Production B.V.Bill Gall, Kingsley Management LimitedPete Jefferies, ConocoPhillipsRob Miles, Health and Safety ExecutiveAllen Ormond, ABBGareth Parkes, EIGraham Reeves, BP plcHelen Rycraft, Magnox North SitesDr Mark Scanlon, EIDr John Symonds, ExxonMobil CorporationJohn Wilkinson, Health and Safety Executive

Their contributions to the project’s technical direction are gratefully acknowledged. In addition, the EI gratefully acknowledges the valuable contributions made by others who reviewed and commented on drafts of the resource during its development.

Affiliations refer to the time of participation.

This project was funded through the Winning Hearts and Minds toolkit research and development fund, which is managed by the EI on behalf of Shell International Exploration and Production B.V. For further information see www.energyinst.org.uk/heartsandminds

Mark Scanlon coordinated the project and technical editing was carried out by Gareth Parkes and Mark Scanlon. Formatting was carried out by Stuart King and assisted by Shell International Exploration and Production B.V.

Publications Information

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Publication

informationPublications information

© Energy Institute

1st edition, December 2009

The information contained in this resource is provided as guidance only and while every reasonable care has been taken to ensure the accuracy of its contents, the Energy Institute cannot accept any responsibility for any action taken, or not taken, on the basis of this information. The Energy Institute shall not be liable to any person for any loss or damage which may arise from the use of any of the information contained in any of its publications.

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