James Reason’s 12 Principles of Error Management

James Reason, Professor Emeritus, University of Manchester, set out 12 systemic human factors centric principles of error management in his book Managing Maintenance Error: A Practical Guide (co-written with Alan Hobbs and published in 2003). These principles are valid beyond aviation maintenance and are well worth re-visiting:

  1. Human error is both universal & inevitable: Human fallibility can be moderated but it can never be eliminated.
  2. Errors are not intrinsically bad: Success and failure spring from the same psychological roots.  Without them we could neither learn nor acquire the skills that are essential to safe and efficient work.
  3. You cannot change the human condition, but you can change the conditions in which humans work:  Situations vary enormously in their capacity for provoking unwanted actions.  Identifying these error traps and recognising their characteristics are essential preliminaries to effective error management.
  4. The best people can make the worst mistakes: No one is immune. The best people often occupy the most responsible positions so that their errors can have the greatest impact…
  5. People cannot easily avoid those actions they did not intend to commit: Blaming people for their errors is emotionally satisfying but remedially useless.  We should not, however, confuse blame with accountability.  Everyone ought to be accountable for his or her errors [and] acknowledge the errors and strive to be mindful to avoid recurrence.
  6. Errors are consequences not causes: …errors have a history.  Discovering an error is the beginning of a search for causes, not the end.  Only be understanding the circumstances…can we hope to limit the chances of their recurrence.
  7. Many errors fall into recurrent patters: Targeting those recurrent error types is the most effective way of deploying limited Error Management resources.
  8. Safety significant errors can occur at all levels of the system: Making errors is not the monopoly of those who get their hands dirty.  …the higher up an organisation an individual is, the more dangerous are his or her errors.  Error management techniques need to be applied across the whole system.
  9. Error management is about managing the manageable: Situations and even systems are manageable if we are mindful.  Human nature – in the broadest sense – is not.  Most of the enduring solutions…involve technical, procedural and organisational measures rather than purely psychological ones.
  10. Error management is about making good people excellent: Excellent performers routinely prepare themselves for potentially challenging activities by mentally rehearsing their responses to a variety of imagines situations.  Improving the skills of error detection is at least as important as making people aware of how errors arise in the first place.
  11. There is no one best way: Different types of human factors problem occur at different levels of the organisation and require different management techniques.  Different organisational cultures require different ‘mixing and matching’….of techniques.  People are more likely to buy-in to home grown measures…
  12. Effective error management aims as continuous reform not local fixes:  There is always a strong temptation to focus upon the last few errors …but trying to prevent individual errors is like swatting mosquitos…the only way to solve the mosquito problem is drain the swamps in which they breed.  Reform of the system as a whole must be a continuous process whose aim is to contain whole groups of errors rather than single blunders.

Error management has three components, says Reason:

  1. Reduction
  2. Containment
  3. Managing these so they remain effective

Its the third aspect that is most challenging according to Reason:

It is simply not possible to order in a package of Error Management measures, implement them and then expect them to work without further attention  You cannot put them in place and then tick them off as another job completed.  In an important sense, the process – the continuous striving toward system reform – is the product.

Further Reading on Safety (UPDATED)

The UK Civil Aviation Authority (CAA) has commented that:

Human Factors training alone is not considered sufficient to minimise maintenance error. Most of the [contributing factors] can be attributed to the safety culture and associated behaviours of the organisation.

Two other books by James Reason are also worth attention:

Plus there is this presentation given to a Royal Aeronautical Society (RAeS) Human Factors Group conference in 2006 on Risk in Safety-Critical Industries: Human Factors Risk Culture

Amy Edmonson discusses psychological safety and openness:

This paper by the Health and Safety Laboratory is worth attention: High Reliability Organisations [HROs] and Mindful Leadership.  Mindfulness is developed further in a paper by the Future Sky Safe EU research project and by Andrew Hopkins at the ANU.

You may also be interested in these Aerossurance articles:

UPDATE 26 April 2016: Chernobyl: 30 Years On – Lessons in Safety Culture

UPDATE 1 August 2016: We also recommend this article: Leicester’s lesson in leadership, published in The Psychologist.

UPDATE 10 August 2016: We also like this article by Suzette Woodward after she delivered the James Reason Lecture.  She highlights:

  1. The first thing you can do [when investigating] is learn to listen
    • Listen to what people are saying without judgement
    • Listen to those that work there every day to find out what their lives are like
    • Listen to help you piece the bits of the jigsaw together so that they start to resemble a picture of sorts
  2. The second thing you can do is resist the pressure to find a simple explanation
  3. The third thing you can do: don’t be judgemental

She goes on:

  • Find the facts and evidence early
  • Without the need to find blame
  • Strengthen investigative capacity locally
  • Support people with national leadership
  • Provide a resource of skills and expertise
  • Act as a catalyst to promote a just and open culture

UPDATE: 28 August 2016: We look at an EU research project that recently investigated the concepts of organisational safety intelligence (the safety information available) and executive safety wisdom (in using that to make safety decisions) by interviewing 16 senior industry executives: Safety Intelligence & Safety Wisdom.  They defined these as:

Safety Intelligence the various sources of quantitative information an organisation may use to identify and assess various threats.

Safety Wisdom the judgement and decision-making of those in senior positions who must decide what to do to remain safe, and how they also use quantitative and qualitative information to support those decisions.

The topic of weak or ambiguous signals was discussed in this 2006 article: Facing Ambiguous Threats


Aerossurance was pleased to sponsor this Royal Aeronautical Society (RAeS) Human Factors Group: Engineering conference on 12 May 2015 at Cranfield University: Human Factors in Engineering – the Next Generation

Aerossurance is pleased to be supporting the annual Chartered Institute of Ergonomics & Human Factors’ (CIEHFHuman Factors in Aviation Safety Conference for the third year running.  This year the conference takes place 13 to 14 November 2017 at the Hilton London Gatwick Airport, UK with the theme: How do we improve human performance in today’s aviation business?

ciehf 2017


Aerossurance is an Aberdeen based aviation consultancy.  For advice you can trust on practical and effective safety management, contact us at: enquiries@aerossurance.com