Topic area 3: Accident Aetiology

Estimated Duration: 3 Hours


  • To outline how accidents are caused.
  • To demonstrate the role of human error in accident causation.
  • To outline strategies for reducing human error.

Lecture Plan

  • Basic theories of accident causation
  • Heinrich's Domino Theory
  • Loss Causation Model
  • The Role of Human Error in Accidents
  • The traditional concept of human error - the blame approach
  • Organisation failures in recent disasters
    • King's Cross Station underground file
    • Capsize of the Herald of Free Enterprise
    • Clapham Junction Rail Crash

Classification of Human Errors - Latent and Active Failures

  • Active failures - these are the 'errors' made by operators/maintenance staff ie those with hands-on control of the system/equipment. They occur immediately prior to the accident event and are often seen as the 'immediate cause'. Active failures are those errors which traditionally have been described as human error - driver error and pilot error being typical examples.
  • Latent Failures - these are decisions and actions that dormant in an organisation for some time until revealed by active failures. These are evident in poor procedures, poor design, inadequate training, poor attitudes to safety.

Classification of Active Failures

  • A slip/lapse is an error which occurs during the execution of the correct plan of action.
  • A mistake is an error which occurs during the planning of what to do in a given circumstance when a choice has to be made between different courses of action and the wrong choice is made.
  • A violation is a deliberate error where the individual concerned gas breached an established rule or procedure

Examples of Latent Failures

  • Rules and procedures;
  • Insufficient training
  • Poor safety commitment
  • Insufficient supervision
  • Poor plant and equipment design
  • Poor job design
  • Poor working conditions

Strategies for Reducing Human Error
Actions for overcoming Active failures

  • Slips & Lapses - Design improvements
  • Mistakes- Training
  • Violations - Determination of motive to violate

Addressing latent failures

Suggested Reading & Other Resources

  • HSE - ACSNI Study Group on Human Factors 3rd Report: Organising for Safety, HSE Books, 1993
  • HSE - Reducing error and influencing behaviour HS(G)48, HSE Books, 1998.
  • Mason S - Practical Guidelines for Improving Safety through the Reduction of Human Error,
  • The Safety and Health Practitioner, May 1992 pp 24-30
  • Kletz T - An Engineering View of Human Error, IChemE Books, 1990.
  • Department of Energy - The Public Enquiry into the Piper Alpha Disaster, HMSO, 1990
  • Department of Transport - Herald of Free Enterprise formal Report - HMSO, 1987
  • Fennell D - Investigation into the King's Cross Underground Fire, Department of Transport, HMSO, 1988
  • Glendon AI & McKenna E, Human Safety and Risk Management, Chapman & Hall, 1995

Course documents

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Updated 2021-03-26