incident

HUMAN factors no15

Institute of Petroleum Human Factors Briefing Note No. 15

briefing notes

For background information on this series of publications, please see Briefing Note 1 – Introduction.

For background information on this series of publications, please see Briefing Note 1 - Introduction RootofCause: accidents happen at often, the endthe of aimmediate chain of events. Very the ROOT CAUSE: accidents happen at the end a chain of events. Very cause, justoften, before immediate cause, just before the accident, is a human error. But before that, the accident, is a human error. But before that, there will be other actions, decisions or events influenced by there will be actions, decisions or events influenced by itvarious conditions various conditions that are part of the overall cause ofother the accident. By finding the root causes, may be that are part of the overall cause of the accident. By finding the root causes, it possible to prevent future similar accidents.

Root Cause Analysis

may be possible to prevent future similar accidents

root cause analysis

Purpose of This Briefing Note

This Briefing Note introduces root cause analysis methods. These are used as a means of tracing the origin of accidents incidents (near misses). They Purpose of this briefingand note organisations learn from these experiences This briefinghelp note introducestoroot cause analysis methods. and indicate what steps to takethe to prevent These are used as a means of tracing origin offuture accidents and incidents (near misses). They help organisations to learn occurrences. from these A experiences indicate what to take to large numberand of techniques exist.steps You are advised prevent future occurrences. number of course techniques to read further or A tolarge attend a training before exist. You are advised to read further or to attend a training using any of them. course before using any of them. should develop a policy for when to CompaniesCompanies should develop a policy for when to conduct root conduct rootbe cause analysis; it may be applied to allthose cause analysis; it may applied to all incidents or only incidents or only those with major accident potential. with major accident potential.

Case study and and analysis Case Study Analysis

Management decisions

Unsafe acts

Accidents

Why rootWhy causeRoot analysis? Cause Analysis?

Sparks fromSparks a welding fell torch onto solvent paintfrom torch a welding fell ontoand solvent and paint-soakedThe ragsHealth and Safety Commission issued a consultative The Health and Safety Commission issued a Consultative soaked ragsleft leftininthe thework work area causing a small fire. This area causing a small fire. This was quickly document on the subject of accident investigation, but rather Document on the subject of accident investigation and are was quickly extinguished extinguishedbyby the welder. Paintwork andand cable the welder himself. Paintwork cable ducting than introduce a legal duty, it plans to develop guidance to likely to make it a legal duty under the RIDDOR or MHSWR ducting werewere damaged £2500. 500. damagedwith withrepair repaircosts costs of around around £2 help employers to conduct investigations. Regulations to conduct investigations. Many companies would review information look and look no Many companies wouldthis review the above and information no further than the than immediate causes:causes: litter was left in the further the immediate someone left litter in the Many accidents are blamed on the actions or omissions “Many accidents are blamed on the actions or omissions of an workplace and the did not remove this orThe put adequate of fire workplace and adequate firewelder blanketing was not used. an individual who who waswas directly involved or individual directly involvedininoperational operational or in place.the The result and wouldpainting be to discipline and result wouldblanketing be to discipline welder crew the welder maintenance work. Thiswork. typical short-sighted response maintenance Thisbut typical but short-sighted response and to perhaps issue a to notice all workers to pay more and perhapspainting issue acrew notice all workers pay to more ignores the ignores fundamental failures which led to the the fundamental failures which ledaccident. to the accident. to housekeeping. attention to attention housekeeping. These are usually rooted deeper in the organisation’s These are usually rooted deeper in the organisation’s design, Such an analysis explore true underlying causes of this management and decision-making functions. Such a basic analysis doesdoes not not explore thethe true underlying design, management and decision-making functions”. event: root cause analysis methods do. Source: Reducing errorHSE, and Influencing behaviour HSE Error HSG48 HSE causes of this event provided by the three root cause [Source: (1999) HSG48, ‘Reducing and This Briefing Providesto examples of 3accident root cause analysis Books tools (1999) ISBN 0 7176 2452 8 analysis methods whichNote are applied the above Influencing Behaviour’] applied in this briefing note.to the above accident.

HSG65 Approach HSG65 approach

HSE’s Document, ‘Successful Health and Safety Management’ provides good practical advice on accident investigation. It suggests the investigation team should: HSE’s Successful health and safety that management (reference 5), provides good practical advice on accident investigation. It 1. Collect Evidence suggests that the investigation team should:

• Visit the site and directly observe the conditions where the accident occurred noting the layout (where the welder was 1. Collect evidence located, where the flammable materialswhere were, the of occurred safety equipment directly observe the conditions theposition accident noting etc) the layout (in this case, the location of • Visit the site and • Review documents – procedures for the painting work and the welding work, permits, policy documents, risk assessments etc the welder, flammable materials, safety equipment, etc) Conductprocedures interviews with those involved, witnesses the accident its outcome, those who any involvement for –the painting and weldingtowork; permits;orpolicy documents; riskhad assessments, etc.before the • Review •documents: accident (eg. supervisors, inspectors, maintenance crew). involved; witnesses to the accident or its outcome; and those involved before the accident (e.g. supervisors, • Interview: those 2. Assemble and Consider inspectors, maintenance crew). the Evidence Using HSE’s of human factors (See Briefing Note 8) identify the ‘immediate causes’ of an accident (those concerned themodel evidence 2. Assemble •and consider with ‘Personal Factors’ and ‘Job ie. behaviour of the of human factors (seeFactors’ briefing– note 8) identify the:painting crew, the welder and the supervisor who signed off the • Using HSE’s model to of work, work conditions, adequacy of guards, Identify the ‘underlying causes’ - ‘Immediate permit causes’ an accident i.e. those concerned withseparation ‘personaldistances factors’ etc), and ‘job factors’; e.g. behaviour of(those the concerned with ‘Management and Organisational Factors’ – pressure on paint crew to complete too many jobs in a shift, failures painting crew, the welder and the supervisor who signed off the permit to work, work conditions, adequacy of guards, safety policy separation in distances etc. and risk assessment etc). 3. Compare Findings with legal and company - ‘Underlying causes’ i.e. those concerned with standards ‘management and organisational factors’ e.g. pressure on paint crew to • too Were thejobs standards applied (eg. is in there a standard for housekeeping, is it enforced?) complete many in a shift, failures safety policy and risk assessment, etc. with legal and company standards • Were the standards themselves adequate? 3. Compare findings • Were the standards applied (e.g. is there a standard for housekeeping; is it enforced)? 4. standards Draw conclusions based on the evidence themselves adequate? • Were the 5. Make improvements track progress against these (are they in place; are they working?) by regular monitoring and checking. based on theand evidence 4. Draw conclusions 5. Make improvements and track progress against these by regular monitoring and checking (e.g. are they in place; are they working?) HSG65 provides further guidance on how to conduct the investigation logically. Starting with ‘premises’ – workplace problems, consider if these were significant in the accident. Then consider ‘Plant and Substances’ - was there sufficient guarding of

HSG65 provides further guidance on to conduct the‘Procedures’ investigation logically. Starting with ‘premises’ consider workplace equipment or containment ofhow substances? Were adequate and used correctly? Consider ‘People’ and iftheir behaviour etc. problems were significant in the accident. Then consider ‘plant and substances;’ was there sufficient guarding of equipment or containment of substances? Were ‘procedures’ adequate and used correctly? Consider ‘people’ and their behaviour etc.

HFBr.0043.211102.Root Cause Analysis BN page 1.rev2.D.W.doc

Copyright © 2003 by The Institute of Petroleum, London: A charitable company limited by guarantee. Registered No. 135273, England

SCAT (Systematic cause analysis technique)

This method is based on the International safety rating system (ISRS), which is extensively used in the petroleum industry. ISRS measures the safety management system in a plant against a number of control ‘elements’: SCAT helps the user to interpret accidents and incidents in terms of which of the elements failed. The software version (E-scat), allows the user to enter: • A description of the accident (date, time, what happened) • Details of the ‘loss potential’ which comprises the following factors: - loss severity potential - i.e. how bad could it have been? In the example - ‘serious’ - the fire could have been worse - probability of reoccurrence - ‘moderate’ - a similar problem could arise until measures are taken to remove the causes - frequency of exposure - ‘moderate’ - welding is a common task but not a daily occurrence • Type of contact - SCAT provides various choices. In the example, the contact is, ‘with heat’ (other choices are with: cold; radiation; caustics; noise; electricity etc) From lists the user then selects the immediate causes (ICs) - substandard acts or substandard conditions. These include: ‘failure to follow procedure/policy/practice’ and ‘failure to check/monitor’. These were both causes of the fire in the example. The user then selects the basic underlying causes (BCs) which are split into ‘personal factors’ and ‘job factors’. The user can choose to see only the most probable BCs that apply to the ICs chosen in the last step. BCs include: ‘abuse or misuse’ which can be described as ‘improper conduct that is not condoned’. Or, ‘improper motivation’ which leads to ‘improper attempt to save time or effort’. From the ICs and BCs identified, SCAT will suggest a number of ‘control actions needed’ (CANs) based on ISRS principles, that will help to remove or reduce the impact of the underlying causes of the accident. CANs include, for this example: ‘task observation’ - the need for a scheme to carry out ‘spot checks’ on tasks; ‘rules and work permits’ review of how compliance with rules is achieved; and, ‘general promotion’ (of safety) - promotion of critical task safety and promotion of housekeeping systems.

MORT (Management oversight risk tree)

The following is a simplified description of MORT, as this technique can be quite complex. In general, MORT views an accident as occurring because an unwanted ‘energy flow’ reached a ‘target’. So, in the example, sparks (a form of heat energy) from welding fell onto flammable materials (the target) leading to a fire. The fire, i.e. more heat energy, then burned paintwork and cable ducting (another ‘target’) causing damage. Energy flows can only be stopped by some form of ‘barrier’ and ‘barrier analysis’ is a key part of MORT. In the example, there should have been a barrier to contain the flammable material (e.g. put the rags in containers and take them away). A second barrier, fire blankets, should have covered a larger area. MORT provides a ‘tree’ structure that guides the analyst to consider whether: • similar (worse) events could happen in future • the accident had been assumed and already considered as an inevitable given the type of operations carried out (MORT calls this an ‘assumed risk’), or, • the accident is unacceptable, and the underlying causes need to be investigated The investigation then proceeds to identify what specifically went wrong and why. The analysis considers: • what happened • what elements of the protection system were ‘less than adequate’ - recovery mechanisms (where they failed to reduce the consequences of the event. In the example, they did work as the fire was extinguished) - ‘barriers’ that failed to stop the event occurring (flammable materials were not contained; protective blankets badly positioned) - management factors that did not protect against the event (permit system and supervision/checking not carried out effectively).

Summary of main components

According to reference 1, there are three key components of root cause analysis systems: 1. A method of describing and representing the incident sequence and its contributing conditions (e.g. a ‘tree’ diagram) 2. A method of identifying the critical events and conditions in the incident sequence (often a checklist to stimulate ideas) 3. Based on the identification of the critical events or active failures, a method for systematically investigating the management and organisational factors that allowed the active failures to occur The three example methods described here show how these components are used in practice.

Useful reference information 1. Root causes analysis: literature review HSE Contract Research Report CRR 325/2001 HSE Books (2001) ISBN 0 7176 1966 4 2. Accident investigation - the drivers, methods and outcomes HSE Contract Research Report CRR 344/2001 HSE Books (2001) ISBN 0 7176 2022 0 3. MORT User’s Manual: www.nri.eu.com/ 4. SCAT demonstration/purchase: www.dnvcert.com/DNV/trainingandconsulting/products/software/e-scat/default.asp 5. Succesful health and safety management HSE HSG65 HSE Books (2000) ISBN 0 7176 1276 7 © Crown copyright material is reprodued with the permission of the Controller of HMSO and Queen’s Printer for Scotland