IEC 62740:2015

Root cause analysis (RCA)

IEC 62740:2015 describes the basic principles of root cause analysis (RCA) and specifies the steps that a process for RCA should include. This standard identifies a number of attributes for RCA techniques which assist with the selection of an appropriate technique. It describes each RCA technique and its relative strengths and weaknesses. RCA is used to analyse the root causes of focus events with both positive and negative outcomes, but it is most commonly used for the analysis of failures and incidents. Causes for such events can be varied in nature, including design processes and techniques, organizational characteristics, human aspects and external events. RCA can be used for investigating the causes of non-conformances in quality (and other) management systems as well as for failure analysis, for example in maintenance or equipment testing. RCA is used to analyse focus events that have occurred, therefore this standard only covers a posteriori analyses. It is recognized that some of the RCA techniques with adaptation can be used proactively in the design and development of items and for causal analysis during risk assessment; however, this standard focuses on the analysis of events which have occurred. The intent of this standard is to describe a process for performing RCA and to explain the techniques for identifying root causes. These techniques are not designed to assign responsibility or liability, which is outside the scope of this standard. Keywords: root cause analysis (RCA), RCA techniques

Analyse de cause initiale (RCA)

L'IEC 62740:2015 décrit les principes basiques de l'analyse de cause initiale (RCA) et spécifie les étapes qu'il convient qu'un processus de RCA inclue. La présente norme identifie plusieurs attributs de techniques de RCA, qui aident à sélectionner la technique appropriée. Elle décrit chaque technique de RCA, ainsi que ses points forts et limites. La RCA est utilisée pour analyser les causes initiales des événements d'accent, que leurs conséquences soient positives ou négatives, mais est plus couramment utilisée pour l'analyse des défaillances et des accidents. Les causes de tels événements peuvent être de nature multiple, notamment en fonction de la conception, des processus et des techniques, des caractéristiques organisationnelles, des aspects humains et des événements externes. La RCA peut être utilisée pour étudier les causes de non-conformité en termes de qualité (ou autres) des systèmes de gestion ainsi que pour l'analyse des défaillances, par exemple lors de la maintenance ou de l'essai des équipements. La RCA est utilisée pour analyser des événements d'accent qui se sont produits, cette norme ne couvre donc que les analyses a posteriori. Il est reconnu que certaines des techniques de RCA avec adaptations peuvent être utilisées de manière proactive lors de la conception et du développement d'entités et pour l'analyse causale au cours de l'évaluation des risques; cependant, la présente norme met l'accent sur l'analyse des événements qui se sont produits. L'objectif de la présente norme est de décrire un processus en vue de réaliser une RCA et d'expliquer les techniques permettant d'identifier les causes initiales. Lesdites techniques n'ont pas été conçues pour identifier la responsabilité ou la fiabilité, car ceci ne fait pas partie du domaine d'application de la présente norme. Mots clés: analyse de cause initiale (RCA), de techniques de RCA

General Information

• Status: Published
• Publication Date: 12-Feb-2015
• ICS: 03.120.01 - Quality in general
• Technical Committee: TC 56 - Dependability
• Current Stage: PPUB - Publication issued
• Start Date: 13-Feb-2015
• Completion Date: 15-Feb-2015

Overview

IEC 62740:2015 is an international standard published by the International Electrotechnical Commission (IEC) that outlines the fundamental principles and structured steps for Root Cause Analysis (RCA). This standard provides guidance on performing RCA to systematically identify the underlying causes of focus events, especially failures and incidents. Root Cause Analysis is a critical tool used across industries to improve safety, quality management, and maintenance by investigating issues that have already occurred (a posteriori analysis). IEC 62740:2015 does not extend to assigning responsibility or liability but concentrates on understanding causes to prevent recurrence.

Key Topics

• RCA Process Framework: The standard describes a step-by-step RCA process that includes initiation, establishing facts, analysis, validation, and presentation of results. This ensures a thorough and organized approach to investigating events.

• RCA Techniques: Various techniques are detailed, including their strengths, weaknesses, and suitable applications. Techniques covered range from cause-and-effect charts, fault trees, fishbone diagrams (Ishikawa), to advanced system models such as STAMP (Systems Theoretic Accident Model and Processes).

• Selection Criteria for Methods: IEC 62740:2015 assists users in selecting an appropriate RCA technique based on specific problem attributes, organizational needs, and event characteristics.

• Human Factors Analysis: The standard addresses the analysis of human performance and cognitive errors, referencing methods such as TRACEr (Technique for Retrospective and Predictive Analysis of Cognitive Errors) and the Human Factors Analysis and Classification Scheme (HFACS).

• Use of Tools for RCA: Modern data mining and clustering techniques are recognized as useful tools for enhancing root cause determination, leveraging data patterns.

• Scope and Limitations: The standard focuses exclusively on retrospective analysis of events and does not cover proactive risk assessment, although some RCA techniques may be adapted for that purpose.

Applications

• Failure and Incident Investigation: Organizations can apply IEC 62740:2015 to conduct systematic investigations into electrical, electronic, and related technological failures that disrupt operations or safety.

• Quality and Compliance Management: RCA is employed to identify the causes of non-conformances in quality and other management systems, supporting continuous improvement efforts.

• Maintenance and Equipment Testing: Root cause analysis helps in diagnosing equipment failures, allowing for targeted corrective actions to enhance reliability.

• Organizational Learning: By using RCA techniques, businesses can uncover systemic issues related to design processes, organizational practices, human factors, and external influences, promoting learning and preventive strategies.

• Safety Enhancement: The standard facilitates understanding accidents and near-misses holistically to strengthen safety barriers and controls.

Related Standards

• IEC 60050 – Electrotechnical Vocabulary: Provides foundational terms and definitions which complement RCA terminology used in IEC 62740.

• ISO 31000 – Risk Management: While IEC 62740 focuses on a posteriori causation analysis, ISO 31000 addresses proactive risk identification and mitigation.

• IEC 61508 – Functional Safety of Electrical/Electronic Systems: Incorporates failure analysis principles relevant to root cause investigations guided by IEC 62740.

• Other IEC Normative Documents: Various technical specifications and reports on reliability, safety, and human factors analysis support the implementation of RCA as standardized by IEC 62740.

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By adopting IEC 62740:2015, organizations gain a robust, internationally recognized framework for conducting root cause analysis that enhances failure investigation accuracy, supports systemic problem solving, and drives continual operational improvements across diverse technical fields.

Standards Content (Sample)

IEC 62740 ®
Edition 1.0 2015-02
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Root cause analysis (RCA)
Analyse de cause initiale (RCA)

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IEC 62740 ®
Edition 1.0 2015-02
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Root cause analysis (RCA)
Analyse de cause initiale (RCA)

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 03.120.01 ISBN 978-2-8322-2246-1

– 2 – IEC 62740:2015 © IEC 2015
CONTENTS
FOREWORD . 6
INTRODUCTION . 8
1 Scope . 9
2 Normative references . 9
3 Terms, definitions and abbreviations . 9
3.1 Terms and definitions . 9
3.2 Abbreviations . 12
4 RCA – Overview . 12
5 The RCA process . 13
5.1 Overview. 13
5.2 Initiation . 14
5.3 Establishing facts . 15
5.4 Analysis . 17
5.4.1 Description . 17
5.4.2 The analysis team . 18
5.5 Validation . 19
5.6 Presentation of results . 19
6 Selection of techniques for analysing causes . 20
6.1 General . 20
6.2 Selection of analysis techniques . 20
6.3 Useful tools to assist RCA. 21
Annex A (informative) Summary and criteria of commonly used RCA techniques . 22
A.1 General . 22
A.2 RCA techniques . 22
A.3 Criteria . 23
Annex B (informative) RCA models . 26
B.1 General . 26
B.2 Barrier analysis . 26
B.2.1 Overview . 26
B.2.2 Strengths and limitations . 27
B.3 Reason’s model (Swiss cheese model) . 27
B.3.1 Overview . 27
B.3.2 Strengths and limitations . 28
B.4 Systems models . 28
B.5 Systems theoretic accident model and processes (STAMP) . 29
B.5.1 Overview . 29
B.5.2 Strengths and limitations . 29
Annex C (informative) Detailed description of RCA techniques . 30
C.1 General . 30
C.2 Events and causal factors (ECF) charting . 30
C.2.1 Overview . 30
C.2.2 Process . 31
C.2.3 Strengths and limitations . 31
C.3 Multilinear events sequencing (MES) and sequentially timed events plotting
(STEP) . 32

C.3.1 Overview . 32
C.3.2 Process . 32
C.3.3 Strengths and limitations . 33
C.4 The ‘why’ method . 35
C.4.1 Overview . 35
C.4.2 Process . 36
C.4.3 Strengths and limitations . 36
C.5 Causes tree method (CTM) . 36
C.5.1 Overview . 36
C.5.2 Process . 39
C.5.3 Strengths and limitations . 39
C.6 Why-because analysis (WBA) . 39
C.6.1 Overview . 39
C.6.2 Process . 42
C.6.3 Strengths and limitations . 42
C.7 Fault tree and success tree method . 42
C.7.1 Overview . 42
C.7.2 Process . 43
C.7.3 Strengths and limitations . 44
C.8 Fishbone or Ishikawa diagram . 44
C.8.1 Overview . 44
C.8.2 Process . 45
C.8.3 Strengths and limitations . 46
C.9 Safety through organizational learning (SOL) . 46
C.9.1 Overview . 46
C.9.2 Process . 46
C.9.3 Strengths and limitations . 47
C.10 Management oversight and risk tree (MORT) . 48
C.10.1 Overview . 48
C.10.2 Process . 48
C.10.3 Strengths and limitations . 48
C.11 AcciMaps . 49
C.11.1 Overview . 49
C.11.2 Process . 49
C.11.3 Strengths and limitations . 51
C.12 Tripod Beta . 51
C.12.1 Overview . 51
C.12.2 Process . 52
C.12.3 Strengths and limitations . 52
C.13 Causal analysis using STAMP (CAST) . 53
C.13.1 Overview . 53
C.13.2 Process . 56
C.13.3 Strengths and limitations . 57
Annex D (informative) Useful tools to assist root cause analysis (RCA) . 58
D.1 General . 58
D.2 Data mining and clustering techniques . 58
D.2.1 Overview . 58
D.2.2 Example 1 . 58
D.2.3 Example 2 . 58

– 4 – IEC 62740:2015 © IEC 2015
D.2.4 Example 3 . 59
Annex E (informative) Analysis of human performance . 60
E.1 General . 60
E.2 Analysis of human failure . 60
E.3 Technique for retrospective and predictive analysis of cognitive errors
(TRACEr) . 61
E.3.1 Overview . 61
E.3.2 Process . 62
E.4 Human factors analysis and classification scheme (HFACS) . 63
E.4.1 Overview . 63
E.4.2 Process . 63
Bibliography . 66

Figure 1 – RCA process . 14
Figure B.1 – Broken, ineffective and missing barriers causing the focus event . 26
Figure C.1 – Example of an ECF chart . 31
Figure C.2 – Data in an event building block . 32
Figure C.3 – Example of a time-actor matrix . 34
Figure C.4 – Example of a why tree . 35
Figure C.5 – Symbols and links used in CTM . 37
Figure C.6 – Example of a cause tree . 38
Figure C.7 – Example of a WBG . 41
Figure C.8 – Example of a fault tree during the analysis . 43
Figure C.9 – Example of a Fishbone diagram . 45
Figure C.10 – Example of a MORT diagram . 48
Figure C.11 – Example of an AcciMap . 50
Figure C.12 – Example of a Tripod Beta tree diagram . 52
Figure C.13 – Control structure for the water supply in a small town in Canada . 55
Figure C.14 – Example CAST causal analysis for the local Department of health . 56
Figure C.15 – Example CAST causal analysis for the local public utility operations
management . 56
Figure E.1 – Example of an TRACEr model [25] . 61
Figure E.2 – Generation of internal error modes . 62
Figure E.3 – Level 1: Unsafe acts . 64
Figure E.4 – Level 2: Preconditions . 64
Figure E.5 – Level 3: Supervision Issues . 65
Figure E.6 – Level 4: Organizational Issues . 65

Table 1 – Steps to RCA . 13
Table A.1 – Brief description of RCA techniques . 22
Table A.2 – Summary of RCA technique criteria . 23
Table A.3 – Attributes of the generic RCA techniques . 25
Table B.1 – Examples of barriers . 27
Table B.2 – Example of the barrier analysis worksheet . 27
Table C.1 – Direct and indirect causal factors . 47

Table E.1 – External error modes. 63
Table E.2 – Psychological error mechanisms . 63

– 6 – IEC 62740:2015 © IEC 2015
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
ROOT CAUSE ANALYSIS (RCA)
FOREWORD
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International Standard IEC 62740 has been prepared by IEC technical committee 56:
Dependability.
The text of this standard is based on the following documents:
FDIS Report on voting
56/1590/FDIS 56/1608/RVD
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– 8 – IEC 62740:2015 © IEC 2015
INTRODUCTION
Root cause analysis (RCA) refers to any systematic process that identifies factors that
contributed to a particular event of interest (focus event). RCA is performed with the
understanding that events are addressed by understanding the root causes, rather than the
immediately obvious symptoms. RCA aims to reveal root causes so that either the likelihood
of them occurring, or their impact if they do occur, can be changed.
An important distinction to make is that RCA is used to analyse a focus event that has
occurred and therefore analyses the past (a posteriori). However, knowledge of the root
causes of past events can lead to actions that generate improvements in the future.
This International Standard is intended to reflect current good practices in the conduct of
RCA. This standard is general in nature, so that it may give guidance across many industries
and situations. There may be industry specific standards in existence that establish preferred
methodologies for particular applications. If these standards are in harmony with this
publication, the industry standards will generally be sufficient.
This standard is a generic standard and does not explicitly address safety or accident
investigation although the methods described in this standard may be used for this purpose.

ROOT CAUSE ANALYSIS (RCA)
1 Scope
This International Standard describes the basic principles of root cause analysis (RCA) and
specifies the steps that a process for RCA should include.
This standard identifies a number of attributes for RCA techniques which assist with the
selection of an appropriate technique. It describes each RCA technique and its relative
strengths and weaknesses.
RCA is used to analyse the root causes of focus events with both positive and negative
outcomes, but it is most commonly used for the analysis of failures and incidents. Causes for
such events can be varied in nature, including design processes and techniques,
organizational characteristics, human aspects and external events. RCA can be used for
investigating the causes of non-conformances in quality (and other) management systems as
well as for failure analysis, for example in maintenance or equipment testing.
RCA is used to analyse focus events that have occurred, therefore this standard only covers a
posteriori analyses. It is recognized that some of the RCA techniques with adaptation can be
used proactively in the design and development of items and for causal analysis during risk
assessment; however, this standard focuses on the analysis of events which have occurred.
The intent of this standard is to describe a process for performing RCA and to explain the
techniques for identifying root causes. These techniques are not designed to assign
responsibility or liability, which is outside the scope of this standard.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and
are indispensable for its application. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any
amendments) applies.
IEC 60050 (all parts), International Electrotechnical Vocabulary
3 Terms, definitions and abbreviations
For the purposes of this document, the definitions given in IEC 60050-192, as well as the
following, apply.
3.1 Terms and definitions
3.1.1
cause
circumstance or set of circumstances that leads to failure or success
Note 1 to entry: A cause may originate during specification, design, manufacture, installation, operation or
maintenance.
[SOURCE: IEC 60050-192:2014, 192-03-11 modified – addition of the words “circumstance
or” and "or success" in the term]

– 10 – IEC 62740:2015 © IEC 2015
3.1.2
causal factor
condition, action, event or state that was necessary or contributed to the occurrence of the
focus event
3.1.3
contributory factor
condition, action, event or state regarded as secondary, according to the occurrence of the
focus event
3.1.4
event
occurrence or change of a particular set of circumstances
Note 1 to entry: An event can be one or more occurrences, and can have several causes.
Note 2 to entry: An event can consist of something not happening.
Note 3 to entry: An event can sometimes be referred to as an “incident” or “accident”.
[SOURCE: ISO Guide 73:2009, 3.5.1.3, modified – Deletion of Note 4 [1]]
3.1.5
failure
loss of ability to perform as required
Note 1 to entry: A failure of an item is an event that results in a fault of that item.
Note 2 to entry: Qualifiers, such as catastrophic, critical, major, minor, marginal and insignificant, may be used to
categorize failures according to the severity of consequences, the choice and definitions of severity criteria
depending upon the field of application.
Note 3 to entry: Qualifiers, such as misuse, mishandling and weakness, may be used to categorize failures
according to the cause of failure.
Note 4 to entry: This is failure of an item, not more generally of behaviour.
[SOURCE: IEC 60050-192:2014, 192-03-01, modified – Introduction of new Note 4]
3.1.6
failure mechanism
process that leads to failure
Note 1 to entry: The process may be physical, chemical, logical, psychological or a combination thereof.
[SOURCE: IEC 60050-192:2014, 192-03-12, modified – the word "psychological" has been
added]
3.1.7
focus event
event which is intended to be explained causally
3.1.8
immediate causal factor
condition, action, event or state where there is no other causal factor between this causal
factor and the focus event
_______________
Numbers in square brackets refer to the Bibliography.

Note 1 to entry: There may be more than one immediate causal factor.
3.1.9
necessary causal factor
condition, action, event or state, that resulted in the given event or state, without which the
given event or state would not have occurred
3.1.10
human error
discrepancy between the human action taken or omitted, and that intended or required
Note 1 to entry: The first edition of IEC 60050-191:1990 identified “mistake” as a synonym for "human error", but
a mistake is a type of human error.
Note 2 to entry: The term human error applies to any situation where the outcome is not as intended whether the
intent of the person was correct or not.
[SOURCE: IEC 60050-192: 2014 192-03-14, modified – Omission of the example, addition of
Note 1 and 2]
3.1.11
item
subject being considered
Note 1 to entry: The item may be an individual part, component, device, functional unit, equipment, subsystem, or
system.
Note 2 to entry: The item may consist of hardware, software, people or any combination thereof.
Note 3 to entry: The item is often comprised of elements that may each be individually considered.
[SOURCE: IEC 60050-192: 2014, 192-01-01, modified – omission of internal references and
Notes 4 and 5]
3.1.12
root cause
causal factor with no predecessor that is relevant for the purpose of the analysis
Note 1 to entry: A focus event normally has more than one root cause.
Note 2 to entry: In some languages, the term root cause refers to the combination of causal factors which have no
causal predecessor (a cut set of causal factors).
3.1.13
root cause analysis
RCA
systematic process to identify the causes of a focus event
Note 1 to entry: IEC 60050-192:2014, definition 192-12-05 provides the following more restrictive definition
“systematic process to identify the cause of a fault, failure or undesired event, so that it can be removed by design,
process or procedure changes”. This standard uses an extended definition to allow a wider applicability of the
process.
Note 2 to entry: This note applies to the French language only.
3.1.14
stakeholder
person or organization that can affect, be affected by, or perceive themselves to be affected
by a decision or activity
[SOURCE: IEC 60300-1:2014, 3.1.15] [2]

– 12 – IEC 62740:2015 © IEC 2015
3.1.15
stopping rule
reasoned and explicit means of determining when a causal factor is defined as being a root
cause
3.2 Abbreviations
BGA Ball grid array
CAST Causal analysis using STAMP
CCT Causal completeness test
CT Counterfactual test
CTM Causes tree method
ECF Events and causal factors
EEM External error mode
FTA Fault tree analysis
GEMS Generic error modelling system
HFACS Human factor analysis and classification scheme
IEM Internal error mode
MES Multilinear events sequencing
MORT Management oversight and risk tree
PEM Psychological error mechanism
PSF Performance shaping factors
RCA Root cause analysis
SOL Safety through organizational learning
STAMP Systems theoretic accident model and processes
STEP Sequentially timed events plotting
TRACEr Technique for restrospective and predictive analysis of
cognitive errors
WBA Why-because analysis
4 RCA – Overview
RCA refers to any systematic process that identifies the cause or causes that contribute to a
focus event. The immediate or obvious cause of a focus event is often a symptom of
underlying causes and may not truly identify the root cause or causes that should be identified
and addressed. RCA provides a greater understanding about why events have occurred. RCA
may identify the following:
a) a single root cause;
b) multiple root causes in which the elimination of any cause will prevent the focus event
from occurring;
c) root causes which are contributory factors where elimination will change the likelihood of
the focus event occurring but may not directly prevent it;
d) root causes of successes.
By addressing the root cause or causes it is possible to make decisions regarding appropriate
actions that will generate better outcomes in the future; implementing appropriate actions
based on RCA are more effective at preventing the same or similar events with negative

outcomes occurring or increasing the probability of repeating events with positive outcomes,
when compared with just addressing the immediately obvious symptoms.
RCA can be applied to any focus event whether success or failure, for example:
1) investigation for technological, medical and occupational focus events;
2) failure analysis of technological systems, to determine why an item failed to perform as
and when required;
3) analysis of quality control and business processes;
4) analysis of successful outcomes.
RCA can be carried out at various levels of decomposition, for example, from system to
component level or by selecting different events or outcomes as a starting point. The level
appropriate to conduct the analysis will be dependent on the focus event.
RCA is used to analyse focus events which have actually occurred and is therefore applicable
during the testing and operational phases of a project or product life cycle. RCA can identify
problems of process including design, quality control, dependability management and project
management.
The benefits of performing RCA include:
• obtaining a greater understanding into what has happened;
• finding the source of problems so corrective action can prevent future events;
• identifying the causes of events with beneficial outcomes so they can be repeated;
• identifying more effective actions to address the causes of focus events;
• achieving the objectives of focus event investigations more effectively;
• supporting traceability between focus event investigation evidence and conclusions;
• increasing consistency between investigations of similar focus events;
• increasing objectivity of focus event analysis.
5 The RCA process
5.1 Overview
To be effective, RCA should be performed systematically as an investigation, with the root
causes and conclusions backed up by documented evidence. To achieve this, RCA should
include the five steps shown in Table 1 and illustrated in Figure 1.
Table 1 – Steps to RCA
Step Concepts and tasks to be performed
Initiation Based on the knowledge available on the focus event, determine the need to carry
out RCA and define the purpose and scope
Establishing facts Collect data and establish the facts of what happened, where, when and by whom
Analysis Use RCA tools and techniques to ascertain how and why the focus event occurred
Validation Distinguish and resolve the different possibilities as to how and why the focus event
was caused
Presentation of results Present the results of the focus event analysis

RCA is iterative in nature, especially for data collection and analysis, in that data is collected
on ‘what’ happened, which is then analysed in order to determine what other data needs to be
collected. Once gathered, further analysis is conducted and any gaps identified, for which

– 14 – IEC 62740:2015 © IEC 2015
further data is collected. This process is repeated until the purpose of the analysis is fulfilled
and the root causes identified. The outputs of the RCA will be dependent on its purpose and
scope.
Establish What, How and why Potential
the need, Where, (identify causes
purpose & When & By potential distinguished
scope Whom causes) and resolved
Outputs
Current Data Application of Further data
Knowledge Collection specific tools and testing
Step 5: Presentation
Step 1: Initiation Step 2: Establishing Facts Step 3: Analysis Step 4: Validation
of Results
IEC
Figure 1 – RCA process
5.2 Initiation
The first step initiates the RCA process by evaluating the need to carry out RCA. It defines
the purpose and scope of the analysis, in response to the focus event, and establishes a team
and resources to carry out the RCA.
There is usually some criterion which is used to determine when an RCA is required, which
may include:
• any single event with a large effect;
• multiple similar undesirable events;
• a parameter moving out of a defined tolerance level;
• failures or successes (whatever the level of effect) that involve critical items of equipment
or activities.
When defining the type of events that require the conduct of RCA, it is important to consider
that an event with a large effect may have common root causes to events with minor effects.
Analysing and addressing root causes for events with minor effects may prevent a large effect
event occurring. Examples of events where RCA may be required include: completion of a
project (successes and failures), failures that result in unaccepfigure costs, injury or fatality,
unacceptable performance or delays, large contractual consequences and equipment
breakdown.
If a RCA is required, the focus event(s) to be analysed is/are described and an appropriate
team appointed for the analysis. The description should include the background and context in
which the focus event(s) occurred. A good description of a focus event is short, simple and
easy to understand and should not be biased towards a specific solution. This description is
used to identify appropriate members of the analysis team and ascertain where to start
collecting data.
The purpose and scope of the RCA should be determined, taking into account knowledge of
system, functions, interfaces etc. In some cases, the purpose of the analysis is to identify the
causes of the focus event. In others, the purpose may be broader, for example, to also
identify matters of concern outside those that led to the focus event.

There are in general two different types of RCA that have different objectives and should not
be mixed up. These two types can be described as follows:
1) analysing a focus event using only verifiable factual information;
2) analysing a focus event to obtain hypotheses of sequences of events and cause.
The first version focuses on observed facts only. It may be an analysis "per se" according to
the purpose of the study and no hypothesis about event occurrence is acceptable for this
analysis. The second can be implemented when sufficient factual information is not available
and hypotheses of potential causes are acceptable for the purpose of the analysis.
The outputs required of the RCA should also be identified. Examples are as follows:
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