IEC 61069-6:2016

Industrial-process measurement, control and automation - Evaluation of system properties for the purpose of system assessment - Part 6: Assessment of system operability

IEC 61069-6:2016 specifies the detailed method of the assessment of operability of basic control system (BCS), based on the basic concepts of IEC 61069-1 and methodology of IEC 61069-2; defines basic categorization of operability properties; describes the factors that influence operability and which need to be taken into account when evaluating operability; provides guidance in selecting techniques from a set of options (with references) for evaluating the operability. This second edition cancels and replaces the first edition published in 1998. This edition constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition:
- reorganization of the material of IEC 61069-6:1998 to make the overall set of standards more organized and consistent;
- IEC TS 62603-1 has been incorporated into this edition.

Mesure, commande et automation dans les processus industriels - Appréciation des propriétés d'un système en vue de son évaluation - Partie 6: Évaluation de l'opérabilité d'un système

L'IEC 61069-6:2016 spécifie la méthode d'évaluation détaillée de l'opérabilité d'un système de commande de base (BCS) reposant sur les principes de base de l'IEC 61069-1 et la méthodologie de l'IEC 61069-2; définit la classification de base des propriétés d'opérabilité; décrit les facteurs ayant une influence sur l'opérabilité et dont il faut tenir compte lors de l'appréciation de l'opérabilité; donne des lignes directrices concernant les techniques de sélection à partir d'un ensemble d'options (avec références) pour l'appréciation de l'opérabilité. Cette deuxième édition annule et remplace la première édition parue en 1998. Cette édition constitue une révision technique. Cette édition inclut les modifications techniques majeures suivantes par rapport à l'édition précédente:
- réorganisation des informations contenues dans l'IEC 61069-6:1998 visant à mieux organiser l'ensemble complet de normes et à le rendre plus cohérent;
- l'IEC TS 62603-1 a été incorporée dans cette édition.

General Information

• Status: Published
• Publication Date: 14-Jun-2016
• ICS: 25.040.40 - Industrial process measurement and control
• Technical Committee: SC 65A - System aspects
• Drafting Committee: WG 16 - TC 65/SC 65A/WG 16
• Current Stage: PPUB - Publication issued
• Start Date: 15-Jun-2016
• Completion Date: 15-Jul-2016

Relations

• Revises: IEC 61069-6:1998 - Industrial-process measurement and control - Evaluation of system properties for the purpose of system assessment - Part 6: Assessment of system operability
• Effective Date: 05-Sep-2023

Overview

IEC 61069-6:2016 is an international standard developed by the International Electrotechnical Commission (IEC) focused on industrial-process measurement, control, and automation. This standard specifically addresses the assessment of system operability within basic control systems (BCS). It builds on the foundational concepts outlined in IEC 61069-1 and the methodologies from IEC 61069-2 to provide a comprehensive framework for evaluating a system's operability. As a second edition and technical revision of the 1998 original, IEC 61069-6:2016 reorganizes the material for improved clarity and incorporates insights from IEC TS 62603-1, ensuring a modernized and consistent approach to system operability assessment.

Key Topics

This standard provides a detailed method to assess operability by considering various operability properties and relevant influencing factors:

• Operability Properties:

  • Efficiency: Measures how effectively system operators can perform tasks using the control system.
  • Intuitiveness: Evaluates how easily operators understand and interact with the system.
  • Transparency: Assesses the clarity and availability of information presented to operators.
  • Robustness: Gauges the system’s resilience to disturbances and operator errors.

• Factors Influencing Operability:

  • Industrial process characteristics that impact control system performance.
  • Operator tasks, including frequency and complexity of actions.
  • Control strategies applied within the automation system.
  • Human-machine interface (HMI) design considerations.
  • Workplace environment effects on operator performance.
  • Human factors impacting usability and system interaction.

• Assessment Methodology:

  • Defining Objectives: Establishing the purpose and scope of the operability assessment.
  • Design and Planning: Structuring the assessment program and selecting appropriate evaluation techniques.
  • Execution: Conducting the operability evaluation using analytical and empirical methods.
  • Reporting: Documenting findings, insights, and recommendations for system improvement.

• Evaluation Techniques:

  • Analytical techniques to predict operability outcomes.
  • Empirical methods involving operator feedback and observation.
  • Guidance on choosing suitable techniques tailored to operability factors.

• Supporting Guidance:

  • Checklists for system requirement documents focusing on operability.
  • Examples of assessment items especially concerning human-machine interfaces.
  • Consideration of system life cycle phases relevant to operability.

Applications

IEC 61069-6:2016 is essential for professionals involved in the design, implementation, and evaluation of industrial automation and control systems. Practical applications include:

• Industrial Automation Design: Ensuring control systems incorporate effective operability features to enhance operator performance and safety.
• System Assessment and Certification: Providing a standardized approach for auditing control systems on usability and operational reliability.
• Human-Machine Interface (HMI) Development: Guiding design choices that optimize transparency, intuitiveness, and operator workload.
• Operational Risk Management: Identifying and mitigating operability-related risks stemming from poor interface design or system robustness.
• Training and Procedures: Informing operator training programs by understanding operability constraints and human factors.
• Lifecycle Management: Integrating operability assessments throughout system development and maintenance phases to maintain performance standards.

Implementing IEC 61069-6 helps industrial organizations improve control system handling, reduce errors, and enhance overall process safety and efficiency.

Related Standards

IEC 61069-6:2016 complements other standards within the IEC 61069 series, which focus on evaluation of system properties for system assessment in industrial-process environments, such as:

• IEC 61069-1: General concepts for the evaluation of system properties.
• IEC 61069-2: Methodologies for system assessment.
• IEC TS 62603-1: Detailed evaluation criteria for human-machine interfaces incorporated into this edition.
• Additional IEC standards related to industrial automation and human factors engineering.

Together, these standards form a holistic framework to ensure industrial control systems meet rigorous operability and performance requirements, supporting enhanced automation reliability worldwide.

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By adhering to IEC 61069-6:2016, organizations can effectively evaluate and optimize control system operability, bridging technical performance with practical operational needs in industrial automation. This improves operator efficiency, system transparency, and robustness-key drivers of successful industrial process control.

Standards Content (Sample)

IEC 61069-6 ®
Edition 2.0 2016-06
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Industrial-process measurement, control and automation – Evaluation of system
properties for the purpose of system assessment –
Part 6: Assessment of system operability

Mesure, commande et automation dans les processus industriels – Appréciation
des propriétés d'un système en vue de son évaluation –
Partie 6: Évaluation de l’opérabilité d'un système

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IEC 61069-6 ®
Edition 2.0 2016-06
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Industrial-process measurement, control and automation – Evaluation of system

properties for the purpose of system assessment –

Part 6: Assessment of system operability

Mesure, commande et automation dans les processus industriels – Appréciation

des propriétés d'un système en vue de son évaluation –

Partie 6: Évaluation de l’opérabilité d'un système

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 25.040.40 ISBN 978-2-8322-3448-8

– 2 – IEC 61069-6:2016 © IEC 2016
CONTENTS
FOREWORD . 4
INTRODUCTION . 6
1 Scope . 8
2 Normative references. 8
3 Terms, definitions, abbreviated terms, acronyms, conventions and symbols . 8
3.1 Terms and definitions . 8
3.2 Abbreviated terms, acronyms, conventions and symbols . 8
4 Basis of assessment specific to operability . 8
4.1 Operability properties . 8
4.1.1 General . 8
4.1.2 Efficiency . 10
4.1.3 Intuitiveness . 10
4.1.4 Transparency . 11
4.1.5 Robustness . 11
4.2 Factors influencing operability . 12
5 Assessment method . 12
5.1 General . 12
5.2 Defining the objective of the assessment . 12
5.3 Design and layout of the assessment . 12
5.4 Planning of the assessment program . 13
5.5 Execution of the assessment . 13
5.6 Reporting of the assessment . 13
6 Evaluation techniques . 14
6.1 General . 14
6.2 Analytical evaluation techniques . 15
6.2.1 General . 15
6.2.2 Efficiency . 15
6.2.3 Intuitiveness . 15
6.2.4 Transparency . 16
6.2.5 Robustness . 16
6.3 Empirical evaluation techniques. 16
6.3.1 General . 16
6.3.2 Efficiency . 16
6.3.3 Intuitiveness . 16
6.3.4 Transparency . 17
6.3.5 Robustness . 17
6.4 Additional topics for evaluation techniques . 17
Annex A (informative) Checklist and/or example of SRD for system operability . 18
A.1 General . 18
A.2 Factors resulting from the industrial process itself . 18
A.3 Factors related with the task of the operators, their frequency, percentage of
time spent, required number of actions, etc. . 19
A.4 Factors due to the control strategy required . 19
A.5 Factors concerning the human-machine interface design . 20
A.6 Influence of the workplace on the operability requirements . 20
A.7 General human factors . 21

Annex B (informative) Checklist and/or example of SSD for system operability . 22
B.1 SSD information . 22
B.2 Check points for system operability . 22
Annex C (informative) Example of a list of assessment items (information from
IEC TS 62603-1) . 23
C.1 Overview. 23
C.2 Operability properties of Human Machine Interface (HMI) . 23
C.2.1 General . 23
C.2.2 Control room HMI hardware – system configuration . 23
C.2.3 Control room HMI hardware – machines . 23
C.2.4 Control room HMI hardware – monitors . 24
C.2.5 Control room HMI hardware – special displays . 24
C.2.6 Control room HMI software . 24
C.2.7 Requirements for Local Operator Interface . 25
C.2.8 BPCS localisation . 25
Annex D (informative) Phase of a system life cycle . 26
Bibliography . 27

Figure 1 – General layout of IEC 61069 . 7
Figure 2 – Operability . 10

Table D.1 – Phases of a system life cycle . 26

– 4 – IEC 61069-6:2016 © IEC 2016
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
INDUSTRIAL-PROCESS MEASUREMENT, CONTROL AND AUTOMATION –
EVALUATION OF SYSTEM PROPERTIES FOR
THE PURPOSEOF SYSTEM ASSESSMENT –

Part 6: Assessment of system operability

FOREWORD
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indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 61069-6 has been prepared by subcommittee 65A: System
aspects, of IEC technical committee 65: Industrial-process measurement, control and
automation.
This second edition cancels and replaces the first edition published in 1998. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) reorganization of the material of IEC 61069-6:1998 to make the overall set of standards
more organized and consistent;
b) IEC TS 62603-1 has been incorporated into this edition.

The text of this standard is based on the following documents:
FDIS Report on voting
65A/794/FDIS 65A/804/RVD
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all parts in the IEC 61069 series, published under the general title Industrial-process
measurement, control and automation – Evaluation of system properties for the purpose of
system assessment, can be found on the IEC website.
The committee has decided that the contents of this publication will remain unchanged until
the stability date indicated on the IEC web site under "http://webstore.iec.ch" in the data
related to the specific publication. At this date, the publication will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates
that it contains colours which are considered to be useful for the correct
understanding of its contents. Users should therefore print this document using a
colour printer.
– 6 – IEC 61069-6:2016 © IEC 2016
INTRODUCTION
IEC 61069 deals with the method which should be used to assess system properties of a
basic control system (BCS). IEC 61069 consists of the following parts.
Part 1: Terminology and basic concepts
Part 2: Assessment methodology
Part 3: Assessment of system functionality
Part 4: Assessment of system performance
Part 5: Assessment of system dependability
Part 6: Assessment of system operability
Part 7: Assessment of system safety
Part 8: Assessment of other system properties
Assessment of a system is the judgement, based on evidence, of the suitability of the system
for a specific mission or class of missions.
To obtain total evidence would require complete evaluation (for example under all influencing
factors) of all system properties relevant to the specific mission or class of missions.
Since this is rarely practical, the rationale on which an assessment of a system should be
based is:
– the identification of the importance of each of the relevant system properties;
– the planning for evaluation of the relevant system properties with a cost-effective
dedication of effort to the various system properties.
In conducting an assessment of a system, it is crucial to bear in mind the need to gain a
maximum increase in confidence in the suitability of a system within practical cost and time
constraints.
An assessment can only be carried out if a mission has been stated (or given), or if any
mission can be hypothesized. In the absence of a mission, no assessment can be made;
however, evaluations can still be specified and carried out for use in assessments performed
by others. In such cases, IEC 61069 can be used as a guide for planning an evaluation and it
provides methods for performing evaluations, since evaluations are an integral part of
assessment.
In preparing the assessment, it can be discovered that the definition of the system is too
narrow. For example, a facility with two or more revisions of the control systems sharing
resources, for example a network, should consider issues of co-existence and inter-operability.
In this case, the system to be investigated should not be limited to the “new” BCS; it should
include both. That is, it should change the boundaries of the system to include enough of the
other system to address these concerns.
The series structure and the relationship among the parts of IEC 61069 are shown in Figure 1.

IEC 61069: Industrial-process measurement, control and automation –
Evaluation of system properties for the purpose of system assessment
Part 1: Terminology and basic concepts
• Basic concept
• Terminology ‐ Objective
‐ Common terms ‐ Description of system
‐ Terms for particular part ‐ System properties
‐ Influencing factors
Part 2: Assessment methodology
• Generic requirements of procedure of assessment
‐ Overview, approach and phases
‐ Requirements for each phase
‐ General description of evaluation techniques
Parts 3 to 8: Assessment of each system property
• Basics of assessment specific to each property
‐ Properties and influencing factors
• Assessment method for each property
• Evaluation techniques for each property

IEC
Figure 1 – General layout of IEC 61069
Some example assessment items are integrated in Annex C.

– 8 – IEC 61069-6:2016 © IEC 2016
INDUSTRIAL-PROCESS MEASUREMENT, CONTROL AND AUTOMATION –
EVALUATION OF SYSTEM PROPERTIES FOR
THE PURPOSEOF SYSTEM ASSESSMENT –

Part 6: Assessment of system operability

1 Scope
This part of IEC 61069:
– specifies the detailed method of the assessment of operability of basic control system
(BCS), based on the basic concepts of IEC 61069-1 and methodology of IEC 61069-2;
– defines basic categorization of operability properties;
– describes the factors that influence operability and which need to be taken into account
when evaluating operability;
– provides guidance in selecting techniques from a set of options (with references) for
evaluating the operability.
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 61069-1:2016, Industrial-process measurement, control and automation – Evaluation of
system properties for the purpose of system assessment – Part 1: Terminology and basic
concepts
IEC 61069-2:2016, Industrial-process measurement, control and automation – Evaluation of
system properties for the purpose of system assessment – Part 2: Assessment methodology
3 Terms, definitions, abbreviated terms, acronyms, conventions and symbols
3.1 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 61069-1 apply.
3.2 Abbreviated terms, acronyms, conventions and symbols
For the purposes of this document, the abbreviated terms, acronyms, conventions and
symbols given in IEC 61069-1 the following apply.
4 Basis of assessment specific to operability
4.1 Operability properties
4.1.1 General
For a system to be operable the system provides the operator with a transparent and
consistent window into the tasks to be performed, through its human-machine interface. The
extent to which means for interaction with these tasks provided by the system are efficient,

intuitive, transparent and robust interaction can be expressed by the operability system
property.
The human-machine interface functions are part of the system and enable the operator to
monitor and manipulate the system itself, the external systems and the process.
The requirements for operability are strongly affected by the skill and knowhow of the
personnel operating the system.
The degree of the operability system property varies depending on the phases of the system
mission during its life cycle.
Operability requirements can differ between these phases of the life cycle of the system. They
depend upon the tasks to be performed during the phase and the duration of the phase.
The operability requirements can be high where the duration of a phase is short and its
relevance for the system mission critical. The requirements can be low where the duration of
a phase is long, so that sequences of required actions for certain operations can be learnt by
the operator over the long term the system is used.
In the assessment of operability, one is concerned with the way which information given by
the operator to the system (such as commands and requests), is processed by the system.
Additionally, one is concerned with the transparency of information coming from the system to
the operator, such as process/system state and values, trends, reports, etc.
While special operability measures are sometimes needed during the design and/or
maintenance phases of the system, the operability requirements are mostly understood as
those necessary during the operational phase of an industrial process plant.
All phases of life cycle of the system should be taken into account for evaluation of system
operability properties. During each phase the system will typically be operated by a different
group of operators, with different operability requirements.
In addition, planned, unplanned and disturbed plant operation might need different operating
schemes and hence operability requirements.
Annex D shows the various phases, the operator(s) using the system during these phases,
their typical tasks and the type of interfaces utilized.
The perception of the operability system property is strongly affected by the performance
system property (especially speed of response) and the functionality system property.
Operability properties are categorized as shown in Figure 2.

– 10 – IEC 61069-6:2016 © IEC 2016
Operability
Efficiency Intuitiveness Transparency Robustness

IEC
Figure 2 – Operability
Operability cannot be assessed directly and cannot be described by a single property.
Operability can only be determined by analysis and testing of each of the operability
properties individually
Some aspects can be quantified by analysing the ergonomic aspects of the properties, and by
measuring the number of actions and time required to accomplish a given task (the efficiency
of the human-machine interface), others can be qualified in a descriptive way.
Efficiency, intuitiveness, transparency and robustness each cannot be quantified as a single
number. However they can be expressed by a qualitative description containing some
quantified elements, such as:
– a coverage factor, obtained by comparing the operating means provided by the system
with the specific requirements as stated in the system requirements document;
– applicable ergonomic standards; and
– the time required to give a command, and to request information.
4.1.2 Efficiency
A system has operability efficiency if it allows the operator, with a minimum risk of making
errors, to perform his task(s) with a minimum amount of mental and physical effort within an
acceptable time frame.
The extent to which the operating means provided by the system minimise operator time and
effort required in using the system to accomplish his tasks within stated constraints is a
measure of the operability efficiency of the system.
The operability efficiency depends, among others, on the following elements:
– the ergonomic design of the devices (keyboard, mouse, voice input, dedicated knobs,
screens, indicators, etc.) used as operating means in support of the human-machine
interface;
– the geographical lay-out, the number of these devices and their relative location on the
operators’ workplace;
– the shape of the operators’ workplace;
– the limitations imposed by the operating environment and protective clothing (indoor,
outdoor, day, night, goggles, gloves, etc.);
– the methods to be used to retrieve information, to issue commands, etc.
4.1.3 Intuitiveness
Intuitiveness represents the simplicity and instant understanding the system provides, which
enables the operators to give commands and present information to the operators.
Additionally intuitiveness takes into account the skills, educational level and general culture of
the operators, who are performing tasks, by using the functions provided by the system.

The degree to which the operational means are consistent with common working practices is
a measure of the operability intuitiveness of the system.
The operability intuitiveness depends on the following factors:
– the extent to which standard generic rules and methods for the operation of “action” items
are followed;
– the conventions followed to present information to the operator, for example red for
emergency conditions, etc.;
– the conventions followed to give commands, for example turning a knob clockwise to
increase a value, etc.
Unlike other operability properties, intuitiveness is not a totally inherent property of the
system. Some of the intuitiveness can depend on the particular user domain.
This domain can be defined in terms of culture, international and/or proprietary standards, etc.
4.1.4 Transparency
Transparency represents the ability, of the operating means provided by the system, to
seemingly place the operator in direct contact with his tasks. This enables the operator to give
commands and view information, returned from the system, with a realistic view of the actions
(and their sequence).
The extent to which these means are provided is a measure of the transparency of the system.
The transparency depends on the following factors:
– the logical principles followed to present the functional and geographical structure of the
process and the tasks to be performed by the operator;
– the way in which labels and names are used to identify the operating means, and the
consistency of their use;
– the consistency in the application of colours, names, audible signals, etc. throughout all
tasks and levels of information;
– the way of the dynamics of the tasks are realistically simulated, to give the operator a
“real” feel of the task to be performed, etc.
Transparency includes that the information presented by the system is clear, concise,
unambiguous, and non-contradictory. Non self-explanatory information can be explained by a
more detailed description in easily accessible documentation or a help function for
transparency.
4.1.5 Robustness
Robustness includes that the operating means provided by the system to enable the operator
to give commands correctly interpret and respond to any operator action. If the operation
means are ambiguous, additional information can be requested by the system for removing
the ambiguities.
Robustness depends on the following factors:
– the extent to which deviation from the standard generic rules is permitted, and is
interpreted;
– the extent to which the system is able to detect and notify deviations and to couple these
deviations with requests for further information, etc.

– 12 – IEC 61069-6:2016 © IEC 2016
4.2 Factors influencing operability
The operability properties of a system can be affected by the influencing factors listed in
IEC 61069-1:2016, 5.3.
For each of the operability properties listed in 4.1, the primary influencing factors are as
follows:
– tasks:
• unusual or infrequent operating scenarios, during commissioning, emergency, etc.
– personnel:
• the operability of a system is in itself not influenced by the abilities of the person, who
operates the system. However, the requirements for the operability are usually based
on an imaginary operator having the statistical mean values of the qualifications, such
as skill and knowhow, of the personnel operating the system. Deviations from these
mean values can influence each of operability properties.
– process:
• noise on the incoming process lines
– utility:
• distortions and disturbances originating from the utilities
– environment:
• temperature, EMC, ageing, mounting, corrosive substances, and dust.
The operability also depends, on other influencing factors:
– procedures for access to and entry of information and data into the system;
– the extent of information obtained by a single request;
– information formats used;
– interface devices used (e.g. touchscreen, light-pen, keyboard).
5 Assessment method
5.1 General
The assessment shall follow the method as laid down in IEC 61069-2:2016, Clause 5.
5.2 Defining the objective of the assessment
Defining the objective of the assessment shall follow the method as laid down in
IEC 61069-2:2016, 5.2.
5.3 Design and layout of the assessment
Design and layout of the assessment shall follow the method as laid down in IEC 61069-
2:2016, 5.3.
Defining scope of assessment shall follow the method laid down in IEC 61069-2:2016, 5.3.1.
Collation of documented information shall be conducted in accordance with IEC 61069-2:2016,
5.3.3
The statements compiled in accordance with IEC 61069-2:2016, 5.3.3 should include the
following in addition to the items listed in IEC 61069-2:2016, 5.3.3:

– the operability properties required for each of the tasks and for the system, arranged in
order of the relevant phase or phases of the system life cycle;
– the knowhow, experience and skill of the operators using the interface to perform each of
the tasks defined in the SRD;
– the number of e.g. information sources, sensors and their association with tasks which
require operators to use the human-machine interface simultaneously.
Depending on the phase of the system life cycle, assessment of operability can only be done
with existing or similar systems in operation. These assessments should include the prior
knowledge, skill and experience of the system designer, the plant-shift supervisors, the
system maintenance personnel, etc.
Documenting collated information shall follow the method in IEC 61069-2:2016, 5.3.4.
Selecting assessment items shall follow IEC 61069-2:2016, 5.3.5.
Assessment specification should be developed in accordance with IEC 61069-2:2016, 5.3.6.
Comparison of the SRD and the SSD shall follow IEC 61069-2:2016, 5.3.
NOTE 1 A checklist of SRD for system dependability is provided in Annex A.
NOTE 2 A checklist of SSD for system dependability is provided in Annex B.
5.4 Planning of the assessment program
The perception of the operability system property can also be sensitive to internal system
factors related to the functionality and performance properties, especially time response and
update frequency.
The evaluation of the operability system property should therefore always be preceded by an
evaluation of the functionality and performance properties, unless results are available from
earlier evaluations.
Planning of the assessment program shall follow the method as laid down IEC 61069-2:2016,
5.4.
Assessment activities shall be developed in accordance with IEC 61069-2:2016, 5.4.2.
The final assessment program should specify points specified in IEC 61069-2:2016, 5.4.3.
5.5 Execution of the assessment
The execution of the assessment shall be in accordance with IEC 61069-2:2016, 5.5.
5.6 Reporting of the assessment
The reporting of the assessment shall be in accordance with IEC 61069-2:2016, 5.6.
The report shall include information specified in IEC 61069-2:2016, 5.6. Additionally, the
assessment report should address the following points:
– No additional items are noted.

– 14 – IEC 61069-6:2016 © IEC 2016
6 Evaluation techniques
6.1 General
Within this standard, several evaluation techniques are suggested. Other methods may be
applied but, in all cases, the assessment report should provide references to documents
describing the techniques used.
Those evaluation techniques are categorized as described in IEC 61069-2:2016, Clause 6.
The techniques given in 6.2, 6.3 and 6.4 are recommended to assess operability.
It is not possible to evaluate the operability system property as one entity. Instead operability
system property should be addressed separately.
a) Satisfaction as a measure of operability
Satisfaction can be a measure of operability, and is the subjective impression of operators of
the operability of the system or in other words it is a measure of the acceptability by the
operators of the human-interface. However, it should be noted that measures of satisfaction
will describe the comfort and acceptability of the whole system to the operator and are not
restricted to the operability system property alone. Satisfaction can only be determined
qualitatively by questioning a representative sample of operators, and sometimes be
quantified statistically using an attitude rating scale during the system operational life time by
evaluating the number of positive or negative comments obtained during its use.
The level of acceptability of operability of the system by operators depends upon the following
points:
– how the requests and actions to the system can be performed by the operators;
– how the information given by the system, in response to the request and actions, can
be recognized by the operators;
– how the information and their processing by the system is coherent and logical and
how they conform to the expectations of the operators;
– how the level of positive stress to the mental and physical abilities of the operator is
induced by the system.
The questions, directed to the operator group selected for the evaluation to obtain a measure
of satisfaction, should therefore be carefully worded and only be related to the operability
aspects of the system.
Measures of satisfaction can provide a useful indication of the operators’ perception of
operability, even if it is not possible to obtain measures of effectiveness or efficiency.
b) Consideration of qualifications of operators
The objective of assessment is to assess operability as a system property and not the
qualifications of the operator to perform a task, nevertheless their qualifications should be
taken into account when designing the assessment.
The qualifications of the operators are formed and affected by the following abilities and
aspects:
– physical abilities such as the sensitivity of the eye (optical signals, colour blindness,
heights of letters and symbols, etc.), sensitivity of the ear (acoustical signals, range of
audibility), dimensions of hands, feet, human stature (mechanical actions, dimensions
of knobs, etc.), etc.;
– mental abilities such as aptitude, education level, experience, etc.;

– psychological aspects such as temperament, character, cultural and ethnic background,
heritage, etc., but also expectations, etc.
The group of operators selected for the assessment of satisfaction should therefore be
chosen carefully and in accordance with the operating phase for which the human-machine
interface is to be assessed.
This group should be provided with the system support recommended by the system supplier.
System support is dealt with in IEC 61069-8.
NOTE An example of a list of assessment items is provided in Annex C.
6.2 Analytical evaluation techniques
6.2.1 General
An analytical evaluation is a qualitative analysis complemented, if possible, with quantification
of the statements made.
To perform an analytical evaluation of the operability of a system, a representative model of
the system to be assessed should be defined. This model shall include at least each of the
typical classes of tasks, which the operators will encounter during the phases of the lifetime of
the system.
All tasks should be examined individually and collectively to check whether the human-
machine interface uses measures and methods in accordance with existing standards and the
requirements.
6.2.2 Efficiency
To analytically evaluate the efficiency of operability, time and effort shall be determined.
An estimation of the time to fulfil each task is made by:
– subdividing each of the tasks or classes of tasks into actions and/or steps,
– counting the number of steps,
– utilizing known times for each step (If step times are not known, them assuming each step
requires approximately the same time may be utilized), and
– multiplying time and steps, to yield the total time.
An estimation of the effort to fulfil each task is made by:
– subdividing each of the tasks or classes of tasks into actions and/or steps,
– comparing the lay out (position, relative position, order, etc.),
– comparing physical dimensions (of the layout, buttons sizes, etc.),
1 1
– utilizing ergonomic standards such as ISO 9241-10 [7] and ISO 11064-7 [13] , and
– adding each aspect, to yield the total effort.
6.2.3 Intuitiveness
To analytically evaluate intuitiveness, the system interface solutions should be carefully
compared with the system requirements document and the degree of correspondence
___________
Numbers in square brackets refer to the Bibliography.

– 16 – IEC 61069-6:2016 © IEC 2016
quantified. Unless the analysis is followed by an empirical evaluation the data obtained are
subjective.
6.2.4 Transparency
It should be checked that the operator’s actions and corresponding system reactions and
presentations are related to the task in a cognitive manner. This means that paperwork or
extensive mental processes are not required, to convert the human understanding of the task
into its system representation.
6.2.5 Robustness
The documented functions (hardware and/or software) provided in the system to ensure
robustness should be analysed to check whether these cover for example:
– a method to acknowledge the receipt of information during transfer of data between
modules;
– the ab
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