Reference number
ISO 26262-10:2012(E)
©
ISO 2012
INTERNATIONAL
STANDARD
ISO
26262-10
First edition
2012-08-01
Road vehicles — Functional safety —
Part 10:
Guideline on ISO 26262
Véhicules routiers — Sécurité fonctionnelle —
Partie 10: Lignes directrices relatives à l'ISO 26262
ISO 26262-10:2012(E)
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© ISO 2012 – All rights reserved
ISO 26262-10:2012(E)
© ISO 2012 – All rights reserved iii
Contents Page
Foreword ............................................................................................................................................................iv
Introduction.........................................................................................................................................................v
1 Scope ......................................................................................................................................................1
2 Normative references............................................................................................................................1
3 Terms, definitions and abbreviated terms ..........................................................................................2
4 Key concepts of ISO 26262...................................................................................................................2
4.1 Functional safety for automotive systems (relationship with IEC 61508) .......................................2
4.2 Item, system, element, component, hardware part and software unit.............................................4
4.3 Relationship between faults, errors and failures ...............................................................................5
5 Selected topics regarding safety management..................................................................................6
5.1 Work product .........................................................................................................................................6
5.2 Confirmation measures ........................................................................................................................6
5.3 Understanding of safety cases ............................................................................................................9
6 Concept phase and system development.........................................................................................10
6.1 General .................................................................................................................................................10
6.2 Example of hazard analysis and risk assessment...........................................................................10
6.3 An observation regarding controllability classification ..................................................................11
6.4 External measures...............................................................................................................................12
6.5 Example of combining safety goals ..................................................................................................13
7 Safety process requirement structure - Flow and sequence of safety requirements ..................14
8 Concerning hardware development ..................................................................................................17
8.1 The classification of random hardware faults ..................................................................................17
8.2 Example of residual failure rate and local single-point fault metric evaluation ...........................22
8.3 Further explanation concerning hardware .......................................................................................34
9 Safety element out of context ............................................................................................................36
9.1 Safety element out of context development .....................................................................................36
9.2 Use cases .............................................................................................................................................37
10 An example of proven in use argument ............................................................................................45
10.1 General .................................................................................................................................................45
10.2 Item definition and definition of the proven in use candidate ........................................................46
10.3 Change analysis ..................................................................................................................................46
10.4 Target values for proven in use .........................................................................................................46
11 Concerning ASIL decomposition.......................................................................................................47
11.1 Objective of ASIL decomposition ......................................................................................................47
11.2 Description of ASIL decomposition ..................................................................................................47
11.3 An example of ASIL decomposition ..................................................................................................47
Annex A (informative) ISO 26262 and microcontrollers ..............................................................................51
Annex B (informative) Fault tree construction and applications ................................................................73
Bibliography......................................................................................................................................................89
ISO 26262-10:2012(E)
iv © ISO 2012 – All rights reserved
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies
(ISO member bodies). The work of preparing International Standards is normally carried out through ISO
technical committees. Each member body interested in a subject for which a technical committee has been
established has the right to be represented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the
International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 26262-10 was prepared by Technical Committee ISO/TC 22, Road vehicles, Subcommittee SC 3,
Electrical and electronic equipment.
ISO 26262 consists of the following parts, under the general title Road vehicles — Functional safety:
Part 1: Vocabulary
Part 2: Management of functional safety
Part 3: Concept phase
Part 4: Product development at the system level
Part 5: Product development at the hardware level
Part 6: Product development at the software level
Part 7: Production and operation
Part 8: Supporting processes
Part 9: Automotive Safety Integrity Level (ASIL)-oriented and safety-oriented analyses
Part 10: Guideline on ISO 26262
ISO 26262-10:2012(E)
© ISO 2012 – All rights reserved
v
Introduction
ISO 26262 is the adaptation of IEC 61508 to comply with needs specific to the application sector of electrical
and/or electronic (E/E) systems within road vehicles.
This adaptation applies to all activities during the safety lifecycle of safety-related systems comprised of
electrical, electronic and software components.
Safety is one of the key issues of future automobile development. New functionalities not only in areas such
as driver assistance, propulsion, in vehicle dynamics control and active and passive safety systems
increasingly touch the domain of system safety engineering. Development and integration of these
functionalities will strengthen the need for safe system development processes and the need to provide
evidence that all reasonable system safety objectives are satisfied.
With the trend of increasing technological complexity, software content and mechatronic implementation, there
are increasing risks from systematic failures and random hardware failures. ISO 26262 includes guidance to
avoid these risks by providing appropriate requirements and processes.
System safety is achieved through a number of safety measures, which are implemented in a variety of
technologies (e.g. mechanical, hydraulic, pneumatic, electrical, electronic, programmable electronic) and
applied at the various levels of the development process. Although ISO 26262 is concerned with functional
safety of E/E systems, it provides a framework within which safety-related systems based on other
technologies can be considered. ISO 26262:
a) provides an automotive safety lifecycle (management, development, production, operation, service,
decommissioning) and supports tailoring the necessary activities during these lifecycle phases;
b) provides an automotive-specific risk-based approach to determine integrity levels [Automotive Safety
Integrity Levels (ASIL)];
c) uses ASILs to specify applicable requirements of ISO 26262 so as to avoid unreasonable residual risk;
d) provides requirements for validation and confirmation measures to ensure a sufficient and acceptable
level of safety being achieved;
e) provides requirements for relations with suppliers.
Functional safety is influenced by the development process (including such activities as requirements
specification, design, implementation, integration, verification, validation and configuration), the production
and service processes and by the management processes.
Safety issues are intertwined with common function-oriented and quality-oriented development activities and
work products. ISO 26262 addresses the safety-related aspects of development activities and work products.
Figure 1 shows the overall structure of this edition of ISO 26262. ISO 26262 is based upon a V-model as a
reference process model for the different phases of product development. Within the figure:
the shaded “V”s represent the interconnection between ISO 26262-3, ISO 26262-4, ISO 26262-5,
ISO 26262-6 and ISO 26262-7;
the specific clauses are indicated in the following manner: “m-n”, where “m” represents the number of the
particular part and “n” indicates the number of the clause within that part.
EXAMPLE “2-6” represents Clause 6 of ISO 26262-2.
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