CEN/CLC/TR 17602-80-03:2021
(Main)Space product assurance - Software dependability and safety
Space product assurance - Software dependability and safety
This Handbook provides guidance on the application of the dependability and safety requirements relevant to software defined in EN 16602-80 (equivalent of ECSS-Q-ST-80).
This Handbook provides support for the selection and application of software dependability and safety methods and techniques that can be used in the development of software-intensive space systems.
This Handbook covers all of the different kinds of software for which EN 16602-80 (equivalent of ECSS-Q-ST-80) is applicable. Although the overall software dependability and safety workflow description is mainly targeted to the development of spacecraft, the described approach can be adapted to projects of different nature (e.g. launchers, ground systems).
The methods and techniques described in the scope of this Handbook are limited to assessment aspects, not including development and implementation techniques for dependability and safety (e.g. fault tolerance techniques, or development methods like coding standards, etc.).
Although dependability is a composite term, including reliability, availability and maintainability, this Handbook addresses in particular the reliability aspects. Software maintainability and availability are not covered in depth by this handbook, because the relevant methods and techniques are still undergoing improvement. Nevertheless, whenever a link can be made to either of these two characteristics, it is explicitly mentioned in the corresponding section.
Raumfahrtproduktsicherung - Zuverlässigkeit und Sicherheit von Software
Assurance produit des projets spatiaux - Fiabilité et sécurité logiciel
Zagotavljanje kakovosti proizvodov v vesoljski tehniki - Zanesljivost in varnost programske opreme
General Information
Standards Content (Sample)
SLOVENSKI STANDARD
01-december-2021
Zagotavljanje kakovosti proizvodov v vesoljski tehniki - Zanesljivost in varnost
programske opreme
Space product assurance - Software dependability and safety
Raumfahrtproduktsicherung - Zuverlässigkeit und Sicherheit von Software
Assurance produit des projets spatiaux - Fiabilité et sécurité logiciel
Ta slovenski standard je istoveten z: CEN/CLC/TR 17602-80-03:2021
ICS:
03.120.99 Drugi standardi v zvezi s Other standards related to
kakovostjo quality
35.080 Programska oprema Software
49.140 Vesoljski sistemi in operacije Space systems and
operations
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
TECHNICAL REPORT
CEN/CLC/TR 17602-80-
RAPPORT TECHNIQUE
TECHNISCHER BERICHT
October 2021
ICS 49.140; 35.240.99
English version
Space product assurance - Software dependability and
safety
Assurance produit des projets spatiaux - Fiabilité et Raumfahrtproduktsicherung - Zuverlässigkeit und
sécurité logiciel Sicherheit von Software
This Technical Report was approved by CEN on 13 September 2021. It has been drawn up by the Technical Committee
CEN/CLC/JTC 5.
CEN and CENELEC members are the national standards bodies and national electrotechnical committees of Austria, Belgium,
Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy,
Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of North Macedonia, Romania, Serbia,
Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United Kingdom.
CEN-CENELEC Management Centre:
Rue de la Science 23, B-1040 Brussels
© 2021 CEN/CENELEC All rights of exploitation in any form and by any means Ref. No. CEN/CLC/TR 17602-80-03:2021 E
reserved worldwide for CEN national Members and for
CENELEC Members.
Table of contents
European Foreword . 4
Introduction . 5
1 Scope . 6
2 References . 7
3 Terms, definitions and abbreviated terms . 8
3.1 Terms from other documents . 8
3.2 Abbreviated terms. 8
4 Principles . 9
4.1 General concepts . 9
4.1.1 Software failures and faults . 9
4.1.2 Software reliability . 9
4.1.3 Software maintainability . 10
4.1.4 Software availability . 10
4.1.5 Software safety . 11
4.1.6 System level and software level . 11
4.1.7 Fault prevention, removal, tolerance, and forecasting . 11
4.2 Relation to other ECSS Standards and Handbooks . 12
5 Software dependability and safety programme . 13
5.1 Introduction . 13
5.2 Software dependability and safety workflow. 13
5.2.1 General . 13
5.2.2 Software dependability and safety requirements . 14
5.2.3 Software criticality classification . 15
5.2.4 Handling of critical software . 21
5.2.5 Hardware-Software Interaction Analysis . 21
6 Software dependability and safety methods and techniques . 23
6.1 Introduction . 23
6.2 SFMEA (Software Failure Modes and Effects Analysis) . 23
6.2.1 Purpose . 23
6.2.2 Procedure . 24
6.2.3 Costs and benefits . 27
6.3 SFTA (Software Fault Tree Analysis) . 28
6.3.1 Purpose . 28
6.3.2 Procedure . 28
6.3.3 Costs and benefits . 29
6.4 SCCA (Software Common Cause Analysis). 29
6.5 Engineering methods and techniques supporting software dependability and
safety . 30
6.6 Software availability and maintainability techniques . 30
6.6.1 Software maintainability . 30
6.6.2 Software availability . 32
6.7 Software failure propagation prevention . 33
6.8 Defensive programming . 36
Annex A Software dependability and safety documentation . 38
A.1 Introduction . 38
A.2 Software criticality analysis report . 38
A.2.1 Criticality classification of software products. 39
A.2.2 Criticality classification of software components . 40
A.2.3 Software dependability and safety analysis report . 40
Bibliography . 42
Figures
Figure 5-1 – Software dependability and safety framework . 14
Figure 5-2 – Software dependability and safety requirements . 14
Figure 5-3 – System-level software criticality classification . 16
Figure 5-4 - Software-level software criticality classification . 19
Figure 5-5 – Feedback from software-level to system-level analyses . 20
Figure 5-6 – Hardware-Software Interaction Analysis . 22
Figure 6-1: Fault, error, failure propagation . 34
European Foreword
This document (CEN/CLC/TR 17602-80-03:2021) has been prepared by Technical Committee
CEN/CLC/JTC 5 “Space”, the secretariat of which is held by DIN.
It is highlighted that this technical report does not contain any requirement but only collection of data
or descriptions and guidelines about how to organize and perform the work in support of EN 16602-
80.
This Technical report (CEN/CLC/TR 17602-80-03:2021) originates from ECSS-Q-HB-80-03A Rev.1.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such
patent rights.
This document has been prepared under a mandate given to CEN by the European Commission and
the European Free Trade Association.
This document has been developed to cover specifically space systems and has therefore precedence
over any TR covering the same scope but with a wider domain of applicability (e.g.: aerospace).
Introduction
Dependability and safety are issues of paramount importance in the development and operations of
space systems. The contribution of software to system dependability and safety is a key factor,
especially in view of the growing complexity of the software used in space critical applications,
together with the increasing cost and schedule constraints. Hence, the need for more dependable and
safe software has led to the publication of this Handbook, meant to provide guidelines on the
implementation of the software dependability and safety requirements defined in ECSS-Q-ST-80C and
on the application of some methods and techniques for software dependability and safety.
Analyses and activities aiming at assessing and ensuring the system dependability and safety are
carried out since the early stages of the development, and software needs to be properly addressed by
these system-level activities. Hardware and software products are classified based on their criticality,
in order to focus engineering and product assurance activities on the most critical items. At later
stages, the inherent complexity of software calls for application of specific methods and techniques,
aiming at refining the software criticality classification and supporting the implementation and
verification of measures for critical software handling.
This handbook provides an overall description of the entire software dependability and safety
workflow, considering the different activities at system and software level, the lifecycle phases and the
customer-supplier relationships, with reference to the dependability and safety requirements defined
in ECSS-Q-ST-80C. Some individual software RAMS techniques are also presented. They have been
selected from the list of methods and techniques mentioned in different national and international
standards and literature, from which a choice has been made based on their relevance to the
requirements defined in the ECSS Standards.
Scope
This Handbook provides guidance on the application of the dependability and safety requirements
relevant to software defined in ECSS-Q-ST-80C.
This Handbook provides support for the selection and application of software dependability and
safety methods and techniques that can be used in the development of software-intensive space
systems.
This Handbook covers all of the different kinds of software for which ECSS-Q-ST-80C is applicable.
Although the overall software dependability and safety workflow description is mainly targeted to
the development of spacecraft, the described approach can be adapted to projects of different nature
(e.g. launchers, ground systems).
The methods and techniques described in the scope of this Handbook are mainly focused on
assessment aspects, though specific development and implementation techniques for dependability
and safety (e.g. software failure propagation prevention, defensive programming) are addressed.
References
For each document or Standard listed, a mnemonic (used to refer to that source throughout this
document) is proposed in the left column, and then the complete reference is provided in the right one.
EN Reference Reference in text Title
EN 16602-30 [ECSS-Q-30] ECSS-Q-ST-30C – Space product assurance -
Dependability
EN 16602-30-02 [ECSS-Q-30-02] ECSS-Q-ST-30-02C – Space product assurance –
Failure modes, effects and criticality analysis
(FMECA/FMEA)
EN 16602-30-09 [ECSS-Q-30-09] ECSS-Q-ST-30-09C – Space product assurance –
Availability analysis
EN 16602-40 [ECSS-Q-40] ECSS-Q-ST-40C – Space product assurance – Safety
EN 16602-40-12 [ECSS-Q-40-12] ECSS-Q-ST-40-12C – Space product assurance – Fault
tree analysis – Adoption notice ECSS/IEC 61025
EN 16602-80 [ECSS-Q-80] ECSS-Q-ST-80C – Space product assurance – Software
product assurance
EN 16602-80-04 [ECSS-Q-80-04] ECSS-Q-HB-80-04A – Space product assurance –
Software metrication programme definition and
implementation
EN 17603-40 [ECSS-E-HB-40] ECSS-E-HB-40A – Space engineering – Software
guidelines
EN 16601-00-01 [ECSS-S-ST-00-01] ECSS-S-ST-00-01C – ECSS – Glossary of terms
Terms, definitions and abbreviated terms
3.1 Terms from other documents
a. For the purpose of this document, the terms and definitions from ECSS-S-ST-00-01 and ECSS-Q-
...
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