ISO 16404:2020

INTERNATIONAL ISO
STANDARD 16404
Second edition
2020-05
Space systems — Programme
management — Requirements
management
Systèmes spatiaux — Management de programme — Management
des Exigences
Reference number
©
ISO 2020
© ISO 2020
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ii © ISO 2020 – All rights reserved

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Abbreviated terms . 3
5 Objective and scope of requirements management . 4
5.1 Objective of requirements management . 4
5.2 Scope and interfaces. 4
5.2.1 Requirements management scope . 4
5.2.2 Interfaces and support for other disciplines . 5
6 Requirements management overall process . 7
6.1 General . 7
6.2 Capture needs and develop requirements . 8
6.3 Allocation and flow down requirements . 9
6.4 Validate requirements . 9
6.5 Verify design against requirements . 9
6.6 Verify product against requirements . 9
6.7 Requirements change management . 9
7 Requirements management plan .10
7.1 General .10
7.2 Functional and technical specifications .10
7.3 Requirements management plan .10
8 Rules for requirements management .11
8.1 General .11
8.2 Rules for deployment of requirements management activities .11
8.3 Rules for requirements management .12
8.4 Key performance indicators .12
Annex A (informative) Requirements management plan template .14
Bibliography .15
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
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ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).
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. Details of
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on the ISO list of patent declarations received (see www .iso .org/ patents).
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iso/ foreword .html.
This document was prepared by Technical Committee 20, Aircraft and space vehicles, Subcommittee
SC 14, Space systems and operations.
This second edition cancels and replaces the first edition (ISO 16404:2013), which has been technically
revised.
The main changes compared to the previous edition are as follows:
— The terms and definitions have been updated to be consistent with ISO 10795.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www .iso .org/ members .html.
iv © ISO 2020 – All rights reserved

Introduction
There is a consensus that successful aerospace programmes/projects depend on meeting the needs and
requirements of the stakeholders/customers. When the requirements are for a complex system or for a
system that may take many years to be developed, a formal requirements management (RM) process is
mandatory and justified.
Requirements management concerns the collection, analysis, and validation of requirements with all
the communications and negotiations inherent in working with people.
This document will help to clarify and enhance current practices to improve programme management.
It is intended to be used by space programmes when establishing, performing, or evaluating
requirements management processes in the space sector.
This document describes requirements management functions and principles and defines a common
requirements management terminology for use with any product line.
Requirements management is an integral element of any programme, but, in space, it is particularly
important due to
— specific environmental conditions in space,
— a need for a high level of performance,
— a limited number of models,
— limited access to the product during operations,
— quasi-impossibility of repairing in the case of failure during flight,
— often high complexity of the organization, and
— associated high costs.
The deployment of this standardized common set of requirements management is intended to
encourage and facilitate international space cooperation.
Annex A gives the general template for a requirements management plan.
INTERNATIONAL STANDARD ISO 16404:2020(E)
Space systems — Programme management —
Requirements management
1 Scope
This document presents the requirements for requirements management (RM) for space projects.
This document addresses the space programme/project management requirements, applicable through
a top-down approach in a contractual relationship between customers and suppliers.
The objective of this document is to state and establish a common reference framework for all the
customers and suppliers in the space sector to deploy requirements management for all space products
and projects.
This document on requirements management includes
— a definition of the requirements management scope for the space sector,
— the standard processes for requirements management within the product lifecycle management, and
— a set of rules for requirements management activities to be implemented by the actors (customers
and suppliers), including rules derived from best practices.
The primary target audience for this document includes
— the requirements management/systems engineering process owners of the customers and suppliers,
— the programme/project managers managing the space programmes, and
— the chief engineers and the quality managers.
The term "programme" is understood as a group of several projects. Both “programme” and “project”
can be used in the same context throughout this document.
In addition, this document allows customer/supplier flexibility in its implementation and tailoring.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 9000, Quality management systems — Fundamentals and vocabulary
ISO 10795, Space systems — Programme management and quality — Vocabulary
ISO 14300-1, Space systems — Programme management — Part 1: Structuring of a project
ISO 21351, Space systems — Functional and technical specifications
3 Terms and definitions
For the purposes of this document, the terms and definitions in ISO 9000, ISO 10795 and the
following apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
3.1
design verification
evaluation of the implementation of the design (architecture, components) against the requirements
(3.5) to determine that they can be met
Note 1 to entry: This is compliant with ISO 9001 verification.
3.2
product lifecycle
description of all stages of the product throughout its life starting from the expression of its need until
the disposal, whatever the form is
3.3
product verification
evaluation of the implementation of the product against the requirements (3.5) to determine that they
have been met
Note 1 to entry: This is compliant with ISO 9001 verification.
3.4
qualification
act or conduct by the supplier to provide evidences to prove that design, manufacturing (including
manufacturing process) of hardware/software is adequate to fulfil all requirements (3.5) under
required environment conditions
Note 1 to entry: This may be implemented by analysis, test, inspection, or demonstration.
[SOURCE: ISO 10795:2019, 3.183]
3.5
requirement
need or expectation that is stated, generally implied or obligatory
Note 1 to entry: “Generally implied” means that it is custom or common practice for the organization and
interested parties, that the need or expectation under consideration is implied.
Note 2 to entry: A specified requirement is one that is stated, for example in documented information.
Note 3 to entry: A qualifier can be used to denote a specific type of requirement, e.g. product requirement, quality
management requirement, customer requirement, quality requirement.
Note 4 to entry: Requirements can be generated by different interested parties or by the organization itself.
Note 5 to entry: It can be necessary for achieving high customer satisfaction to fulfil an expectation of a customer
even if it is neither stated nor generally implied or obligatory.
Note 6 to entry: This constitutes one of the common terms and core definitions for ISO management system
standards given in Annex SL of the Consolidated ISO Supplement to the ISO/IEC Directives, Part 1. The original
definition has been modified by adding Notes 3 to 5 to entry.
[SOURCE: ISO 9000:2015, 3.6.4]
3.6
requirements baseline
set of requirements (3.5) that has been formally reviewed and agreed upon, that thereafter serves as the
basis for further development, and that can be changed only through formal change control procedures
2 © ISO 2020 – All rights reserved

3.7
requirements management
RM
discipline that covers all the tasks that are performed to manage requirements (3.5), such as gathering,
developing, organizing, tracing, analysing, reviewing, allocating, changing, and validating requirement
objects, as well as managing documents and databases that contain them with the purpose of defining
and delivering the right product or service
3.8
requirements management plan
RM plan
management plan which describes all the activities related to requirements management (3.7) for
a specific project or programme that includes the requirement (3.5) cascading activity and the
requirements management interaction with configuration management and functional analysis
Note 1 to entry: This plan describes the activities that need to be performed to support the verification and
validation activities in order that the design and product can be verified against requirements.
3.9
requirement validation
set of activities to ensure that requirements (3.5) are correct and complete so that the product meets
upper-level requirements and user needs
3.10
stakeholder
customer, user, person who will receive the goods or services and is the direct beneficiaries of the
systems, or other interested party who affects or is affected by the project, providing overarching
constraints within which the customers' needs should be achieved
[SOURCE: ISO 18676:2017, 3.9, modified — The definition has been editorial updated to define
"stakeholder" in its singular form.]
3.11
systems engineering
interdisciplinary approach governing the total technical and managerial effort required to transform a
set of stakeholder (3.10) needs, expectations, and constraints into a solution and to support that solution
throughout its life
[SOURCE: ISO/IEC/IEEE 24748-1:2018, 3.57]
3.12
traceability
ability to trace the history, application or location of an object
Note 1 to entry: When considering a product or a service, traceability can relate to:
— the origin of materials and parts;
— the processing history;
— the distribution and location of the product or service after delivery.
Note 2 to entry: In the field of metrology, the definition in ISO/IEC Guide 99 is the accepted definition.
[SOURCE: ISO 9000:2015, 3.6.13]
4 Abbreviated terms
The following abbreviated terms are used in this document.
CM configuration management
KPI key performance indicators
PLM product lifecycle management
RM requirements management
ROI return on investment
SE systems engineering
SMART specific, measurable, achievable, relevant, and traceable
TBC to be confirmed
TBD to be defined
V&V validation and verification
5 Objective and scope of requirements management
5.1 Objective of requirements management
The objective of requirements management is to ensure that stakeholders' needs (customers, users,
system's operating environment, trade and marketing, regulations, etc.) are understood, agreed
upon, and realized (i.e. that the final design and the delivered products fulfil stakeholders' needs).
The best opportunity for requirements management to influence a good outcome of the project is an
early implementation. Greatest return on investment (ROI) of requirements management is if it is
implemented early.
5.2 Scope and interfaces
5.2.1 Requirements management scope
a) Requirements management is a transversal activity that lasts for the whole product lifecycle.
Requirements management shall be started as early as possible and shall be sustained through all
the phases of the project, including
1) concept and definition,
2) design and development,
3) production,
4) support, and
5) disposal.
b) Requirements management is a discipline that shall be applied to all engineering domains.
Requirements management shall, as a minimum, apply to technical requirements, although non-
technical requirements may also be managed.
c) Requirements management covers the following high-level functional processes described in
Clause 6:
1) capture the needs and develop the requirements;
2) allocate and flow down the requirements;
4 © ISO 2020 – All rights reserved

3) validate the requirements;
4) verify the design against the requirements;
5) verify the product against the requirements;
6) manage the requirement changes.
d) Requirements management is an essential part of systems engineering. It is strongly linked to all
elements of systems engineering.
e) The major objects managed by requirements management are
1) “requirement” (object to be detailed with attributes such as stakeholder, source, rationale,
identification, author, status, allocation to design, and statement of the verification method),
2) “links” (object to be detailed as the link between requirements, but also links from/to other
objects enabling requirements management to reach its primary objective and ensuring that
stakeholders' needs are understood
...