ISO 27026:2023

INTERNATIONAL ISO
STANDARD 27026
Second edition
2023-08
Space systems — Programme
management — Breakdown of project
management structures
Systèmes spatiaux — Management de programme — Éléments de
structures de gestion de projet
Reference number
ISO 27026:2023(E)
© ISO 2023

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ISO 27026:2023(E)
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© ISO 2023
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ISO 27026:2023(E)
Contents Page
Foreword .iv
Introduction .v
1 Scopes . 1
2 Normative references . 1
3 Terms, definitions and abbreviated terms . 1
3.1 Terms and definitions . 1
3.2 Abbreviated terms . 2
4 Overview of project breakdown structures . 2
4.1 General . 2
4.2 Relationship of project breakdown structures . 2
4.3 Purpose of project breakdown structures . 3
4.4 Tailoring . 4
5 Processes and requirements of project breakdown structures . 4
5.1 General . 4
5.2 Specification tree . 4
5.3 Function tree . 5
5.4 Product tree . 5
5.5 Work breakdown structure . 6
5.6 Cost breakdown structure . 7
5.7 Business agreement breakdown structure . 7
5.8 Organizational breakdown structure . 8
Annex A (informative) Specification tree . 9
Annex B (informative) Function tree .10
Annex C (informative) Product tree .11
Annex D (informative) Work breakdown structure .12
Annex E (informative) Cost breakdown structure .13
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ISO 27026:2023(E)
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
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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 document 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).
ISO draws attention to the possibility that the implementation of this document may involve the use
of (a) patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed
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www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 20, Aircraft and space vehicles,
Subcommittee SC 14, Space systems and operations.
This second edition cancels and replaces the first edition (ISO 27026:2011), which has been technically
revised.
The main changes are as follows:
— updated the normative references in Clause 2;
— updated the terms and definitions references in Clause 3.
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.
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ISO 27026:2023(E)
Introduction
Space programmes, and the space systems developed by them, are complex, incorporate many different
technologies, and can last for many years progressing through several different stages from conception
to disposal or other disposition. When a space programme advances from one stage to another,
substantial changes in the breakdown of project management structures, hereinafter collectively
called project breakdown structures, of the programme and the type and amount of resources required
can occur; a programme is often composed of one or more projects. In addition, there can be attendant
risks to either the success of the project or to the well-being of project equipment or to personnel. Well-
regulated project breakdown structures can be an important factor in ensuring that all factors are
ready for these changes through controlled changes to the project breakdown structures that form a
framework for the project in each of the several different stages, and assist in ensuring that the risks
are well understood and accepted. Use of this document as a basis for the framework of activities
comprising the project, the necessary resources, controls, inputs, outputs, and results is intended to
enhance communications between different organizations that participate in a project, and can assist
in reducing costs and schedule of performing the project in each stage.
This document is intended to complement and supplement similar project breakdown structure
processes, requirements and recommendations contained within ISO 14300-1, which serves as a
higher-tier International Standard for this document and for such other space systems and operations
International Standards that require formal project breakdown structures.
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INTERNATIONAL STANDARD ISO 27026:2023(E)
Space systems — Programme management — Breakdown
of project management structures
1 Scopes
This document specifies processes, requirements and recommendations for the breakdown of
project management structures, collectively called project breakdown structures, in terms of the
various specification (i.e. requirements), functional, product, work, cost, business and organizational
breakdown structures that are established and implemented to contribute to the success of a space
programme, which is often composed of one or more projects. It specifies the various types of project
breakdown structures and gives processes, requirements and guidance concerning the composition of
these breakdown structures.
This document is applicable to project breakdown structures for a project, including at the top level of
a programme, i.e. level 0, as indicated in ISO 14300-1. It is intended to be used either by an independent
developer as a partial basis for programme processes or as a basis for an agreement between a supplier
and a customer.
This document also provides descriptions of the kinds of project breakdown structures that are
commonly useful in contributing to the success of a space project. Other project breakdown structures
not described in this document also often contribute to the success of a space project.
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 10795, Space systems — Programme management and quality — Vocabulary
ISO 14300-1, Space systems — Programme management — Part 1: Structuring of a project
ISO 23462, Space systems — Guidelines to define the management framework for a space project
3 Terms, definitions and abbreviated terms
3.1 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 10795 and the following apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1.1
breakdown structure
framework for efficiently controlling some aspect of the activities of a programme (3.1.2) or project
(3.1.3)
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ISO 27026:2023(E)
3.1.2
programme
group of projects (3.1.3) managed in a coordinated way to obtain benefits not available from managing
them individually
3.1.3
project
unique process consisting of a set of coordinated and controlled activities with start and finish dates,
undertaken to achieve an objective conforming to specific requirements, including the constraints of
time, cost and resources
[SOURCE: ISO 9000:2015, 3.4.2, modified — The notes to entry have been removed.]
3.2 Abbreviated terms
CBS cost breakdown structure
OBS organizational breakdown structure
WBS work breakdown structure
WP work package
4 Overview of project breakdown structures
4.1 General
4.1.1 There are generally several types of project breakdown structures that are generated to
provide a framework for efficiently controlling the programme, or its projects, and producing the
product agreed to between the customer and the supplier. The project breakdown structures shall have
the organizational framework of a tree in accordance with ISO 23462.
4.1.2 A project breakdown structures tree as used in this document is an arrangement of related
items or elements characterized by having a top-level node, or summit, that is broken down into lower-
level elements or nodes until the lowest-level elements are determined; the lowest level is usually
based upon some degree of reasonableness or of diminishing returns of further breakdown. A tree is
generally constructed for project breakdown structures because the lower-level elements are more
easily managed. In a project breakdown structures tree, a hierarchical relationship exists between
elements at the same level of breakdown to the next higher related node element above; in addition,
elements at the same level of breakdown often have interfaces with other items at the same level.
4.1.3 The project breakdown structures described in this clause and in Clause 5 are expressed in terms
of a business agreement or contract between a supplier and a customer, where the project breakdown
structures are based upon the supplier's workshare. However, the same principles, processes and
requirements for project breakdown structures can be used by an independent developer, in which case
the project breakdown structures are for the complete system product that can be developed entirely
by the independent developer, or by the independent developer and subcontracted suppliers.
4.2 Relationship of project breakdown structures
4.2.1 In the context of ISO 14300-1, the various project breakdown structures within a programme or
project originate with the level 0 customer's set of requirements. Based upon the business agreement
and from the customer's requirements, a level 1 supplier develops a set of specifications, each containing
requirements, that satisfies the level 0 customer's requirements. The specifications are organized in a
hierarchical specification tree, with lower-level specifications containing requirements that flow down
from higher-level specifications.
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ISO 27026:2023(E)
4.2.2 From the requirements contained in the specification tree, a function tree shall be generally
generated. The functions determine what shall be performed by the level 1 supplier's workshare portion
of the system, which can be the complete system; the functional requirements in the specification tree
specify how well the requirements shall be performed. The specification and functional trees shall
be used to generate the design elements of the system product, which is arranged as a product tree.
The development of the specification, and hence requirements, tree, is an iterative process with the
development of the function tree and the product tree to develop lower levels of each of the trees.
Depending upon the situation, the requirements within the specification tree may often contain the
functions expressed as functional requirements in sufficient manner that a function tree may not need
to be separately generated, in which case only a specification tree may be generated.
4.2.3 The tasks needed to develop the trees resulting in the system product are arranged in a work
breakdown structure (WBS), which is a hierarchical tree with lower-level tasks providing more detail
related to the node task above. The WBS serves as a reference for the identification of cost elements
arranged into a cost breakdown structure (CBS), which is a hierarchical tree of lower cost elements
related to the next higher node cost element above.
4.2.4 The WBS and CBS, along with the overall management organization of the level 1 supplier,
result in a programme or project organizational breakdown structure (OBS) for the level 1 supplier's
workshare, which is arranged as a hierarchical tree of lower organizational elements reporting, or
related, to the next higher-level node organization.
4.2.5 In the context of ISO 14300-1, when the level 1 supplier subcontracts part of the product
development to one or more level 2 suppliers, each level 2 supplier develops a similar set of lower-
level project breakdown structures based upon the requirements contained in the sub-contractua
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