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Technical report | A Systems Thinking Approach to Engineering Challenges of Military Systems-of-Systems


System(s)-of-Systems (SoS) is broadly acknowledged as an engineering challenge for defence organisations, due to high complexity of various military SoS and their development processes. Inadequate understanding of SoS problems and inability to manage complexity encountered in planning, development and operation of multiple interdependent SoS can undermine not only performance and effectiveness of engineering practice and development activities, but also quality of their products and outcomes. This report introduces a systems thinking-based approach, SoS thinking, which offers a language and a thoughtful process to conceptualise, understand, communicate about and assess military SoS. Based on the multidimensional thinking, high complexity of SoS problems can be explored and addressed through using a set of SoS lenses in a number of important aspects, including the problem space, diversity, interdependencies, design paradigm, development states and technical statuses. SoS thinking provides a foundation for further developments of adequate methods, metrics and solutions for SoS engineering practice.

Executive Summary

System(s)-of-Systems (SoS) is broadly acknowledged as an engineering and management challenge for defence organisations, in particular in pursuing joint force integration and in delivering effective future networked force capabilities. Military SoS vary across Defence, ranging across information-based SoS, platform-based SoS, capability-based SoS, and operation-based SoS. The ubiquity of military SoS is a reality facing planning, analysis, development and operation of modern defence force and capabilities. Inadequate understanding of SoS problems and inability to effectively manage the complexity of multiple interdependent SoS can undermine performance and effectiveness of architectural approaches, systems engineering practice and development activities. This also results in problems and quality issues of products and outcomes generated in force design and integrated capability development. The high complexity of military SoS directly contributes to major cost and schedule overruns in development, acquisition and operation of integrated systems and capabilities.

In many areas within Defence, there is often a collection of interdependent human-cyberphysical systems to be dealt with. Realising the required levels of integration and interoperability for such a collection of systems in an often evolving technical and operational context can become messy if their interdependencies and interrelationships are not properly specified, engineered, and managed. Dealing with a messy collection of systems with no adequate conceptualisation and contextualisation is a failure of engineering and management that an organisation should avoid. The applications of traditional systems engineering practice and architectural approaches may become problematic or even fail if they are applied to such a messy collection of systems.

Understanding the difference between a single SoS and a SoS problem space where there are multiple interdependent and interrelated SoS is important. An inability to effectively conceptualise the SoS problem space or meaningfully and manageably identifying the SoS is one of the underlying causes resulting in major problems in undertaking engineering activities and developing architectures involving multiple SoS.

The challenge of designing and delivering SoSs is a reality facing the whole Defence. It requires clear guidance and a commonly agreed approach that can enable key stakeholders and professionals to systematically design adequate processes for joint force integration and capability development, and consistently deal with SoS challenges.

The SoS thinking approach proposed in this report is an extension of systems thinking, specifically introduced as an enabler for tackling SoS problems. It offers a language and an approach to conceptualise, understand, communicate about and assess military SoS. It offers an approach to address the high complexity of SoS problems so that they can be contextualised, explored and addressed through using a set of SoS lenses in a number of important perspectives, including:

  • awareness of a SoS problem space with its engineering factors
  • SoS categorisation and identification
  • SoS interdependencies
  • SoS development states
  • SoS technical statuses
  • SoS design relevance and paradigm
  • extended SoS community of practice.

SoS thinking offers a strategy and approach to establishing a systematic understanding of SoS, which, based on a set of SoS concepts associated with those perspectives, can be used to address SoS engineering challenges. SoS thinking can be applied as a 7-step-based process to help SoS activities (from planning, analysis, design, development, integration, assessment, management to operation) and engineering practice. In particular, it enables practitioners to effectively conceptualise and manage a SoS problem space and avoid dealing with a messy collection of systems or SoS.

SoS thinking has the potential to help review and examine various problems and issues encountered in architecture and engineering practice. It can also provide a shared foundation for further developments of adequate methods, metrics, solutions and tools for SoS engineering practice. Further applications of SoS thinking can help address a number of important issues or tasks of military SoS development and management in a joint manner or through using a shared thinking strategy and approach, including:

  • categorisation-based SoS design (or architecture) requirement specifications
  • development state-based SoS development control and management
  • SoS thinking-based mission space (scenarios) and capability design management
  • SoS identification and relationship-based SoS engineering artefacts management
  • SoS identification and relationship-based SoS integration management and assessment
  •  SoS design and technical status assessment and management
  • SoS identification and relationship-based SoS lifecycle management.

This research proposes a new thinking strategy and innovative approach of systems thinking specifically to SoS problems. SoS thinking introduces new concepts, metrics, methods and a language to the research and practice of systems engineering for SoS. In particular, it helps development activities achieve conceptualisation with theory, shared understanding, and consistent contextualisation in a SoS problem space. SoS Thinking provides approaches and potential solutions to facilitate Defence in addressing SoS engineering challenges in joint force design and integration to develop integrated capabilities.

The challenge of military SoS requires an enhancement of professional skills in many areas in Defence to effectively understand and deal with various military SoS. SoS thinking is specifically developed to help defence stakeholders and professionals understand and communicate SoS problems they face. The application of SoS thinking can potentially enhance force design and bring significant benefits to engineering practices required for planning, development and management of joint force integration and integrated capabilities. It also has the potential to enhance warfighters’ understanding of the SoS they are using and improve their confidence in management and operation of SoS-based joint force and integrated capabilities.

The following recommendations are made in this report:

  • Defence needs clear and authoritative guidance on effective use of the term, SoS, as part of relevant development or process guidance, in order to effectively address SoS challenges and get real benefits from relevant disciplines;
  • Defence needs the best practice and innovative approaches in conceptualisation and contextualisation for its military SoS problems;
  • Defence should establish the lifecycle management concept for military SoS in different categories, in order to achieve objectives and outcomes of force design and joint force integration with required interoperability;
  • Defence should establish accountability management against military SoS in different categories for key stakeholders in different areas;
  • Defence needs to develop and use adequate methods, solutions and tools for practices of SoS thinking and SoS engineering (SoSE); and
  • Defence should develop adequate training courses on SoS thinking and SoSE.

Key information


Pin Chen and Mark Unewisse

Publication number


Publication type

Technical report

Publish Date

September 2016


Unclassified - public release


System-of-systems, SoS thinking, SoS engineering, SoS conceptualisation, SoS design