Enabling the Open Architecture approach in military systems: a systems thinking analysis

<p dir="ltr">Military systems, with their extended lifecycles, face persistent challenges such as man- aging obsolescence, adapting to evolving operational demands, and ensuring interoperability across diverse contexts. Open Architectures (OAs) have been pursued to address these issues by replacing proprietary solutions with widely recognised interface standards, enabling more flexible and cost-effective system modifications. However, inconsistencies in how OA is understood, questions about how its intended benefits are realised, and the complexity of establishing effective OA environments—encompassing technical, commercial, and organisational dimensions—continue to hinder widespread adoption. Existing knowledge remains largely confined to the practices of a few governments. </p><p dir="ltr">These challenges highlight the need for a holistic and systemic examination of OA in the defence sector, leading to the aim of this research: to advance conceptual clarity and offer practical guidance on the adoption of the OA approach, thereby enabling military organisations to understand and adapt it within their specific contexts and systems. To explore this complex socio-technical issue, the study employed systems thinking tools, principles of the Soft Systems Methodology (SSM), and the system praxis paradigm to connect conceptual and practical elements. Perspectives from government and industry were integrated, addressing the ‘what’, ‘why’, and ‘how’ of OA adoption with the aid of conceptual models and actionable frameworks.</p><p dir="ltr"><br>Key contributions and insights include: articulation of holistic characteristics of the OA approach through a systemigram, clarifying the concept through dimensions such as enterprise, community of practice, technical considerations, and purpose -- highlighting that success depends on defining, with the community, ‘open for whom’, ‘to what level of detail’, and ‘in which parts of the system’; a benefits chain, combined with the BATWOVE framework (a variant of the CATWOE from the SSM), which interrelates perceived benefits and links them to broader organisational goals while also addressing conditions and considerations as ‘benefit for whom?’; and a model titled the Triangle of Adoption Conditions, which captures the dynamic interactions among key OA adoption factors: strategic investment, active engagement of a community of practice, and maturity in technical and legal domains. In addition, a framework for mapping enabling activities towards the OA approach was developed. The applicability of these tools was demonstrated through a case study in the Brazilian Army’s Armoured Forces Programme, from which tailored recommendations were derived for early-stage adopters.<br></p><p dir="ltr"><br></p><p dir="ltr">This study provides strategic guidance for tailoring OA to specific contexts and contributes to broader systems engineering and systems thinking discourse, helping bridge the gap between concept and application -- particularly for early-stage adopters.<br></p>