Evolution of MBSE

The journey of systems engineering in the aerospace and defense (A&D) sector has been marked by significant advancements. In the 1970s and 1980s, systems engineering relied heavily on paper-based documentation. Requirements, system architecture design, validation, and verification were manually traced through extensive hard-copy artifacts. This method was cumbersome and prone to errors, as any change required meticulous manual updates across all documents.

The introduction of DOORS in the 1990s marked the first major shift, automating the document-based approach. This transition to a database allowed for easier traceability yet still involved dealing with numerous "shall" statements and maintaining clear connectivity to engineering design artifacts.

The late 1990s saw the emergence of the Unified Modeling Language (UML), a graphical language designed for object-oriented software development. In the early 2000s, UML was appropriated to articulate systems engineering models. This eventually led to the development of SysML (Systems Modeling Language) by the Object Management Group (OMG) and the International Council of Systems Engineering (INCOSE). SysML, tailored specifically for systems engineering, became widely adopted around 2008-2009. 

The Shift from Documents to Models

Model-Based Systems Engineering (MBSE) revolutionized the field by moving from document-based systems to a model-centric approach. A well-structured model provides a graphical representation of processes, structures, and workflows, making it easier to understand and manage. Changes made within a model propagate automatically, ensuring consistency and reducing labor.

MBSE allows for an authoritative source of truth (ASoT) for systems, depicting components as interconnected blocks with defined boundaries and interfaces. This visual representation aids both technical and non-technical stakeholders in comprehending complex systems. For example, in developing a new turbofan engine, MBSE can map interactions between the engine and external systems like avionics and flight controls.

Why the Shift from Document-Based to Model-Based Systems Engineering?

  1. Efficiency Metrics:
    • Reduction in Time to Market: MBSE should streamline the development process, leading to faster product launches.
    • Cost Reduction: By using models effectively, organizations can reduce costs associated with rework, errors, and inefficiencies.
  2. Effectiveness Metrics:
    • Improvement in Product Quality: MBSE aims to enhance system design and reduce defects. Executives can measure this by tracking the quality of systems engineering outputs.
    • Stakeholder Satisfaction: MBSE should lead to better communication and collaboration. Monitoring stakeholder satisfaction can provide insights into its effectiveness.
  3. Impact Metrics:
    • Return on Investment (ROI): Executives should assess the financial impact of MBSE. This includes cost savings, increased productivity, and improved product quality.
    • Strategic Alignment: MBSE should align with the organization’s strategic goals. Executives can evaluate whether MBSE contributes to long-term success.

A Wiser DOD Mandates MBSE

Despite its success, the F-35 program faced numerous challenges, including significant budget overruns and delays. Key  issues were the challenged of maintain and evolving unified systems engineering artifacts, traceability, communications, incomplete validation & verification requirements, and  the lack of reuse of systems developed in earlier programs. The F-35 was developed as an entirely bespoke effort, with everything built from the ground up. This approach highlighted the need for a more efficient system.


Learning from past challenges, the Department of Defense (DOD) has issued a mandate to build a systems engineering infrastructure using MBSE to address the shortcomings of classical SE methods. MBSE artifacts serve as the Authoritative Source of Truth (ASoT), ensuring consistency throughout the program, reducing the risk of systems architecture divergence, better documenting V&V requirements, and improving communication. Additionally, MBSE facilitates the creation of reusable models for future development, borrowing principles from object-oriented software design. This approach allows for the incorporation of reusable components into new projects, thereby decreasing development time, costs, and risks.


This approach is similar to object-oriented software design and allows for well-documented and consistent software architecture  and libraries of reusable components to be incorporated into new applications, thereby decreasing development time, costs, and risks.

Advantages of MBSE in A&D

  • Enhanced Traceability and Consistency: MBSE ensures that all changes are automatically updated throughout the system, maintaining consistency and reducing manual effort.
  • Improved Communication: The graphical nature of MBSE models facilitates better communication among stakeholders, including non-technical personnel, by providing clear visualizations of system interactions.
  • Reuse of Models: Models can be stored in libraries and reused in future projects, significantly reducing development time and costs. This is particularly beneficial in A&D, where similar components like turbines or engines can be repurposed with minimal modifications.
  • Reduced Risk of Overruns: MBSE provides a clear and consistent roadmap that mitigates risks associated with budget overruns and project delays.
  • Seamless Independent Validation and Verification: Independent Validation & Verification (IV&V) is critical to any systems engineering process. Validation ensures that the correct system is being built according to requirements (validating against the CONOPS), while Verification ensures that the system is being built correctly (meeting the requirements). MBSE supports IV&V by mapping these cases both graphically and tabularly, creating clear linkages between requirements, validation, and verification. This reduces errors and simplifies the verification process to ensure the system works and that test cases are included in the model.

Pitfalls and Challenges Implementing MBSE

Transitioning to MBSE is not without its challenges. Organizations often face resistance due to the significant paradigm shift required. Key challenges include:


  • Organizational Buy-In: Senior management must be convinced of MBSE's benefits, necessitating a top-down approach to implementation.
  • Training and Education: Employees need to learn a new vocabulary and syntax, transitioning from text-based documentation to graphical models. Comprehensive training is essential to facilitate this shift.
  • Infrastructure and Tools: Implementing MBSE requires substantial investment in tools and IT infrastructure. Tools like Cameo can be expensive, and setting up the necessary back-end support involves additional costs.
  • Cultural Resistance: There is often resistance from experienced personnel accustomed to traditional methods. Younger employees may adapt more readily, but older staff may see little value in changing established practices.

Lessons From System Implementation Failures In Other Industries

Examining the famous debacles of system implementations in other industries can provide valuable insights for avoiding similar mistakes in MBSE adoption within aerospace and defense.


  • NCTC Railhead Project: The National Counter-Terrorism Intelligence Center (NCTC) Railhead Project is an example of a failed management approach. An overemphasis on using only Scrum to manage the process without a clear systems engineering process led to chaos. Requirements were managed without a Concept of Operations (CONOPS), and the proposed systems lacked defined behaviors and structures. Different Scrum teams were left to their own devices to develop solutions without an architectural roadmap, relying solely on a list of assigned user stories. The result was a series of failed or partially completed Scrums and limited to no deliveries of working systems.
  • FoxMeyer Drug ERP Failure: FoxMeyer, once the fifth-largest drug wholesaler, went bankrupt in 1996 due to a failed ERP implementation. The lack of defined systems engineering processes and poor management decisions led to this catastrophic outcome. This case highlights the need for robust systems engineering frameworks and careful management.
  • TRAILBLAZER Program at NSA: This $1 billion program aimed to develop new analytic capabilities but failed due to the absence of defined systems engineering processes and proper stakeholder commitment. The program's failure emphasizes the necessity of clear processes and committed participation from all stakeholders.

Strategies for Successful MBSE Implementation

To ensure a smooth transition to MBSE, A&D organizations can take several steps and consult partners like Quest Defense:


  • Develop Systems Engineering Fundamentals: Establishing a solid systems engineering process is crucial before transitioning to MBSE. This includes developing a requirements definition and management process, configuration management, and validation and verification methods.
  • Evangelize MBSE Benefits: Clearly communicate the advantages of MBSE to all stakeholders, emphasizing improved efficiency, traceability, and reduced risk. Projects using an MBSE approach cost 55% less than projects using a traditional SE approach. In addition, projects using an MBSE approach delivered on time 62% of the time, compared to 59% of the time with a traditional SE approach, and up to 70% of defects have been identified during the modeling and simulation stage.1
  • Provide Comprehensive Training: Invest in training programs to help employees understand and adopt MBSE practices.
  • Invest in the Right Tools: Carefully select and invest in MBSE tools and infrastructure, ensuring compatibility and scalability for future projects.
  • Build a Culture of Continuous Improvement: Encourage a culture that values continuous improvement and adaptation to new methodologies. This includes fostering collaboration and open communication among all team members.

Quest Defense's Facilitating MBSE Adoption In Aerospace and Defense

Quest Defense has been instrumental in helping its clients navigate the complexities of MBSE implementation. Recent projects have demonstrated Quest Defense's capability to streamline systems engineering processes and deliver tangible ROI for its clients.

One notable project involved using DOORS for requirements management and various COTS and bespoke tools to design a new engine. The MBSE effort was used as a learning device to develop skills and methods for formalizing the systems engineering process. This approach ensured that the client built a strong MBSE-compliant organization for future programs, minimizing the risk of program failure.

Quest Defense's expertise extends beyond just technical implementation. They work closely with clients to address organizational and cultural challenges, providing comprehensive training and support to ensure smooth transitions.

The future of MBSE in the A&D sector looks promising, with increasing mandates for its adoption to avoid past pitfalls and improve project outcomes. As organizations continue to recognize the benefits of MBSE, its implementation will become more widespread, leading to more efficient and effective systems engineering processes.

Quest Defense stands ready to assist organizations in this transition, offering the expertise and support needed to navigate the complexities of MBSE implementation. With careful planning, training, and investment in the right tools, organizations can successfully navigate this transition and achieve greater efficiency and effectiveness in their systems engineering processes.


1. Systematic Literature Review: How is Model Based Systems Engineering Justified? Edward R. Carroll and Robert J. Malins, SANDIA REPORT SAND2016- 2607 Unlimited Release March 2016.

The Evolution and Impact of MBSE in Aerospace and Defense


Todd. B. Cutick

ESEP, Lead Model-Based Systems Engineer and Systems Engineering Subject Matter Expert, EXB Solutions, A Quest Global Subsidiary

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