A HYBRID SYSTEMS ENGINEERING APPROACH FOR MANAGING COMPLIANCE AND ADAPTABILITY IN AEROSPACE AND DEFENSE

Abstract

The aerospace and defense industry operates in complex, safety critical, and highly regulated environments. Programs must maintain strict compliance while responding to evolving sustainment and operational needs. Traditional Waterfall methodologies provide structure, documentation, and traceability. However, they often struggle when requirements change late in the lifecycle, leading to increased cost and schedule delays. Agile approaches offer flexibility and frequent stakeholder engagement, but they can fall short of the verification, validation, and documentation rigor required in regulated aerospace programs.This dissertation examines how a Hybrid approach outperforms pure Waterfall and Agile approaches in aerospace sustainment programs. The research is conducted in three stages. First, surveys and interviews capture practitioner perspectives on requirement management and development practices, showing that most aerospace programs already operate using Hybrid execution models, whether formally defined or not. Second, a comparative analysis of projects executed under Waterfall, Agile, and Hybrid identifies performance patterns and clarifies when Hybrid execution should lean more toward Agile or more toward Waterfall based on safety criticality, certification demands, and time pressure. Third, a detailed case study applies Model-Based Systems Engineering (MBSE) as an analytical tool to evaluate how these methodologies perform when applied to the same sustainment system. The results show that the Hybrid approach reduces requirement rework and shortens verification and validation cycles. It also improves cost and schedule performance while maintaining compliance with safety and certification requirements. These findings are reinforced through surveys and interviews with industry practitioners, which capture current perspectives on requirement management across development methodologies. The data confirm that most aerospace and defense programs already operate in Hybrid environments. This study concludes that Hybrid frameworks, supported by MBSE, provide a balanced and sustainable solution for aerospace sustainment programs. The results demonstrate not only why Hybrid outperforms pure Agile and Waterfall approaches, but also how MBSE enables Hybrid to deliver requirements faster, at lower cost, and with stronger alignment to stakeholder and regulatory needs.