Keywords: Model-Based Systems Engineer, MBSE, Systems Engineer, Systems Engineering, SysML, Cameo, MagicDraw, MSOSA, Rhapsody, Architecture Modeling, System Architecture, Mission Systems, Avionics Systems, Fighter Aircraft, Air Dominance, Phantom Works, Weapons Systems, Aircraft Systems, Complex Systems, Requirements Engineering, Requirements Decomposition, Requirements Traceability, DOORS, DOORS Next Gen, IBM DOORS, Verification and Validation, V&V, Test Planning, Integration Engineering, Interface Control Documents, ICD, System Interfaces, System Integration, Trade Studies, Risk Management, System Modeling, Digital Engineering, Digital Thread, Digital Twin, Safety-Critical Systems, Mission-Critical Systems, Airworthiness, Certification, MIL-STD, MIL‑STD‑516, DO‑178C, DO‑254, Aerospace Engineering, Defense Engineering, DOD Programs, Secret Clearance, Cleared Engineer, Security Clearance, St. Louis MO, Berkeley MO, Onsite Engineering, Model-Based Design, Model Development, Aircraft Integration, Simulation, Engineering Lifecycle, Requirements Baseline, Confluence, Jira, Agile Systems Engineering, Cross‑Functional Engineering, Defense Contractor, Combat Systems, Operational Architecture, Functional Architecture. Responsibilities of the Model-Based Systems Engineer (Level 3): • Develop and maintain SysML models using MBSE tools such as Cameo or MSOSA • Translate high-level system requirements into detailed, traceable subsystem requirements • Use DOORS to manage, organize, and maintain requirement baselines and traceability • Partner with architects, software engineers, hardware teams, and mission systems experts to design and integrate complex system solutions • Support system architecture definition, interface management, and integration planning • Participate in trade studies, risk assessments, and milestone technical reviews • Contribute to verification and validation (V&V) planning for mission-critical and safety-critical systems • Document system behaviors, relationships, and architecture elements within the MBSE environment • Work closely with engineering leadership and Subject Matter Experts to ensure consistent application of Systems Engineering best practices.