Date of Award

3-2025

Document Type

Thesis

Degree Name

Master of Science

Department

Department of Systems Engineering and Management

First Advisor

Kip E. Johnson, PhD

Abstract

Increasingly complex defense systems that are routinely overbudget and behind schedule are driving digital engineering initiatives in the defense acquisition industry. MBSE offers a solution to counter this issue but the lack of guidance on how to implement it has led to significant experimentation. One MBSE area of interest is system safety. This research demonstrates how to conduct model-based Systems Theoretic Process Analysis (STPA) to meet the unique system safety process requirements from MIL-STD882E. Based in systems theory, STPA extended for coordination enables a safety-driven design process of complex systems. This research investigated conducting STPA in the SysML-RAAML modeling language across a sUAS case history delivering 41 design considerations for PDR and 78 for CDR. A framework mapped STPA artifact to MIL-STD-882E requirements, used to construct model-based system safety representations tailored to DoD acquisitions. Qualitative observations during PDR and the PDR-to-CDR transition along with quantitative workload data provided insights into the process. An experiment gathered mixed methods survey data from SMEs on using the model as the primary means of communicating system safety information. Contributions of this research include development of the first STPA-Coordination mapping to MIL-STD-882E system safety process elements, documenting the STPA-Coordination transition from PDR to CDR, and guiding model-based system safety reviews using STPA-Coordination represented in SysML-RAAML.

AFIT Designator

AFIT-ENV-MS-25-M-057

Comments

An embargo was observed for this posting.

Distribution A: Approved for public release, Distribution Unlimited. PA case number 88abw-2025-0532

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