Avionics Test Software Engineer, Senior, Lead, Staff

Why Castelion, Why Now 

Castelion is moving incredibly fast to develop and deliver advanced defense systems at a time when execution matters more than ever. We believe focus, ownership, and excellence are decisive advantages - and we're building a world-class team to turn bold ideas into real capability. 

This is a rare opportunity to join at an early stage, where you'll have significant ownership, collaborate with exceptional teammates, and make a direct, measurable impact on our mission and the future of the company - regardless of your function.  

Avionics Test Software Engineer 

An Avionics Test Software Engineer at Castelion owns the architecture, design, and technical direction of the software frameworks used to develop, automate, execute, and analyze avionics hardware testing.  This role establishes scalable software architectures and reusable frameworks that enable rapid development, integration, verification, and production test across complex avionics systems.  The Engineering Lead works closely with avionics, electrical, software, test, manufacturing, and systems engineering teams to translate test requirements into robust and maintainable software solutions. 

Responsibilities 

• Own the architecture and technical direction of avionics test software frameworks, establishing scalable patterns, interfaces, APIs, and infrastructure that support rapid hardware development and test execution. 
• Design and develop reusable test software frameworks, libraries, drivers, and services that enable engineers and technicians to quickly develop and execute automated hardware tests. 
• Define software architecture standards, development practices, coding standards, configuration management, and design patterns for avionics test software. 
• Develop software interfaces to avionics hardware, instrumentation, data acquisition systems, power supplies, communication buses, databases, and other test equipment using appropriate hardware and software protocols. 
• Partner with avionics and Flight Software engineers to translate hardware requirements, test requirements, and verification objectives into automated test architectures and software implementations. 
• Establish common abstractions and reusable components for test sequencing, instrumentation control, hardware configuration, data acquisition, telemetry, logging, reporting, and test result management. 
• Lead the development of test automation infrastructure that supports hardware bring-up, development testing, qualification, verification, and production test while minimizing test development and execution time. 
• Establish software architecture that supports deterministic and repeatable test execution, robust fault handling, test recovery, and clear identification of hardware versus test-system failures. 
• Develop and maintain automated test capabilities using Python and other appropriate software technologies, with an emphasis on maintainability, reliability, extensibility, and ease of use. 
• Define and implement software interfaces between test frameworks and engineering systems, including hardware configuration databases, test data systems, manufacturing systems, and other enterprise tools. 
• Establish automated software build, test, validation, and deployment processes, including appropriate use of version control, continuous integration, automated testing, and code review. 
• Lead technical reviews of test software architecture and implementations, identifying opportunities to improve reliability, scalability, development velocity, and long-term maintainability. 
• Mentor and provide technical leadership to test software engineers and other developers, establishing best practices while maintaining a high level of individual technical contribution. 
• Troubleshoot complex software, hardware, and integration issues during test execution and drive root-cause investigations across software and hardware boundaries. 
• Develop software and data tools that improve test visibility, automate analysis, identify anomalies, and accelerate engineering decision-making. 
• Identify and implement opportunities to reduce manual test operations, increase test coverage, improve test repeatability, and shorten hardware test cycle time. 
• Support continuous improvement initiatives focused on test efficiency, software quality, hardware reliability, development velocity, and overall engineering effectiveness. 

Basic Qualifications 

• Bachelor's degree in computer science, computer engineering, electrical engineering, software engineering, or a related technical field with 7+ years of relevant professional experience; or 10+ years of relevant professional experience in software development, test automation, avionics test, or a related technical field. 
• Strong professional experience developing software for automated hardware testing, laboratory test systems, manufacturing test, or hardware-in-the-loop environments. 
• Demonstrated experience designing and implementing software architectures, frameworks, APIs, or reusable software platforms. 
• Strong proficiency in Python or another modern programming language. 
• Experience with software development practices including version control, code review, automated testing, debugging, and continuous integration. 
• Experience developing software that interfaces directly with hardware, instrumentation, or external systems. 
• Develop and maintain relational and/or time-series databases for test data, telemetry, configuration, and test results, including schema design, SQL queries, data integrity, performance optimization, and integration with automated test frameworks. 

Preferred Skills and Experience 

• Experience architecting test software frameworks for avionics, aerospace, defense, automotive, robotics, or other complex hardware systems. 
• Strong experience with Python test frameworks and development ecosystems such as pytest, packaging, resource management, dependency management, and automated testing. 
• Experience developing reusable hardware abstraction layers, instrument drivers, device interfaces, communication protocols, and test APIs. 
• Experience with avionics communication interfaces such as CAN, ARINC 429, MIL-STD-1553, Ethernet, RS-232/422/485, SPI, I2C, or similar protocols. 
• Experience developing hardware-in-the-loop (HIL), software-in-the-loop (SIL), automated test equipment (ATE), or laboratory automation systems. 
• Experience with test sequencing architectures and frameworks designed to support complex multi-step hardware test procedures. 
• Experience integrating test software with oscilloscopes, power supplies, electronic loads, data acquisition systems, signal generators, network analyzers, and other laboratory instrumentation. 
• Experience with distributed systems, networked test architectures, RPC frameworks, message-based systems, or service-oriented architectures. 
• Experience designing test data architectures, telemetry systems, structured logging, automated reporting, and post-test data analysis. 
• Experience with CI/CD infrastructure and development tools such as Git, GitHub/GitLab, Jenkins, Docker, or similar technologies. 
• Experience designing software for deployment across engineering laboratories, production test stations, or distributed test environments. 
• Experience with real-time systems, embedded software, firmware, or low-level hardware interfaces. 
• Experience establishing software development standards and mentoring engineers across a growing technical organization. 
• Strong understanding of software architecture principles, object-oriented design, modularity, abstraction, dependency management, and API design. 
• Strong analytical and problem-solving abilities with an emphasis on speed, reliability, and practical execution. 
• Highly self-directed, adaptable, and capable of prioritizing technical work in a fast-paced hardware development environment. 
• Experience leading cross-functional technical initiatives involving software, electrical, avionics, test, manufacturing, and systems engineering teams.

Castelion offers a generous benefits package. Please refer to the bottom of our Careers page for more details.  

Other Duties 

Please note this job description is not designed to cover or contain a comprehensive listing of activities, duties or responsibilities that are required of the employee for this job. Duties, responsibilities and activities may change at any time with or without notice. 

Additional Eligibility Requirements 

This position may require access to classified information or restricted U.S. Government sites, systems, or information, as determined by the Company and/or applicable U.S. Government requirements. If the position is so designated, your employment in the role may be contingent upon your ability to obtain and maintain the required U.S. Government security clearance or other government authorization, and to satisfy any citizenship or other eligibility requirements imposed by applicable law, regulation, executive order, or government contract requirements. You will be notified if and when such requirements apply. 

Affirmative Action/EEO Statement 

Castelion is an Equal Opportunity Employer. We are committed to providing equal employment opportunities to all applicants and employees without regard to race, color, religion, sex, sexual orientation, gender identity, national origin, age, disability, genetic information, protected veteran status, or any other characteristic protected by applicable federal, state, or local law. 

Castelion is committed to providing reasonable accommodations to qualified individuals with disabilities throughout the application and hiring process. If you require a reasonable accommodation to complete an application, participate in the interview process, or otherwise participate in the hiring process, please contact hr@castelion.com. Requests for accommodation will be considered on an individual basis and handled in accordance with applicable law. 

Castelion is committed to fostering a workplace where employment decisions are based on qualifications, business needs, and the ability to perform the essential functions of the role, with or without reasonable accommodation. 

EAR/ITAR Requirements 

This position requires access to export-controlled information, and as such, employment (or hiring of a contractor) is contingent upon the candidate’s ability to access all applicable export-controlled information without additional export licensing being required by the Bureau of Industry and Security and/or the Directorate of Defense Trade Controls.