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 invol
