Flight Software Engineer

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.  

Flight Software Engineer (7+ years of experience)

As a Flight Software Engineer, you will play a key role in designing, developing, and testing flight software that powers these advanced systems. You'll work closely with multidisciplinary teams to deliver high-performance, real-time embedded software that operates reliably under extreme conditions.

This is a hands-on role for an engineer who thrives on solving hard problems, building robust systems from the ground up, and moving fast without compromising quality.

Responsibilities

• Design, develop, and test real-time embedded flight software for missile systems
• Collaborate with GNC engineers, systems engineers, and hardware teams to ensure seamless integration
• Implement and maintain software for high-reliability, safety-critical environments
• Support simulation, hardware-in-the-loop (HIL), and flight testing to validate performance
• Participate in root cause analysis and debugging across software and system interfaces
• Follow rigorous software lifecycle practices, including configuration management and verification
• Contribute to defining and improving development processes, tools, and standards
• Stay informed on emerging technologies and best practices relevant to flight software and real-time systems

Basic Qualifications

• Bachelors or Master's degree in Computer Science, Electrical Engineering, Aerospace Engineering, or related field
• Experience: Open to candidates across all experience levels, from early-career engineers to senior technical contributors. Professional experience, internships, research, open-source contributions, or other hands-on technical work will be considered.
• Proficiency in C/C++ and experience with real-time operating systems (RTOS)
• Familiarity with hardware/software integration and real-time system constraints
• Experience working with GNC systems or similar control-intensive applications
• Strong understanding of testing practices including simulation and HIL environments
• Excellent problem-solving skills and attention to detail
• Ability to work effectively in a fast-paced, multidisciplinary team environment
• Active or eligible for a Top-Secret security clearance

Preferred Skills and Experience

• Experience developing flight software for missile, launch vehicle, or spacecraft systems
• Exposure to FPGA-based systems and embedded software optimization techniques
• Knowledge of secure software development and cybersecurity best practices
• Familiarity with agile or iterative development methodologies
• Hands-on experience with software verification, validation, and integration in defense environments
• [Skills and experiences]

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 [email protected]. 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.