Flight Software Engineer (All Levels)

About the role

Castelion is bringing a new approach to defense development and production: one that focuses on short, iterative design cycles, rapid testing in development, and modern commercial manufacturing strategies for production at scale. We're designing, building, and testing next generation long range strike weapons systems to give America and its Allies a definitive edge and deter future conflicts. 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

Requirements

• Bachelors or Master's degree in Computer Science, Electrical Engineering, Aerospace Engineering, or related field
• 2+ years of experience in embedded software development, preferably in aerospace or defense
• 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
• Must be a U.S. citizen or national, lawful permanent resident (green card holder), refugee under 8 U.S.C.1157, asylee under 8 U.S.C.1158, or eligible to obtain the required authorizations from the U.S. Department of State (ITAR compliance)

Skills

• 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
• Bias to Action and Creative Problem Solving – desire and experience questioning assumptions in ways that lead to breakthrough ideas that are ultimately implemented
• Ability to bring applicable processes/concepts/materials from other industries to achieve efficiency gains
• Ability to personally resolve minor issues in development without requiring significant support
• High Commitment, High Initiative – genuine passion for Castelion's mission and consistently look for ways to contribute to the company's technical goals and prevent hardware blockers
• Ability to work in a fast paced, autonomously driven, and demanding atmosphere
• Strong sense of accountability and integrity
• Clear Communicator – proactively communicates blockers, trusted to be voice of company with regulators, suppliers, gate keepers and customers, capable of tactfully managing relationships with stakeholders
• Emails, IMs and