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About the job

About Castelion

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.

Flight Software Engineer

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

Leadership Qualities

Bias to Action and Creative Problem Solving . Desire and experience questioning assumptions in ways that lead to break through ideas that are ultimately implemented. Successfully bring in 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 . A successful candidate will have a 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 in previous roles to be voice of company with regulators, suppliers, gate keepers and customers. Capable of tactfully managing relationships with stakeholders to achieve company-desired outcomes without compromising relationships. Emails, IMs and verbal interactions are logical, drive clarity, and detailed enough to eliminate ambiguity.

ITAR Requirements

To conform to U.S. Government export regulations, applicant must be a (i) U.S. citizen or national, (ii) U.S. lawful, permanent resident (aka green card holder), (iii) Refugee under 8 U.S.C. § 1157, or (iv) Asylee under 8 U.S.C. § 1158, or be eligible to obtain the required authorizations from the U.S. Department of State.

Employment with Castelion is governed on the basis of competence and qualifications and will not be influenced in any manner by race, color, religion, gender, national origin/ethnicity, veteran status, disability status, age, sexual orientation, gender identity, marital status, mental or physical disability or any other legally protected status.

All employees are granted long-term stock incentives as part of their employment as Castelion. All employees receive access to comprehensive medical, vision, and dental insurance, and the company offers four weeks of paid time off per year.