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.

Senior Navigation and State Estimation Engineer

We are seeking a Senior Navigation and State Estimation Engineer to lead the development of advanced navigation solutions for next-generation hypersonic missile systems on the GNC team. In this senior GNC role, you will serve as a technical authority on inertial navigation, guiding architectural decisions and ensuring robust performance in extreme, high-dynamic environments. You will shape system-level strategy, and drive algorithm maturity from concept through to production.

Responsibilities

• Lead the design, development, and validation of high-performance state estimation algorithms for hypersonic missile applications (EKF, UKF, sensor fusion).
• Implement filter software and integrate navigation filter with flight and GNC simulation software.
• Define navigation architecture and requirements, working closely with avionics, and flight software teams.
• Develop high-fidelity sensor and environment models (IMU, GNSS, alt-PNT) to support performance prediction and algorithm robustness.
• Conduct Monte Carlo analysis, covariance studies, and sensitivity assessments to quantify navigation accuracy and uncertainty growth.
• Support pre-flight analysis and post-flight reconstruction of navigation solution performance.

Basic Qualifications

• Bachelors or Masters degree in aerospace engineering, mechanical engineering, electrical engineering, physics, applied mathematics, or a related field.
• Strong foundation in estimation theory, nonlinear filtering, and rigid-body dynamics.
• Experience developing algorithms into flight software with computational and timing constraints.
• Proficiency with Python and Rust or C++.
• Understanding of navigation sensor error modeling and multi-sensor fusion.

Preferred Skills and Experience

• Experience with hypersonic or high-Mach flight environments, including modeling of aero-thermal effects on sensors and navigation accuracy.
• Familiarity with seeker-aided and alt-PNT navigation.
• Experience integrating navigation algorithms into real-time flight software.
• Familiarity with high-rate inertial navigation systems, gyro/accelerometer calibration, and stochastic error propagation.
• Knowledge of trajectory simulation frameworks and Monte Carlo analysis.

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

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.