Senior Flight Software Engineer

ABOUT POSEIDON AEROSPACE: Poseidon Aerospace is reimagining how the world moves goods. We build and operate full-size autonomous cargo aircraft - capable of carrying two tons of payload over a thousand nautical miles. From remote communities to contested logistics operations, our platforms unlock a new cost curve for air freight, making it faster, cheaper, and accessible anywhere it's needed. Headquartered in the San Francisco Bay Area with locations in Washington DC, Oregon, and Maine; we're building something consequential. ABOUT THE ROLE Flight software is the code that runs on the flight computers of our autonomous cargo aircraft. As a Senior Flight Software Engineer you will own major parts of that software, from architecture through flight test. You will decide how the software is structured, how it handles failures, and how it is tested, and you will write a large share of the code yourself. You will also set the technical bar for the engineers around you. RESPONSIBILITIES - Own the architecture of major flight software subsystems, including timing, partitioning, and redundancy - Design and implement deterministic, real-time embedded flight software in C++ - Design fault detection and response for the aircraft, including redundancy management, degraded modes, and lost-link behavior - Define software requirements and interfaces with avionics, GNC, and flight test, and trace them to tests - Implement the GNC team’s algorithms in flight code and verify them against simulation - Set the test strategy across unit tests, software-in-the-loop, and hardware-in-the-loop - Build telemetry, logging, and command paths between the aircraft and the ground station - Lead software integration on the aircraft and support ground testing and flight test, including travel to our flight test site - Set coding standards and review practices, and lead design reviews - Mentor other flight software engineers REQUIRED QUALIFICATIONS - B.S. in computer science, engineering, or a related field, or equivalent experience - 5+ years of professional C or C++ development on embedded, real-time, or safety-critical systems - Owned a flight software subsystem or equivalent from architecture through fielded operation - Took software through hardware integration and test on a real vehicle (aircraft, spacecraft, or automotive) - Designed fault detection and response for a system where failure had safety consequences - Led design reviews and set technical direction for other engineers PREFERRED QUALIFICATIONS - Flight software experience on crewed or uncrewed aircraft, or on spacecraft - RTOS or bare-metal development, with a deep understanding of scheduling, timing, and memory - Experience designing redundant or fault-tolerant flight computer architectures - Experience developing software under DO-178C or a comparable standard such as ISO 26262 - Experience supporting flight test or vehicle test campaigns - Python for tooling, test automation, and flight data analysis - Clear technical writing WHY THIS ROLE Flight software touches every system on the aircraft: avionics, propulsion, flight controls, and the ground station. You will make the decisions that shape how those systems work together, at a stage where the architecture is still yours to set. You will work directly with flight hardware and watch your code fly an aircraft that carries two tons.   WHAT YOU GET FROM US - Competitive salary and meaningful early-stage equity - Relocation support if applicable - Employee Health Benefit Plans - 6% Retirement matching - Flexible PTO - Free lunches, snacks, and a stocked fridge at our offices - AI tools and subscriptions