For a next-generation spaceplane, ALTEN Technology was instrumental in developing advanced flight software. Their comprehensive approach included creating base and vehicle subsystem classes to fulfill functional requirements, conducting rigorous code reviews and pull requests, and providing valuable recommendations based on in-depth requirements analysis. ALTEN Technology also took on the responsibility of serving as a backup lead and point of contact for various spaceplane flight software subsystems. Their significant contributions resulted in the successful development of flight software for critical vehicle components such as the vehicle mode manager, environmental control and life support system, flight control actuation system, sensor and control interface module, and action sequences. Furthermore, ALTEN Technology led multiple flight software subsystem certification efforts, identified and implemented improvements to data processing pipelines that reduced telemetry data processing time by 50% and optimized server disk usage, and added support for multiple operational data formats. They also contributed to pathfinding efforts for AI tools, workflows, and containerization. This complex work was successfully executed utilizing key technologies including C++, Python, Linux, VxWorks, and Cmake.