Seeking an experienced Principal Systems Integration Engineer for onsite work supporting military and mission-critical systems across air, ground, maritime, and multi-domain platforms. The role involves leading system integration, configuration, and demonstrations, coordinating multidisciplinary teams, and serving as the primary technical interface with military customers. Candidates must have a STEM degree, 8+ years of relevant experience, and an active Secret security clearance, with travel up to 50%. Preferred qualifications include a Top Secret clearance and experience with military system integration, secure environments, and mission networking. The position offers comprehensive benefits, competitive salary, and opportunities to contribute to advanced aerospace and defense solutions. Applicants must pass security and background checks, with roles primarily onsite in Cedar Rapids, IA. The application window closes approximately 40 days from posting. RTX is an equal opportunity employer.