Aircraft assembly lines are characterized by low-volume production, extensive manual work, limited buffer space, specialized resources, long cycle times, and a large network of external suppliers. Unlike in the automotive industry, where a cycle takes only a few minutes, a single cycle in aerospace assembly can last several days or even weeks. For technical reasons, many tasks require skilled manual labor. Assembling large, complex aircraft components requires fine human dexterity, and specialized skills that are difficult to automate or teach to robots. In a growing aerospace market, meeting planned delivery dates becomes increasingly difficult because of numerous known and unknown performance detractors (worker absence, equipment breakdowns, missing parts, etc.). A first step in this direction is to assess how, and to what extent, a nominal scheduling decision can withstand uncertainty. In this work, we focus on stress-testing a given Target Cycle Time (TCT) in aerospace manufacturing systems.