We address systems which have multiple objectives: broadly speaking, these objectives can be thought of as safety and performance goals. Guaranteeing safety is our first priority, satisfying performance criteria our second. In this paper, we compute the system’s safe operating space and represent it in closed form, and then, within this space, we compute solutions which optimize a given performance criterion. We describe the methodology and illustrate it with two examples of systems in which safety is paramount: a two-aircraft collision avoidance scenario and the flight management system of a VSTOL aircraft. In these examples, performance criteria are met using mixed-integer nonlinear programming (MINLP) and nonlinear programming (NLP), respectively. Optimized trajectories for both systems demonstrate the effectiveness of this methodology on systems whose safety is critical.