This paper describes how to achieve a desired speedup by careful selection of appropriate algorithms for parallelization. Our target simulation is the total airport and airspace model (TAAM), a worldwide standard for aviation analysis. TAAM is designed as a sequential program, and we have increased its speed by incorporating multithreaded algorithms with minimal changes to the underlying simulation architecture. Our method was to identify algorithms that are bottlenecks in the computation and that can be executed concurrently, producing a hybrid sequential and parallel simulation. Our results show a performance gain that varied between 14% and 33%.