Analysis of large, complex systems requires simulations of hybrid-system dy
namics (i.e., dynamics best described by a combination of continuous-time a
nd discrete-event models) and their interactions. To serve as valuable rese
arch tools, such simulations must also be computationally efficient, readil
y modifiable, capable of simulating systems using models of a wide range of
fidelity, and easily reconfigurable to simulate parts or all of the system
of interest. The development of a simulation architecture meeting these cr
iteria is described. Issues with its development are described conceptually
, and its application to safety analysis of the national airspace system is
discussed. In particular, an object-oriented approach to hybrid-system sim
ulation is detailed, and computationally efficient methods of updating the
simulation are described and compared. New asynchronous with resynchronizat
ion methods of timing individual objects are applied in an example, demonst
rating a significant improvement in simulation efficiency.