This paper proposes an ${\cal H}_{\infty}$ control strategy for swarm formation of multiple-unmanned aircraft systems based on the virtual structure considering wind effects and measurement noise. The proposed strategy provides a rigid body formation of unmanned aircraft with motion synchronization in a decentralized manner. Unlike the current strategies in the literature, which consider motion synchronization in specific topologies, this approach proposes a general topology for coupling agents and guarantees the stability of the multiagent system in the presence of communication delays. Simulation results for a multiple-unmanned aircraft system confirm the accuracy of the proposed control strategy for formation flight.