Solid-state power controllers can be designed to meet the stringent performance and reliability requirements for aircraft electrical systems. Every stage in the design requires complete understanding of the science and the art of the technical disciplines involved. Moreover, an integrated systems approach is necessary to take full advantage of each technology. The complete safe-area characteristic of the power transistor is most important in design of dc controllers. High surge capability, as well as high di/dt and dv/dt capability, is important in design of ac controllers. Finally, the power-handling capability of the hybrid module package must be consisered.