Abstract: In a de-icing system for preventing the formation of ice on, or for de-icing, icing-prone areas of an airplane, the icing-prone areas include dielectric composite structural materials, which are highly permeable for electromagnetic waves, and at least two microwave sources are provided and connected to microwave uncoupling areas disposed adjacent the icing-prone areas, and the microwave sources are interconnected by redundant switchable microwave guides permitting bridging of a microwave source in case of failure of such microwave source.