By Barry Fox Forschungszentrum Karlsruhe of Germany has come up with an alternative to chemicals for protecting aircraft from icing up. The company’s idea is to use microwaves instead. The areas of the aircraft’s skin that are most at risk are scored with slits and filled with a material that is transparent to microwaves. Wave guides carry microwaves—at frequencies safely beyond those used in radio and navigation equipment—from a generator inside the aircraft to the slits (WO 99/25614). The radiation passes through and melts any icy build-up.