A thermal anti-ice system in an aircraft. A controlled valve receives air from a compressor bleed port of an engine of the aircraft. A self-regulating valve is fluidly connected between the controlled valve and an inlet of the engine. A first pressure sensor senses pressure between the valves. A second pressure sensor senses pressure between the self-regulating valve and the inlet. The system can be used to de-ice aircraft inlet lip skins made of composite materials that have comparatively lower design temperatures than other comparable materials.