A dual channel inflight ice detection system to detect ice accretion on an aircraft surface by illuminating an ice collecting surface mounted on an aircraft with linear polarized light. The backscattered light is acquired in two light conductors one with polarization sensitivity aligned to the transmitted light and the second with polarization sensitivity orthogonal to the first. The presence of ice is determined by the change in the ratio of light intensities in the two light conductors.

An ice detection system that detects the onset of ice accreation on an aircraft's external surfaces, continuously measures its thickness and growth time history and provides the type of ice, glaze or rime, is disclosed along with an independent way to confirm that the contaminant is known to be ice and only ice. Total impedance data, thermal conductivity value and complex dielectric properties are used to discriminate between ice, water, deicing fluid and snow with measurements made by low cost, low power consumption, low profile, miniature electronic chips, components and devices collocated together on the external surface in a thin pliant patch that does not effect the airflow about the aircraft. The ice detection system provides ice accreation data and warning signals to displays and aural signaling devices in the cockpit for the pilot and to the control console of a ground controller flying the aircraft if it is unmanned.