Abstract: An icing hazard avoidance system and method utilizes a forward-looking, single frequency, dual-polarization pulse radar system as well as temperature sensing means to determine if supercooled liquid water (SLW) drops are present in an aircraft's flight path. A processor determines the ratio of co-polarized and cross-polarized returns. This ratio and the temperature of the atmosphere indicate if SLW drops exists. If an icing hazard is determined, an indicator in the cockpit of the aircraft alerts pilots so that avoidance measures may be taken.

Abstract: An airborne Icing Hazard Detector for aircraft uses dual frequency radar beams which are transmitted into a cloud ahead of the aircraft. The reflected signals at each of the two frequencies are compared and processed to determine the presence, amount and location of regions of liquid water in the cloud. The presence of liquid water is determined as a result of liquid water attenuating the power of one of the signals a greater amount than the other signal, due to different attenuation characteristics of the two signals at the two frequencies. A temperature sensor provides ambient temperature information to determine if the detected liquid water is super-cooled. Upon detection of a predetermined amount of liquid water and the determination that it is super-cooled, an advance warning indication is provided to allow the pilot to avoid flying through the volumetric region of supercooled liquid water and risking ice formation on the aircraft.