A new type of aircraft icing detection system

Ice accretion by the impact of supercooled water drops, or mixtures of these drops with ice, onto an aircraft in flight is a hazard referred to as icing. Aircraft certified to fly in icing conditions like airliners, currently have simplistic icing detection probes. Aircraft certification specifications recently developed in response to the discovery that ice accretion by the impact of supercooled large droplets (SLDs) has caused many aircraft accidents imply the need for an icing detection system (IDS) capable of discerning between ordinary icing conditions and the more hazardous SLD icing conditions. It is desirable that these new IDS be capable of measuring both the ice accretion onto the aircraft and the icing-hazard potential of the atmosphere around the aircraft. We report the development and flight test of an IDS consisting of a microwave resonator unit to measure ice accretion onto the aircraft and an optical unit to estimate the icing-hazard potential of the atmosphere around the aircraft. The results of flight tests in a jet aircraft with reference scientific measurements indicate that our new IDS is capable of detecting ice accretion in the aircraft and of discriminating between common icing conditions and the more hazardous SLD icing conditions.