The FAA recently published a Notice of Proposed Rule Making (NPRM) that proposes expanding the requirements for aircraft encountering icing conditions. Recent high-profile cases of engine flameouts attributed to airborne ice crystal ingestion have focused attention on detecting and quantifying not only liquid water droplets but also airborne ice crystals.
In response to these events and the FAA publication, Goodrich is developing a lidar-based airborne optical icing conditions detector (OICD) that distinguishes ice crystals from liquid water droplets using circularly polarized light. The sensor is also capable of measuring optical extinction of a cloud, a parameter that can be used to quantify water content.
This paper discusses recent OICD test results for a wide variety of clouds generated in the NASA Glenn Icing Research Tunnel (IRT) and encountered during flight test campaigns with the University of North Dakota (UND.) The results demonstrate the capability of the OICD to measure cloud density and to discriminate between pure ice, pure liquid, and mixed-phase clouds.