On January 5, 2015, the FAA enacted new regulations to improve safety for flight in icing conditions, including Supercooled Large Drop (SLD) conditions, for a portion of transport category airplanes determined to be affected by these icing conditions. The new regulations include a new icing certification rule, §25.1420, and introduce an FAA engineering standard, Appendix O, that defines the SLD environments, including freezing drizzle and freezing rain, for certification for affected aircraft. These SLD regulatory changes necessitate improvements to icing weather information in the terminal area, both at the surface and aloft. Identification and discrimination of SLD environments and other types of icing environments are necessary to allow flight planning and operational decisions consistent with these new regulations and certification basis.
As a result, the FAA has initiated a research and development project named Terminal Area Icing Weather Information for NextGen (TAIWIN). The purpose of TAIWIN is to develop the capability and associated requirements to enable provision of reliable, highly resolved, accurate diagnoses and forecasts of icing conditions, both SLD and Appendix C, at the surface and aloft in the terminal area to support flight mission planning and aircraft operations. The TAIWIN project, near-term requirements, and follow-on plan to reach more mature TAIWIN capability needs will be discussed.
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