Comparisons of Cloud In Situ Microphysical Properties of Deep Convective Clouds to Appendix D/P Using Data from the High-Altitude Ice Crystals-High Ice Water Content and High Ice Water Content-RADAR I Flight Campaigns

In situ cloud data from three international flight campaigns are compared to the Federal Aviation Administration (FAA) Title 14 Code of Federal Regulations Part 33 Appendix D mixed-phase/glaciated environmental envelope and the corresponding identical European Union Aviation Safety Agency (EASA) CS-25 Appendix P envelope. The appendices consist of a temperature-altitude envelope, a 99th percentile total water content (TWC) envelope at the 17.4 Nm distance scale, a distance factor for estimation at other distance scales, ice crystal median mass diameter (MMD), and recommended liquid water content (LWC) levels in mixed-phase icing conditions. The data were collected during 54 flights out of one subtropical and two tropical locations, with 472 runs from about 17,000 ft to 39,000 ft in approximately 115 clouds. The campaigns provide about 29,600 Nm of in situ data in deep convection over four targeted temperature intervals: −10°C, −30°C, −40°C, and −50°C, all ±5°C. The dataset is a modern and unique documentation of the deep convective cloud ice crystal icing (ICI) environment, and the results described in this article will contribute to regulatory and industry assessment of Appendices D and P.