Originally Posted by jcjeant
No I have no idea
Maybe reading
NPA 2011-03 will give you some idea.
An international working group (led by the Aviation Rulemaking Advisory Committee (ARAC), tasked by the Federal Aviation Administration (FAA), USA) worked between 1997 and 2009 to prepare recommendations for a regulation change. (...)
The proposed rule would require consideration of the SLD icing conditions (freezing drizzle and freezing rain) defined in the proposed new CS-25 Appendix O, part I, in addition to the existing CS-25 Appendix C icing conditions. The proposed Appendix O was developed by the ARAC IPHWG, which included meteorologists and icing research specialists from industry, FAA/FAA Tech Center, Meteorological Services Canada, National Aeronautics and Space Administration (NASA) and Transport Canada/Transport Development Center. The IPHWG collected and analysed airborne measurements of pertinent SLD variables and developed an engineering standard to be used in aircraft certification.