Be careful. Icing is defined in Appendix C of Part 27 and 29, but it only covers water droplet sizes up to 50 microns - that's 0.5mm (or the thickness of a mechanical pencil lead). In that condition, the droplets are more or less suspended in mid-air.
Anything larger than 0.5mm is considered to be freezing precipitation - and no aircraft (fixed or rotary wing) is cleared for flight in those conditions. So if it's not snow, and you encounter something falling from the sky and freezing, stay on the ground.
Last edited by Shawn Coyle; 19th Feb 2009 at 21:04.
Reason: minor correction