RELEVANT DISCUSSION: FAR 91.527, 91.1101, 121.629, 125.221, 135.227, 135.345, AIM 7-5-14, OPSPEC A023, AC 20-73, AC 20-117, AC 120-58, AC 120-60, AC 135-17, NASA
There are four standard aircraft deicing and anti-icing fluid types: Type I, II, III and IV.
Type I fluids (red-orange in color) are the thinnest of the fluids. They are essentially deicing fluids but can also be used for anti-icing. Because they’re not thickened, they will shear or blow off the airplane at relatively low airspeeds (around 60 knots). However, their low viscosity results in the shortest set of holdover times (HOT). Type I is always applied heated and diluted; it flows off easily, and can fail suddenly. Type I is available throughout the world.
Type II fluids (clear or straw color) add thickening agents to…