This specification covers additives for aviation fuels used to inhibit ice formation in aircraft fuel systems. Three types of fuel system icing inhibitors are provided as follows: type I - ethylene glycol monomethyl ether, type II - anhydrous isopropanol, and type III - diethylene glycol monomethyl ether. The relative density, color, distillation range, non-volatile matter, and odor shall be tested to meet the requirements prescribed. The water properties, heptanes miscibility, acidity, water miscibility, and flash point shall be tested to meet the requirements prescribed.