that their products conform to the AMS 1424 and 1428 standards using the defined High Speed Ramp Test, Low Speed Ramp Test, and Water Spray Endurance Test. The objective of these standards is to ensure acceptable aerodynamic characteristics of the deicing/anti-icing fluids as they flow off aircraft lifting and control surfaces during the takeoff ground acceleration and climb. With the development of non-glycol deicing fluids these standards are evolving to address additional factors such as corrosion, foaming, thickening, residue formation, slipperiness, and mold formation. Cautions The repeated application of Type II, Type III or Type IV anti-icing fluid may cause residues to collect in aerodynamic quiet areas, cavities and gaps. These residues may rehydrate and freeze under certain temperature changes, in high humidity and/or rain conditions. In addition, they may block or impede critical flight control systems. An appropriate inspection and cleaning program should be established when using these types of fluids. Environmental impacts Many de-icing fluids, including glycol-based fluids, are toxic to humans and other mammals, and damage the ecosystems where the fluids are discharged, such as the areas around airports. The use of such fluids can cause changes to nearby acquatic habitats that harm fish and other wildlife. Ethylene glycol and propylene glycol exert high levels of biochemical oxygen demand (BOD) during degradation in surface waters. Large quantities of dissolved oxygen (DO) in the water column are consumed when microbial populations decompose propylene glycol. This process can adversely affect fish and other aquatic life by consuming oxygen needed for their survival. Thickened fluids typically use alkylphenol ethoxylate (APE) surfactants, the biodegradation products of which have been shown to be endocrine disruptors, and as such these are banned in Europe and are under EPA scrutiny in the U.S. A number of fluids also use benzotriazole or tolyltriazole corrosion inhibitors, which are toxic and non-biodegradable and thus persist in the environment. Research is ongoing to find less problematic alternatives. This is proving to be challenging due to the many performance and safety factors that need to be considered. One U.S. FAA-approved deicing fluid (Kilfrost DF Sustain) is 1,3-propanediol, a fermentation product of corn, as a freezing point depressant instead of ethylene glycol or propylene glycol. Benzotriazole (and tolyltriazoles), although not highly toxic, is not readily degradable and has a limited sorption tendency. Hence, it is only partly removed in wastewater treatment plants and a substantial fraction reaches surface water such