Aircraft deicing has been going on since the advent of flying in some form or fashion. In the early days aircraft were deiced in a pure mechanical operation. The control surfaces were scraped or brushed or both in many cases. As time and technology progressed, so did the cleaning of the aircraft.
In the 1950s the industry moved toward the use of deicing solutions. By the 1960s, commercial aviation had accepted the use of deicing solutions utilizing hot water and some mixture of glycol. It was during this era that inventors such as Ted Trump and the engineers at the John Bean Co. emerged. These inventors manufactured some of the first aircraft deicers of a vehicular design that incorporated the use of aerial devices to spray the aircraft with a heated fluid. This fluid was heated to almost boiling and then utilized to remove any frozen precipt from the control surfaces, fuselage and flight instruments. As the equipment evolved, so did the use of other equipment from the fire fighting industry. Fluid pumps and spray nozzles were both adapted. The use of hot fluid applied at a pressure of 150 psi with an adjustable flow of 20 to 60 gallons per minute became the norm in the aviation community. Many operators simply drowned the aircraft with 60 GPM of fluid when, in reality, 20 to 30 GPM would get the job done just as fast.
Operators were trained and re-trained, as most of the industry deicing was an infrequent occurrence. Only Mother Nature would determine the need for deicing. Deicing equipment was usually readied for service in September of each year with the utilization continuing through April 15. The season would vary depending on the location. In the early years aircraft mechanics would usually perform the deicing function. This was the norm until well into the 1970s, when some commercial airlines trained specific employees to perform the function. However, it was always and still is the captain’s responsibility to ensure the aircraft is clean and ready for flight.
As the technology and equipment progressed, so did the aircraft and the rest of the industry. By the early 1980s, a large part of the aviation industry was using pre-mix fluid ratios and spraying the heated solutions onto the aircraft to clean them for flight. Everyone seemed pretty content with the way the industry was working and things were good.
Then entered the EPA and the recognition that ethylene glycol was an environmental hazard. Millions of gallons of this fluid were sprayed around the world each year. It was soon realized that propylene glycol was not nearly as harmful to the environment and thus the industry switched to spraying propylene. Even with the change to propylene, there was a large amount of discussion regarding the reclamation of sprayed fluid. This continues today and is monitored closely at airports throughout the world. Many airports are reclaiming sprayed glycol and making it ready for re-use. Technology continues to improve this operational capability with many companies working on improving the reclamation of fluid.
Anti-icing fluid entered the deicing scene first in Europe and then in the mid to late 1980s in the US. This fluid was designed to coat the control surfaces and absorb falling precipt for a given time period. During this time frame, the aircraft would taxi out and on take-off roll, the fluid would begin to shear off the control surfaces at 80 knots, providing a clean wing for flight. This fluid was known as Type II and was made by a few chemical companies. The use of Type II fluid posed a problem for the equipment manufacturers in that the fluid was fragile and had to be handled and applied to the aircraft in a very specific manner. By the early 1990s, Type II fluid was widely accepted and used throughout the United States.