ii. Introduction
This case study concerns the impact of deicing of airplanes to the living things and the environment. This topic is important to be investigated because the deicing process caused many problems to the living things and the environment but at the same time, this process is crucial to be done for a safe take off.
Deicing of airplanes is a process that removes ice from the airplanes bodies. It helps an airplane to function properly during cold weather. In cold weather, the airplanes need to deal with ice, snow, and frost that built upon their bodies. The built-up ice, snow, and frost may change the geometry shape of the wings of an airplane, disrupt the airflow and thus, decrease the lift ability. As we know, each part of an airplane is designed to create lift force. Most of the lift force is generated by the wings and rear tail of an airplane. Both wings and rear tail of an airplane is designed or engineered with a specific shape that crucial for the airplane to have a proper lift to fly. This shape made the lift possible but the built-up ice, snow, and frost due to cold weather might change the shape of those parts and this may lead the parts to function in dangerous and in the improper way. Besides, the built-up ice, snow, and frost may increase the drag and restrict the moving parts of an airplane too.
In order to prevent a dangerous take-off, deicing process is urged to be done. In the deicing process, some chemicals are used. The common one is the de-ice type I. It prevents the ice built up in a short period of time and is used when the temperatures are not very cold or extremely low. This fluid is heated to 80 degrees Celsius before the fluid is sprayed on the surface of an airplane to remove all the built up ice, snow, and frost.
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The deicing fluid is applied on the along the centerline of the fuselage at the upper part and then over the side of the fuselage. The fluid is preventing contact with the window. At the wings, the fluid is sprayed starting from the front edge to the trailing edge. The workers in charge have to take precautions to not letting the fluids from getting into the engines and minimize the fluids application at the landing gear and wheel bays areas.
In the United States, the Federal Aviation Administration (FAA) is controlled and managed for the deicing procedures. The FAA put on some criteria for approving the deicing chemicals while the federal and state environmental agencies are those that respond to evaluate the impacts of the deicing chemicals or fluids to the environment and to regulate the discharge of the fluids accordingly. The deicing process has often been done during the winter storms, so the runoff from the storms will transport the deicing chemicals from the airfield into the local receiving waters such as wetlands, rivers, coastal areas, creeks, and lakes. However, most of the federal and state environmental agencies that existed do not include the limits on deicing chemicals in the stormwater discharges. The airports used this advantage to freely discharging the stormwater that contaminated with deicing fluids. This lead to water pollution issue.
As the air travel is increasing over time, the volume of deicing fluids discharged to the environment is increasing too. Thus, the airports are struggling to decrease the impacts of the deicing fluids to the environment while maintaining the safe air transportation.
iii. Literature Review
In history, the airplanes could not fly during the winter. As time flies, the new techniques were started to exist but they need to perform the techniques manually to remove the ice that adhered to the airplanes bodies. Somehow, a series of tragic crashed happened in 80s caused the commercial aviation industry to take more scientific approaches to de-icing.
Deicing of airplanes remove and inhibit the formation of ice, snow and frost at the bodies of airplanes especially at the fuselage, wings and rear tail. This practice, remove all the accumulation at the airplanes bodies before take-off.
Based on a research, Logan airport applying deicing fluids on airplanes surfaces as a hot mixture under pressure using a nozzle mounted on a vehicle. During deicing process, in about only 20%-50% of the deicing fluids remained on the airplanes bodies while the rest in about 80% end up as runoff. Besides, an airplane can reach from 10 gallons to thousands gallons usage of deicing fluids. Either airline or the service company is responsible to do this procedure.
There are four types of deicing fluids which are Type I, Type II, Type III and Type IV. These four types of deicers are distinguished by the composition and the holdover over time of deicing fluids application. In this study, the Type I deicers will be focused on because the other three type deicers are actually the anti-icing fluids. The deicing fluids and anti-icing fluids are differ in compositions. The composition of deicing fluids are usually ethylene glycol, diethylene glycol or propylene glycol based fluids containing water, corrosion inhibitors, wetting agents and dye while anti-icing has the addition of polymeric thickeners which can prevent the ice formation for a longer period of time compared to deicing.
IV. Method (Findings)
Types of deicing chemicals
Deicing chemicals divide into two major types which are the organic chemical with potassium acetate and the other one is chlorate which contains NaCl, CaCl2, MgCl2, KCl and others. The organic chemical is effective and almost non-corrosive but it is quite expensive, so it is usually used in airport only. The other kind is generally called deicing salts. It is much cheaper but the breakage by the salts is quite serious.
Working principle
The salty water is not easy to ice up because of its ability to absorb heat and it has lower freezing point. That is why the deicing chemicals can decrease the melting point of snow and ice. Thus, make it easier for the ice and snow to turn from solid phase to liquid phase.
