Safety On The Line

Safety On The Line

National Air Transportation Association offers aircraft deicing training through its Safety 1st, Professional Line Service Training program

By Michelle Garetson/p>

By National Air Transportation Association

April 2002

Winter weather can present a variety of conditions in which caution must be used. For example, aircraft ramps are often more slippery than city streets because of a mixture of fuel, oil, and frozen water. Ramps are often dark asphalt, which creates a phenomenon known as "black ice," a layer of ice that is invisible. Winter conditions may reduce the visibility on the airport, demanding that you further reduce speed. Since a fully loaded 3,000-gallon refueler can weigh nearly 40,000 pounds (20 tons), this is a considerable amount of weight to bring to a stop whether you are driving on a dry, wet, or icy surface.

If your operation is located in a winter climate, you may be called upon to prepare aircraft for departure during or after snow or freezing precipitation. There are many methods which are used to prepare the aircraft for flight, including: placing the aircraft in heated hangars, brushing loose snow off with a soft bristle broom, or by spraying a heated glycol-based chemical fluid (called "deicing").

In addition, you may also spray a coating of alcohol-based anti-icing liquid onto the aircraft wings and control surfaces, to inhibit the formation of ice, slush, and snow on the aircraft during taxiing and preparation for takeoff.

Studies indicate that the formation of snow or frost in a thickness comparable to that of medium sandpaper can degrade the lift of an aircraft by as much as 30 percent. Consequently, glycol based chemicals are used as the most effective method of providing and inhibiting snow and ice on the aircraft.

Deicing refers to the removal of snow, frost and ice. Anti-icing refers to the coating of the aircraft to inhibit snow and ice accumulation.
There are several types of fluids; however, there are two that are primarily used for general aviation aircraft. Type I Fluid is used in the deicing process and is a medium consistency flowing liquid. Type II Fluid is an anti-icing compound used primarily in a two-step process after deicing. Type II is a much thicker consistency, designed to stick to aircraft surfaces. (Refer to the material safety data sheets for glycol handling procedures).

Different aircraft may have specialized deicing and anti-icing procedures. Some aircraft are not approved for Type II fluid. Check with the flight crew for special aircraft needs prior to deicing any aircraft.

Aircraft Deicing Procedures

• Start at the tail of the aircraft to remove the heaviest accumulations of snow and ice first. This will prevent the aircraft from becoming unbalanced or tail heavy.
• DO NOT spray fluid directly into engine inlets, APU inlet or exhaust ports, pitot tubes, or static ports.
• DO NOT spray hot deicing fluid directly at flight deck or cabin windows. Sudden temperature changes can cause damage.
• When deicing wings and tail surfaces, the spray should be directed from the leading edge backward, much like the air passes over the aircraft while in flight. This will avoid accumulation of fluid inside the surfaces. Use a sweeping motion from the leading edge aft to effectively remove snow and ice from the aircraft's surface.
• Wings should be sprayed from outboard to inboard to avoid the weight of snow and ice on the outboard sections of the wing.

When completed, treated areas on the wings should have a glossy fluid appearance. Some flight crew members may have you perform a touch test to determine if all ice and snow is removed.