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|  CHAPTER FIVE
AVIATION WEATHER
are equipped with anti-icing and/or deicing equipment. There are three common methods for
preventing and/or eliminating ice buildup: mechanical, fluids, and heat.
The mechanical method uses deicing boots, which are rubber bladders installed on the leading
edges of lift producing surfaces. Compressed air cycles through these rubber boots causing them
to alternately inflate and deflate, thus cracking accumulated ice and allowing the air stream to
peel it away.
Anti-icing fluids are freezing point depressants and are pumped through small holes in the
wing's leading edge. This fluid coats the wing, preventing ice from forming on the wing's
surface. Additionally, ground crews use deicing fluids to remove and prevent ice buildup before
takeoff.
Heat application capability to wings, props, tail surfaces, or engine intakes is installed in most
aircraft. Systems of this nature can be designed for either anti-icing or deicing purposes. Critical
areas can be heated electrically or by hot air bled from the engine's compressor section.
Recommended Precautions
Keep these precautions in mind when flying in the vicinity of icing conditions:
1.
Do not fly into areas of known or forecast icing conditions.
2.
Avoid flying in clouds with temperatures from 0 to 20 degrees C.
3.
Do not fly through rain showers or wet snow with temperatures near freezing.
4.
Avoid low clouds above mountain ridges or crests. Expect the heaviest icing in clouds
around 5000 feet above the mountaintops.
5.
Do not make steep turns with ice on the airplane due to increased stall speeds.
6.
Avoid high angles of attack when ice has formed on the aircraft since the aircraft is closer
to stall speed in these maneuvers.
7.
Under icing conditions, increased drag and additional power required increases fuel
consumption.
8.
Change altitude to temperatures above freezing or colder than -20 C. An altitude change
also may take you out of clouds.
9.
In freezing rain, climb to temperatures above freezing, since it will always be warmer at
some higher altitude. Do not delay your climb; ice can accumulate quickly. If you are going to
descend, you must know the temperature and terrain below.
10.
Do not fly parallel to a front while encountering icing conditions.
11. Avoid icing conditions as much as possible in the terminal phase of flight due to reduced
airspeeds.
12.
Expect to use more power on final approach when experiencing structural icing.
13.
Always remove ice or frost from airfoils before attempting takeoff.
5-18
Weather Hazards of Turbulence, Icing, Ceilings, Visibility, and Ash Clouds
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