Post on 23-Feb-2016
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Sep 2012Lesson 4.8
Meteorology
Icing & Turbulence
Reference
From the Ground UpChapter 6.10 & 6.11:Icing & TurbulencePages 154 - 159
Introduction• Icing is the accumulation of ice on an
aircraft during flight or on the ground. Turbulence is the abrupt vertical movement of air.
• Icing and turbulence can create serious conditions for aircraft during flight.
Outline• Icing• Turbulence
Icing• Clear Ice
– Glass-like coating of ice– Formed by large supercooled water droplets that freeze slowly and
spread
Icing• Rime Ice
– Opaque, milky white ice– Formed by instant freezing of small supercooled water droplets
Icing• Frost
– White, feathery crystalline ice– Usually formed on the ground by sublimation on clear nights
Icing• Frozen Dew
– Clear, crystalline ice– Dew formed in the morning freezes
Icing Protection• Fluids
– Alcohol-based fluid released from leading edge of wings and propellers
– Makes it difficult for ice to form
Icing Protection• Rubber Boots
– Rubber membrane on leading edge that pulsates– Breaks off formed ice
Icing Protection• Heating Devices
– Heats ice-prone areas to melt or prevent ice
Turbulence
Turbulence Classes• Light
– Momentary, slight change in altitude and/or attitude– Occupants may feel slight strain against seat belts
• Moderate– Slightly more intense– Occupants feel strain on seatbelt– unsecured objects move around
• Severe– Large and abrupt changes in altitude, attitude and/or airspeed– Airplane may go out of control momentarily– Occupants forced violently against seatbelts
• Extreme– Airplane tossed around violently and impossible to control– Structural damage may occur
Turbulence Types• Mechanical Turbulence
– Friction between air and rough ground (hills, trees, buildings etc)
• Thermal Turbulence– Ground heating creates upward currents of warm air
• Frontal Turbulence– Warm air is forced over cold front, turbulence at boundary
• Wind Shear– Sudden change in wind speed or direction between layers of air– Usually associated with strong inversions or fast-moving cold fronts
• Clear Air Turbulence– Unexpected, violent turbulence at high altitudes in clear air
Next Lesson
4.9 – MeteorologyWeather Reports & Forecasts
From the Ground UpChapter 6.14.3 & 6.14.4:Aviation Weather Reports & ForecastsPages 163 - 172