Chapter 15 - Icing Flashcards
If an aircraft with anti-icing capabilities flies through freezing rain below a front, what should the aircraft do?
Climb to get out out of the freezing rain and into the warmer air mass.
If an aircraft with no anti icing capabilities flies into freezing rain below a front, what should the aircraft do?
Turn around and avoid the freezing rain.
Where does freezing rain occur in a front?
Between the 0degC isotherms, in the different fronts, but inside the cold air mass.
What is anti-icing?
Methods that prevent icing happening.
What is de-icing?
Methods that remove ice.
What are the characteristics of rime ice and how is it formed?
Rough
Milky
Opaque
Formed from small SCWD in 0 - -40degC temperatures (worst in 0 - -7degC)
What are the characteristics of clear ice and how is it formed?
Glassy
Clear
Translucent
From large SCWD in temperatures between 0 - -20degC
What are the labels for icing severity?
Cereal bowl with vertical line
1 for light
2 for moderate
3 for severe
How does airframe icing occur?
From SCWD hitting the airframe or from supercooled airframe hitting water droplets
What Issues does icing produce for an aicraft in flight?
Lift is reduced
Weight is increased
Drag is increased
Thrust is decreased (due to prop/blade icing)
Where does rime icing occur?
At a warm front or an occulusion.
What is hoarfrost and when does it occue on an aircraft?
Icing that occurs without visible moisture (deposition)
Occurs when cold soaked aircraft flies through warmer air usually during clear winter nights.
What is the clean wing principle?
All aerodynamic surfaces must be clean before flight.
How does intake icing occur?
Intake air velocity increases (due to ducting) and causes a drop in pressure and temperature to within icing range, with high humidity.
Generally what conditions create the worst icing?
Large number of SCWD
Thin aerofoil
High air speed
OAT approximately -10 - -20degC
How does carburettor icing occur and when is it worst?
A combination of fuel vaporisation, causing temperature to drop, and pressure reduction at the carburattor venturi causes air temperature to drop below freezing.
It is worst in warm moist conditions with throttle at or close to idle.
What kind of icing occurs in Cirrus, Cirrostratus and and Cirrocumulus clouds?
Rare, trace/light
What kind of icing occurs in altocumulus, altostratus and stratus clouds?
light to moderate rime icing
What kind of icing occurs in stratocumulus clouds?
Moderate and mainly rime icing.
What kind of icing occurs in nimbostratus clouds?
Rime or moderate clear ice, occasionally severe
What kind of icing occurs in cumulus clouds?
Moderate or severe main clear ice.
What kind of icing occurs in cumulonimbus clouds?
Moderate or severe mainly clear ice.
