Icing Flashcards
When does active frost form
Frost will form on an unprotected surface, or re-form on a surface protected with de/anti-icing fluid when the holdover time has expired
Definition of anti-icing
It is a procedure in which an Aircraft Anti-Ice Fluid (AAF) is supplied to a surface free of frozen contaminants for a limited period of time
What is clear ice
Clear ice is a coating of ice, generally clear and smooth, but with some air pockets. It is formed on exposed objects at temperatures below, or slightly above freezing temperature, with freezing of super-cooled drizzle, droplets or raindrops.
Definition of de-icing
De-icing is a procedure by which frost, ice, snow or slush is removed from an aircraft by use of a heated Aircraft De-Icing fluid (ADF), to provide surfaces free of contamination.
Definition of icing condition
When OAT on ground, or TAT in flight is at or below +10°C and there is visible moisture in the air, such as clouds, rain, ice crystals or fog with a visibility of 1 mile or less, or there is standing water, slush, ice or snow present on the taxiways or the runway.
When shall engine anti ice be selected on
When in icing conditions and temp is between +10°C to -40°C in climb and cruise, and anytime the temp is lower than +10°C in descent
What is the minimum speed in extended icing conditions
VLS +15 kt in clean configuration, or VLS +5 kt
How much shall landing distance be increased with in extended icing conditions
Multiply landing distance with 1.1
When is FAN ICE SHEDDING procedure required
When on ground in icing conditions with NO freezing fog in temp of +3C or below
Describe the FAN ICE SHEDDING procedure
Increase N1 to 50% for 10 sec for every hour on the ground, and before takeoff
What is required if freezing fog is present
Apply the CORE ICE SHEDDING procedure
Describe the ICE CORE SHEDDING procedure
Increase
What is the maximum cumulative taxi time in freezing fog
45 min
What action need to be taken after taxi in freezing fog
Write up total taxi time in the tech log
If taxing out for departure in freezing fog, and the taxi time is less than 45 min, is an log book entry required
No
Icing conditions are deemed severe if
When there is approximately 5 mm of ice accretion on the airframe
When using rain repellent, how long does it take for the windows to be covered
30 sec
Ground power should be used for APU start if OAT is
-15°C or lower
How long does IRS alignment take if OAT is -15°C or lower
15 minutes
What type of icing is acceptable on the aircraft surface
Thin hoarfrost on the upper surface of the fuselage and underside the wing tank area. Maximum layer of 3 mm of hoarfrost
When does hoarfrost form
On a cold and cloudless night
Hoarfrost is thin enough to…
Distinguish surface features underneath
When is the probe/window heat switched to auto
After the first engine start
Cold soak can occur in ambient temp range of…. And the aircraft structure temp of…
-2°C to +15°C, 0°C or below
In what visibility does freezing fog occur
Less than 1km
When does the start of the holdover time begin
At the start of the anti-ice treatment
How is a pre-takeoff contamination inspection carried out
By a flight crew member from inside the aircraft, within 5 min of takeoff
How is a pre-takeoff contamination check carried out
Externally by ground crew if the HOT has been exceeded, also within 5 min of takeoff
What are the lower vs the higher HOT values for
Moderated vs light precipitation
Where are the HOT tables for heavy precipitation found
They do not exist
Under which precipitation condition is takeoff not allowed
Moderate or heavy freezing rain
What is the definition of a contaminated runway
More than 25% of the runway is covered by snow, slush, standing water, ice or compacted snow
When is a runway surface considered wet
When the surface is covered with 3 mm of…
What are the considerations when taxi out in icing conditions
• at speeds below 10 kt: Anti-skid deactivates
• Engine anti-ice will increase ground idle thrust
• To minimize the risk of skidding during turns, avoid large tiller inputs
•
