Icing

Question 1

Variables that determine where and how much ice an aircraft with pick up:

Answer 1

Speed of aircraft
Shape of airfoil
Type of cloud encountered
Type of ice encountered
Length of time in the icing conditions

Question 2

4 types of icing

Answer 2

Hoar frost
Clear ice
Rime ice
Mixed ice

Question 3

Hoar frost

Answer 3

Greyish-white, feathery, crystalline formation the can cover the entire surface of an aircraft
Very thin, easily removed

Question 4

Clear ice

Answer 4

Clear, hard ice that forms on the leading edges of the wings and spreads over the wing surfaces
When air temperature is between 0 to -10 degrees
Very difficult to remove

Question 5

Rime ice

Answer 5

Opaque, whitish ice that forms on the leading edged of the wings but does not spread over wing surfaces
Form between -15 to -20 degrees
Not as difficult to remove as clear ice

Question 6

Mixed ice

Answer 6

Mixture of clear and rime ice
Form between -10 and -15 degrees
Stronger than rime ice weaker than clear ice

Question 7

Icing intensities: Trace

Answer 7

Accumulation rate: less than 1/4 inch per hour
Not a problem for aircraft
Pilot should consider exiting icing before it worsens

Question 8

Icing intensities: light

Answer 8

Accumulation rate: 1/4 to 1 inch per hour
Occasional cycling of manual de-icing systems to minimize ice accretion
Not normally a problem unless exposed for length period of time
Pilot should consider exiting icing

Question 9

Icing intensities: Moderate

Answer 9

Accumulation rate: 1 to 3 inch per hour
May lead to potentially hazardous icing
Pilot should exit icing asap
Diversion might be required

Question 10

Icing intensities: Severe

Answer 10

Accumulation rate: more than 3 inches per hour
Rate of accumulation is not reduced/ controlled by anti-icing/ de-icing systems
Immediate exit from icing is necessary (change in heading/ altitude)

Question 11

Conditions that produce icing

Answer 11

Aircraft must be flying through visible water (rain/ cloud droplets)
When water droplets strike a surface, their temperature/ temperature of the surface must be 0 degrees or lower

Question 12

Which cloud types produce the heaviest icing

Answer 12

CU
TCU
CB

Question 13

Which cloud types produce the most frequent icing

Answer 13

SC (stratocumulus)

Question 14

Carburetor icing

Answer 14

Can form in clear air when humidity is high and outside temperature is well above freezing

Air passing through carburetor may drop up to 15 degrees in a fraction of a sec, if temperature in carburetor reaches 0 or lower, frost/ ice will form in carburetor passage.

Question 15

How icing affects aircraft performance

Answer 15

Lift is decreased
Drag is increased
Weight of aircraft increased
Propeller efficiency is decreased
Airflow to the engine is reduced
Aircraft may stall above normal stalling air speeds

Question 16

Pilot must include 6 items when reporting icing conditions:

Answer 16

Position
Time
Altitude
Type of aircraft
Type of ice & intensity
Weather icing is experienced in precipitation (ie. freezing rain to wet snow)