Icing

Question 1

What is a supercooled water droplet?

Answer 1

Droplets that form and exist at below 0C temperatures.

Question 2

Explain the effects of ice on an airplane’s thrust, lift, drag and weight.

Answer 2

Decreases: Thrust and lift.
Increases: Weight and drag.

Question 3

Icing does what to indicator readings of airspeed, altimeter and rate of climb?

Answer 3

May give erroneous readings.

Question 4

Water droplets form in two basic forms: slow and ____ freeze.

Answer 4

Quick

Question 5

MET factors that affect icing are:

Answer 5

LWC, Droplets Size and Temperature.

Question 6

What temperature range does the worst and most icing occur?

Answer 6

Worst: 0 to -10C
Most: 0 to -15C

Question 7

What temperature has no icing?

Answer 7

-40C and lower.

Question 8

Describe Clear icing and its properties.

Answer 8

Glass-like
Highly cohesive and adhesive
Spreads from leading edge, may cover whole air craft
More serious than rime ice

Question 9

Convective cloud types and freezing rain/ drizzle produce which type of icing?

Answer 9

Clear icing.

Question 10

Which icing is rough, milky and opaque, formed by the instantaneous freezing of small super-cooled water droplets?

Answer 10

Rime icing.

Question 11

Rime icing forms in what cloud types and at what temperatures?

Answer 11

Higher cloud types, AS, AC and NS @ temperatures below -15C.

Question 12

Which icing type is easily removed by de-icing equipment?

Answer 12

Rime icing.

Question 13

Which icing type appears milky, rough and clear in some spots?

Answer 13

Mixed icing.

Question 14

Explain the icing path of each icing type from the initial point of contact. (down/ upflow)

Answer 14

Clear: Down-flow
Rime: Up-flow
Mixed: Both up and down-flow

Question 15

Which cloud types does mixed icing occur in near warm fronts and in strong upslope flow?

Answer 15

NS and AS

Question 16

Mixed icing occurs in thick ST and SC in what temperatures?

Answer 16

Warmer sub-zero temperatures.

Question 17

Which icing intensity does not require de-icing unless icing is encountered for greater than 1 hour.

Answer 17

Trace

Question 18

Which icing intensity does not present a problem so long as de-icing equipment is used?

Answer 18

Light icing

Question 19

Which icing intensity requires the use of de-icing or diversion?

Answer 19

Moderate icing

Question 20

Which icing intensity renders de-icing equipment useless?

Answer 20

Severe icing

Question 21

Which is worst for icing, freezing rain or freezing drizzle?

Answer 21

Freezing rain results in severe icing, freezing drizzle is light to moderate.

Question 22

What type of icing occurs when air is in contact with an object at temperatures sufficiently below freezing?

Answer 22

Hoarfrost.

Question 23

True or False?

For hoarfrost to form in lower humidity, the surface temperature must be colder than in high humidity.

Answer 23

True

Question 24

What the the 3 aerodynamic factors that influence icing formation?

Answer 24

Airfoil size & shape
Aircraft/ airfoil speed
Aircraft skin temperature

Question 25

True of False? An airfoil with a smaller radius of curvature collects more ice per unit area?

Answer 25

True, sharp edges will ice first and more quickly.

Question 26

With regards to aircraft speed, what is true regarding icing?

Answer 26

The greater the speed, the greater collection efficiency and more icing.

Question 27

Does increased speed increase or decrease the aircraft skin temperature? Why?

Answer 27

Increases temperature due to friction and compression warming.