Met - Airframe Icing

Question 1

What will cause a super cooled water droplet to freeze …..

Answer 1

any disturbance to its spherical shape

Question 1

Why is airframe ice not possible beyond -30⁰C …..

Answer 1

because all the water vapor in the air is already ice and this does not stick to the skin of the plane

Question 2

Rime ice forms in the following types of clouds ……

Answer 2

1. Ac or As
2. Sc and St or Cu but only above freezing

Question 2

Describe catch efficiency ….

Answer 2

the thinner the cross section the higher the catch efficency of it

Question 3

In supercooled water droplets - the smaller the droplet the ….. the temp needs to be to freeze

Answer 3

lower

Question 4

Hoar frost forms when ….

Answer 4

the airframe is below freezing and moves into a warmer more humid air. The moisture skips the condensation phase and moves from vapor to ice (deposition)

Question 6

Frost is …..

Answer 6

frozen dew and should be removed before flight

Question 6

for clear ice to form there needs to be 3 things …..

Answer 6

1. Sub zero temps
2. super cooled water droplets
3. Large water droplets

Question 7

Supercooled water may be found at temps as low as ….

Answer 7

-40⁰C

Question 8

Describe how clear ice forms …..

Answer 8

Large super cooled droplets spread out before freezing onto the airframe creating a layer if clear ice

Question 10

Rime ice creates a ….. ….. disrupting the airflow

Answer 10

mushroom effect

Question 10

Describe the danger of freezing rain …..

Answer 10

if a plane flys through freezing rain and its airframe temp is below 0⁰C then clear ice may form

Question 12

clear ice needs small/large droplets

Answer 12

large

Question 14

Rime ice needs small/large droplets …..

Answer 14

small

Question 15

Rime ice forms on ……

Answer 15

leading edges and pitots

Question 16

Clear ice forms in what types of clouds ……

Answer 16

Thick As or in Cu, Cb and NS above freezing

Question 17

Rime ice forms at temps …..

Answer 17

-10⁰C to -30⁰C