Page 320 - PPL-engelsk 2025

Meteorology

3.9.2.1 Four main types of ice

When talking about ice on an aircraft, there are three main types of ice:

- Clear Ice

- Rime Ice
- Mixed Ice

- Rim Frost

Clear ice forms from large droplets. The droplets hit the profile, break apart,

and spread out before freezing.

As the name suggests, the ice is clear and

homogeneous.

Clear ice is the most dangerous type of icing
during flight.

Here’s how clear ice appears on a

profile and how it affects the airflow

around the profile.

Clear ice can increase drag by up to 500%.

The dangers of clear ice are big due to:

- Loss of lift due to the altered wing profile and disruption of smooth

airflow over the wings and tail surfaces

- Increased drag from the enlarged wing profile area

- The weight of the large ice mass that can accumulate quickly

- Vibration caused by uneven loading on the wings and propeller blades.

When large chunks break off, vibrations can become severe enough to

significantly damage the aircraft's structure.

Flight Theory PPL(A)(UL)/LAPL Henning Andersen, Midtjysk Flyveskole© 2025 320