The Atmosphere
Movement in the Atmosphere
Atmospheric Stability
Localised Winds
Clouds
Fronts
Visibility and Fog
Aircraft Icing
Thunderstorms
Altimetry
Weather Reports and Forecasts
Practice Exam

Icing and its Hazards

Ice forming on an aircraft can pose significant hazards and has been the cause of many accidents over the years.

Airframe Icing

Ice forming on an aircraft will:

Change the shape of the wing
Reduce lift
Increase drag
Increase weight
Potentially block pitot tubes and static vents, causing instrument failure

This significantly reduces performance, with the aircraft possibly not being able to maintain altitude or becoming uncontrollable.

Significant frost can form on the airframe overnight. It ALL must be removed before flight!
All ice must be removed from the airframe before departure. There is no such thing as ‘only a little ice’!

Engine Icing

Ice buildup on engines, propellors and internal components can:

Change the shape of the propeller, reducing thrust
Block air intakes
Buildup inside engine components, restricting airflow into the engine

This can leads to reduced power output or even complete engine failure.

Ice on a helicopter rotor blade:
Photo Credit: NASA

As a general rule, external airframe ice only occurs when flying in visible moisture (cloud, rain, fog etc.) with temperatures between 0°C and -20°C. Generally, ice does not form on the airframe in temperatures below -20°C. Instead, it will already be frozen ice pellets that ‘bounce’ off the airframe.

However, other forms of icing (particularly piston engine icing) can occur above 0°C and you will need an understanding of the different icing types.