When we travel, there are many things we often do pay attention at, and ice is one of them. When an aircraft is cruising, the temperature typically ranges between -40 °C and -50 °C, and during this phase, pilots face their main threat: icing conditions. Ice formation on crucial aircraft surfaces can lead to severe consequences, requiring its prevention and management.
Fortunately, aviation never stops evolving; airplanes have systems to prevent ice formation on crucial parts. In this article, we will not talk about these systems, but we will talk about everything we should know about ice formation on airplanes.
What is icing?
Icing is ice formation on different aircraft surfaces, including wings, ailerons, propellers, and even pitot tubes.
Ice formations must be avoided as it increases the aircraft’s weight and air resistance which can lead to issues with movable parts.
It is crucial to note that an aircraft is meticulously designed for minimal air resistance and optimal aerodynamics. Ice disrupts this aerodynamic efficiency, increasing resistance and diminishing lift, potentially causing accidents like the SAS Flight 751 or Continental Airlines Flight 1713 incidents.

Aircraft Ice Formation and Types of Ice
As we explained earlier, airplanes fly at altitudes where temperatures are very low. However, during winter, ice is also a concern while the aircraft is on the ground. If the temperature is below freezing, it’s easy for ice to accumulate during the time the plane is stationary, especially if it’s snowing.
There are different types of ice, and we will explain the main ones:
Clear Ice
Clear ice forms when the temperature ranges between 0 °C and -10 °C. This is likely one of the most dangerous types in aviation.
It occurs when large water droplets impact the wing’s leading edge and gradually freeze.
Clear ice can be particularly hazardous as it alters the wing’s shape, creating a deformed second layer on the upper part of the wing. This significantly increases the aircraft’s resistance, reduces lift, and raises the probabilities of an accident.


Granular Ice
Granular ice forms when the temperature is close to -15 °C. Granular ice forms instantaneously, unlike clear ice, when freezing tiny water droplets collide with the aircraft’s surfaces.
Mixed Ice
Mixed ice occurs when the two types above combine—small droplets instantly freezing and larger ones freezing progressively.


Frost
Frost forms when an aircraft spends several hours parked outdoors. It results from water vapor in the atmosphere condensing upon contact with the aircraft’s fuselage and freezing. Frost is expected during the night or when temperatures are extremely low.
Aircraft Parts Most Affected by Ice
No part of the aircraft is exempt from freezing, but some parts are more susceptible and experience more significant repercussions from ice formation. These include:
Propellers
Propellers are usually located at the nose of the aircraft or on the wings. For proper functioning, there should be nothing in front of them. Water striking directly against the propellers increases the chances of freezing.
Ice formation on propellers can be hazardous, reducing the propeller’s aerodynamics, decreasing the thrust produced, and directly affecting the aircraft’s speed.


Pitot Tube
This part of the aircraft measures both total and static pressure, enabling the airspeed indicator and altimeter to function properly.
The pitot tube is one of the most affected by ice, and due to its significance, it has a heating system to prevent ice formation, safeguarding its operation.
Wings
Wings are among the most critical surfaces of the aircraft, responsible for creating lift for flying.
Ice formation disrupts the wings’ task by interrupting the airflow, reducing lift, and increasing air resistance.
Additionally, ice adds significant weight to the aircraft, and this weight on the wings can limit the rate of climb or even necessitate descent.

Most aircraft are equipped with systems to prevent ice formation, such as “wing anti-ice,” which prevents ice formation on the wing’s leading edge. In addition to the aircraft’s inherent systems, there are other means to combat ice formation, such as “de-icing” fluid, which is sprayed on the plane to melt existing ice; this can be accompanied by “anti-icing” fluid, which prevents new ice formation on that part of the aircraft. However, we’ll dive further into this topic, which we discuss in our commercial pilot course, in our next article.