• Aircraft de-icing: What is it? Why is it so important?

Photo: © CEphoto, Uwe Aranas, CC BY-SA 4.0 on Wikimedia Commons

Aircraft de-icing is one of the most important procedures during the coldest months of the year. In winter, airports are obliged to activate their winter plans, which include all the measures and actions to guarantee safe operations.

One of the most crucial parts of winter operations is the de-icing procedure. But how is this done? In other words, how do you de-ice an aircraft? Read on to find out.

What is aircraft de-icing?

Aircraft de-icing is the process by which the ice that forms on the fuselage is removed, as well as any type of contamination that may affect the aircraft’s performance.

The de-icing equipment consists of trucks that, by means of a telescopic arm, spray the aircraft with a mixture of water and anti-icing agent. These tankers are equipped with boilers that heat the mixture to 82ºC.

De-icing fluid mixture is composed of water and glycol: the water melts the existing snow and the glycol slows down the formation of ice on the aircraft.

In addition, a dye is added so that operators can check which areas have been decontaminated.

Which surfaces are de-iced?

Typically, the surfaces that are de-iced are the vertical tail stabiliser, the horizontal stabiliser and the wings of the aircraft. These are the most important because they are where the control surfaces are located, so they need to be completely clear.

In addition, the landing gear doors, and also the radome (where the weather radar is located), are other parts to be de-iced.

However, it is true that, in extreme conditions, the aircraft must be de-iced in its entirety.

The importance of coordination in the aircraft de-icing process

The aircraft de-icing process at the airport is carried out in remote parking positions close to the runways.

It must be taken into account that it takes about five minutes to decontaminate an aircraft; in addition, from the beginning of the process, there are very limited time slots in which the aircraft can take off.

If this time is exceeded, and in order to ensure the highest safety standards, the aircraft would have to restart the de-icing procedure, resulting in high costs for the airline and a readjustment of airport slots.

Therefore, there needs to be full coordination between the de-icing teams and the control tower, which must allow the aircraft to take off immediately after receiving the de-icing process.

At multi-runway airports, one runway is usually reserved for take-offs only, in order to avoid possible delays.

  • By Matthew Groh - Own work, CC BY-SA 4.0

In-flight aircraft de-icing systems

Commercial aircraft are equipped with systems to prevent, or reduce, surface icing. These systems are used at very specific times of the flight, as they significantly reduce engine performance.

In addition, aircraft spend most of the flight out of icing conditions, so there is no need to use them continuously. The aircraft fly at altitudes of 36,000 feet, or 11 kilometres, at -56°C, so icing is impossible.

The most critical phases for icing are take-off and landing, which is when clouds are passing through, or it is raining at low temperatures.

The most favourable temperature for icing is between -5°C and 10°C, with high humidity. If you want to learn more about ice formation on aircraft, we recommend the linked post.

How is de-icing done in general aviation?

We have mentioned that commercial aircraft are equipped with powerful anti-icing systems, but how do our aircraft do it? How do we de-ice small aircraft?

To begin with, we have to bear in mind that most of our operations are carried out under VFR visual flight rules, so our flights are not performed under these conditions.

Even so, during the more advanced phases of training, when it is necessary to practice IFR instrument flights, the aircraft have several systems.

For example, the pitot tube, which registers the external pressure, is equipped with a heater, as is the propeller. In addition, the Diamond DA42s have a system in the wings to coat them with an anti-icing liquid or de-ice.

Every airport has its winter de-icing plan

You have already learned the importance of aircraft de-icing systems to ensure safe operations. But, in addition to that, airports all over the world have their ‘Winter Plan’: specific actions to adapt operations to seasonal weather conditions.

These include the maintenance of runways with snow ploughs or the use of melting liquids to prevent passengers from falling in transit areas.

In addition, during winter operations, the runway coefficient of friction is measured more frequently, as it is a fundamental data for pilots to calculate the necessary take-off and landing distances.

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