Safe and punctual flying during the winter conditions
De-icing is an important part of flight preparations and safe operation in winter. Our home hub, Helsinki Airport, has excellent de-icing capabilities, which ensures efficient traffic even in winter frosts. Finnair is one of Europe's most punctual airlines despite the challenging winter conditions in the north.
The airport’s de-icing area gets busy on a snowy day. In addition to Finnair, it’s used by other airlines. It is a pilot’s call to book a slot for de-icing. It depends on the weather and conditions what kind of de-icing treatment is required.
Ice forms when it rains and is cold
“If the air humidity is high, it is snowing or raining, and the temperature is below freezing or zero, de-icing is required. However, other factors like low wing temperatures after landing may require de-icing as well,” says Juha Ekström, responsible for de-icing at Finnair's ground operations. On the other hand, dry, frosty weather does not necessarily need it. The most challenging condition is freezing rain, as ice forms on the aircraft's wings quickly.
Pilots use an application that allows them to choose suitable de-icing based on weather conditions. This avoids unnecessary use of liquids and, at the same time, saves jet fuel that is consumed during de-icing.
At Helsinki Airport, the de-icing season lasts for nine months. “We are ready from the beginning of September until the end of May, but sometimes de-icing has been carried out in June as well,” Juha recalls.
Aircraft are designed to operate in the cold. At flight altitude, the temperature drops to minus 50 degrees Celsius. Anti-icing equipment protects sensitive parts of the aircraft during the flight.
De-icing is done on the ground before departure so the aircraft can safely take off. Sometimes, de-icing is also done right after landing if ice has accumulated on the flaps during its approach. The flaps are retracted after landing to allow ground handling services around the aircraft.
Have you seen de-icing trucks and de-icing professionals at work?
Orange removes, green keeps clean
Critical surfaces of the aircraft must remain clean during takeoff to maintain optimal performance. “Aircraft wings and tail stabilisers are cleaned of snow, ice, and frost before departure. If necessary, the treatment is enhanced with a protective chemical that prevents ice from forming on aircraft surface," Juha says.
If you see bright orange liquid sprayed on aircraft, it’s the chemical that removes ice and snow. The anti-ice chemical is green and can be applied after deicing if extra protection is required. This is typical in rainy weather.
De-icing is not carried out in very cold weather since the lowest operating temperature of propylene-based de-icing fluid is -33 degrees Celcius. However, cancellations due to cold weather are extremely rare.
Helsinki has excellent facilities and expertise for de-icing
The facilities and de-icing equipment are at a superior level at Helsinki Airport. There are two de-icing areas located near runways. Aircraft will taxi from the departure gates to the de-icing area in a coordinated manner, so they don’t form a queue. From the de-icing area, aircraft proceed directly to the runway.
The de-icing area can fit five aircraft, with four de-icing trucks working around each aircraft simultaneously. In early autumn, when there is mostly frost, de-icing is completed in a few minutes. On a snowy day, the two-stage de-icing of a wide-body aircraft takes about 10 to 30 minutes.
De-icing times are defined and vary based on aircraft type and prevailing weather conditions. The additional minutes reserved for de-icing are considered in the flight schedules during the winter season.
Even when it's snowing outside, it’s warm enough in the de-icing truck to wear only a t-shirt.
De-icing is precise work
De-icing trucks are specifically designed for this purpose. The trucks have a high-rise basket and a movable extension. Nozzles are located at the end of the extension. The driver controls the extension so that they have a good view of the areas which they clean. The nozzles have an optimal distance from the surface so that cleaning is efficient and only the required amount of fluid is consumed. After spraying, the driver checks that the surfaces are clean.
In summer, the de-icing equipment gets checked and thoroughly maintained. This includes trucks and, for example, de-icing fluid tanks. Late summer is also the time for additional training for de-icing specialists.
De-icing chemicals have evolved from the past and are now less environmentally harmful. Nevertheless, it’s well taken care of that chemicals are recycled.