Prepared for the worst

Copenhagen Airport (CPH) is located on the borderline between cold Scandinavia and the more temperate northern European continent. This means that there are frequent and rapid changes from mild winter days to fierce blizzards. These changing weather conditions make great demands on the winter preparedness at the largest airport in Scandinavia.

”Be prepared.” This proud motto of the Scouts could also be the motto of Airside Support, the department at Copenhagen Airport in charge of ensuring that the airport is operational round the clock and throughout the year, regardless of the weather and how high the winds are.

Copenhagen Airport is located in a coastal climate region where the winter weather normally varies between mild windy and rainy days and cold days of sleet, snow and freezing rain. Now and then, Copenhagen Airport is hit by a blizzard, or every few years by an “ice winter”, a long period of temperatures well below freezing that causes even the coastal waters to freeze over. On average, the airport is affected by snow only 19 days a year, but there are wide fluctuations in winter weather from year to year. In spite of a trend towards milder weather in recent years, a total of 120 centimetres of snow fell at Copenhagen Airport in the winter of 2005/2006, which is highly unusual.

A day ahead

The staff of the winter response team must be prepared for any kind of weather at any time so reliable weather forecasts are vital. Copenhagen Airport keeps at least 24 hours ahead of meteorological events by consulting the national, regional and local weather forecasts from the national Danish weather service and information from a computer system developed by the former counties of Denmark. The system collects and processes measurements from hundreds of weather stations all over Denmark.

To this should be added Copenhagen Airport’s own weather forecasting system: four weather stations and 26 sensors spread all over the airport area that measure wind, precipitation, humidity and temperatures on and above ground, as well as the quantity of chemicals on the runways, and report all this information to a central computer which then provides a precise picture of the weather at the airport.

In 1999, Copenhagen Airport was the first airport in the world to establish such a system. Another of the systems the airport has developed is one in which data from the airport’s friction vehicle is transmitted automatically from the vehicle’s computer to the command centre at Airside Support, the air traffic management service and the pilots in the air.

By combining these different forecasting systems, Copenhagen Airport is able to predict the next hour of weather at the airport with a reliability rate of 95%. Danish national weather service forecasts have a reliability rate of only 40% for local weather at the airport.

The right stuff

Copenhagen Airport uses these precise weather forecasts to help determine what should be used to combat the winter weather: e.g. the type and amount of chemicals, number and type of snow-clearing machines and other equipment, and the number of employees to be deployed. Its decisions are based not only on the amount of precipitation, but just as much on the temperature, the level of humidity in the air and the direction and speed of the wind, both when and after snow falls.

Another example of how these unique systems are useful is that they allow Copenhagen Airport to predict with great precision how much de-icer should be spread to prevent ice formation on the runways, taxiways and aprons. Not only does this increase operational reliability; it also reduces consumption of chemicals, as preventive use is effective with only half the amount of chemicals required once freezing rain has fallen.

The entire airport operational area can be treated with de-icers in 20 minutes, and only environmentally friendly chemicals are used. As opposed to airports that only rarely see snow, Copenhagen Airport cannot combat snow and ice with chemicals alone: a thorough snow clearing is also necessary.

A crew of 200

With its regular crew of 12, Copenhagen Airport can handle snow clearing after minor snowfalls, but the airport can draw on a crew of up to 200 when a heavy snowfall or blizzard is forecast. The staff have all been through extensive training in snow clearing, both in theory and practice, and the full team of 50 people per 24-hour shift can be called in at an hour’s notice at all times of the day. In that way, Copenhagen Airport can maintain continuous snow clearing for four days and nights.

Airside Support has a total of 22 large snow-clearing machines, the largest of which weighs close to 30 tonnes and can clear snow in a path more than five metres wide. There are also four large snowblowers and a number of other vehicles.

Snow clearing on the runways is carried out by convoys of up to 14 vehicles at a time. With military precision, the snowplows, snowblowers and sweepers move in a carefully planned pattern, driving in a staggered convoy at speeds of up to 40 kilometres an hour, allowing them to clear a runway 45 metres wide and 3,600 metres long in just ten minutes – or in 20 minutes if eight vehicles are used. Whilst snow is being removed from the runways, the other roads in the airport area are also cleared so aircraft can taxi safely all the way to the terminal.

Collaboration and safety

If there is a heavy snowfall, it is crucial that all the actors at the airport play their part in helping traffic flow as problem-free as possible. For example, the airlines are responsible for ensuring that there are enough resources to de-ice the aircraft before departure (a process carried out in practice by the handling companies SAS Ground Services and Nordic Aero at Copenhagen Airport), and it is also vital that the airlines tow away parked aircraft to allow snow to be cleared from the aircraft stands.

With reliable weather forecasts, well-trained staff and the right equipment, Copenhagen Airport is able to handle even the most difficult of winter weather conditions. Very rarely is the weather so bad that the airport’s Traffic Department reduces capacity to zero for safety reasons. Safety comes first, of course, and we must be prepared to make the decision to close the airport for a limited period of time, but this has not yet been necessary.