While the demands for runway slipperiness prevention are higher than for highways, there is also a need to avoid unnecessary use of anti-icing chemicals in air traffic. However, it is extremely difficult to measure the success of chemical optimization, because the used amount of the chemicals is also affected by weather conditions. The object of this Innomikko study was to develop a weather model, which is able to eliminate the effect of various weather conditions on the chemical use, and therefore estimate the success of chemical optimization at different winter periods. In this project, the model was tested at the largest airport in Finland: Helsinki-Vantaa airport.
The created weather model is based on the Helsinki-Vantaa chemical use diary and the weather data from neigbourhood Keimola road weather station. The weather data from airport could not be used, because after the renewal of the runway weather system, the homogenous historical data was not long enough. The model was based on the winter seasons 2005-2013.
After trying several different methods, the final model was based on a chart, which describes average consumption of the anti-icing chemicals (kg/ 15 min) in relation to surface temperature, rain, snow drift (wind blowing snow to the runway) and frost equation (dew point above the surface temperature and surface temperature below 0 degrees Celsius) . In practice, the chart looked like chart 1, where each cell described the use of anti-icing chemicals (kg/ 15 min) in certain combination of weather conditions.
Chart 1. The chart layout describing the average use of anti-icing chemicals in different combination of weather conditions. Keimola surface temperature = runway surface temperature – 0,85°C. Snow drift = wind blowing snow to thw runway.
After that, it was calculated, what was the timely amount of different weather condition combinations in each winter season. Furthermore, based on chart 1, it was easy to calculate the predicted amount of anti-icing chemicals at different winters. When this prediction was compared to actual use, we got the result shown in figure 1.
In figure 1, you can see, that the use of anti-icing chemicals at winter season 2005-2006 is 42% higher than the prediction (=assumed consumption based on weather data). On the contrary, the consumption at winter season 2012-2013 is 25 % less than the prediction.
According to the results, the optimization of anti-icing chemicals has been quite successful in Helsinki-Vantaa airport. However, the development at last few winters has not been as significant as at winter seasons 2005-2010.