NARSIM has facilitated a large-scale (55+ actors) winter exercise for Schiphol Airport three times. The scenario comprises sudden unexpected snowfall for operational airside representatives from Amsterdam Airport Schiphol, KLM, LVNL and the meteorological institute KNMI. The goal of the training is to minimise impact of unexpected snowfall on the daily operation while maintaining safety. It focusses on enhancing collaborative decision making (CDM) between team members and teams. For this exercise NARSIM Tower and Radar have been coupled for an integrated simulation. All involved parties were very satisfied with the exercise and simulation environment and are now prepared for any upcoming though Dutch winters.