Wondering what’s going on?

Several pilots asked, what’s going on at Schiphol, what are all these cars, is there an alarm, etc. etc. Groundcontrol gave the explanation: Stichting Hoogvliegers dagen. Children with chronic diseases are visiting Schiphol and driven around in Patrol and Firearm cars, after they had a flight around. So please wave to them!. All pilots responded: nice, this is great.