I know one of the pilots (the British national living in Holland). Not personally but he's one of the many pilots that fly for the Dutch charity Stichting Hoogvliegers, where I'm one of the core volunteers. This charity aims to offer air experience flights to sick and disabled children throughout the Netherlands. He was a member since January 2010 and flew 3 such flights since then.
And he was actually scheduled to fly another charity flight a day or so after the accident. Nobody made the connection at the time, so this family was waiting at the airfield for him, but he never showed up. Obviously we have now contacted the family and will reschedule the flight.
Within this charity we're sort-of used to getting notice of children that are deceased every now and then. One of the children that I flew with a while go died a month later on the consequences of acute leukemia. Very sad. But I think this is the first time we've lost an active pilot. He'll be missed.