Children from the Caritas Heimverbund Kreis Heinsberg sit in the flight deck of a KC-135 Stratotanker during a visit to NATO Air Base Geilenkirchen, Germany, Dec. 18, 2014. The visit was part of Operation Nikolaus, or OPN, a tradition which started in the 1980s to bring a little bit of fun and holiday cheer to children from orphanages and child care facilities near the base.