A child from the Caritas Heimverbund Kreis Heinsberg tries on an oxygen mask during a tour of an AWACS at 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.