Army Rangers stand on a flightline while pilots prepare a CH-47 Chinook helicopter for takeoff on Fort Knox, Ky., April 21, 2014. The pilots are assigned to the 160th Special Operations Aviation Regiment. Army Rangers stand on a flightline while pilots prepare a CH-47 Chinook helicopter for takeoff on Fort Knox, Ky., April 21, 2014. The pilots are assigned to the 160th Special Operations Aviation Regiment. SHARE: Download: Full Size (2.44 MB) Tags: Photo Essays Credit: VIRIN: 905274-M-HVC07-487.jpg Photo Gallery