Refueling in Flight A KC-135 refuels an F-35A Lightning II during a flight to Graf Ignatievo Air Base, Bulgaria, April 28, 2017. The F-35 is assigned to the 34th Fighter Squadron. Air Force photo by Staff Sgt. Kate Thornton SHARE: Download: Full Size (0.69 MB) Credit: Staff Sgt. Kate Thornton VIRIN: 170428-F-YG608-0109C.JPG Photo Gallery