Four F-35 Lightning II aircraft prepare for takeoff at Hill Air Force Base, Utah, May 4. Hill's active duty and Reserve F-35 pilots recently began flying routine four-ship configurations, just as they would in combat. This marks a key milestone in getting the Air Force's newest fighter jet to reach Initial Operational Capability later this year, at which time it will be combat-ready. (U.S. Air Force photo by Paul Holcomb)