Four F-16 Fighting Falcons assigned to the Thunderbirds, the Air Force’s air demonstration squadron, fly off the wing of a KC-135 Stratotanker before conducting an aerial refueling en route to Tinker Air Force Base, Okla., May 18, 2017. The Thunderbirds will headline Tinker's Star Spangled Salute Air Show. Air Force photo by 2nd Lt. Caleb Wanzer