FALCON FOUR Four U.S. Air Force Thunderbird F-16 Fighting Falcon aircraft fly in formation during the Dakota Thunder Air Show on Ellsworth Air Force Base, S.D., May 31, 2009. More than 40,000 people attended the two-day event. SHARE: Download: Full Size (0.05 MB) Credit: VIRIN: 174555-D-SSZ16-508.jpg Photo Gallery