USAF F-22A block 10 no. 99-4011 and an F-15C Eagle from the USAF School's 433rd WPS pull into a vertical climb over the Nevada Test and Training Range on July 16th, 2010. [USAF photo by MSgt. Kevin J. Gruenwald]
The U.S. Air Force ended the stand-down of all 170 jets after 12 incidents of pilots' experiencing hypoxia. With a mystery still swirling around why some pilots became light-headed while flying F-22 Raptors, the jets returned to the skies Wednesday nearly five months after the nation's fleet was grounded.