LAST CONFERENCE Air Force Secretary Michael B. Donley smiles as Air Force Chief of Staff Gen. Mark A. Welsh III thanks him for his service during what Donley said would be his last scheduled press briefing as secretary, at the Pentagon, May 24, 2013. Donley announced plans to step down as the Air Force's top civilian after serving in the position for nearly five years. SHARE: Download: Full Size (0.05 MB) Credit: VIRIN: 232422-T-NWG94-090.jpg Photo Gallery