SWAN SONG As seen through a night-vision device, U.S. Air Force MH-53 Pave Low helicopters from the 20th Expeditionary Special Operations Squadron conduct their last combat mission over Iraq, Sept. 27, 2008. The MH-53 is being retired after nearly 40 years of service to the Air Force. SHARE: Download: Full Size (0.07 MB) Credit: VIRIN: 242121-F-OHX25-703.jpg Photo Gallery