A U.S. Air Force pilot conducts a pre-flight check. A U.S. Air Force pilot from the 20th Expeditionary Special Operations Squadron conducts a pre-flight check of an MH-53 Pave Low helicopter prior to the final combat mission at Joint Base Balad, Iraq, on Sept. 27, 2008. The Pave Low is being retired after nearly forty years of service to the Air Force. SHARE: Download: Full Size (0.07 MB) Credit: VIRIN: 332958-T-VGB19-647.jpg Photo Gallery