High Quality Content by WIKIPEDIA articles! Osan Air Base (K-55), is a United States Air Force facility located in the Songtan section of Pyeongtaek City, South Korea, 64 km (40 mi) south of Seoul. Despite its name, Osan AB is not within Osan City, which is 7.5 km (4.7 mi) to the north. The base is the home of the Pacific Air Forces` 51st Fighter Wing, and a number of tenant units, including the headquarters for Seventh Air Force. The base is also the headquarters of the ROK Air Force Operations Command. Osan Air Base is also the departure and arrival point for US-government contracted "Patriot Express" flights bringing servicemembers and their family members to Korea.