Osan Air Base (K-55; Korean: 오산공군기지; Hanja: 烏山空軍基地), is a United States Air Force base located near Songtan Station in the county of Pyeongtaek, 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 U.S. government-contracted "Patriot Express" flights bringing service members and their family members to South Korea from Seattle-Tacoma International Airport in the U.S.