Osan Air Base is a United States Air Force (USAF) and Republic of Korea Air Force (ROKAF) base located near Songtan station in the city 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 headquarters for Seventh Air Force, Pacific Air Forces' 51st Fighter Wing, and a number of tenant units. The base is also the headquarters of the Republic of Korea Air Force (ROKAF) 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. state of Washington, Misawa Air Base and Yokota Air Base in Japan.