UPS Airlines is a cargo airline based in Louisville, Kentucky. The second-largest cargo airline worldwide (in terms of freight volume flown), UPS Airlines flies to 815 destinations worldwide.[ A wholly owned subsidiary of UPS (United Parcel Service) since its launch in 1988, the airline marked its 30th year of operation in 2018. In line with passenger airlines, UPS Airlines operates under the hub-and-spoke model. The airline's primary hub in the United States is at Louisville International Airport, where it built a 5,200,000 square foot facility known as UPS Worldport. In addition to Worldport, UPS has several secondary hubs across the United States and international hubs in Germany, China, and Hong Kong. The pilots of UPS Airlines are represented by the Independent Pilots Association.