 In contrast to chief competitor Federal Express (which owned its own aircraft), in the early 1980s, air operations of UPS were undertaken by several contractors, including Evergreen International Airlines, Interstate Airlines, Ryan Air, and Orion Air.Through its contractors, UPS flew its packages using a fleet of commercial aircraft converted to freighters, including Boeing 727-100s, 727-200s, Douglas DC-8s, and Boeing 747-100s.In 1982, UPS introduced its Next-Day Air service, guaranteeing overnight delivery on certain packages.