USAS is software suite for mainframe computers, mainly intended for use in the airline, transportation, and hospitality industries. It is made up of a series of diverse and relatively complex applications written for the Unisys 1100-series, 2200-series, and Clearpath IX environments.
All Nippon Airways became the first company to adopt the system in the late 1970s. Its name was originally an acronym for Univac Standard Airline Systems, but the product line is now referred to simply as "USAS". With advancements in computing, USAS is slowly being replaced in the airline industry with other software, with Unisys also developing AirCore to replace its USAS offering.