Big Sky operated scheduled commuter passenger services to ten cities and maintained a hub at Billings Logan International Airport in Billings, Montana, from which the airline flew more of its nonstop routes than it did from any other airport. The airline was a crucial air link within the state of Montana, serving as the primary (and in some cases, only) commercial air carrier to several small airports in the state. The airline also began and ended service to a number of other locations over the years, often operating as a contract carrier under the federal government's Essential Air Service (EAS) program.