Big Sky Airlines had a federal contract to provide Essential Air Service to seven Montana cities: Havre, Lewistown, Glasgow, Wolf Point, Sidney, Miles City and Glendive. The company quit providing flights to Billings and Helena from those cities March 8.
Prairie Aviation http://www.controller.com/dealers/detail.aspx?CID=1246942&DTID=2
Full Story: http://www.billingsgazette.net/articles/2008/03/24/news/state/60-airtaxi.txt