Faster by far than covered wagons, Frontier Airlines' planes part the clouds and ply the skies from the Mile High City. The company's primary subsidiary, Frontier Airlines, operates as a budget carrier from its hub at Denver International Airport. The airline maintains a fleet of about 50 Airbus 319 and 318 jets with onboard amenities that include satellite TV. With subsidiary Lynx Aviation, it serves about 50 cities, primarily in the US west of the Mississippi but also in Mexico and Costa Rica. In April 2008, Frontier Airlines entered Chapter 11 bankruptcy protection. It emerged in October 2009 after it was acquired by Republic Airways for about $109 million.