http://www.marketwatch.com/story/fr...-in-september-2011-07-11?reflink=MW_news_stmp Frontier Airlines, a wholly owned subsidiary of Republic Airways Holdings, Inc. today announced plans to add nonstop service between Denver (DEN) and Rockford, Ill. (RFD) to its route map. Additionally, members of Frontier's EarlyReturns frequent flyer program can earn double miles for every qualifying trip they take systemwide throughout September. For details and to register, visit FrontierAirlines.com/memberoffers. The carrier also extended its selling schedule through March 18, 2012, which includes the resumption of its nonstop seasonal service between Denver and both Ixtapa/Zihuatanejo, Mexico (ZIH) and Liberia, Costa Rica (LIR). Denver-Rockford nonstop service will operate three days each week beginning Dec. 15, 2011. Service will be provided on 138-seat Airbus 319 aircraft, which feature available STRETCH seating with up to 5 inches of additional legroom and 24 channels of DirecTV(R) at every seat. Frontier will be the only airline offering nonstop service on the new route.