The low-cost airline Frontier on Friday morning flew its first flight from Denver to Costa Rica, its tenth destination outside the U.S. Denver-Costa Rica flights will operate four times a week until January 5, when Frontier will expand the service to include a fifth flight on Saturdays. Flights depart Denver at 12:10 a.m. and arrive in San Jose, Costa Rica, at 6:25 a.m. Return flights leave Costa Rica at 7:30 a.m. and arrive in Denver at 12:15 p.m. Visit www.frontierairlines.com. (JM)