Frontier Airlines said it will start service to Cancun and Los Cabos Dec. 15. They will be the first nonstop flights from McCarran International Airport to Mexico from a U.S.-based air carrier Frontier will fly 186-passenger Airbus A-320 jets on its routes to Mexico from Las Vegas. Las Vegas was Frontier’s third largest market behind Denver and Orlando in 2017 with 1.4 million seats routed to Las Vegas annually.