Barry Biffle, chief executive of Frontier Airlines (F9, Denver International), has said that the ultra-low-cost carrier (ULCC) model is “alive and well” in the United States, responding to claims from counterpart United Airlines CEO Scott Kirby that the model had failed. Participating in a travel conference in New York, Biffle said that cost advantages for ULCCs continue to widen, so the model is successful. United and Spirit have entered into a war of words, with the former also announcing additional capacity from markets served by the latter in case the ULCC collapses. Look, the people that fly Frontier are not people that spill from [United]. They are people that would have never flown [United] in the first place," Biffle said, as reported by Reuters.