Sun Country is largely missing out on the golden age that U.S. carriers have been basking in since 2015. In the past 12 months (ending with the second quarter, the most recent to be reported) all the U.S. carriers posted operating profit margins ranging from a healthy 9% to an excellent 16%—except for Sun Country, which delivered a distant 4% margin.

Will Sun shine again? One airline enjoying the U.S. party is Frontier, which had a solid second quarter despite a 19% increase in operating costs. Talks of an Emirates-Etihad merger have heated up, according to a Bloomberg report. A merger might save Etihad, but who will save these other troubled airlines? South African Airways, Fastjet and Jet Airways are all facing dire straits. Lastly, JetBlue is adding a basic economy fare class. Will it be the last U.S. airline to do so?