Spirit Airlines has filed for bankruptcy protection, becoming the first major airline in America to declare bankruptcy since American Airlines in 2011. Spirit, a low-cost carrier, has not made an annual profit since 2019 and, like other discount rivals, has seen ticket prices fall amid a surplus of seats. In January, a judge blocked the takeover by JetBlue Airways on competitive grounds. A proposed merger with Frontier Airlines also came to nothing. Spirit regularly tops lists for America’s most hated airline, a crowded field.