Frontier Airlines proposes merging with bankrupt Spirit -- again. Spirit says no / Frontier Airlines is trying to merge with Spirit -- again / Spirit's woes reveal the dismal state of America's budget airlines / What Spirit's Bankruptcy Means for US Holiday Travel / Budget airline Spirit files for bankruptcy / Halloween costume chain Spirit bet on the pop-up model and won / From Southwest to Spirit, budget airlines are in a tailspin / With new changes at Southwest and Spirit, it's getting harder to tell the airline brands apart / JetBlue and Spirit appeal judge's ruling that blocks their proposed merger