Spirit Airlines has filed for bankruptcy twice in the last year Sign up to Simon Calder’s free travel email for expert advice and money-saving discounts Get Simon Calder’s Travel email Get Simon Calder’s Travel email Email * SIGN UP I would like to be emailed about offers, events and updates from The Independent. Read our Privacy notice Spirit Airlines is in trouble, and it could be in part because major airlines co-opted the airline’s business model and beat it at its own game. Major U.S.