JetBlue Airways pilots have voted to join the Air Line Pilots Association. This marks the third time JetBlue pilots voted on the matter, after rejecting joining in 2009 and in 2011. It also marks the end of JetBlue's status as the biggest U.S. airline without a union. Shares fell on news of the unionization, on worries it would mean higher costs for the budget carrier's customers. Already, JetBlue warned this year that costs are expected to rise due to an agreement to raise pilots' base pay.