United Airlines pilots filed suit against the carrier.

The suit, filed in U.S. District Court in Chicago on behalf of the Air Line Pilots Assn., would prevent the airline from terminating the pilots’ pension fund and using the funds for corporate purposes. ALPA’s labor contract at United specifically forbids reversion of pension funds until all pilot benefits are paid, said a statement issued by the union. United has yet to receive a copy of the suit and had no immediate comment, airline spokesman Chuck Novak said.