Northwest to Cooperate With Labor Department

Northwest Airlines Corp. said it would cooperate with Labor Department investigators looking into its underfunded pension plan. The Labor Department is investigating “whether any person has violated or is about to violate” pension law, according to a letter sent with the subpoena issued in January.

Northwest had fought the broad subpoena, saying it requested documents such as the carrier’s business plan that would harm Northwest if the Labor Department disclosed the documents to competitors. Northwest demanded that the agency sign a confidentiality agreement, which the department signed Monday, Northwest said.