AIRLINES

Delta Challenges Northwest’s Antitrust Status: Delta Air Lines Inc. said it petitioned the Transportation Department to rescind antitrust immunity granted last month to Northwest Airlines and KLM Royal Dutch Airlines. Delta said it protested the immunity on the grounds that it damaged the U.S. airline industry. “Immunized carriers would enjoy unique and substantial competitive advantages in the marketplace to the detriment of all other U.S. carriers,” it said. Last month, the Transportation Department approved an alliance of KLM and Northwest. The two airlines plan to begin joint flights April 4.