The nation’s system for relaying information about suspicious airplane incidents needs improvement, according to a federal review of a flight on which 13 Syrian men aroused the suspicions of passengers, pilots and air marshals.

The three-page unclassified summary released Monday by the Department of Homeland Security answers few of the questions raised by a freelance journalist Annie Jacobsen, who was on Northwest Airlines Flight 327. Her stories ignited a debate between those who thought she was being paranoid and those who believed the men were staking out the flight for a future attack.