A United Airlines flight bound for Minneapolis-St. Paul International Airport from Chicago diverted to Madison, Wisconsin, on Friday night to address a "security concern with an unruly passenger," the company said.

A United Airlines flight bound for Spain from Newark Liberty International Airport turned around midflight Saturday due to a possible security threat in flight.

Air traffic control audio reviewed by CNN captured crew members of United flight 2005 describing a passenger who had made “multiple attempts to try to breach the cockpit” before law enforcement office...