The FAA said in a statement that the Denver Air Route Traffic Control Center lost communications for approximately 90 seconds. McIntosh said both the primary and main backup frequencies went down, so the controllers had to turn to an emergency frequency to communicate.

Denver ATC communication loss affects several pilots, sparking FAA investigation. The incident highlights ongoing air traffic control system issues and modernization needs.

A portion of the Denver air route traffic control center experienced a 90-second loss of communications late Monday, the Federal Aviation Administration said in a statement.