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.

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.

The outage occurred on Monday and lasted about 90 seconds. The FAA said controllers were still able to communicate with pilots.