Air traffic controllers in Denver had to scramble to use backup frequencies after their main communications lines went down for 90 seconds earlier this week in the latest Federal Aviation Administration equipment failure.

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 Federal Aviation Administration said on Thursday that Denver air traffic control lost communications for about two minutes on Monday but was able to maintain contact through an emergency frequency.