Chicago's two airports were still not providing full service Sunday, two days after a fire at an air traffic control center in Aurora, Ill., hobbled the major hubs.
As of midday Sunday, more than 550 flighted had been canceled at Chicago O'Hare International and more than 50 were canceled at Midway Airport, the Chicago Department of Aviation said.
Some flights were getting in and out of the two airports, but not as many as normal because air traffic controllers must manually transfer flight data, Doug Church, spokesman for the National Air Traffic Controllers Association told CNN.
Airlines were having to fax flight plans to the airports, he added.
A fire was intentionally set Friday by Brian Howard, a contract employee at the air traffic control center, police said. He was charged with one count of destruction of aircraft or aircraft facilities, a felony that could earn him 20 years in prison.
By Friday evening, some 2,000 flights were canceled due to the fire.