A total to 2,000 flights had to be cancelled at the O'Hare and Midway International Airports in Chicago, US, following an act of sabotage when an employee set fire to a control centre.
The US Federal Aviation Authority (FAA) said in a statement that it will restore the operations of the damaged centre to full service by 13 October.
The FAA said: "Air traffic controllers who normally work at the FAA's Chicago En Route Center in Aurora, are now working at other surrounding FAA air traffic facilities to help safely maximise the traffic flow in and out of the Chicago-area airports while the FAA and its telecommunications contractor, Harris Corporation, repair damaged communications equipment at Chicago Center."
FAA has steadily increased the number of flights arriving and departing at both airports.
Air traffic controllers safely managed approximately 60% of typical traffic today at O'Hare and over 75% at Midway.
The Guardian newspaper reported that 36-year-old Brian Howard of Naperville, Illinois, was charged with the destruction of aircraft or aircraft facilities. According to the criminal complaint, paramedics found him trying to cut his own throat. The FBI said Howard remains hospitalised and no court date has been scheduled.
The FAA said that it was managing the Aurora facility's traffic through centres in Minneapolis, Kansas City, Indianapolis and Cleveland to assist controllers at those locations and minimise disruptions for travellers.
The Chicago Tribune quoted US Senator Dick Durbin as saying that because of the extent of damage at the FAA's radar facility in Aurora, flight delays at Chicago airports are likely to continue into the work week until new computer equipment can be installed.