Disinfection of Midway International Airport's air traffic control tower has reached the final stages, the Federal Aviation Administration reported Monday.
The tower closed March 17 after several technicians tested positive for the coronavirus, COVID-19.
"Cleaning operations ongoing -- on phase three of three," an FAA update stated. The employees are in self-quarantine and officials are tracing their contacts.
The Midway tower is one of 11 FAA airport facilities affected by spiraling cases of COVID-19, a respiratory disease that can cause pneumonia.
Some locations, including John F. Kennedy and LaGuardia international airports, have completed cleaning of air traffic control towers after employees tested positive for COVID-19.
Airlines using Midway, including Southwest Airlines, have canceled hundreds of flights since March 17. As of midmorning Monday, 67% of 502 flights at Midway were slashed.
"Every air traffic control facility in the country has a contingency plan to keep air traffic moving safely when events impede normal operations," the FAA stated.
"In some cases, this means transferring duties to adjacent facilities. Each disruption has a distinct impact on the air traffic system. We are experiencing this at the handful of facilities already affected by COVID-19. This is frustrating and inconvenient, but is necessary in the interest of safety."
Without air traffic controllers in the tower, Midway is operating on a "one in, one out" basis for airplanes.
Much of the air traffic in and out of Midway has been handed off to the Chicago Terminal Radar Approach Control (TRACON) facility in Elgin.
TRACON controllers will manage flights until within sight of Midway, then arriving pilots will announce their presence on the airport frequency. Outbound pilots will announce their presence before departing, then be picked up by TRACON staff.