The ground stop was triggered by a fire at an FAA facility in Aurora. It was lifted at 11 a.m., but planes are moving at a "reduced rate." The headaches could continue for travelers for days due to extensive damage at the FAA facility.
"We came in to look at the display. As you see, delayed and canceled. Delayed and canceled. Now it's time to find a car and see if we can get back to where we're going," Stephen Cody, passenger at Midway, said.
At Midway, about 400 flights were canceled on Friday. Southwest Airlines proactively canceled all flights at Chicago Midway International Airport and Milwaukee's General International Airport through "close of business" on Friday.
At O'Hare, the cancellations and delays, which average more than 30 minutes, continue. Many passengers told they would not be able to fly out Friday made other plans.
"My wife's going to come pick us up, and we're going to head back home for the rest of the afternoon and try again tomorrow," Mark Wierda, O'Hare passenger, said.
"We've booked some rooms and we're just going to stay in Chicago for tonight," Sardou Mertilus said.
PHOTOS: Fire at regional FAA facility grounds Chicago flights
Airlines are urging travelers to check the status of their flights at www.fly.faa.gov.
Officials said the fire at the FAA facility was intentionally set, but is not considered a terrorist attack.
VIDEO: Fire set at FAA facility, police say