MADISON, Wis. -

A fire in Chicago affected air travel throughout the region Tuesday, and even diverted flights from Chicago to Dane County Regional Airport.

Terminal Radar Approach Control is located in Elgin in the northwest suburbs of Chicago, and a fire broke out in that building around 11:30 a.m. Smoke was coming from the ventilation system in the building.

Workers were ordered out of the building including about 20 people who handle air traffic from 5 to 40 miles out from O’Hare International Airport and Chicago Midway International Airport.

So that led to a ground stop, where nobody takes off, nobody lands and flights on the way to those airports are diverted to other airports, including Madison. A dozen Chicago-bound flights were sent to Madison on Tuesday.

“We have a plan in place, it’s called an irregular operations plan, which means that we have designated procedures on how to handle and park those aircraft,” Dane County Regional Airport Communications Director Brett McHenry said. “Depending on the size, they go in a specific parking spot. Depending on whether they’re international and need to be deplaned or not.”

After about a half hour, crews figured out the fire was caused by a faulty motor in the heating system in the building. They got the all clear and traffic controllers were allowed back in.

About 1:30 p.m., flights were again allowed to take off and land at the two Chicago-area airports, but it will take a while for the system to catch up. The fire impacted tens of thousands of travelers across the country.

“Today we handled 11. We could have taken about 12, given the volume of other planes that are here generally,” McHenry said.