More than half of Chicago O'Hare's runways lose lighting

O'Hare International Airport lost some lighting on its north airfield for about 40 minutes last night, affecting four of its seven runways, officials said.

The cause of the loss of lighting is under investigation, said Karen Pride, spokeswoman for the Chicago Department of Aviation.

The extent of the loss was not known but it delayed the landing of some arriving flights, Pride said.

The outage began at 9:20 p.m., she said.

"The issue was resolved about 10 p.m. and some arrival flights were impacted but I don’t have a specific length of time for that," Pride said. "At this time of night there’s fewer flights but some flights were impacted." 

Low visibility also caused delays of about 90 minutes at O'Hare, according to the aviation department.

More than 180 flights were cancelled there today, according to the department, which also reported delays of about 30 minutes at Chicago Midway International Airport.