Of the nation's 29 busies airports, Chicago's Midway International was the worst in January in terms of on-time departures.
Just 69 percent of flights scheduled to leave from the city's smaller airport got off on time, the U.S. Department of Transportation said in its monthly report, released Tuesday.
O'Hare didn't fare much better. It landed in 26th place on the list, with 74 percent of its departures leaving as scheduled.
When it comes to arrivals, the government said 78 percent of flights arrived at Midway on time. For O'Hare, 76 percent of arrivals came in on time.
Overall, U.S. airlines had their best January in four years when it comes to on-time arrivals.
Among the major carriers, Chicago-based United Airlinesposted the best on-time performance in January.
Beginning in April, air travelers will get regulatory protection against tarmac delays of three hours or longer.
Published at 9:29 PM CST on Mar 9, 2010 | Updated at 9:45 PM CST on Mar 9, 2010