Midway ranked dead last for on time departures among the nation's 29 largest airports. Only 70 percent of flights left on time.
O'Hare International Airport did not fare much better. It ranked 27th, with almost 71 percent of flights leaving on time.
Midway did a little better in on time arrivals, ranking 19 out of 29.
O'Hare ranked 25th for on time arrivals.