Chicago’s Midway International Airport is ranked dead last among the 29 busiest airports in the nation in on-time departures. That’s according to new statistics from the Department of Transportation for the month of November.

Joe Schwieterman, a transportation expert at DePaul University, said, “Midway’s feeling the pain of just growing volumes, and Southwest (Airlines) is increasingly running it as a hub. It’s the second largest airport in the Southwest system. So they face the problem of having to hold flights often for late-arriving flights. So one late-arriving flight can delay a half a dozen departing flights. It’s a real problem.”

Schwieterman said Southwest has a “massive East Coast operation.” And he said the East Coast had terrible weather in November which led to some delays.

Chicago Department of Aviation spokeswoman Karen Pride said the department is not aware of any operational issues at the airport causing delays, other than occasional bad weather.

O’Hare International Airport was 10th in on-time departures in November. Both O’Hare and Midway ranked in the middle-of-the-pack among airports in on-time arrivals for the month.