The Bureau of Transportation Statistics ranked the 10 U.S. airports with the worst records for on-time arrivals in 2011. The bureau also provides data for on-time departures. Its survey covers 29 major airports, defined as serving at least 1 percent of total passengers boarding domestic flights in one year, so small airports weren’t included. Some U.S. airports have more late or missed connections than others, depending, in part, on which airlines use them and where they’re located. Some airlines are notoriously unreliable, and some airports are in cities that take regular beatings from bad weather.