Good news and bad news from the world of tarmac rules and unintended consequences. The good news is that there were only 5 tarmac delays of three hours or more in May 2010, down from 34 similar delays last year. The bad news is that many of the people who would have been sitting on the tarmac were instead sitting in the terminal. Because their flights got delayed and then canceled. Predictably.

Two points need to be made here. First, the increase in flight cancellations was as dramatic as the decrease in tarmac delays. May 2009 saw 4,792 cancellations, while May 2010 had a whopping 6,716 canceled flights. Second, this isn't a matter of "well, passengers are going to sit on the tarmac or sit in the terminal, so we might as well have them sitting in the terminal." The numbers released by the Department of Transportation show that, on balance, the net delay per passenger was longer by hours and sometimes even days.