What are the odds your flight will be delayed? Depends on the airport.

We all know the drill: you show up at the airport with plenty of time to spare, only to discover that your flight’s been delayed and now you have hours to kill. Or worse yet, you’ve already boarded your flight and now you’re stuck on the tarmac.

Where is this most likely to happen? You can’t eliminate delays, of course, but you can play the odds—some airports have better track records than others (as do some airlines, which is why we rank the best and worst airlines for on-time performance). Statistics from the Bureau of Transportation Statistics on flights that departed more than 15 minutes behind schedule (in this instance from April 1, 2008, to March 31, 2009) show the best—and worst—airports for on-time performance.

There is some good news overall: the worst airport (there’s a new winner this year) improved on its delays by 3 percentage points. It was also the only airport to have 30 percent or more of its flights delayed; last year, four airports broke the 30 percent barrier.

This upward trend meant that even though some airports improved their on-time performance, their ranking may not have changed much. Dallas decreased its flight delays by a lot—6 percentage points—but it remained at the No. 4 spot in the top 10 worst airports. And JFK—despite decreasing its delays 11 percentage points over the past 2 years—tied with Dallas for that No. 4 spot.

Some of these airports will come as no surprise: the skies around New York City continue to be congested, backing up traffic at all three area airports. And other hubs like Atlanta and Chicago remain on the list of offenders.

But both the best and worst lists have some newcomers this year. Philadelphia—on neither list in 2007 or 2008—showed up in the top 10 worst airports (22 percent of flights were delayed). Orlando had sunnier news, breaking into the 10 best list with just 18 percent of its flights delayed (good news, of course, for visitors to Disney World). Detroit, too, joins the ranks of the elite, with 17 percent of its flights delayed.

And of course some airports have disappeared from the lists. That’s unfortunate for Seattle, which was one of the 10 best in 2008. It’s better news for Chicago Midway (MDW), which at 25 percent was one of the 10 worst in 2008.

So consult this list before you book your next ticket: if you can fly out of an alternate airport like Midway, the odds are better that you’ll arrive at your destination on time. And these days, on-time arrivals are just about the only thing airlines aren’t charging extra for.

America’s Top Five Best Airports 2009

1. Salt Lake City (SLC)

2. Portland (PDX)

3. (Tie) Washington, D.C. (DCA)

3. (Tie) Minneapolis St. Paul (MSP)

5. (Tie) Los Angeles (LAX)

5. (Tie) San Diego (SAN)

5. (Tie) Tampa (TPA)

America’s Top Five Worst Airports 2009

1. Newark (EWR)

2. Chicago (ORD)

3. Miami (MIA)

4. (Tie) Dallas Ft. Worth (DFW)

4. (Tie) New York (LGA)

4. (Tie) New York (JFK)