Yet another reason not to fly.

As air travelers' summer of hell draws to a close, stories of canceled flights, lost luggage and late arrivals abound. But while it might seem that the whole system is a mess, which carriers are actually the biggest culprits?

Other than JetBlue's much publicized ice storm fiasco in February, customers seem to be engaged in a general rage against the industry machine. And it's true that some common annoyances, like long security lines, come courtesy of the government and tend to affect airlines across the board.

Check out the worst airlines at our partner site, Forbes.com.

But when it comes to delivering for customers, there can still be quite a difference from one carrier to another. To measure the worst performing airlines for the 12 months ended July 31, 2007, we analyzed the U.S. Department of Transportation's Air Travel Consumer Report for the three criteria that consumers say are nearest and dearest to their hearts--flight delays, cancellations and mishandled bags.

Overbooked planes were also cited in consumer complaints--who doesn't detest getting bumped from an oversold flight? But because the problem affects only a tiny fraction of the flying population, we didn't include the category in our calculation.

The numbers show that Atlantic Southeast Airlines, a former Delta Air Lines unit that still has working agreements for baggage and other ground operations with its former parent in Atlanta, and which ranks at or next to the bottom in all three categories, has earned the dubious distinction of America's worst airline. Right behind are Delta's low-fare subsidiary Comair, which has the nation's highest cancellation rate, and American Airlines' unit American Eagle, which ranks among the bottom four in all categories.

---Man, I truly hate airliners.---