(MONEY Magazine) – The place: Boston's Logan International Airport. The time: evening rush hour. As I boarded my USAir flight to Philadelphia, I suddenly realized that I might be the only passenger who knew our real odds. Not our odds of getting there. Like all major carriers, USAir has a superb safety record. I meant our odds of getting there on time -- which, in a word, / were lousy. Arguably, this flight -- or at least this route -- had the worst on-time performance in America. How did I know? Because we at MONEY had deliberately set out to find the most-often-delayed flight. We started with the so-called list of shame -- the U.S. Department of Transportation's monthly compendium of flights that are at least 15 minutes late 80% or more of the time. Since some airlines renumber their flights, we focused on carriers and routes -- and USAir flights from Boston to Philly, and vice versa, made the list 18 times in the previous 12 months, more than twice as often as the next worst carrier and route. What was the problem? ''Philadelphia and Boston are a double whammy,'' explains Jim Tabor, the airline's director of operations and performance (more simply, its on-time guru), since both airports handle a lot of traffic, especially at rush hours. Tabor tried to fix one tardy Philadelphia-to-Boston flight by using a seldom-delayed plane coming from Raleigh to make the run, rather than an oft-delayed one from Orlando. But on another problem flight -- this one from Boston to Philadelphia -- he did what every other airline does as a last resort: he tacked 12 minutes onto its one-hour-and-nine-minute scheduled flight time. ''It's a bow to reality,'' Tabor says. ''You might even get there early.'' At the airports and in the air, USAir's rank and file offered their own explanations of the delays -- on condition of anonymity. ''Boston's near the water and gets lots of fog,'' said one pilot. A Philly gate agent suggested the problem might be that whenever an unexpected rush of business travelers showed up, it took time to load on more meals. That sounded logical -- until I remembered that my flight served only peanuts and drinks. The passengers, meanwhile, seemed to take delays in stride. ''Except that on Fridays, it's a zoo,'' admitted Sandy Yodesky, a sales executive who lives in Philadelphia. On the Monday flight I took, however, things were distinctly un-zoolike. The flight to Philadelphia arrived precisely on time; the return flight to Boston was 10 minutes early. So maybe Jim Tabor's fixes will allow USAir to pass the ''worst flight'' baton to some other airline. Or so I was thinking as I settled into my seat on the Pan Am Shuttle back to New York the next morning, munching crackers and cheese, reading a self-congratulatory newspaper ad that proclaimed Pan Am as ''No. 1 in on-time performance.'' Suddenly, I heard the pilot's voice. . Because of air traffic delays, he said, we'd have to circle in a holding pattern -- and land 20 minutes late. -- B.K.