As Northwest Airlines counts it, Janis Cavinder endured a two-hour delay during a quick trip to London to celebrate the Fourth of July with a college roommate. But by her count, it was a full-day ordeal that diverted her to Newark and ended last night with a flight on another airline.

Ms. Cavinder, a 27-year-old Air Force captain who is headed to Afghanistan soon, missed a connection after her first flight from San Diego to Detroit. That led to the diversion to Newark and a six-hour layover. She made the best of it, quickly visiting the Statue of Liberty and ground zero, but felt sorry for her friend, a fellow Air Force officer, who was alone for the holiday in London.

“We were going to be the Americans in London celebrating the Fourth. Now we’re going to be celebrating the Fifth,” said Ms. Cavinder, of Abilene, Tex., who finally made a Continental Airlines flight.

As anyone who has flown recently can probably tell you, delays are getting worse this year. The on-time performance of airlines has reached an all-time low, but even the official numbers do not begin to capture the severity of the problem.