On-time performance worsened last year, with 78.3 percent of flights arriving on time, down from 82 percent in 2003. Skywest was on time the most, American Eagle the least.
The problem of deteriorating airline service came to a head over the Christmas holidays, when delays and cancellations inconvenienced more than 500,000 passengers. Regional carrier Comair canceled all its flights during the holiday weekend, and US Airways' baggage system failed.
A report by the Transportation Department's inspector general blamed bad weather and computer problems at Comair, and faulted poor planning and poor labor relations at US Airways.
"In a simpler system they seem to be able to do this better," Headley said. "When it's more taxed, the quality goes down."
Complaints about airline service rose 27 percent last year, a much higher increase than the 3.3 percent growth in passengers. US Airways generated the most complaints, and Southwest the least.
Last year, 4.83 bags were lost, stolen or damaged for every 1,000 passengers. Atlantic Southeast had the highest rate of mishandled bags, while AirTran had the lowest.
There was a small increase in the number of passengers "bumped," or denied boarding for space — 0.87 passengers per 10,000 boardings in 2004, up from 0.86 per 10,000 in 2003.
The report rated the 16 U.S. airlines that carried at least 1 percent of the 630 million passengers who flew domestically last year. Two carriers, Comair and SkyWest, met that threshold for the first time in 2004.