WASHINGTON (AP) – Congested skies and bad weather last year resulted in more flight delays, more mishandled baggage and more complaints about airline service than in 2003, the government announced Thursday.

Arriving at least 15 minutes late last year were 21.9 percent of flights for the biggest airlines, which carry the vast majority of passengers. That represents a 22 percent increase in late arrivals over 2003, the Bureau of Transportation Statistics says in a report.

The lowest fares since 1988 have drawn more passengers than ever onto commercial airlines, according to the Air Transport Association, which represents major airlines.

David Stempler, president of the Air Travelers Association, said many of those people are now being carried on smaller planes.

“Each airplane is a unit that the Federal Aviation Administration has to deal with, whether it holds 50, 150 or 350 passengers,” Stempler said. “The more of these regional jets and small aircraft that enter the system, the more delays we’ll experience.”

Last year, the FAA began taking steps to minimize delays. Air traffic controllers started to hold some planes on the ground longer if they were headed toward crowded airports. That way, backed-up planes could get into the air more quickly when the weather clears because the space over the airport was less crowded.

Hawaiian Airlines had the best arrival performance, landing on schedule 93.8 percent of the time. Delta subsidiary Comair had the worst, at 62.5 percent.

One flight, SkyWest Airlines Flight 6973 from Indianapolis to Chicago, was late 100 percent of the time.

The report also included statistics from the stormy holiday month of December, which was fraught with problems that reached a climax on Christmas. Then, tens of thousands of travelers were stranded after Comair canceled all of its flights and US Airways separated planeloads of passengers from their luggage.

Kenneth Mead, the Transportation Department’s inspector general, is investigating why US Airways and Comair grounded 1,100 flights on Christmas.

Throughout December, airports didn’t just seem more crowded with passengers who had nowhere to go; the report showed one-third more flights were canceled than December 2003.

Nearly a third – 28.4 percent – of all flights arrived late that month as well. The number of complaints in December soared to 976, more than double the number filed that month a year earlier with the Transportation Department.

Complaints of mishandled baggage also rose by 60 percent in December, to 9.11 reports per 1,000 passengers from 5.69 reports per 1,000 the year before.

“This just confirms what a horrendous month December was,” Stempler said. “Between the snowstorms, the piled-up baggage, the canceled flights, it was just a horrible month in an unremarkable year.”

For the year, mishandled luggage reports rose from 4.19 per 1,000 passengers in 2003 to 4.91 in 2004. Consumer complaints increased from 5,983 to 7,477.

The Transportation Department’s report says the most common cause of late arrivals was the air traffic control system, accounting for 30 percent of late arrivals. Slightly fewer delays – 28.6 percent – resulted from the previous flight arriving late.

Factors within the airline’s control, such as maintenance or crew problems, accounted for a quarter of all delays in December, and only about 4.5 percent were caused by extreme weather, the report said.

The Air Transport Association, however, takes issue with those numbers. ATA general counsel David Berg said the FAA keeps separate data that shows most delays are caused by weather.

“They are packaging the numbers in such a way to support the notion that demand management is a good idea,” Berg said.

The ATA opposes demand management, which it characterizes as government scheduling of airline flights. It contends expanded airport and runway capacity is needed to solve the delay problem.