The most recent government data, which also showed a surge in fliers' complaints, was released less than a week after President Bush promised to help fix the problem.

Forcing carriers to shrink their flight schedules or to pay more to fly during peak travel periods are some of the steps the government is considering.

The nation's 20 largest carriers reported an on-time arrival rate of 71.7 percent in August, down from 75.8 percent a year ago, the Department of Transportation's Bureau of Transportation Statistics said Wednesday. The on-time rate was 69.8 percent in July and 68.1 percent in June.

Through August, more than 25 percent of flights have arrived late — the industry's worst on-time performance since comparable data began being collected in 1995.

The airline industry and the Federal Aviation Administration blame the delays on outdated air traffic control technology, bad weather and increasing passenger traffic. Analysts say commercial airlines' use of smaller planes is partly to blame for increased congestion in the skies and on runways, as is an increase in general aviation aircraft used by corporate travelers.

Whatever the cause of the worsening delays, travelers have noticed.

Customer complaints nearly doubled to 1,634 in August compared with 864 in the same month last year. Poor weather conditions were blamed for more than 38 percent of delays in August, a slight increase from a year ago.

"Endless hours sitting in an airplane on a runway with no communication between a pilot and the airport is just not right," Bush said last week after meeting with Transportation Secretary Mary Peters and the acting head of the FAA, Bobby Sturgell.

Peters asked airlines to form a plan to improve scheduling at New York's John F. Kennedy International Airport, one of the nation's busiest. Without an industry solution, the department is prepared to issue a scheduling reduction order, she said.

The government also could force a so-called congestion pricing model upon the industry, Peters said, but airline executives last week told Congress that raising flying costs during peak periods would simply result in higher fares.

The airlines and the FAA are pressing for a new, satellite-based air traffic control system that will cost about $15 billion and take nearly 20 years to complete. Airline traffic is projected to double by 2025.

The FAA in late August awarded ITT Corp. a contract worth up to $1.8 billion to build the first portion the system, known as NextGen. The agency on Tuesday said it wants all planes to be equipped to use the new navigation technology by 2020.

"NextGen is pie in the sky. What about Now-Gen?" Patrick Forrey, president of the National Air Traffic Controllers Association, quipped Tuesday in a conference call with reporters.

The union says delays will worsen unless the government hires more members and pays them better. The FAA and the union have been locked in a contract dispute since the agency declared an impasse last year.

Bush on Saturday signed a stopgap spending bill to keep Cabinet departments running at current levels through mid-November. Congress has until then to reauthorize the FAA and possibly raise taxes and fees to pay for upgrades to the air traffic control system and other programs. Commercial airlines are battling corporate jets and small plane operators over what share of the cost they each should shoulder.

The commercial airline industry and the White House say a House-passed FAA funding bill does not fairly link fees to system use.

August's on-time performance was the second worst on record for that month, topped only by a 70 percent arrival rate in 2000. But not all airline performance was poor.

Aloha, Hawaiian snag top spots for being on time

Aloha Airlines had the highest on-time arrival rate at 97 percent, followed by Hawaiian Holdings Inc.'s Hawaiian Airlines at 93.7 percent and Southwest Airlines at 77.7 percent, according to government data.

But almost half of Atlantic Southeast Airlines were delayed, and two of its flights arrived late every time they took off. The Delta Connection carrier, which is owned by SkyWest Inc., had the lowest on-time arrival rate at 55 percent, followed by United Airlines at 66.2 percent and Alaska Airlines at 67.1 percent.