WASHINGTON — Despite record-level delays, nearly 16 million passengers will fly on U.S. airlines over the Labor Day weekend, a 2.6 percent increase over a year ago, an industry group estimates.

The Air Transport Association forecasts that 15.7 million passengers will travel globally on U.S. airlines between Aug. 29 and Sept. 5.

The group, which represents AMR Corp.'s American Airlines, UAL Corp.'s United Airlines and others, said that while most delays are weather-related, a modernized air traffic control system is needed to reduce congestion.

The airlines and the Federal Aviation Administration are pushing Congress to authorize financing of a multibillion-dollar upgrade of the air traffic control system. There is an ongoing dispute over what share the commercial airlines should pay and whether corporate jets and small-plane operators should shoulder more of the cost.

The antiquated system uses 50-year-old analog radar technology. An updated system would use GPS satellites that could handle nearly three times the current traffic levels. It would also allow aircraft to fly closer together safely, experts say.

"While we cannot get in the way of Mother Nature, passengers can demand that Congress fairly fund the sorely needed modernization of our nation's airspace, which can help to mitigate future delays," James May, ATA's president, said in a release.

Passenger delays are at 12-year highs. The Department of Transportation this month said the industry's on-time performance in the first half of 2007 was its worst since comparable data began being collected in 1995. Nearly a third of domestic flights on major U.S. airlines were late in June.