Flights landed on schedule barely half the time at Newark Liberty International during the first seven months of this year, once again giving the hub the worst on-time arrival performance in the nation, new government records show. Just 56.83 percent of the roughly 600 flights landing at Newark Liberty each day between January and July were on time, according to U.S. Bureau of Transportation statistics released yesterday. While Newark finished last among the 32 airports monitored, the region's two other major airports weren't far ahead of it. According to the report, flights landed on time at La Guardia Airport just 58.59 percent of the time, while those arriving at John F. Kennedy International landed on schedule 59.16 percent of the time. The best arrival performance so far this year has been at Oakland International Airport in California, where nearly 80 percent of the landings came within 15 minutes of the scheduled time, the government's benchmark for punctuality. In response to yesterday's report, officials with the Port Authority of New York and New Jersey, the bistate agency that operates the metropolitan area's three airports, urged the Federal Aviation Administration to use the metropolitan region as the test site for a new satellite-based navigation system designed to better manage air traffic. Delays are nothing new at Newark Liberty; it has ranked last in on-time arrivals in three of the previous four years. The FAA has repeatedly maintained that most of the delays at Newark are due to poor weather -- there or elsewhere along flight routes. The three New York-area airports fared slightly better during the first seven months of the year when it came to departures, the report showed. Among the 32 major airports, Newark ranked 30th, with 65.73 percent of planes leaving on time. JFK was 31st with a 65.31 percent on-time departure rate, while La Guardia was 26th, with 71.12 percent of flights taking off on schedule. The best on-time departure rate so far this year -- nearly 84 percent -- has been at Portland International Airport in Oregon. The navigation system that the FAA is proposing would change the decades-old, radar-based technology to one relying on global positioning system technology. Proponents say GPS is a way to bring more planes in and out of airports because the enhanced technology requires less spacing between aircraft. In a letter to the heads of the FAA and federal Department of Transportation, the Port Authority urged that they scrap plans to initially test the new system in smaller markets. "It is vital that the FAA make the New York region, the largest and most critical market in the country, its first priority for implementation of the new technology," Anthony Coscia, the PA's chairman, and Anthony Shorris, the executive director, wrote. "Delays already threaten the system in our region more than anywhere in the nation," they added. "The FAA should put the needs of the more than 100 million passengers to our airports first." At the same time, Coscia and Shorris asked that the FAA to refrain from setting limits on the number of flights that currently use the region's airports. FAA administrator Marion Blakey had not yet seen the letter but is "pleased the Port Authority of New York and New Jersey recognizes (satellite-based navigation) as the solution for relieving delays in New York and throughout the country," agency spokesman Jim Peters said. The new system is one of the FAA's key proposals to solve ongoing flight delays around the nation. Proponents say GPS is a way to bring more planes in and out of airports, because the enhanced technology requires less spacing between aircraft. Robert Poole Jr., director of transportation for the California-based Reason Foundation, called Newark Liberty's on-time arrival performance "pretty pathetic." He said limits on operations are one way to curtail delays while satellite-based navigation systems are implemented over the next decade or two. "Without enforceable limits on operations per hour, you're going to continue to have horrendous congestion there," Poole said. "It's because the demand is just greater than the existing available capacity." Poole said he believes the best way to alleviate the problem is a flat-rate pricing system for airport landing fees, as opposed to the current charges, which are based on a plane's weight. Such a system, he predicted, would encourage airlines to fly a greater number of larger planes, holding more passengers.