Resistance to change at all levels of the Federal Aviation Administration has hindered progress over the years on modernizing the nation's air traffic control system, aviation experts have concluded.

The finding, included in a General Accountability Office report, was especially critical of agency management and noted a shortage of technical expertise that has left the government overly dependent on contractors, whose interests may differ from regulators.

A panel of former high-level FAA officials, economists, academics and industry experts conducted its review late last year.

Last spring, an office was created within the agency to overhaul management of the modernization programs, a step that has been welcomed by Congress and the industry.

An FAA spokesman, Greg Martin, said the latest criticism is unfair considering efforts over the past year to make meaningful change in key areas of air traffic modernization.

"We have been consistently meeting targets and meeting deadlines. We're implementing financial management controls. We're hiring top level executives that have substantial operational experience," Martin said.

The FAA began a program to modernize the national airspace system -- the flight routes used by commercial airlines and private pilots -- and the air traffic control system in 1981.

Emphasis was placed on replacing old equipment and accommodating booming growth in air traffic. More than 1 billion travelers are expected to fly on US airlines each year within a decade, according to an FAA forecast.

The agency has been sharply criticized by government watchdogs in the past for projects -- including a computer system for helping controllers guide aircraft near airports -- that were years behind schedule and millions of dollars over budget.

The GAO study took a fresh swipe at an agency where change is historically slow.

"Such resistance is a characteristic of FAA personnel at all levels," the GAO panelists said. "And management, in the experience of some panelists, is more resistant than employees who may fear that technologies will threaten their jobs."

But the panel also said continuing budget cuts for modernization -- USD$400 million this year and a projected cut of nearly USD$80 million in 2006 -- could erode the quality of air traffic services.

Overall problems with modernization efforts, the panel noted, were "at odds" with the financially stressed aviation industry and its need for updated systems and procedures to enhance capacity and reduce flight delays.

The findings are to be discussed at a House of Representatives aviation subcommittee hearing on Thursday.