WASHINGTON (AP) _ The Federal Aviation Administration has intentionally become less detail-oriented in the way it maintains and certifies the safety of the country's air traffic control equipment, overhauling inspection standards in place since the 1970s.

The change is aimed at making agency inspectors more efficient, and is made possible by the fact that modern radar and other communications equipment is more reliable, FAA officials said. Instead of routine checkups on individual pieces of equipment, the agency now emphasizes "system performance."

But unions representing air traffic controllers and technicians, including one group locked in a bitter contract dispute with the FAA, say the overhaul could compromise safety, or at the very least result in more travel delays.

The squabble over inspection standards for 45,000 pieces of ground-based equipment comes at a time when the FAA is struggling to ensure airlines are adhering to their own set of maintenance orders and guidelines. Earlier this month, roughly 250,000 U.S. passengers were affected by flight cancellations after AMR Corp.'s American Airlines grounded hundreds of jets so mechanics could inspect wiring in wheel wells.

A former FAA official and other industry analysts said the agency's policy shift shouldn't diminish safety, because there are secondary and even tertiary back-ups in place throughout the system.

"From a management perspective, it makes sense" to maximize taxpayer dollars with the limited resources available, said Sid McGuirk, coordinator of the air traffic management program at Embry-Riddle Aeronautical University in Daytona Beach, Fla., and a former air traffic controller and FAA manager for 35 years. "I see no degradation of safety with this policy shift."

But the FAA acknowledged some other problems Thursday. The agency said the top two managers of an air traffic control facility in Dallas-Fort Worth had been removed from their jobs after the Transportation Department inspector general found that management there routinely and intentionally misclassified instances where airplanes were allowed to fly too close together.

The FAA had promised to fix the problem in 2005 but "today it's clear to us those commitments were not taken seriously by people in my organization who were responsible," said Hank Krakowski, a former United Airlines pilot and safety executive who became FAA's chief operating officer last year. He said the inspector general's report found no evidence of widespread misclassification issues at other facilities.

While flying on U.S. airlines has never been safer the last domestic crash of a jumbo jet was in November 2001 industry and government officials have blamed record delays in the past year on a combination of crowded skies and runways, as well as outdated air traffic control equipment. The airlines and the FAA are pressing Congress to authorize funding for a new, more than $15 billion satellite-based air traffic control system, dubbed NextGen, that will take nearly 20 years to complete to improve operations.

"While there always will be room for improvement, we must remain focused on initiatives that move us forward and not backward," said David Castelveter, a spokesman for the Air Transport Association, the airline industry's main trade group.

Michael Nolan, a professor of aviation technology at Purdue University, said the only way to tell if the FAA made a good decision in changing its ground equipment certification practices will be to compare system performance under the old rules versus the new ones.

At issue is an FAA policy notice issued in December that "exempts maintenance personnel from performing (periodic) system and subsystem certification" as required in technical handbooks.

"This policy places increased value on end-to-end system certification, and eliminates unnecessary periodic equipment certifications which historically had little or no affect on total system performance and safety," said FAA spokeswoman Tammy Jones.

Tom Brantley, president of the Professional Aviation Safety Specialists union that represents FAA technicians and inspectors, disagrees.

"Down the road, this will lead to major (flight) disruptions" because problems identified during preventative checks that led to planned outages will no longer exist, Brantley said.

The National Air Traffic Controllers Association, which the FAA has been in a contract dispute with since 2006, earlier this month filed a grievance against the agency for failing to brief and then bargain with its members over the changes and asked that it immediately stop implementing them.

The exact issue the FAA is now cracking down on airlines for not complying with the deadlines to comply with safety orders is what the agency is eliminating internally, said Larry Ihlen, NATCA's regional representative in Alaska and an electronic engineer with more than 30 years of FAA experience.

The safety specialists union did not join NATCA in filing a grievance against the FAA because it did not want to spend resources on a process that is unlikely to end with the agency changing its policy, Brantley said.

A NATCA spokesman said the FAA has not replied to its grievance, and acknowledged "the only way they will stop is with public outcry or congressional action."

FAA spokesman Paul Takemoto said the revision to certification rules for ground equipment simply equates to "looking at the whole chain rather than one link," and has nothing to do with the agency's ongoing review of airlines' compliance with airworthiness directives.

AP Writer Michael J. Sniffen contributed to this report.

Copyright 2008 The Associated Press.