WASHINGTON – The Federal Aviation Administration on Thursday acknowledged badly mishandling a whistle-blower's complaints that air traffic control managers in North Texas routinely covered up errors, almost a decade after the practice began.

It was the second time this month that top FAA officials conceded serious failures in a regional office and proposed changes to address the problems. The misconduct continued for two years even after the FAA said it would address the allegations of a controller, Anne Whiteman, who was transferred because colleagues harassed her for exposing the problems.

"We failed as an organization in executing those commitments," said Hank Krakowski, chief operating officer of the FAA's air traffic organization.

The FAA briefed reporters before an independent investigation about the operational errors and treatment of Ms. Whiteman was ready to be released. But the FAA released one finding – that FAA managers misattributed 62 air-traffic control errors to pilots or called them "non-events" between 2005 and 2007.

"Needless to say, the report is disturbing," FAA Acting Administrator Robert A. Sturgell said.

Ms. Whiteman, 51, said she remains "exhausted" and "sad" after nearly a decade of battling the FAA over a culture that permitted close calls and allowed her to be intimidated and threatened by colleagues. The FAA denied her account in 2005.

"There is a strategy to everything they are doing," Ms. Whiteman said Thursday. "Last time, they 100 percent lied to the public about everything that took place."

Expressing regret

FAA officials said they deeply regretted the way whistle-blowers have been treated, though they did not directly address Ms. Whiteman's claims of personal harassment. Earlier this month, the agency conceded that two air-safety inspectors in North Texas were retaliated against for pushing investigations of Southwest Airlines.

"We're not going to stand for this," Mr. Sturgell said. "It's an issue of integrity for me."

Ms. Whiteman reported dangerous actions by controllers in 2002. In 2004, she reported her concerns to the U.S. Office of Special Counsel, which reviews the complaints of whistle-blowers.

After an investigation largely supported her allegations, the FAA committed to make changes in 2005, including more audits and supervision of the Dallas/Fort Worth Terminal Radar Approach Control (Tracon), which handles air traffic throughout North Texas. Ms. Whiteman was transferred to another position out of concern for her safety.

The FAA failed to follow through, however, and Ms. Whiteman and another whistle-blower made new complaints last year of controllers issuing faulty instructions to pilots.

"These problems exist because of a culture of complacency and cover-up in FAA," Scott Bloch, the U.S. special counsel, said Thursday.

The FAA removed the manager and deputy manager at Dallas Tracon in January and assigned them to administrative duties at another station.

Mr. Bloch said Thursday he remains concerned about "a national trend" of suppressing controller errors and the "complicity of higher management" at the FAA.

But Mr. Krakowski said the investigation by the Department of Transportation's inspector general didn't find evidence of problems at other Tracon facilities. The investigation showed that 25 percent of errors were misclassified in Dallas; the rate was about 3 percent elsewhere, he said.

Still, Mr. Krakowski said he wasn't confident "that it can't happen elsewhere" and wanted to reduce the probability.

New measures

To that end, Mr. Krakowski announced new measures, including establishing an independent quality-assurance group to investigate possible errors and make determinations about them. FAA facility managers will no longer have the authority to determine whether an incident was caused by a controller.

The FAA also will introduce a computer system at Dallas Tracon by the end of 2008 that tells controllers how far apart to space planes.

A new vice president for air safety, a former Air Force brigadier general, is to "take a complete stem-to-stern look at the safety organization within air traffic – how it's organized, what we measure and how we hold people accountable," Mr. Krakowski said.

The National Air Traffic Controllers Association, which has fought the FAA over labor issues, blamed the errors on a shortage of controllers.

It called the staffing at Dallas Tracon, with 57 fully certified controllers, "atrocious and dangerously unsafe." The number was 99 in January 2006, according to the union.

"The FAA has no choice but to cook the books because they don't want to be seen as unsafe," said Darrell Meachum, southwest regional vice president of the National Air Traffic Controllers Association.

Ms. Whiteman said she appreciated a call from Mr. Sturgell on Thursday thanking her for her sacrifices. She still wants the agency to retract a letter written to her congressman several years ago that characterized her as "some crazy broad who was out of control," she said.

"I have been ostracized beyond belief," said Ms. Whiteman. "I have my position and title only. I'm not a part of the FAA."

Rep. Michael Burgess, R-Flower Mound, said he recalled the tone of the FAA's letter as somewhat "dismissive."

"It has taken a long time to get an answer," Mr. Burgess said of Ms. Whiteman's complaints. "But I'm grateful that she came forward and she brought the facts to light."