The report was requested by the special counsel's office, which is tasked with protecting government whistleblowers. That office said in a statement that between November 2005 and July 2007 FAA managers intentionally misclassified 62 events as safety errors by pilots in an attempt to shift blame away from air traffic controllers at the Texas airport.
The inspector general previously had confirmed a similar underreporting of safety errors at the airport in 2004. After that incident, FAA officials promised to take steps to fix the problem.
Acting Special Counsel William Reukauf, in a letter Thursday to President George W. Bush, said increased "scrutiny of FAA and its implementation of the corrective measures proposed to resolve the continued misconduct and mismanagement is critical."
According the special counsel, the inspector general's report recommends 10 corrective measures be taken in response to the coverup, including a reorganization of air traffic control management at Dallas-Fort Worth and a comprehensive top-to-bottom review of FAA's overall air traffic safety management.
FAA spokeswoman Laura Brown said the agency already has implemented all of the inspector general's recommendations that don't relate to personnel matters, which she is prohibited from discussing.
"I can tell you we take them very seriously, and we're taking appropriate action on those as well," Brown said.
The National Air Traffic Controllers Association has said previously that safety errors by controllers increased because airport towers and other radar control facilities are understaffed and experienced controllers are leaving the FAA.