FAA spokeswoman Laura Brown refuses to comment on a dispute between the agency's air traffic division and its independent investigative arm, USA Today reports.
The FAA's Air Traffic Safety Oversight Service has ordered managers of the Memphis airport to stop the practice of allowing incoming passenger jets to fly directly over the tops of planes landing on nearby runways.
Earlier this year a midair collision between a Northwest Airlines DC-9 and a commuter plane at Memphis was narrowly averted.
That incident and others associated with landings on two nearby runways prompted an April 2 memo from the FAA's oversight service demanding immediate changes.
However, the demand is reportedly being ignored by the agency's air traffic division.
Brown says the FAA is currently working to address all safety concerns at the airport.