The pilots under scrutiny are military veterans who told the Federal Aviation Administration that they are healthy enough to fly, yet failed to report — as required by law — that they were also collecting veterans benefits for disabilities that could bar them from the cockpit.

Veterans Affairs investigators discovered the inconsistencies more than two years ago by cross-checking federal databases, but the FAA has kept many details of the case a secret from the public.

FAA spokesman Matthew Lehner acknowledged in a statement that the agency has been investigating about 4,800 pilots "who might have submitted incorrect or false information as part of their medical applications." The FAA has now closed about half of those cases, he said, and has ordered about 60 pilots — who Lehner said "posed a clear danger to aviation safety" — to cease flying on an emergency basis while their records are reviewed.