One air traffic controller was doing work normally assigned to two people in the tower at Reagan National when the collision happened, according to a report by the Federal Aviation Administration obtained by The Associated Press.

The report, reviewed by The New York Times, said that one controller was communicating with both helicopters and planes. Those jobs are typically assigned to two people, not one.

Staffing was “not normal for the time of day and volume of traffic” at Ronald Reagan National Airport, near where an American Airlines (AAL)

Recovered black box recorders from the downed jet --may hold key clues to sketching out what happened before that fiery midair collision in Washington D.C. A preliminary FAA report obtained by NBC notes staffing in the air traffic control tower was "Not normal" at the time of the crash with one controller handling both planes and helicopters but that is considered acceptable by FAA standards.