Federal investigators are scrutinizing an air traffic control staffing decision made before the deadly collision between an American Airlines flight and a U.S. Army Black Hawk helicopter over the Potomac River near Washington, D.C. The Federal Aviation Administration (FAA) confirmed that staffing levels were lower than normal at the time of the crash, which killed all 60 passengers and four crew members aboard the plane, along with three military personnel in the helicopter.

A supervisor at Reagan National Airport reportedly allowed an air traffic controller to leave early from their shift, consolidating the responsibilities of monitoring both airplane and helicopter flight paths before the scheduled transition time, according to The New York Times and NBC News. Typically, two controllers are on duty before 9:30 p.m.-one for helicopters and another for airplanes. After 9:30, a single controller manages both. On the night of the crash, the consolidation occurred before the scheduled shift change, though it remains unclear why the decision was made.

Radio transmissions from the moments leading up to the crash revealed that the lone air traffic controller warned the Black Hawk helicopter about its proximity to the American Airlines aircraft. The helicopter pilot, described as experienced, acknowledged the warning. However, investigators believe the pilot may have mistaken another departing jet of the same model for the approaching airliner and maneuvered away from the wrong aircraft.

"The FAA has already said staffers were 'not normal for the time of day and volume of traffic,'" The New York Times reported. The FAA has not yet explained whether the staffing shortage contributed to the crash.

Speculation over the cause of the crash has been further fueled by President Donald Trump, who suggested that diversity-hiring initiatives may have played a role in the incident. The FAA has not responded to the president's remarks, and investigators have not cited hiring practices as a factor.

The National Transportation Safety Board (NTSB) is also investigating whether the Black Hawk was flying above its designated altitude, a factor that could have increased the risk of conflict with commercial flights departing from Reagan National. The agency has recovered both black boxes from the American Airlines jet, which may provide additional details on the final moments before the crash.

Harrowing air traffic control audio has emerged, capturing the controller's urgent call for the helicopter crew to maneuver behind the plane just moments before impact. Officials continue to analyze flight data and communications as part of their investigation.