A supervisor allowed an air traffic controller at Ronald Reagan National Airport to leave early, hours before the passenger plane collided with an Army helicopter in midair, according to reports.

Both aircraft plunged into the icy Potomac River shortly before 9 p.m. Wednesday and all 64 passengers on the American Airlines regional jet, along with three soldiers on the Black Hawk helicopter, are presumed dead.

A single controller was left to handle the air traffic of planes and helicopters flying over the airspace when two people would typically be monitoring both flight paths, sources told NBC.

The Federal Aviation Authority reportedly confirmed in a preliminary safety report of the crash that one controller was doing the job of two, according to the New York Times. Airplane and helicopter traffic is normally handled by two separate controllers until 9:30 p.m., but a supervisor allegedly merged the two jobs before the allotted changeover time, a source told the newspaper.

Staffing levels were ?not normal for the time of day and volume of traffic? over the airspace, the report said, according to the outlet.

Air traffic staffing will be one of several areas investigators probe as they try to piece together what led to the deadliest U.S. air disaster since 9/11. There are also new reports raising concerns about the helicopter?s flight pattern including whether the aircraft was flying above its designated airspace.

Wreckage of the Black Hawk military helicopter in the Potomac River after it collided with an American Airlines jet. Sixty-seven people died in the crash. Investigators are now probing staffing levels at air traffic control towers and the helicopter?s flight patterns

Wreckage of the Black Hawk military helicopter in the Potomac River after it collided with an American Airlines jet. Sixty-seven people died in the crash. Investigators are now probing staffing levels at air traffic control towers and the helicopter?s flight patterns (EPA)

Radio transmissions from the night of the crash reportedly detail how the lone controller warned the helicopter crew that it was coming too close to the passenger plane.

The Independent has contacted the FAA and the National Safety Transport Board, which is leading the investigation, for comment.

In addition, the helicopter may have been flying too high and outside the approved flight path when it collided with the American Airlines plane, the Times also reported.

The helicopter was above 300 feet when it should have been below 200 feet, four people briefed on the matter reportedly told the Times.

It was also reportedly at least half a mile off the approved flight path when it smashed into the plane carrying 64 people.

According to the official who spoke anonymously with the Times, the pilots had flown the route before and were ?well aware? of the restrictions and where they were permitted to fly near the airport.

On Friday the FAA announced it is indefinitely limiting helicopter flights near the Reagan National Airport, according to Reuters. The restrictions will be in place ?for the foreseeable future,? according to the agency.

It will also only permit police and medical helicopters in the area between the airport and nearby bridges.

The bodies of the three soldiers aboard the helicopter have been recovered from the wreckage.

Two of them have been named as Crew Chief Ryan O?Hara from Georgia and Chief Warrant Officer 2 Andrew Eaves of Mississippi.

Both of the passenger plane?s black boxes have been recovered from the Potomac River and have been taken to labs to examine their contents. (The Independent)

Update news