BLACK boxes that could reveal crucial clues about what caused the American Airlines plane crash have been recovered.

Investigators are probing how the collision that left 67 dead happened amid questions over staffing and close calls at the airport.

The passenger jet and a US Army helicopter plunged into the Potomac River in Washington DC on Wednesday night after crashing mid-air.

Divers dredged up two black boxes from the passenger jet in the freezing water on Thursday.

The boxes record flight data and what the pilots say – and could be vital in offering clues about what caused the disaster.

A preliminary report is expected to be issued in 30 days, the National Transportation Safety Board (NTSB) said.

Both boxes were transported to one of the board’s labs on Thursday to be analyzed following the horror crash on Wednesday night.

It comes as…

All 64 people on the CRJ700 airplane were killed, as well as the three crew members on the Black Hawk chopper.

Divers now aim to “salvage the aircraft” and find additional components.

Authorities have not pinpointed a reason for the collision, which happened as the regional jet was trying to land at Ronald Reagan Washington National Airport.

But air traffic control staffing numbers were “not normal”, according to an initial Federal Aviation Administration (FAA) report.

The controller who was directing helicopters was also instructing planes, The New York Times reported.

These jobs are typically assigned to two people.

Minutes before landing, air traffic controllers asked the incoming plane if it could land on a shorter runway at Reagan National.

The pilots said they could and controllers cleared the jet to land on Runway 33.

Flight tracking sites showing the jet adjusted its approach.

Less than 30 seconds before the crash, one controller asked the helicopter if it could see the plane.

The controller made another call to the chopper just moments later, saying: “PAT 25 pass behind the CRJ.”

But seconds later, the plane and helicopter crashed.

Former air traffic controller Michele Robson said instructions from air traffic control could have been clearer.

She told Sky: “I would expect them to have specified the airline as well so that there wasn’t any confusion.

“In the dark in a city environment with lots of lights, and at that distance, I don’t think the helicopter would have been able to tell what type [of plane] the Airbus was that far away, so may have just assumed.”

It has also emerged at least two other pilots reported near-misses with helicopters while landing at the airport in the three years before the deadly crash.

A passenger flight had to abort a landing at the airport just a day before the tragedy.

Republic Airways Flight 4514 was forced to back out of touching down and had to make a second approach after a helicopter appeared near its flight path, the Washington Post reported. 

Radio communications from Wednesday night’s disaster meanwhile showed that air traffic controllers alerted the helicopter about the approaching jet and ordered it to change course.

A newly-engaged pilot, a group of friends on a hunting trip, and teenage figure skaters were among the victims aboard the American Airlines plane.

Three soldiers on the Black Hawk, including a new dad from Atlanta, died when the military helicopter smashed into the passenger jet that had traveled from Wichita, Kansas.

The plane shattered into three pieces, and both aircraft sank into the inky black waters just before 9 pm ET on Wednesday.

Hopes for survivors quickly faded as rescue crews worked through the night in dark, cold conditions.

Authorities yesterday confirmed there were no survivors – making this the deadliest US air crash since November 2001, when 260 people died after a plane plunged into a Queens neighborhood.

American Airlines CEO Robert Isom said the pilot of the American Eagle Flight 5342 had about six years of flying experience.

The Bombardier jet was operated by PSA Airlines, a regional subsidiary.

Defense Secretary Pete Hegseth said the helicopter was flown by a “fairly experienced crew” of three soldiers who were wearing night-vision goggles on an annual training flight.

Officials said they were grounding other flights from the Army unit involved in the crash and would reevaluate training exercises in the region.