Audio from LiveATC.net, a respected source for in-flight recording, captured the final communications between the three crew members of the helicopter - call sign PAT25 - before it collided with the CRJ700 Bombardier jet carrying 64 passengers and crew.
"PAT25, do you have a CRJ in sight? PAT25, pass behind the CRJ," an air traffic controller said at 8.47pm on Wednesday (Thursday AEDT).
Seconds later, another aircraft called in to air traffic control, saying, "Tower, did you see that?" - apparently referring to the crash. An air traffic controller then redirected planes heading to runway 33 at Reagan Washington National Airport to go around.
The explosion in mid-air occurred over the frigid Potomac River near the airport.
"Crash, crash, crash, this is an alert three," one of the air traffic controllers can be heard saying in the audio from around the time of the crash.
"I don't know if you caught earlier what happened, but there was a collision on the approach into 33. We're going to be shutting down operations for the indefinite future," another controller remarked.
"Both the helicopter and the plane crashed in the river," a third air traffic controller can be heard saying.
"It was probably out in the middle of the river," the controller said.
"I just saw a fireball and then it was just gone. I haven't seen anything since they hit the river. But it was a CRJ and a helicopter that hit."
The crash was caught on a webcam at the John F. Kennedy Centre for the Performing Arts in Washington. The clip shows the aircraft exploding in flames and plummeting to earth after it is struck by the helicopter.
