With no survivors expected to be found, the focus is turning to how a military helicopter on a training exercise collided with an American Airlines passenger jet.
What we know so far
At 8.47pm, with the plane at 600ft and preparing to cross over the river, an air traffic controller contacted the helicopter’s pilot to tell them to pass behind the plane.
“PAT25 [military helicopter] do you have the CRJ [passenger jet] in sight? PAT25, pass behind the CRJ.”
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Airport security cameras captured the helicopter on a collision course with the plane in the final seconds before the crash.
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Flight tracking websites lost sight of the plane at 8.48.03pm local time. Its last reported altitude was 275ft.
Seconds after the crash, a gasp can be heard coming from the air traffic control room.
“Did you see that?” someone asks.
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The emergency alert was sounded around one minute later, at 8.48pm.
“Crash crash crash – this is Alert 3,” rang the alert over the Metropolitan Washington Airports Authority Public Safety communications system.
“It’s on the, uh… approaching runway 3-3. Approaching runway 3-3. Helicopter crash.”
After several minutes, someone asks to confirm the details.
“You said that was a helo and a CRJ?”
“That is affirmative. A helo and a CRJ approaching at 3-3.”
“Ok. How many souls on board?”
“We don’t have any of that information.”
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Police began to receive reports of a crash at 8.53pm. By 8.58pm, the first emergency response vehicle had arrived at the site and reported an aircraft in the water.
Six minutes later, at 9.04pm, the search and rescue mission was launched, with the first boat arriving at 9.11pm.
Why did the aircraft collide?
Transport secretary Sean Duffy told a press conference that the crash was “absolutely preventable”.
Asked if the plane was aware there was a helicopter in the area, Mr Duffy replied: “I would say the helicopter was aware that there was a plane in the area.”
A map published by the Federal Aviation Administration, which manages US airspace, advises helicopters flying to the east of the airport along the Potomac River to stay below 200ft.
Flight tracking data, however, shows the military helicopter had quickly ascended to 300ft before the crash – 100ft above the recommended altitude.
It’s unclear if the helicopter took any action in response to the warning issued by air traffic control.
Andrew Nicholson, chief executive of aviation security firm Osprey Flight Solutions, told Sky News that Black Hawk helicopters are typically very capable of avoiding obstacles in the sky, though a number of things could have gone wrong to cause the crash.
Former air traffic controller Michele Robson suggests the instructions from the air traffic tower could have been clearer, especially considering there was another plane, an Airbus A319, in the helicopter’s line of sight.
“I would expect them to have specified the airline as well so that there wasn’t any confusion,” she says.
Ms Robson says it’s possible that the helicopter pilot thought the Airbus, which was 9.2km away, was the much smaller American Eagle plane just 4.5km away.
“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.
“The CRJ and Airbus look quite different, but in the dark it would make it much harder.”
Timeline shows how the crash response unfolded
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