Investigators have found the black boxes from both aircraft in the deadly Washington crash, the US National Transportation Safety Board says.

The breakthrough came as former Olympic skater Nancy Kerrigan joined those paying emotional tributes to some of those, including children and young teenagers, who died aboard the commercial plane.

Also on Thursday (local time), Washington DC fire and emergency authorities said they had searched “all areas that are accessible” in the Potomac River after Wednesday’s midair collision between the American Airlines plane and a military helicopter.

“Tomorrow (Friday, AEDT), divers will work with NTSB to conduct additional searches to locate aircraft components, to support the investigation, and begin operations to salvage the aircraft,” Washington DC’s fire and emergency services department posted on X.

“Overnight, boats will remain on scene for security and surface searches from local, state, and federal regional partners.”

Earlier, it was revealed the US Army helicopter that collided with the domestic passenger jet was being operated on a training flight by a “fairly experienced crew” with night-vision goggles.

All 64 people on board the American Airlines’ plane and the three on board Black Hawk helicopter died in the fiery crash. About 28 bodies have already been recovered.

The toll is likely to make it the deadliest aviation disaster in the US since the September 11 attacks of 2001.

Daniel Driscoll, US President Donald Trump’s nominee for Army secretary, said the crash appeared to have been preventable.

The helicopter struck the jet near Ronald Reagan Washington National Airport, with both aircraft plunging into the Potomac River. The cause of the crash is under investigation.

“The people in the helicopter should have seen where they were going,” Trump said at the White House.

At one point, he said warnings from air traffic control came too late.

“For some reason, you had a helicopter that was at the same height and going at an angle that was unbelievably bad.”

In a video statement, US Defence Secretary Pete Hegseth said a crew of three soldiers were on the training flight.

“It was a fairly experienced crew and it was doing a required annual night evaluation,” he said.

“We anticipate that the investigation will quickly be able to determine whether the aircraft was in the corridor and at the right altitude at the time of the incident.”

Chinese and Russian state media have both reported citizens aboard the American Airlines plane. Other passengers also included young figure skaters from the Skating Club of Boston.

Among them were teenagers Jinna Han and Spencer Lane and their mothers, Jin Han and Christine Lane. Club director Doug Zeghibe said the loss was immense.

“It’s hard to believe Jinna was only 13,” Zeghibe said. “We got to watch her grow up from a spindly little kid into this long, lithe skating beauty at 13, which was just amazing.”

He said Spencer was “a firecracker” and a dynamic skater with a bright future after taking up the sport only about three years ago.

“His technical ability for such a short time was incredible, almost unheard of,” Zeghibe said.

Kerrigan, a former club member, paid her own teary tribute.

“It’s heart-wrenching. Everybody who died is somebody’s somebody,” she said.

“We just wish them well and the families the courage and the strength to make the next steps. I don’t know how – you look at people who go through tragedies, and you wonder how they do it – I don’t know, but we’re so strong.”

‘Should not have been a problem’

Later, with Trump at the White House, Hegseth said there appeared to have been an elevation issue with the Black Hawk.

Jonathan Koziol, chief of staff of the Army’s aviation directorate, said the instructor – the designated pilot in command – had 1000 flying hours while the other pilot had 500 hours. The third soldier was a crew chief, typically riding in the back of the helicopter.

Koziol, a former Army aviator, said that the route over the Potomac, known as Route 4, was flown regularly by military pilots.

Koziol said crew members ordinarily would use visual cues and interact with air traffic control to ensure that they avoided any risk.

“This should not have been a problem,” Koziol said.

At the White House, Trump and Hegseth said the era of diversity, equity and inclusion (DEI) in US government was over.

Trump baselessly blamed policies in air traffic control for the crash. He also accused the previous Biden and Obama administrations of imposing workplace policies that led to recruits with physical and psychological impairments.

“The FAA (Federal Aviation Administration) is actively recruiting workers who suffer severe intellectual disabilities, psychiatric problems, and other mental and physical conditions under a diversity and inclusion hiring initiative spelled out on the agency’s website,” he said.

“Can you imagine?”

Koziol played down those concerns.

“As for women in the military, flying a helicopter is like driving a car. You just got to learn how to do it and anyone can do it with the proper training,” he said.

The Black Hawk crew were two male and one female soldier. The helicopter was from the 12th Aviation Battalion, based at Fort Belvoir in Virginia.

On Thursday (local time), Driscoll appeared at his confirmation hearing before the Senate Armed Services Committee.

“I am seeing the same things I believe you are, on television. It is an accident that seems to be preventable from what we can tell today,” Driscoll said.

He said if he was confirmed there would be a focus on a culture of safety in the US Army.

“I think we might need to look at where is an appropriate time to take training risk, and it may not be near an airport like Reagan,” Driscoll said.

-with AAP