Learjet tail part found miles from deadly Florida plane crash

Investigators have determined the plane involved in a deadly crash in south Florida was breaking up midair before it hit the ground.

The flight encountered bad weather and crashed in Greenacres, about 11 kilometres south-west of West Palm Beach, on Sunday local time.

The Learjet took off from Austin, Texas.

The impact scattered plane fragments over a large area, with parts of the jet's tail discovered kilometres from the crater.

Plane part reveals key moment before crash

National Transportation Safety Board member Tom Chapman said on Tuesday local time the tail's elevator — which controls the pitch up and down — was broken into three parts.

Without that intact, the pilot would not have been able to pull the plane out of its nosedive, he said.

"Knowing that it was lost is a very important piece of evidence in terms of pointing us towards other things to investigate," Mr Chapman said.

He earlier said the weather conditions would also feature in the investigation.

Final moments recorded in devastating air traffic call

Co-pilot Nathalia Gadelha Filgueiras told air traffic controllers minutes before the crash that ice was accumulating on the plane and that severe turbulence had thrown it up and down by more than 210 metres.

She could be heard screaming "we're going to die!" before the jet slammed into the ground and erupted in a fireball.

The family of pilot Jeff Gregory, 55, confirmed he was one of two crew members in the cockpit of the Bahamas-bound Learjet 60.

Mr Gregory has been described online as an experienced pilot, devoted father and Christian.

His family are convinced Mr Gregory could be heard praying in the background of the copilot's final radio transmissions to air traffic control.

A fundraiser, organised by a close friend and the director of operations at the company that operated the flight, Upper Jets, has raised more than 50 per cent of the $US16,000 target since it was posted earlier this morning.

Mr Gregory held airline transport pilot and flight instructor certificates, according to Federal Aviation Administration records.

He previously worked for a charter company based in Allentown, Pennsylvania.

"We are deeply saddened to learn that Captain Jeff Gregory was among those who lost their lives," said April Honnen, the director of charter sales for East Coast Jets, Inc, where Mr Gregory worked in 2016 and 2017.

"Our prayers go out to Jeff's family, his fellow crew member, the passengers and everyone affected by this heartbreaking tragedy."

Images of the moment just before the aircraft made impact appear to show the elevator — a horizontal stabiliser — missing from the tail.

About 600 nearby residents remain displaced, but only one injury was reported on the ground.

The victims included technology entrepreneur Adam Robinson, his wife, Helen Sharp, and their two young children, relatives said.

Ms Filgueiras's stepfather, Thiago Corteleti, told the New York Post that Ms Filgueiras texted her boyfriend about 10 minutes before the crash, telling him: "I've got turbulence, I've got ice."

The texts were sent before the situation became critical.

In the last two minutes of the flight, Ms Filgueiras shifted from calmly communicating with air traffic controllers to calling out terrifying updates as the plane plummeted.

A preliminary report describing what happened will be released in about a month, but it will likely take more than a year to determine the cause of the crash.