Learjet may have been breaking up before it crashed in Florida, NTSB says

A Learjet that slammed into a Florida roadway on Sunday, killing all nine people aboard, may have been breaking up before it hit the ground, the National Transportation Safety Board said Monday.

"We do have some indication that the aircraft was breaking up before impact, and so some of this is yet to be determined. We may find parts of the aircraft some distance away from the actual impact site," NTSB board member Tom Chapman said at an afternoon news conference in West Palm Beach, Florida.

Chapman said before beginning a rapid descent from 35,000 feet and making a Mayday emergency call to air traffic control, the aircraft's two-person crew reported they were experiencing icing on the aircraft and "moderate turbulence."

NTSB officials said they do not have precise numbers on the Learjet's airspeed, but said it was traveling at a high rate of speed before the crash.

Aircraft maintenance records showed there was a cockpit voice recorder installed on the jet, according to Chapman, but he said it's unclear if it was still onboard the aircraft during its final flight.

An official from the Palm Beach Sheriff’s Office said it is too early for victims' identities to be released. The medical examiner's office is engaged in the "lengthy process" of DNA collection and assessment, officials said.

The 22-year-old twin-engine Learjet 60 crashed in Palm Beach County after plummeting to the ground at 350 feet per second, the Federal Aviation Administration (FAA) said Sunday, creating a huge crater in a roadway.

In addition to the two crew members and seven passengers who perished in the catastrophic event, one man who was in a vehicle on the ground "immediately adjacent" to the crash site sustained a leg injury, according to NTSB investigator in charge Timothy Monville.

While the names of those killed have not been released, the co-pilot's stepfather identified her to ABC News on Monday as 20-year-old Nathalia Gadelha Filgueiras.

Photos and videos online showed a jet hitting the ground nose-first and bursting into a fireball. The impact of the crash left a crater near a shopping center.

The jet crashed just before 1 p.m. ET near Military Trail, between Cresthaven Boulevard and 10th Avenue, in the Greenacres community of Palm Beach County, authorities said.

The crash prompted the evacuation of hundreds of people from 77 mobile homes in the area, county officials said following the NTSB briefing.

During Monday's news conference, Chapman gave a timeline of the air disaster, saying that weather conditions are a major focus of the investigation and that the turbulence the crew reported is "certainly a factor."

The Learjet, which belonged to Aurora Aviation, a private company doing business as Upper Jets, took off from Austin-Bergstrom International Airport in Austin, Texas, around 10:37 a.m. ET on Sunday and was headed to North Eleuthera in the Bahamas, Chapman said, adding that the crew was in communication with air traffic control facilities along the flight route.

At 12:47 p.m. ET, the crew reported they were encountering "moderate turbulence" and "light clear ice" on the aircraft, which the crew said at the time was manageable, according to the NTSB.

While in contact with the Miami Air Route Traffic Center, the crew transmitted that they were at 35,000 feet and that the moderate turbulence was causing the aircraft to experience altitude deviations of about 700 feet, Chapman said. He said the crew also reported that the temperature outside the airplane was minus 47 degrees Celsius, or minus 53 degrees Fahrenheit.

Very soon after, the crew requested permission to climb to 37,000 feet, which was approved by FAA air traffic control, Chapman said. Less than 30 seconds later, a transmission from the airplane announced a descent, followed by a Mayday call.

"Less than 30 seconds later, the airplane transmitted, 'We are in an overspeed condition, descending...,' with the rest unintelligible," Chapman said. "Subsequent communications described that the airplane was descending rapidly and gave an altitude callout."

"Sadly, all aboard were lost," Chapman added.

Neither Monville nor Chapman could say whether the jet flew through an active thunderstorm prior to the aircraft's rapid descent and crash.

Monville estimated that a debris field from the crash measured about one-half mile by four-tenths of a mile in size and was scattered among ball fields, businesses and houses.

"We're finding debris, but haven't identified parts yet," said Monville, adding that NTSB investigators will be at the scene of the crash for several days collecting evidence.

Monville said the "biggest obstacle" investigators are likely to have is recovering wreckage from the huge crater the crash created. He said current weather conditions also are posing difficulty for investigators and that rainwater had seeped into the crater.