NBC Sports executive Dick Ebersol (search) told investigators his chartered jet struggled just 20 feet into the air before it fell back to the runway and broke apart, aviation officials said Wednesday.

Ebersol's 14-year-old son Edward "Teddy" and two crew members were killed when the twin-engine CL-601 Challenger (search) crashed in light snow, fog and freezing temperatures at Montrose Regional Airport on Sunday.

National Transportation Safety Board (search) investigators said the plane had not de-iced before attempting takeoff.

"I would say right now we're looking at environmental factors and (aircraft) performance factors," NTSB lead investigator Arnold Scott said Wednesday.

Scott said investigators do not believe engine failure was a factor because the roar of the jets can be heard on a cockpit voice recorder. He also said the plane did not break apart in the air.

Ebersol, 57, and another son, Charlie, 21, remained hospitalized in Grand Junction but were expected to make a full recovery, NBC said. Dick Ebersol reportedly suffered broken ribs, a broken sternum and had fluid in his lungs, while Charlie suffered a broken hand and had a sore back.

The co-pilot, identified by Denver newspapers as Eric Wicksell, 30, of Daytona Beach, Fla., was in critical condition at a burn unit in Denver.

The NTSB had not interviewed Wicksell. "We don't interview people who are fighting for their life," Scott said.

Charles Eastlake, a professor at Embry-Riddle Aeronautical University in Daytona Beach, Fla., said the evidence seems to point toward ice on the plane as a factor in the crash.

"The behavior of the aircraft makes it more likely that de-icing is an issue," he said.

NTSB spokesman Keith Holloway said investigators want to compare Sunday's crash with a deadly January 2002 crash in England of a CL600 Challenger that tried to take off in freezing temperatures without de-icing.

"We will look at it and see if there are similarities other than that," he said.

The pilot of the Ebersols' plane, 50-year-old Luis Alberto Polanco of the Dominican Republic, and flight attendant Warren T. Richardson III, 36, of Coral Gables, Fla., were also killed. The Federal Aviation Administration (search) will conduct toxicology tests, Young said.

Teddy Ebersol, the youngest son of Ebersol and "Kate and Allie" actress Susan St. James, died after being ejected from the plane and crushed by the wreckage, Montrose County Coroner Mark Young said. Dental records flown from Connecticut were used to positively identify the boy.

Scott said there was no indication Teddy was wearing a seat belt. Charlie was not wearing a seat belt, but Polanco was, he said.

Neither St. James, 58, nor another son was on the plane.

Scott's team wrapped up its field investigation Wednesday and prepared to return to Washington. The debris will be moved to a hangar in Greeley where it may be examined again, he said.

Details of the cockpit voice recording may not be available for months, after the recording is transcribed, he said.