BYERS, Colo. -- The crew of a twin-engine plane that crashed during a snowstorm was told ice could form on the wings, but conditions were not harsh enough for authorities to ground the plane, investigators said Sunday.
The crash Saturday evening killed 10 people, including two Oklahoma State University basketball players and six team staff.
An ice advisory makes crews aware of weather conditions that could cause icing but does not restrict flying, National Transportation Safety Board investigators said.
At takeoff, the temperature at the Jefferson County Airport was minus 4 degrees, with light winds, light snow and visibility of one mile.
John Hammerschmidt, head of the NTSB crash investigation team, said its work would focus on whether de-icing procedures were performed on the plane.
"We have some very detailed and painstaking work ahead of us in what are not the best weather conditions," Hammerschmidt said.
Witnesses said the plane climbed and banked hard to the right before it crashed. They told investigators the propeller plane's engines revved and eased several times before the fiery crash in a field about 40 miles east of Denver.
"It sounded like he was flying full power. Then I heard a thump and saw a low glow," said Jon Carrick, who lives about two miles southwest of the crash site.
Cesar Ronquillo, another area resident, said the plane's engines were whining when he heard a loud noise. "I saw the plane turning around, go up again but all of a sudden go straight down," he said.
There was no distress call from the plane, said Arnold Scott of the NTSB's Denver office.
As light snow fell Sunday, an NTSB investigation team looked for clues to the cause of the crash amid twisted wreckage scattered across a mile. The victims' bodies were removed and taken to the Adams County Coroner's Office.
The engines, de-icing boots and other pieces of the plane were to be taken over the next few days to a hangar in Greeley, where investigators planned to create a mockup of the plane.
Aviation consultant Michael Boyd, president of The Boyd Group in Golden, Colo., said a small amount of ice could reduce the lift on a wing.
"It doesn't take much," Boyd said. "That's why airlines are so intent on de-icing airplanes if they so much as smell ice. You just don't mess with ice because it makes the wing nonaerodynamic."
The Beechcraft King Air 200 Catpass was one of three planes carrying the Oklahoma State men's basketball team and associates back to Stillwater, Okla., after they lost to the Colorado Buffaloes in a Big 12 Conference game at Boulder.
The victims were Oklahoma State players Nate Fleming and Daniel Lawson, sports information employee Will Hancock, director of basketball operations Pat Noyes, trainer Brian Luinstra, broadcast engineer Kendall Durfey, broadcaster Bill Teegins, pilot Denver Mills and co-pilot Bjorn Falistrom.
Also killed in the crash was student manager Jared Weiberg, the nephew of Big 12 commissioner Kevin Weiberg.
The plane, tail number N81PF, was registered to North Bay Charter of Reno, Nev., the FAA said. Greg Feith of the NTSB, interviewed by KUSA-TV, said the aircraft type "has an outstanding record.
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