Investigators said ice may have been one of the factors behind this weekend's plane crash in Montana that left 14 people dead but warned Tuesday that the real cause could take a long time to determine.
Conditions at the time were ideal for ice, meteorologists said, just as in last month's crash of a Continental Airlines commuter plane near Buffalo, N.Y., that killed 50.
National Transportation Safety Board officials have said ice is one possible cause in the Buffalo crash, which is still under investigation.
But unlike the Buffalo crash, there were no flight data or voice recorders onboard the plane -- a Pilatus PC-12, high-end, single-engine turbo prop -- that could help pinpoint a cause.
The weather conditions were conducive to ice formation in the Montana crash, which is one of the two key suspected causes, former National Transportation Safety Board official John Goglia told ABC News. He added that the way the Pilatus nose-dived into the ground was similar to the way the Continental plane crashed in Buffalo.
Another key factor investigators are looking at is weight, or a shift in weight. The multimillion dollar Pilatus was carrying more passengers than it was licensed for, officials said Monday, and they will investigate whether carrying four extra passengers contributed to the crash.
But seven of the 14 passengers were children varying in age from 1 to 9, so it's not clear if weight was a factor. But balance or a sudden shift in weight could be a contributing cause.
ABC News' aviation consultant John Nance said the Pilatus PC-12 is a good, resilient aircraft but that extra people on this type of a plane could create not only a possible weight problem but a balance problem too.
"I'm convinced, even at this early stage, that one of the areas they need to look at the closest is weight and balance," Nance said.
Nance speculated that if people were moving around, the aircraft's center of gravity could have fatally shifted, making it next to impossible for the pilot to control, especially on approach.
"The fact that you've got children onboard, they may see something out of the airplane at the last minute. People unstrap their seat belts, get up and move, and your center of gravity could shift," Nance said. "When you overstuff a number of people on an airplane, you have the potential for getting it outside what we call the envelope of the center of gravity."
Mark Rosenker, acting chairman of the NTSB, said Monday that the agency would calculate the weight of the luggage, fuel and passengers.
"Lap children can be allowed on an aircraft up to the age of 2," Rosenker said. "We can't tell you if in fact they were sitting on the laps or not."
Investigators said they have no reason to believe the plane ran out of fuel or had mechanical problems.
Rosenker emphasized at a briefing Monday that there is unlikely to be a quick answer as to what caused the fatal crash.
"This will be a long and tedious investigation, extremely thorough," Rosenker said. "We will look at every factor which could affect the performance of this aircraft."
On Tuesday, the AOPA Air Safety Foundation -- an aviation association -- cautioned against jumping to conclusions in the fatal accident.