US National Transportation Safety Board (NTSB) investigators believe it could take some time before they know exactly what caused yesterday's crash of a Pilatus PC-12 in Butte, Montana, which resulted in the deaths of all 14 people onboard the aircraft.
Among the factors being explored is whether the single-engined turboprop, carrying seven adults and seven children on a ski vacation, was overloaded. A PC-12 can carry up to nine passengers plus two pilots.
But the NTSB is staying clear of making any early determinations. "We don't do any analysis [at this time]. We've started interviewing family members," says a NTSB spokesman.
The flight originated in Redlands in San Bernardino County, California and made a stop at the California city of Vacaville, and later at the town of Oroville. "Then it was on its way to Bozeman [Montana] but diverted to Butte," says a NTSB spokesman.
He says the pilot "requested the change for diversion to Butte, but did not give a reason for the diversion".
The turboprop, bearing registration N128CM, nose-dived into a cemetery 150m (500ft) short of Butte airport.
Agency officials must conduct their investigation without the aid of a flight data recorder or information from survivors. NTSB chairman Mark Rosenker is quoted in the Los Angeles Times as saying: "It will take us a while to understand. First we have to get the weights of all the passengers, the weight of the fuel, the weights of all the luggage and any cargo that may have been aboard the aircraft. There are a lot of questions that still need to be answered."