premise: A Twin Otter aircraft which had been missing since Friday morning in Papua province of Indonesia, have been found on Saturday morning with 12 passengers and crew seems to have died, a police officer said.
  The plane was found broken to pieces in a deep ravine by a group of missionaries while traveling from Wamena regency to Mulia regency, all people on board predicted to have died, said provincial police spokesman Kartono Wangsa Disastro.
  "The plane has been found, the missionaries said logically no one safe from the accident," Disastro told Xinhua by telephone from the province.
  Bad weather and mountainous field were the cause of the accident, he said.
  "After the plane lower its height preparing for landing, the weather changed to dark, afterwards, the plane crashed to a mountain," he said.
   What caused the plane to be missing since Friday?
hypothesis: plane crashed to a mountain