Unintended flight into IMC? Mechanical/instrument failure during IFR flight? It’s a miracle the girl survived.
That part of Washington is very rugged and remote. The crash must have happened within a few miles of Hwy 20, the only significant road in the area. If the girl had walked any other direction than she did, she would probably still be out there.
It is a rugged area. Once I was backpacking in the area and woke up to 6 inches of snow...in August!