Overview
A visual flight rules (VFR) flight through the Cascade Mountains ended when the pilot encountered instrument meteorological conditions (IMC) at night and the aircraft collided with trees. The flight had been delayed, causing arrival at the pass after dark, and the pilot had changed the route despite an advisory against visual flight.
Flight Planning and Delays
The planned flight was a VFR transit of the Cascade Mountains scheduled for daylight hours. The pilot filed a VFR flight plan and received a weather briefing that indicated VFR conditions were expected. However, unforeseen delays meant that the aircraft arrived at the originally planned mountain pass over one hour later than intended. By that time, the weather was no longer visual meteorological conditions (VMC).
The pilot noticed an alternative pass to the north that appeared to offer better weather and amended the flight plan to proceed via Stevens Pass. This decision was made despite a Flight Service Station (FSS) advisory that visual navigation was not recommended (VNR) under clouds through the Cascades.
The Flight through Stevens Pass
The flight arrived at Stevens Pass after darkness had fallen. The pass was illuminated by lights for night skiing, which allowed the pilot to visually navigate through the pass. The flight continued.
Descent and Loss of Visual Reference
After transiting the pass, the pilot began descending along a highway. During the descent, the pilot reported encountering IMC. He lost visual reference with known high terrain that was present on both sides of the aircraft. The pilot initiated a climb, but the aircraft mushed into trees located on rising terrain ahead.
No probable cause was stated.