Background
A pilot was flying eastbound along the Skagit River at an altitude of approximately 1,500 to 1,800 feet above sea level. During the flight, the pilot observed rain showers ahead and decided to reverse course.
Sequence of Events
The pilot initiated a left turn at a speed of 75 miles per hour with two "notches" (20 degrees) of flaps deployed. During the turn, the pilot noted a sink rate. In response, the pilot applied full power and raised the flaps to one "notch" (10 degrees). Despite these actions, the sink rate continued. The pilot reported that it "felt like the aircraft was getting sucked down." As the aircraft continued its left turn toward a rising, tree-covered hillside, the pilot executed a controlled crash into the trees and terrain.
Terrain Analysis
A topographic chart of the accident vicinity indicated that the terrain gradient was considerably shallower to the south. The left turn initiated by the pilot placed the aircraft flying towards higher gradient terrain. The pilot reported that carburetor heat had been used throughout the flight and that the aircraft's engine had been performing as expected.