Cessna 150
Flight Crew Multiengine; Flight Crew Instrument; Flight Crew Flight Instructor; Flight Crew Commercial
Flight Crew Last 90 Days 22; Flight Crew Total 2359; Flight Crew Type 1404
Situational Awareness
Deviation / Discrepancy - Procedural FAR; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter VFR In IMC; Inflight Event / Encounter CFTT / CFIT
Flight Crew Became Reoriented; Flight Crew Took Evasive Action
Human Factors; Weather
Flight was on a VFR flight plan westbound across Cascade Range at 8;500' MSL CAVU (Clear and Visibility Unlimited). As I neared the flat terrain on the western side of the Cascade Range; I could see the tops of the typical low level clouds which were forecast to be dissipating at around this time. CLS AWOS was reporting ceiling 1500' and visibility 9. I could see the edge of the cloudy area and decided to descend in a river valley to below the ceiling for the remaining 25 miles to my destination. Soon after entering below the ceiling; I could not maintain the required cloud clearance/terrain obstruction clearance. To avoid further descent; and assessing that a 180 turn was not possible due to terrain; I began a climb in the direction of the river valley. I entered IMC and broke out about 500' higher.This situation reflects poor judgment on my part and arose because of an incorrect assumption I had about what was under the cloud layer. My home base is in this area and I expected to see the usual; well-defined ceiling with good visibility underneath. This was not the case in this circumstance.I am well aware that continued VFR into IMC is a leading cause of fatal GA accidents. Yet I relied on my belief that I could continue VFR under the cloud layer. Had I not quickly initiated the climb; the result could very well have been a CFIT accident. I will no longer consider a duck under option in the future.
C150 pilot reported VFR in IMC and CFTT en route when he attempted to duck under the cloud cover to reach the destination airport.