What happened
While flying in instrument meteorological conditions (IMC), a pilot was attempting to set a cross-country glider record by utilizing standing lenticular wave conditions along the Sierra Nevada mountain range. The flight was conducted under an instrument flight plan, with clearance for a block altitude between 18,000 and 28,000 feet.
During the cruise phase of flight, the pilot reported that internal canopy icing had developed, which obstructed visibility through the canopy. While attempting to wipe the frost from the canopy, the pilot noted that the aircraft was approaching cloud layers and would soon enter instrument conditions. In preparation for the transition, the pilot activated the emergency standby electric turn and bank indicator; however, the instrument did not fully spool up before the aircraft entered the clouds. Shortly thereafter, the pilot lost control of the glider, resulting in an in-flight breakup where the wings separated from the fuselage. The pilot successfully bailed out of the aircraft.
Findings
- The pilot was operating in instrument meteorological conditions (IMC).
- Internal canopy icing interfered with the pilot's visibility.
- The emergency standby gyro did not reach full operational status before the aircraft entered clouds.