What happened
While operating under an IFR flight plan at an altitude of 16,000 feet, the aircraft disappeared from radar and radio contact. At the time of the incident, the aircraft was traveling through an east-west cloud band approximately 10 miles in width, as identified by satellite imagery. Local reports from other pilots in the vicinity described significant cloud buildup with tops ranging between 16,000 and 20,000 feet. During this period, pilots in the area reported encountering unexpected moderate turbulence and intense updrafts.
Findings
Investigation into the circumstances revealed that the onboard weather radar was turned off during the flight. The aircraft was traveling at a calibrated airspeed of 141 knots, which exceeded the maneuvering speed of 135 KCAS specified in the pilot's operating handbook for gross weight. The presence of a large cloud band and the reported strength of the updrafts suggest the aircraft was navigating through unstable atmospheric conditions while lacking active radar monitoring.