Beech 99 N198WA accident near Rockland, Maine

Probable cause

The airplane’s encounter with isolated severe turbulence, which resulted in substantial airframe damage.

NTSB analysis

The commercial pilot was conducting a nonscheduled cargo flight. The pilot reported that, as the airplane was descending on an instrument approach, it encountered continuous light-to-moderate turbulence. As the airplane descended through about 2,000 ft mean sea level at an airspeed of 130 knots, it encountered severe turbulence, and the pilot subsequently executed a missed approach and chose to divert to an alternate airport. The airplane continued to encounter light-to-moderate turbulence en route to the alternate airport, and the pilot landed the airplane uneventfully.

Postaccident examination of the airplane revealed that the airframe had sustained substantial damage during the flight. Although there were multiple AIRMETs for widespread moderate turbulence and low-level windshear, there were no pilot reports of, nor SIGMETs forecasting, severe turbulence at the time the pilot received her preflight weather briefing.

Text from the NTSB. Open the NTSB docket for ERA16LA137 for the full record.