Bombardier Inc CL 600 2C10 N745SK accident near Mckellar, Tennessee

Probable cause

An encounter with convective turbulence while maneuvering to avoid conflicting traffic.

NTSB analysis

While in cruise flight around 36,000 ft, the flight crew of the scheduled domestic passenger flight was instructed by air traffic control to turn for traffic separation. The crew reported that, after completing the turn, the airplane entered a cloud and encountered severe turbulence. The seat belt sign was not activated at the time of the encounter, and of the 74 passengers and crew members aboard, one passenger received serious injuries and two flight attendants and eight passengers received minor injuries. The airplane was not damaged.

According to flight data recorder information, during the encounter, vertical acceleration ranged from -0.8g to 1.89g, the airplane lost about 200 ft altitude in 2 seconds, and the airspeed varied by about 15 knots. The airplane entered an 11.6° nose-down pitch attitude and rolled 26 degrees to the left. The crew reported that the flight until the encounter had been smooth. They reported that they could see the cloud build-up as they were approaching it from about 80 to 100 miles away, but that their radar did not indicate that they were going to encounter convective weather.

The company's flight operations manual stated that, before entering an area of thunderstorms, pilots were required to ensure that all personnel were seated and safety belts were fastened.

Text from the NTSB. Open the NTSB docket for DCA17LA183 for the full record.