Boeing 757-232 N684DA accident near Naches, Washington

Probable cause

The airplane's encounter with moderate turbulence at a higher altitude than the flight crew expected, resulting in an injury to a cabin crewmember.

NTSB analysis

The flight crew of the scheduled domestic air carrier passenger flight was advised by the air route traffic control center that, due to a pilot report associated with the area of their routing, they should expect light-to-moderate chop during their descent between 20,000 feet and 16,000 feet. The flight crew, therefore, advised the passengers and the flight attendants that the descent would be bumpy and then advised the flight attendants that all descent and before-landing cabin securing activities should be completed about 10 minutes earlier than normal. Before the descent, the flight crew turned on the seatbelt sign and upon reaching 25,000 feet, the flying pilot began reducing the airspeed to that prescribed for turbulence penetration. As the airplane passed through 24,000 feet (4,000 feet higher than the altitude of the turbulence noted in the pilot report), three flight attendants were just finishing their activities, and the airplane suddenly encountered moderate turbulence for about 30 seconds. Due to the sudden movement of the airplane, the one remaining standing passenger and two of the flight attendants were thrown to the floor, one of whom sustained multiple bone fractures in her right foot.

Text from the NTSB. Open the NTSB docket for WPR11LA149 for the full record.