NTSB Factual Report

On June 10, at 1812 mountain daylight time an Airbus Industrie A-319-114, N302NB, operated by Northwest Air Lines as flight 563, encountered turbulence near Scottsbluff, Nebraska, while descending through 34,000 feet msl. Visual meteorological conditions prevailed at the time of the accident. The flight was being conducted on an IFR flight plan under the provisions of 14 CFR Part 121. One flight attendant was seriously injured. The remaining 2 pilots, 4 flight attendants, and 120 passengers aboard were not injured. The flight originated at Minneapolis, Minnesota, and was en route to Denver, Colorado.

The aircraft was flying in an area of thunderstorms with the nearest cell 40 miles to the left of course. The captain said the top of a thunderstorm cell was "not painting on radar." They had been expecting light chop but encountered moderate turbulence instead. When the airplane encountered the turbulence, a flight attendant struck the ceiling, and a beverage cart. The seat belt sign was illuminated at the time. An emergency was declared and the aircraft landed at Denver without further incident. The injured flight attendant was taken to a hospital. According to Northwest Airlines, the flight attendant's injuries included two broken ribs, a liver contusion, and an intestinal blockage.

According to the Denver Automated Flight Service Station (AFSS), an AIRMET for "occasional moderate turbulence between FL270 and FL400 associated with jet stream windshear" had been in effect for the area. There were no PIREPS (pilot reports) of turbulence before the accident, but in the 40 minutes after the accident, there were 5 pilot reports of moderate turbulence at altitudes between FL320 and FL380. show that an AIRMET for turbulence existed that covered the area where the aircraft encountered the turbulence.

NTSB Probable Cause

the inflight encounter with moderate turbulence.