Incident Overview
On a flight in the vicinity of Charlotte, North Carolina, an MD-82 experienced turbulence that caused serious injuries to one passenger. The captain reported that the ride had been smooth with only occasional light chop prior to the event. Approximately seven people were standing at the time, including the three flight attendants, as the seat belt sign was off.
Flight Conditions and Sequence
The aircraft was cruising at flight level 310 (FL310) in night visual meteorological conditions, with stars and ground lights visible. The captain noted that radar indicated a clear flight path, with a significant line of storms approximately 30 miles east of their course. At about 2207, the airplane entered instrument meteorological conditions and quickly encountered moderate chop, followed by a very sharp jolt. The captain immediately turned on the fasten seat belt sign after the first jolt. The aircraft then experienced two more sharp jolts. Rain and Saint Elmo's fire were present. The captain turned the airplane to the right, back towards where they had last seen ground lights, and informed FAA Air Traffic Control Jacksonville Center of the turn and ride condition. Approximately 30 seconds later, the ride became smooth with some light chop, and the aircraft re-entered visual meteorological conditions.
Investigative Findings
The National Transportation Safety Board (NTSB) examined radar and weather data pertinent to the flight. Infrared satellite imagery overlaid with the flight path revealed an isolated thunderstorm with an estimated cloud top of about 36,000 feet in the vicinity of GLOVR intersection around 2145. Additional data at 2202 and 2215 showed that thunderstorm cloud tops had increased in height, and the thunderstorms had expanded outward and moved northeast along the aircraft's track. Digital Doppler weather radar data from Greer, South Carolina, evaluated with respect to the turbulence times, showed reflectivity echoes in the vicinity of the turbulence location, ranging from VIP level 1 (very light) to VIP level 5 (intense). Reflectivity cross sections of radar data along the flight track indicated that the maximum radar tops penetrated by the flight were about 40,000 feet. Examination of the airplane's Flight Data Recorder provided data showing altitude changes and fluctuations in vertical and lateral acceleration consistent with other information. Both the NTSB Meteorological and Flight Data Recorder Factual Group Chairman's reports have been added as attachments to the investigation.
Weather Analysis
The weather data indicated that the aircraft encountered a thunderstorm that developed rapidly and moved along its flight path. The reflectivity levels and cloud tops suggest the presence of severe convective activity, which likely produced the turbulence experienced by the flight.
Aftermath
The aircraft continued to its destination with no further issues. The passenger who sustained serious injuries was attended to after landing. The captain's actions, including turning on the seat belt sign and maneuvering the aircraft, were documented as part of the incident response.