NTSB Factual Report

On August 3, 2003, about 2207 eastern daylight time, a McDonnell Douglas MD-82, N7527A, registered to Wilmington Trust Company Owner Trustee, and operated by American Airlines, Inc., as a Title 14 CFR Part 121 scheduled domestic passenger flight, encountered turbulence in the vicinity of Charlotte, North Carolina. Visual meteorological conditions prevailed, and an instrument flight rules flight plan was filed. The airline transport-rated pilot, first officer, three flight attendants and 127 passengers were not injured. One passenger received serious injuries. The flight originated in New York City, New York, the same day, about 2015.

An official with American Airlines Flight Safety Department stated that the airplane was en route from LaGuardia Airport, New York City, New York, to Tampa, Florida, and while at an altitude of the 31,000 feet, turbulence was encountered. He further stated that doing the encounter, one passenger was in the lavatory and was injured. The flight landed at Tampa International Airport, Tampa, Florida, about 2230, and after examination the passenger was determined to have suffered a serious injury.

The captain stated that the ride had been smooth, and there had been occasional light chop. He further stated that the seatbelt sign was off, and approximately seven people were standing at the time of the incident, including the three flight attendants. About 2 hours into the 3-hour flight while cruising at FL310, he said the radar showing a clear flight path with a significant line of storms approximately 30 miles east of their course. The airplane was in visual meteorological conditions, with stars and ground lights visible, especially to the west, and according to the captain, about 2207, the airplane entered instrument meteorological conditions and quickly encountered moderate chop, followed by a very sharp jolt. He said he had immediately turned on the fasten seatbelt sign after the first jolt, and they then received two more sharp jolts. He said that rain and Saint Elmo's were present, and he turned the airplane to the right, back towards where they had last seen ground lights and then informed FAA Air Traffic Control Jacksonville Center of the turn and ride condition. In about 30 seconds, he said the ride became smooth with some light chop, and they entered visual meteorological conditions again.

The NTSB examined radar and weather data pertinent to the flight, and the data revealed that when the accident airplane's flight path for the period of the flight was overlaid with infrared satellite imagery for the nominal times of 2145, 2202, and 2215, the data showed that from 2151 to about 2200 the flight was flying parallel to a band of thunderstorms located about 20-30 nautical miles off the airplane's left wing. Cloud-top temperatures of the thunderstorms east of the flight's ground track showed tops of the thunderstorms to be about 45,000 feet. Also, the satellite imagery showed that another area of thunderstorms was located near the South Carolina border, about 100 miles from the airplanes 10 o'clock position. Cloud-top temperatures showed tops of these thunderstorms to be at or above 45,000 feet. In addition, the airplane's track and satellite imagery for the nominal time of 2145 showed an isolated thunderstorm with an estimated cloud top of about 36,000 feet in the vicinity of GLOVR intersection, and satellite images at 2202 and 2215 showed those thunderstorm cloud tops were higher, and the thunderstorms had expanded outward and moved northeast along the airplane's track.

Greer, South Carolina (GSP) is located about 068 degrees, 105 nautical miles from the location where the turbulence event occurred. GSP digital Doppler radar data, pertinent to the accident time, was also evaluated and compared to the airplane's flight track. The radar data showed reflectivity echoes that varied from a VIP level 1 (very light) to VIP level 5 (intense), in the vicinity of the turbulence location. Reflectivity cross-sections of the radar data along the airplanes track showed that the maximum radar tops which the flight had penetrated were about 40,000 feet.

In addition, the NTSB also examined the Flight Data Recorder (FDR) from the accident airplane. The FDR recording contained about 91 hours of data, with the incident flight being the fifth to last flight, and lasting about 2 hours, 19 minutes. The data pertaining to the turbulence event showed that the airplane was at 31,007 feet, 286 knots, and 216 deg, when the altitude began to slightly increase, and minor fluctuations in vertical and lateral acceleration began to occur. About 9 seconds after the altitude began to increase, the airplane experienced its maximum positive vertical acceleration of 1.593 g's before dropping to -0.076 g's about two seconds later. About a second after that, the vertical acceleration reached 1.373 g's. The altitude reached was 31,055 feet, 5 seconds later, and then it decreased to 30,991 feet. Over the next minute, the airplane turned to the right to a heading of 237 degrees, and minor fluctuations in vertical acceleration continued until about 10 seconds prior to completion of the turn. The autopilot had remained engaged throughout the event.

NTSB Probable Cause

The pilot-in-command's failure to sufficiently deviate to avoid known weather, and his failure to activate the seatbelt sign to ensure flight attendants and passengers were seated, which resulted in a passenger receiving serious injuries when the flight encountered turbulence.