MIA98LA002

On October 1, 1997, about 2044 eastern daylight time, a McDonnell Douglas DC-9-82, N33052, registered to and operated by American Airlines, Inc., as flight 230, experienced in-flight turbulence during cruise flight near Cross City, Florida. Instrument meteorological conditions prevailed at the time and an IFR flight plan was filed for the 14 CFR Part 121 scheduled, domestic, passenger flight. The airplane was not damaged and the airline transport-rated captain, commercial-rated first officer, and 89 passengers were not injured. One flight attendant was seriously injured and two flight attendants and one passenger sustained minor injuries. The flight originated about 1755 central daylight time from the Chicago-O'Hare International Airport, Chicago, Illinois.

According to the captain, the flight was about 110 nautical miles north of the PIE VORTAC when they encountered a rapidly developing thunderstorm from below. As the cell appeared on radar, he checked the winds aloft on the Flight Management System (FMS) and began a turn to the right. The flight then experienced no more than 1 second of moderate turbulence which injured all 3 flight attendants; there were no reported injuries to any of the passengers. The flight continued and landed uneventfully about 24 minutes later. The seat belt sign was not illuminated at the time of the occurrence. The Digital Flight Data Recorder (DFDR) was removed from the airplane and read out. A copy of the readout is an attachment to this report.

A National Track Analysis Program (NTAP) from the Jacksonville Air Route Traffic Control Center which depicts changes in heading, altitude, and ground speed is an attachment to this report.

Review of the DFDR readout revealed that about 15 seconds before the autopilot system was deactivated and continuing for about 12 seconds, the airplane began a roll to the right which increased to about an 11 degree right wing low attitude. During that time frame, both engine EPRs decreased and the indicated airspeed increased from about 274 knots to a high of about 278 knots and ended at about 276 knots. Two seconds later the aircraft's vertical acceleration increased from a maximum of positive .95 Gs to a maximum of 1.75 Gs, and the aircraft rolled to the right about 15 degrees. One second later the autopilot system was deactivated, and one second after that the airplane rolled to the maximum of about 30 degrees right wing low and the airplane experienced a maximum of negative .28 Gs. The vertical acceleration values diminished and the airplane was returned to cruise flight.

According to the NTSB Meteorological Factual Report which is an attachment to this report, review of Weather Surveillance Radar from Tallahassee, Florida, for the period of 2033.15 to 2042.55, revealed a level 4 radar return located under and to the east of the flight track of the airplane in the area of the accident. Due to the configuration of the radar at the time, the highest elevation for detection was 30,500 feet. The same radar returns for the period 2043.03, and 2052.44, revealed a radar return of level 3 to 6 along and to the east of the flight track. Additionally, about 2 minutes after the accident, or 2046 local, the Jacksonville Air Route Traffic Control Center Weather Service Unit issued Center Weather Advisory 101. This indicated a cluster of level 5 thunderstorm/moderate rain with a diameter of 20 nautical miles with maximum tops to FL450. The center of which was located about 60 nautical miles west-southwest of Cross City, Florida. That location when plotted was about 23 nautical miles west-southwest of the accident location.