Aviation Accident Summaries

Aviation Accident Summary MIA96FA064

Aircraft #1

N7076A

Airbus Industrie A-300B4-605R

Analysis

The flight climbed to 33,000 feet after departure, where it encountered turbulence. The captain turned on the seat belt sign and announcements were made to the passengers to remain seated with their seat belts fastened. ATC informed the pilots that other pilots reported smoother air at 27,000 and 35,000 feet. They descended to 27,000 feet, encountered turbulence and then requested 35,000 feet. After reaching 35,000 feet, they encountered greater turbulence and requested and received clearance to 33,000 feet. During descent, they encountered severe turbulence which resulted in injuries to passengers. A SIGMET had been issued by the National Weather Service for active intensifying thunderstorms at the point of the turbulence encounter. The weather information supplied to the pilots by the operator did not contain this SIGMET; however, it did contain a company forecast for possible isolated thunderstorms within showers as indicated in the flight release.

Factual Information

HISTORY OF FLIGHT On January 17, 1996, about 1438 eastern standard time, an Airbus A300B4-605R, N7076A, registered to and operated by American Airlines, Inc., as flight 869, scheduled, domestic, passenger service from Miami, Florida, to San Juan, Puerto Rico, encountered turbulence during an enroute descent from 35,000 feet (FL350), over the Atlantic Ocean near Cat Island, Bahamas. The flight was conducted in accordance with the provision of Title 14 CFR Part 121. Instrument meteorological conditions prevailed at the time and an instrument flight rules flight plan was filed. The aircraft received minor damage. The airline transport-rated pilot, first officer, 7 flight attendants, and 239 passengers were not injured. Seventeen passengers reported minor injuries and three passengers reported serious injuries. The flight originated from Miami, the same day about 1401. The captain stated in writing and during an interview with the NTSB that he was flying the aircraft. After departing Miami they climbed to 33,000 feet (FL330), where they encountered light to occasional moderate turbulence. He turned on the passenger seat belt sign and it remained on until after the accident. They received information from air traffic control that the ride was reported to be better at 27,000 (FL270) and 35,000 feet (FL350). They asked for and received clearance to 27,000 feet (FL270). Upon reaching 27,000 feet (FL270), they encountered turbulence and observed visible clouds below. They asked for and received clearance to 35,000 feet (FL350). Upon reaching 35,000 feet (FL350) they found the turbulence was worse. He then requested and received clearance back to 33,000 feet (FL330). As they began the descent they encountered severe turbulence. After the aircraft was brought under control he advised air traffic control of the encounter with turbulence and received an injury report from the flight attendants. Based on the information he received from the cabin attendants and doctors who were treating the injured, he elected to continue to San Juan and avoid possible further injury by flying back through the area of turbulence. The first officer stated during an interview with the NTSB that when they reached 35,000 feet (FL350), just before the turbulence encounter, they were in and out of the jagged tops of the clouds. The winds were shifting from the west to northwest. There was no weather showing on radar. As they began the descent to 33,000 feet (FL330), they entered the clouds and were in the clouds at the time of the accident. At the time of the accident the autopilot and autothrottles were on. They had increased airspeed to .81 mach do to fluctuations from the turbulence. During the turbulence encounter the autopilot disconnected. There was nothing remarkable about the weather information they received before takeoff and they did not receive any Sigmet reports from air traffic control. The flight attendants stated that after departure it was bumpy and they delayed starting the meal service. The seat belt sign was on and several announcements were made in both English and Spanish for passengers to remained seated with their seat belts fastened. The flight attendants remained seated with their seat belts on. They stated that during the severe turbulence encounter, passengers who did not have their seat belts fastened or who were not in their seats, struck the overhead areas of the aircraft and received injuries. For additional History of Flight information see the Survival Factors Specialist Report and other attachments to this report. PERSONNEL INFORMATION Information on the captain and first officer is contained in this report under First Pilot Information and in Supplement E to this report. Information on the flight attendants is contained in the Survival Factors Specialist Report. AIRCRAFT INFORMATION Information on the aircraft is contained in this report under Aircraft Information. METEOROLOGICAL INFORMATION A meteorological study was performed by James T. Skeen, Jr., Senior Meteorologist, NTSB, Washington, D.C. The study indicated that satellite images showed an area of clouds existed in the area of the turbulence encounter at the time. Thunderstorms were present in the cloud area. Significant turbulence was present in the area at between 25,000 (FL250) and 36,000 feet (FL360). The National Weather Service had issued Sigmet Echo 1 at 1236. The Sigmet stated that satellite observations show an area of active thunderstorms with tops to 38,000 feet (FL380) in the area of the accident. The area was moving north at 5-10 knots and was intensifying. The Sigmet was in effect until 1640. The flightcrew stated they did not receive this Sigmet in the weather information obtained from American Airlines before takeoff. They further stated they did not hear it broadcast on the normal ATC communications frequencies and did not listen to the weather information frequencies where it was being broadcast. American Airlines produces a variety of tailored aviation forecast and advisory products under the FAA Enhanced Weather Information System program. National Weather Service products are not forwarded to flight crews directly, but are evaluated during the preparation of the American Airlines weather products and are available to flight crews through the computer system.. The American Airlines weather information that was supplied to the flight crew of American Airlines Flight 869 before departure forecast a weak upper level cyclonic circulation producing cloudiness/scattered showers across southern Bahamas. Isolated thunderstorms possible within showers discussed above. No thunderstorm SIGMEC issued. No CAT SIGMEC issued. CAT (clear air turbulence) indicator 0 (smooth). For additional meteorological information see the Meteorology Group Chairman's Factual Report and other attachments to this report. FLIGHT RECORDERS The digital flight data recorder was removed from N7076A after the aircraft landed in San Juan, Puerto Rico, and forwarded to the NTSB Flight Recorder Laboratory, Washington, D.C. for readout and evaluation. The cockpit voice recorder was not retained by NTSB for readout, for the accident event was no longer present on the recorder at the time of arrival in San Juan. Readout of the digital flight data recorder showed that at the time of the turbulence encounter the aircraft was descending through 34,500 feet msl, on a heading of 110 degrees, at an calibrated airspeed of 290 knots. Vertical acceleration increased to 2.088 G's, decreased to -1.032 G's, and then increased to 1.788 G's. See attached Factual Report of Investigation-Digital Flight Data Recorder. WRECKAGE AND IMPACT INFORMATION Wreckage and impact information is contained in the Survival Factors Specialist Report. MEDICAL AND PATHOLOGICAL INFORMATION Medical information is contained in the Survival Factors Specialist Report. ADDITIONAL INFORMATION The aircraft was released by the NTSB to Chris Moran, American Airlines, Flight Safety, on January 19, 1996. The digital flight data recorder and seatbelts from the cabin of N7076A were released by NTSB to Chris Moran on November 6, 1996.

Probable Cause and Findings

the turbulence and failure of the passengers to have their seat belts fastened. A factor relating to this accident was: the failure of the aircraft operator to advise the flight crew of forecast active intensifying thunderstorm conditions in the area of the accident.

 

Source: NTSB Aviation Accident Database

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