|Title:||Loss of control during descent, Airbus A300B4-605R, May 12, 1997|
|Micro summary:||This Airbus A300B4-605R experienced a loss of control during descent.|
|Event Time:||1997-05-12 at 1529 EDT|
|Publishing Agency:||National Transportation Safety Board (NTSB)|
|Site of event:||West Palm Beach, FL|
|Departure:||Logan International Airport, Boston, Massachusetts, USA|
|Destination:||Miami International Airport, Miami, Florida, USA|
|Airplane Type(s):||Airbus A300B4-605R|
|Type of flight:||Revenue|
NTSB short summary:
The flightcrew's failure to maintain adequate airspeed during leveloff which led to an inadvertent stall, and their subsequent failure to use proper stall recovery techniques. A factor contributing to the accident was the flightcrew's failure to properly use the autothrottle.
The flight was assigned an airspeed of 230 knots and cleared to descend from FL240 to 16,000 feet in preparation for landing at Miami. The FDR indicated that while the autopilot was engaged in the descent, the power levers moved from the mechanical autothrottle limit of 44 degrees to the manual limit of 37 degrees. As the aircraft leveled at 16,000 feet the airspeed decreased. The F/O began a right turn to enter a holding pattern and added some power, which stabilized the airspeed at 178 knots. However, the right bank and the resultant angle of attack (AOA) continued to increase, despite left aileron input by the autopilot. As the autopilot reached the maximum input of 20 degrees, bank angle increased past 50 degrees, and the AOA increased rapidly from 7 degrees to 12 degrees. At this point the stick shaker activated, the autopilot independently disconnected, the power was increased, and full left rudder was used to arrest the roll. The bank angle reached 56 degrees, and the AOA reached 13.7 degrees at 177 knots. The aircraft then pitched down, and entered a series of pitch, yaw, and roll maneuvers as the flight controls went through a period of oscillations for about 34 seconds. The maneuvers finally dampened and the crew recovered at approximately 13,000 feet. One passenger was seriously injured and one flight attendant received minor injuries during the upset. According to wind tunnel and flight test data the A300 engineering simulator should adequately represent the aircraft up to 9 degrees AOA. Unlike the accident aircraft; however, the simulator recovered to wings level promptly when the lateral control inputs recorded by the FDR were used. The roll disagreement between the simulator and accident aircraft began at 7 degrees AOA, and it appears that some effect not modeled in the simulator produced the roll discrepancy. Just prior to the upset the accident aircraft entered a cloud deck. The winds were approximately 240 degrees, 35 knots, and the ambient air temperature was approximately minus 4 degrees C. An atmospheric disturbance or asymmetric ice contamination were two possible explanations considered, but unproven.
NTSB factual narrative text:
On May 12, 1997, about 1529 eastern daylight time, an Airbus A300B4-605R, N90070, flight 903, registered to Wilmington Trust Company Trustee, operated by American Airlines Inc., as a 14 CFR Part 121 scheduled domestic passenger flight, experienced an inflight loss of control, about 10 miles north of HEATT intersection in the vicinity of West Palm Beach, Florida. Instrument meteorological conditions prevailed and an IFR flight plan was filed. The airplane sustained minor damage. The airline transport pilot-in-command (PIC), commercial pilot first officer, 6 flight attendants, and 155 passengers sustained no injuries. One passenger sustained serious injuries, and one flight attendant received minor injuries. The flight originated from General Edward Lawrence Logan International Airport, Boston, Massachusetts, about 2 hours 16 minutes before the accident.
According to American Airlines safety personnel, the PIC stated the cabin seatbelt signs were illuminated, and they were level at 16,000 feet. They had received an air traffic control (ATC) clearance to hold at HEATT intersection located southeast of West Palm Beach. Weather was depicted in the vicinity of the holding fix on the weather radar. They requested and received clearance from ATC to hold north of the holding fix. As they were approaching the holding fix, they encountered a loss of control. The airplane pitched up and down, rolled to the left and right, and descended rapidly. The flightcrew initiated the "Escape" procedure and recovered the airplane. The PIC was advised of passenger injuries by the flight attendants. He declared an emergency with ATC and landed at Miami International Airport, Miami, Florida, without further incident.
|Learning Keywords:||Operations - Training Deficiency|
|Operations - Upset in-flight (extreme attitudes, stall, spin)|
|Systems - Autopilot/Autothrottle|
|Consequence - Flight Attendant Fatality - Injury|
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