NTSB Identification: DCA02MA039.
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Nonscheduled 14 CFR operation of FEDERAL EXPRESS CORP
Accident occurred Monday, June 03, 2002 in Subic Bay, Philippines
Probable Cause Approval Date: 12/20/2005
Aircraft: McDonnell Douglas MD-11, registration: N588FE
Injuries: 2 Uninjured.
NTSB investigators traveled in support of this investigation and used data obtained from various sources to prepare this aircraft accident report.
The MD-11 airplane experienced structural damage to the left elevator during an abrupt maneuver while descending to land. The abrupt maneuver was initiated by the flight crew in response to a false ground proximity warning system (GPWS) alert that occurred as the airplane was encountering heavy precipitation at an altitude of about 9,800 feet above mean sea level. The GPWS warning subsided during the maneuver. The airplane landed uneventfully. Both flight crewmembers, the sole occupants, were not injured. Post-flight inspection of the airplane revealed that the outboard portion of the left elevator, including the balance weight, was partially separated. The flight crew stated that they had no problems with aircraft handling after the escape maneuver. The investigation revealed that the escape maneuver was aggressive and consistent with procedures that are published in Federal Express' airplane flight manual for "GPWS Pull Up Warning." The elevator damage occurred as a result of an excedence of the airplane's design aerodynamic stall buffet boundary, which led to a severe vibration of the elevator. The stall buffet boundary was exceeded as a result of the captain's initiation of the escape maneuver. The false reading of the no. 1 and no. 2 radio altimeters prompted the false GPWS warning and was most likely due to their signal return off of heavy precipitation. No post-accident mechanical deficiencies were found with the flight controls, avionics, or elevator structure.
The National Transportation Safety Board determines the probable cause(s) of this accident to be: The momentary operation of the airplane outside of the airplane's aerodynamic design stall buffet boundary that resulted from the captain's initiation of a Ground Proximity Warning System (GPWS) escape maneuver. Factor's contributing to the accident were the false readings of both radio altimeters which prompted the false GPWS warning, and the inadequate structural capability of the elevator design to remain intact during momentary operations outside of the stall buffet boundary. Full narrative available
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