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Statuts:Enquête Officielle
Date:mercredi 11 novembre 1998
Heure:11:20
Type/Sous-type:Silhouette image of generic MD11 model; specific model in this crash may look slightly different
McDonnell Douglas MD-11
Compagnie:Delta Air Lines
Immatriculation: N801DE
Numéro de série: 48565/480
Année de Fabrication:
Heures de vol:24332
Equipage:victimes: 0 / à bord: 11
Passagers:victimes: 0 / à bord: 113
Total:victimes: 0 / à bord: 124
Dégats de l'appareil: Substantiels
Conséquences: Repaired
Lieu de l'accident:Portland International Airport, OR (PDX) (   Etats-Unis d'Amérique)
Phase de vol: A l'atterrissage (LDG)
Nature:Transport de Passagers Nat.
Aéroport de départ:Cincinnati/Northern Kentucky Airport, KY (CVG/KCVG), Etats-Unis d'Amérique
Aéroport de destination:Portland International Airport, OR (PDX/KPDX), Etats-Unis d'Amérique
Détails:
A McDonnell Douglas MD-11, N801DE, experienced a tail strike while landing at Portland International Airport, Oregon. The flight was landing on runway 10R after arriving from Cincinnati, Ohio. Visual meteorological conditions prevailed, and an instrument flight plan had been filed. There were no injuries to the 11 crew members or 113 passengers, but the aircraft sustained substantial damage to the belly skin and stringers.
The flight crew stated that they were unaware the aircraft had experienced a tail strike until maintenance personnel at the arrival gate advised them that there was damage to the number 3 VHF antenna and the skin aft of the antenna mount. After the passengers were deplaned normally through the jetway, the damage was further evaluated, and it was determined that the aircraft would need to be ferried to Atlanta for permanent repair.
During the investigation, it was determined that the weight existing in the Flight Management System (FMS) during the approach and landing sequence was in error approximately 100,000 pounds. As confirmed by a review of the Flight Data Recorder (FDR) readout, the FMS weight was about 292,000 pounds, when in fact the actual aircraft landing weight was approximately 392,000 pounds. This error generated a final approach speed of 136 knots for an approach that should have been flown at 151 knots. This reduced speed resulted in the approach being flown at an eight (8) degree pitch attitude instead of the three to four degrees that would occur during an approach flown at the correct airspeed. The FDR data also showed that approximately 7 seconds before nose gear strut compression, the pitch attitude reached 10.9 degrees.
Although the exact FMS entry error was not determined, the most likely would be the crew missing the hundred thousand entry by one when inputting the takeoff gross weight, entering the empty weight into the zero fuel weight prompt, or entering the zero fuel weight in the aircraft takeoff gross weight prompt.

Probable Cause:

PROBABLE CAUSE: "The flight crew's entry of an incorrect weight figure in the Flight Management System (FMS) computer, resulting in the approach being flown at an improper (low) Vref speed and an excessively nose-high attitude through the landing flare."

Accident investigation:
cover
Investigating agency: NTSB
Status: Investigation completed
Duration: 1 year and 11 months
Accident number: SEA99LA014
Download report: Summary report
Language: English

Sources:
» NTSB


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Plan
Ce plan montre l'aéroport de départ ainsi que la supposée destination du vol. La ligne fixe reliant les deux aéroports n'est pas le plan de vol exact.
La distance entre Cincinnati/Northern Kentucky Airport, KY et Portland International Airport, OR est de 3150 km (1968 miles).

Les informations ci-dessus ne représentent pas l'opinion de la 'Flight Safety Foundation' ou de 'Aviation Safety Network' sur les causes de l'accident. Ces informations prélimimaires sont basées sur les faits tel qu'ils sont connus à ce jour.
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