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Last updated: 21 September 2021
Statuts:Enquête Officielle
Date:mercredi 3 mars 2010
Type/Sous-type:Silhouette image of generic B744 model; specific model in this crash may look slightly different
Boeing 747-409F
Compagnie:China Airlines
Immatriculation: B-18723
Numéro de série: 34266/1379
Année de Fabrication: 2006-10-18 (3 years 5 months)
Heures de vol:15052
Moteurs: 4 General Electric CF6-80C2B1F
Equipage:victimes: 0 / à bord: 3
Passagers:victimes: 0 / à bord: 0
Total:victimes: 0 / à bord: 3
Dégats de l'appareil: Substantiels
Conséquences: Repaired
Lieu de l'accident:Anchorage-Ted Stevens International Airport, AK (ANC) (   Etats-Unis d'Amérique)
Phase de vol: Au décollage (TOF)
Aéroport de départ:Anchorage-Ted Stevens International Airport, AK (ANC/PANC), Etats-Unis d'Amérique
Aéroport de destination:Taipei-Taiwan Taoyuan International Airport (TPE/RCTP), Taïwan
Numéro de vol:CI5233
China Airlines flight 5233, a Boeing 747-400, registration B-18723 and operating as a cargo flight, experienced a tail strike during takeoff from Anchorage-Ted Stevens Anchorage International Airport, Alaska, USA. The airplane continued to its intended destination of Taipei-Taoyuan International Airport (TPE/RCTP), Taiwan. There were no injuries to the crew, and the airplane received substantial damage.
When entering the required data into Runway Analysis System, the pilot took the Max Landing Weight as Max Take-Off Weight obtained from Computerized Flight Plan; which led the calculation to provide erroneous take-off thrust, take-off reference speed and take-off model. The aircraft did not obtain enough lift required for take-off, the angles of ground and attack were too large; which caused that the tail had ground contact. During the take-off roll, the pilot had stick shaker warning, then released stick and set the manual thrust to MAX to continue the take-off. In the air the pilot inspected the instruments of cabin pressure and engines which were normal. After landing at 16:48, maintenance personnel checked and found the rear section of aircraft belly had substantial damage

Probable Cause:

Findings Related to Probable Causes:
1. When entering the required data into Runway Analysis System, CM 1 used the data from Computerized Flight Plan but took the max landing weight mistakenly as max take-off weight. Then CM 2 did not cross check to confirm the accuracy of the input data, and did not review all the data after retrieving take off performance figures from Runway Analysis System; so it was not discovered that the max take-off weight that was entered by mistake caused the mal-calculation of take-off thrust, -reference speed and -model.
2. CM 2 entered the erroneous take-off thrust provided by Runway Analysis System into Flight Management System which failed to calculate take-off reference speed; so the columns of V1, VR ,V2 on the page of the take-off speed showed ’- - - ’ and the pilot did not understand the meaning of ’- - - ’, at the end he decided to use the take-off reference speed calculated by Runway Analysis System to enter into Flight Management System.
3. CM 3 has checked Runway Analysis Manual during taxiing to verify the accuracy of the calculation done by Runway Analysis System. However the source of ‘max take-off weight’ was from the system and not from Weight and Balance Sheet nor Computerized Flight Plan. Therefore it was discovered that the take-off reference speed calculated by Runway Analysis System was much lower than the actual figure that the aircraft should have used.
4. When taking off the aircraft speed reached the VR value calculated by Runway Analysis System, 2 seconds later the aircraft started to roll. Because the actual roll speed of 149 knots/hour was lower than the correct value of 166 knots/hour, the aircraft did not have enough lift required for take-off and angles of ground and attack way too large; which caused the aircraft tail to touch ground.

Accident investigation:
Investigating agency: ASC
Status: Investigation completed
Accident number: ASC-AOR-11-05-001
Download report: Final report

Opérations de secours

ASC issued 12 Safety Recommendations

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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 Anchorage-Ted Stevens International Airport, AK et Taipei-Taiwan Taoyuan International Airport est de 7462 km (4664 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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