This one was Corsair...
Location: Paris, France
History of the flight:
On 10 December 2006, a Boeing 747-400 aircraft, registered F-HLOV, was being prepared for a scheduled passenger service from Paris-Orly airport, with 15 crew and 563 passengers onboard. On arrival at the aircraft, the crew found that the battery of one of the two BLT’s used to calculate the take-off performance parameters was flat; consequently, the second BLT (operating on battery power) was used.
During the pre-flight preparations, the first officer noted a fault message relating to the hydraulic circuit. Discussions with the ground mechanic determined that the issue was being dealt with.
When determining the take-off performance parameters for the flight, the captain provided the first officer with the ZFW from the weight and balance sheet, which he increased by 1.6 tonnes, and the TOW. The first officer then entered the ZFW into the FMS. The TOW was entered into the BLT and the take-off performance parameters calculated. The first officer handed the BLT to the captain to crosscheck the calculations. The BLT then went into standby and the captain handed it back to the first officer who unintentionally turned it off, thus erasing the entered data. At the same time, the captain was dealing with the hydraulic failure issue with the mechanic in the cockpit.
When the new data was being entered into the BLT, the captain inadvertently called out the ZFW instead of the TOW. A weight of 242,300 kg was entered into the BLT instead of 341,300 kg. The captain entered the resultant BLT data into the FMS, replacing the values automatically calculated by the FMS. The first officer then verified that the BLT and FMS values were identical.
The captain entered the assumed take-off temperature into the FMS and queried the reduced thrust value with the first officer. The first officer justified these figures by the fact that the QNH was high and the temperature was low.
The crew performed a rolling takeoff and did not detect that the aircraft’s acceleration was lower than normal. At the V1 speed, the crew noted that there was a reasonable amount of runway length still available and they began to doubt the V speeds. The captain (the pilot not flying) elected to delay the aircraft’s rotation.
When the first officer began the rotation, he immediately noticed that aircraft appeared heavy. The aircraft’s pitch was increased slowly, but the stick-shaker activated. The first officer responded by reducing the aircraft’s nose-up attitude and applying full take-off power. Ground personnel noticed smoke during the aircraft’s rotation.
After the takeoff, the crew suspected a problem with the calculated V speeds and increased the retraction speeds for control surfaces by 20 kts.
Contributing factors
The following factors were identified throughout the subsequent investigation:
•The ZFW was inadvertently read aloud and subsequently entered into the BLT instead of the TOW, resulting in V speeds that were too low
Take-off performance data
Data BLT calculation FMS calculation
TOW 242,300 kg 341,300 kg
V1 120 kts 147 kts
VR 127 kts 159 kts
V2 140 kts 169 kts
• The BLT was not connected to the aircraft’s power source and it went into standby mode.
• The captain was dealing with a hydraulic failure at the time the take-off performance calculations were being calculated.
• After the data had been entered into the FMS, there was no requirement for a comparison to be made with the TOW and the flight limitations.
• There was no requirement to compare the data entered into the BLT with the data entered into the FMS.
Last edited by JammedStab; 21st Jun 2015 at 16:56.