Incident Overview
On 28 September 2017 at 1804 UTC, G-FDZJ, a Boeing 737-8K5 operated on a commercial passenger charter flight from Malta International Airport to Manchester, experienced a serious incident during takeoff. The aircraft had 136 passengers, 2 pilots, and 4 cabin crew on board. The commander, aged 39 with 9,699 total flying hours (782 on type), was the pilot flying. The takeoff acceleration was normal, but at VR the pilot flying pulled back on the control column with normal effort and no rotation occurred. Continued pulling back resulted in a slow rotation at approximately ¾ elevator deflection, and the aircraft became airborne with about 300 m of runway remaining. Once climbing, the pilot applied rearward trim to remove control force. The flight proceeded without further incident; no injuries and no damage were reported.
Recorded Data
Flight data recorder information showed that the elevator deflection required for rotation was 10.9°, compared to a typical 8.3° from the previous six flights. The aircraft was trimmed from the pre-takeoff setting of 4.5 units to approximately 7 units once airborne.
Organizational Information
The flight was operated on behalf of a cruise ship company. Passengers checked in aboard the cruise ship, and the cruise operator allocated seats. Passenger loading details given to the handling agent at Malta included numbers of males, females, and infants but did not specify seating locations. Normally these flights are full, so seating locations are not required. For non-cruise flights, the handling agent checks in passengers and knows their seating positions. Because the cruise operator handled check-in, the handling agent lacked this information and assumed an even distribution of passengers throughout the cabin. The actual passenger distribution was biased toward the front of the aircraft.
Weight and Balance
A manual load sheet produced for the investigation using actual passenger distribution indicated a MACTOW of 17%. A manual load sheet assuming even distribution gave a MACTOW of 23.5%, consistent with the load sheet provided to the flight crew. The flight crew entered the load sheet data into the Flight Management Computer, resulting in a stabiliser trim setting of 4.5 units. Their performance calculations were correct for the load sheet they received.
Operator Safety Action
Following its review, the operator indicated it would update procedures to ensure empty seat positions on cruise flights (or any flight where check-in is not handled by the agent) are communicated by the cruise line representative to the load controller. It also committed to ensuring all handling agents dealing with such flights have a method to determine actual seating positions for partly loaded flights to produce accurate load sheets.
Conclusion
The aircraft took off with incorrect stabiliser trim set because an incorrect MACTOW was shown on the load sheet. This occurred because the seating position of the passengers was not passed to the handling agent, who assumed an even distribution when the actual loading created a forward bias.