What happened
On 28 July 2018, a Boeing 737-8Q8, registration YR-BMF, was preparing for a scheduled passenger flight from Birmingham Airport to Bucharest International Airport. In an effort to meet a specific departure time slot, the flight crew bypassed standard verification procedures. During the turnaround, the commander read the zero fuel weight (ZFW) from the load sheet to the co-pilot, rather than the required takeoff weight (TOW). This incorrect figure was entered into the electronic flight bag (EFB) without being crosschecked against the load sheet or independently verified by the second pilot.
As the aircraft departed Birmingham, the erroneous data resulted in takeoff speeds that were significantly lower than required for the actual aircraft mass. Consequently, the aircraft reached a pitch attitude of 11.95 degrees during rotation, exceeding the manufacturer's recommended threshold for the type. This caused the aircraft to suffer a tailstrike, damaging the APU drain mast and tail skid components.
Following the takeoff, Air Traffic Control (ATC) queried whether the crew had experienced a tailstrike, as a ground observer had reported seeing the tail come very close to the runway. The crew, having not personally noticed any impact, replied that they had not. During the flight, the commander discovered the calculation error in the EFB and learned from a cabin crew member that a strange noise had been heard during the takeoff roll. Despite these indicators, the crew did not consult the Quick Reference Handbook (QRH) and continued to the destination.
The investigation
The investigation examined the flight data, which confirmed the aircraft's rotation and peak pitch rate. The AAIB also reviewed the operator's standard operating procedures (SOPs) and the aircraft's technical manuals. The inquiry focused on why the incorrect weight was used and why the crew failed to initiate the tailstrike checklist despite receiving information from both ATC and the cabin crew.
Findings
- The takeoff performance calculations were based on a mass approximately 12 tonnes lower than the actual weight.
- The crew failed to perform independent calculations or crosscheck the EFB data against the load sheet, as required by the operator's manual.
- The use of the zero fuel weight instead of the takeoff weight was the primary cause of the incorrect performance speeds.
- The crew did not action the tailstrike checklist despite an inquiry from ATC and reports of an unusual noise from the cabin crew.
- The decision to continue to the destination without inspecting the aircraft increased the risk to the flight and its 190 passengers and 6 crew members.