Boeing 737-33A, G-ZAPZ
An onboard hand-held Electronic Flight Bag (EFB) computer was used to calculate the aircraft’s takeoff performance. The commander omitted to enter the aircraft’s takeoff weight into the performance calculation software, which defaulted to the previous flight’s takeoff weight. The crew did not cross-check the data and incorrect speeds and thrust were calculated and subsequently used for the takeoff. As a consequence, the airspeed at rotation was too low and the pitch angle was sufficient to strike the tail on the runway. A broken spring within the aircraft’s elevator feel and centering unit caused reduced resistance in the flight controls in pitch, contributing to the excessive pitch attitude achieved during rotation.
The investigation also revealed wider issues relating to the general design and use of EFB computers to calculate performance data. Two Safety Recommendations are made.
Published 10 December 2014