What happened
On 28 September 2006, a Boeing 767-383, registration G-VKNI, was performing a charter flight for the Ministry of Defence. The aircraft was landing at RAF Brize Norton after a flight from Zagreb, Croatia. During the approach, the aircraft's airspeed was slightly lower than recommended, prompting the co-pilot to apply engine power to correct the descent rate.
Upon touchdown, the aircraft experienced a momentary skip on the runway. During this sequence, the co-pilot manually deployed the speed brakes, and the aircraft's pitch attitude increased significantly. This movement caused the tailskid to make contact with the runway, resulting in light abrasion damage to the friction pad. There were no injuries to the 12 crew members or 136 passengers on board.
The investigation
The investigation, supported by flight data analysis from Boeing, examined the aircraft's loading, the flight crew's actions, and the mechanical state of the aircraft. Investigators reviewed the loading instruction report and the load sheet prepared by the co-pilot. It was discovered that the co-pilot had failed to account for 2,339 kg of loose baggage loaded into the rear bulk hold, which resulted in an actual centre of gravity that was further aft than indicated on the load sheet.
Analysis of the flight data recorder confirmed that the aircraft touched down at a speed of approximately 126 knots, which was 6 knots below the calculated Vref speed. The investigation also looked into a discrepancy regarding the aircraft's takeoff rotation, where the co-pilot reported an uncommanded pitch-up, though data analysis suggested a control input had been made.
Findings
- The primary cause of the tail strike was a nose-up elevator command following the aircraft's skip on the runway, which was likely exacerbated by the manual deployment of the speed brakes.
- The aircraft touched down at a speed below the recommended Vref, which increased the pitch attitude and reduced the clearance margin for the tailskid.
- An error in the load sheet meant the crew did not account for additional weight in the rear bulk hold, resulting in a more aft centre of gravity, making the aircraft more sensitive to pitch changes.
- The manual deployment of speed brakes contributed to the increased pitch-up moment.
- A failure in crew resource management occurred when the co-pilot did not effectively communicate the unusual handling characteristics experienced during the takeoff rotation to the commander.