What happened
On July 11, 2001, at 13:42, an Airbus A340-313 was performing a takeoff from runway 18 at Frankfurt Airport, bound for Caracas, Venezuela. The aircraft was carrying 212 passengers and 14 crew members. During the rotation phase, the aircraft experienced a sudden loss of airspeed, dropping by approximately 17 knots. As the aircraft pitched up, the underside of the fuselage made contact with the concrete runway surface, resulting in a tail strike.
Because the extent of the damage could not be immediately determined by the crew, the decision was made to abort the flight and return to Frankfurt. To ensure the aircraft did not exceed its maximum landing weight, approximately 50 tonnes of fuel were jettisoned. The aircraft landed safely at 15:38 without any injuries to the passengers or crew.
The investigation
The BFU examined flight recorder data and meteorological reports to determine the cause of the contact. Investigators analyzed the wind conditions provided by the German Meteorological Service, noting that while the runway 18 anemometer reported winds of 8 to 10 knots, the surrounding area experienced much higher gusts. Technical inspections of the aircraft revealed that the fuselage skin between frames 72 and 75 had been abraded by approximately 0.7 mm, and the shear web between frames 72 and 73 was deformed. Additionally, a toilet service door was destroyed.
Findings
Investigation of the flight recorder established that a windshear event occurred, characterized by a rapid shift in the wind vector from a headwind to a tailwind within five seconds. At the moment of the tail strike, a tailwind component of approximately 13.5 knots was present. This sudden change caused a loss of airspeed that reduced lift by an estimated 20% to 25%, preventing the aircraft from climbing effectively despite the rotation.
Several contributing factors were identified:
- The sudden transition from headwind to tailwind caused a significant loss of airspeed.
- The pilot's second sidestick input, which increased the elevator deflection to 15 degrees, contributed to the tail strike.
- The pressure in the right main landing gear shock absorber was approximately 8 bar below the required level, which reduced the aircraft's tail clearance by about 20 cm.
- Local wind turbulence may have been caused by nearby trees affecting the accuracy of the anemometer readings near runway 18.