Occurrence Synopsis
On 30 December 2020, a Bombardier BD-700-1A10 (Global 6000) aircraft, registered 9H-OJP, operated by Elit’Avia Malta Limited as flight EAU52P, was conducting an instrument flight rules positioning flight from Incheon International Airport, Republic of Korea, to Taichung International Airport, Taiwan. The aircraft carried two pilots and one cabin crew member. Weather conditions at Taichung were reported as good visibility with strong gusty wind and a significant crosswind for runway 36. During the landing flare, the flight crew applied large control inputs to counteract roll and pitch disturbances caused by the gusty wind. Both wing tips came into contact with the runway surface. The left wing slat and aileron, and the right winglet, aileron, and flap canoes were damaged. No injuries were reported among the occupants.
Weather Conditions
At the time of the occurrence, Taichung International Airport was affected by a strong cold high-pressure weather system. Meteorological reports indicated good visibility, strong gusty winds, and a significant crosswind component for the landing runway 36.
Flight Sequence and Control Inputs
The autopilot was disengaged at 219 feet radio altitude. The pilot flying (PF) had approximately 16 seconds to transition from automatic to manual flight before reaching 30 feet and initiating the flare. Two seconds before touchdown, the flight crew made a significant and rapid control wheel input to compensate for roll and pitch disturbances from the gusty wind. This input resulted in a maximum right wing down roll angle of 6.76 degrees and a nose-up pitch attitude of 9.31 degrees at zero radio altitude. The aircraft touched down hard on the right main landing gear with a right rolling motion, and the right wing tip likely contacted the runway at that moment. After the right main gear bounced, the PF applied a left wing down control input to stop the right roll, causing the aircraft to roll left to a maximum of 9.4 degrees left wing down. With a pitch attitude of 8.26 degrees, the left wing tip then contacted the runway.
Findings
The investigation identified four findings related to probable cause, two findings related to risk, and four other findings. The findings related to risk included that the late autopilot disengagement gave insufficient time to gain complete control, and that differences in Vref speed adders between manuals could create confusion. Other findings confirmed that the flight crew were properly certificated, the aircraft was certified with no technical issues, weight and balance were within limits, and the approach was stable with autopilot coupled.
Probable Cause
The probable cause of the occurrence was the combination of strong and gusty wind conditions, insufficient time to gain complete control of the aircraft due to late disconnection of the autopilot, a rapid decrease of airspeed due to a rapid headwind reduction that was not compensated by increasing thrust, the increased pitch angle from the pilot flying’s pitch-up demand, and the significant and rapid control inputs during the flare to compensate for roll and pitch disturbances from the gusty wind. These factors led to an abnormal runway contact with the wing tips.