Background
While on the right downwind leg, the flight crew advised the air traffic control tower controller of their intention to make a full stop landing. The controller acknowledged and instructed them to extend their downwind, indicating that he would call their base turn. Subsequently, the controller notified the crew of landing traffic on final approach—an Airbus A300-600 heavy aircraft. The flight crew reported having the traffic in sight, and the controller cleared them to land behind the Airbus, advising caution regarding wake turbulence.
Approach and Planning
The flight crew observed the Airbus abeam their position and estimated making their base turn approximately 3 miles from the runway. Prior to turning onto final, they discussed wake turbulence avoidance procedures, planning a steeper approach and aiming to land beyond the Airbus's touchdown point. As an additional precaution, they added 10 to 15 knots to the Vref speed. The reported wind was 180 degrees at 4 knots. The crew noted tire smoke from the Airbus during its touchdown and intended to land beyond that point. The tower controller advised the crew to be prepared for a go-around if the Airbus did not clear the runway in time, which they acknowledged.
Wake Turbulence Encounter
The flight crew estimated that the Airbus had turned off the runway when their aircraft was about 1,000 feet from the threshold and 200 feet above ground level (agl). They reported a stabilized approach to their planned landing point. At approximately 150 feet agl and established on the runway centerline, the aircraft experienced an uncommanded left roll, with the heading swinging left and the nose dropping. The crew reported heavy buffeting. Immediately, the pilot applied full power, using both hands on the control wheel in an attempt to level the wings and recover pitch. The pilot managed to nearly restore level flight, but the right main gear struck the ground short of the threshold and left of the runway. The aircraft then collided with a small drainage ditch and a dirt service road, causing the right main gear and nose gear to collapse.
Investigation Findings
Videos from airport cameras recorded the sequence, showing the accident aircraft was about 51 seconds behind the Airbus. A wake vortex study indicated that the accident aircraft encountered the Airbus's right vortex, and the direction of the left roll was consistent with the counter-clockwise rotation of that vortex.
Probable Cause
The flight crew's decision to fly close behind a heavy airplane, which did not ensure there was adequate distance and time in order to avoid a wake turbulence encounter with the preceding heavy airplane's wake vortex, which resulted in a loss of airplane control during final approach.