What happened
On March 6, 2013, an Air Tractor AT-502B, registration PR-FSF, was performing agricultural seed dispersal operations near the São Francisco Farm aerodrome in Riachable das Neves, Bahia. After completing eight dispersal flights during the morning, the pilot returned to the aerodrome for landing at approximately 13:50 UTC.
During the landing roll, the pilot crossed runway heading 30 at 80 knots. The aircraft experienced a series of bounces, with the first touchdown occurring 400 meters after crossing the threshold. Following a fourth contact with the runway, a wind gust from the right side caused the aircraft to yaw to the left. In an attempt to maintain the centerline, the pilot applied the brakes and reverse thrust simultaneously. The aircraft subsequently veered off the left side of the runway, where the main landing gear sank into a less compacted, loose soil surface. The resulting abrupt deceleration nearly caused the aircraft to nose over, leading the spinner and the left wingtip to strike the ground.
The investigation
The CENIPA investigation established that the runway surface consisted of disturbed earth, which was significantly less compacted than the main runway area. This condition increased the risk of the aircraft losing control during a runway excursion. Investigators also noted the presence of nearby construction, featuring structures approximately 7 meters high located about 50 meters from the runway edge.
While the pilot was highly experienced, with 2,300 hours in the model, and all documentation and aircraft airworthiness certificates were valid, the investigation focused on the interaction between the wind conditions and the runway surface integrity. It was noted that the runway threshold had been relocated by approximately 300 meters by the farm administration to mitigate risks posed by the nearby construction.
Findings
- Pilot judgment regarding the management of the aircraft during the landing roll and the application of simultaneous braking and reverse thrust.
- The presence of uncompacted, loose soil on the runway surface, which contributed to the loss of directional control.
- The influence of a sudden wind gust from the right side during the landing phase.