What happened
On February 18, 2018, at approximately 19:15 UTC, an Air Tractor AT-502B, registration PR-SER, was performing agricultural spraying operations at Fazenda Yowa I, located in São Desidério, Bahia. The aircraft took off from a 900-meter unpaved landing strip to spray a cornfield. Shortly after crossing the opposite end of the runway, the aircraft lost altitude and the left wing struck a corn plantation. The aircraft came to a stop approximately 75 meters beyond the runway threshold, oriented 150 degrees to the right of the takeoff axis. Following the pilot's exit from the cockpit, the aircraft caught fire. The pilot survived the accident without injury, but the aircraft sustained substantial damage.
The investigation
CENIPA investigators examined the takeoff performance, environmental conditions, and aircraft configuration. The investigation found that the pilot was properly licensed and experienced, and the aircraft was airworthy with up-to-date maintenance records. The aircraft was carrying 400 liters of payload, resulting in a takeoff weight of 3,444 kg, which was below the maximum takeoff weight of 3,629 kg. However, the investigation noted that the takeoff strip was unpaved, which increases the friction coefficient and requires a longer takeoff distance compared to paved surfaces.
Analysis of the aircraft's performance manual indicated that for the given altitude (2,500 feet) and high temperatures (averaging 29°C to 30°C), a takeoff on a paved surface at maximum weight would require approximately 1,083 meters of runway—exceeding the available 900 meters. The investigation concluded that the takeoff distance calculation did not conservatively account for the unpaved surface and high temperatures. Additionally, the aircraft's trim was found to be in a position that prompted a nose-down moment, contrary to the manufacturer's recommendations for a loaded aircraft, which likely required extra physical effort from the pilot to rotate the aircraft.
Findings
- Inadequate flight planning, as the takeoff distance required for the unpaved strip under the prevailing temperature and altitude exceeded the available runway length.
- Inadequate operational risk management by the operator regarding the suitability of the landing strip for the aircraft's performance requirements.
- Inadequate management supervision regarding the oversight of aerial activities and flight planning processes.
- The pilot attempted rotation at a speed potentially below the recommended safety margin due to the combination of runway length and reported wind conditions, including a tailwind gust.