What happened
On January 9, 2014, an Aero Boero AB-115, registration PP-GRU, was attempting a ferry flight from Santo Ângelo to Santa Rosa, Rio Grande do Sul. Due to a NOTAM closing the main runway at the Santo Ângelo Aerodrome, the pilot attempted to use an auxiliary landing area intended exclusively for agricultural aircraft.
During the takeoff roll on this grass strip, the pilot realized the aircraft would not reach the necessary parameters for lift-off. In an attempt to gain more lift, the pilot increased the flaps from 15° to full (45°), which inadvertently increased aerodynamic drag. As the pilot initiated an aborted takeoff procedure and applied the brakes, the aircraft lost control and piloned, landing on its back. The aircraft sustained substantial damage to the engine, propeller, wings, and empennage. Both the pilot and the passenger were uninjured.
The investigation
CENIPA's investigation established that the aircraft was operating on an irregular surface. The auxiliary strip was 500 meters long, composed of uneven grass, and featured an uphill gradient in the direction of the takeoff. Additionally, a termite mound measuring 40cm in height was located in the middle of the runway, forcing the pilot to perform a leftward deviation during the takeoff roll.
The investigation also noted that the aircraft was 10kg over its maximum weight limit. Environmental conditions included a temperature of 30°C and a 10kt cross-tailwind component. While the flight manual provides takeoff distances for specific weights and temperatures, the investigation found that the manual's calculations did not account for the uphill slope, the tailwind component, or the specific surface irregularities present during this event.
Findings
- Improper use of the landing area, as the pilot used a strip reserved for agricultural operations without authorization;
- Inappropriate application of flight controls, specifically the decision to use full flaps which increased drag during a critical phase;
- Errors in flight planning and pilot judgment regarding the takeoff performance on an unpaved, uphill surface;
- Operational non-compliance, including the aircraft exceeding its maximum weight limit;
- Lack of management oversight regarding the use of the auxiliary runway.