What happened
On December 3, 2013, an Aero Boero AB-180, registration PP-GIJ, was performing a glider towing operation at the Palmeira das Missões Aerodrome in Rio Grande do Sul, Brazil. During the fifth takeoff of the day, the pilot completed the flight and attempted to land on a grass strip located to the left of the main runway 06/18.
As the pilot was maneuvering from the base to the final approach, ground crew notified the pilot that the aircraft was flying too low due to the presence of high-voltage power lines near the aerodrome. To avoid these obstacles, the pilot adjusted the glide slope to a higher approach. Because the tow cable had not been released, the pilot planned to touch down 250 meters before the threshold of runway 06. However, the corrective maneuver resulted in the aircraft touching down 500 meters from the threshold, effectively halfway down the strip.
Following touchdown, the pilot maintained engine power to keep the tail lifted, preventing the tow cable from snagging on ground obstacles. Approximately 150 meters from the opposite end of the runway, the pilot applied brakes and reduced power. The aircraft failed to stop within the remaining distance, overran the end of the runway, fell into an embankment, and capsized. The pilot sustained minor injuries, while the aircraft suffered substantial damage to the engine, propeller, wings, tail, and landing gear.
The investigation
The CENIPA investigation focused on the pilot's landing parameters and the physical constraints of the grass runway. Investigators noted that the pilot was utilizing a grass strip rather than the primary paved runway. The investigation reviewed the aircraft's flight manual, which specifies that under ISA conditions and a weight of 844kg, the minimum landing distance required for a landing at 1,000ft is 279 meters. The investigation established that the 150-meter distance the pilot attempted to use for braking was insufficient to bring the aircraft to a complete stop.
Findings
- Improper pilot judgment regarding the required stopping distance on the grass strip.
- Failure to release the tow cable prior to landing.
- Inadequate application of flight controls during the landing phase.
- The pilot's decision to use a braking distance of only 150 meters, which was mathematically insufficient for the aircraft's weight and speed.