What happened
On June 5, 2021, a Robin R 3000/160, registration HB-KEH, was performing a private VFR flight from Locarno to Bad Ragaz. During the final approach to runway 30, the pilot encountered turbulent wind conditions and localized rain. To manage the turbulence, the pilot elected to keep the flaps in the 'takeoff' position rather than fully extending them.
As the aircraft approached the runway, it maintained a ground speed of approximately 180 km/h, significantly higher than the manufacturer's recommended approach speed. The aircraft floated over the runway for an extended period, finally making contact with the pavement roughly halfway down the runway. Due to the wet surface, the wheel brakes provided insufficient deceleration. The pilot attempted to stop the aircraft on the adjacent grass area, but the plane continued rolling until it struck a line of trees approximately 240 meters past the runway end. The impact was severe enough to trigger the aircraft's emergency locator transmitter.
The investigation
The SUST investigation focused on the pilot's decision-making regarding approach speed and landing distance. Investigators determined that while the pilot had performed a weight and balance calculation, they had failed to calculate the required landing distance based on the Aircraft Flight Manual (AFM).
Analysis of the environmental conditions showed that heavy rain and gusty winds were present at the time of landing. The investigation also noted that the pilot had previously successfully landed on the grass area during difficult winds, but those prior instances occurred on a dry surface. The investigation compared the aircraft's actual performance against the available runway length of 495 meters, finding that the margin for error was nearly non-existent under the prevailing wet conditions.
Findings
- The primary cause of the accident was the excessive approach speed chosen by the pilot, which resulted in an elongated landing roll.
- The pilot did not initiate a go-around because they were unaware of the critically low landing distance reserves.
- The wet runway surface significantly reduced the effectiveness of the wheel brakes.
- The use of the 'takeoff' flap setting, while intended to manage turbulence, contributed to a higher approach speed and a longer ground roll.
- The pilot's previous experience of stopping on the grass during dry conditions created a false sense of security regarding the available stopping distance on a wet surface.