What happened
On April 20, 2020, a Tecnam P2002-JF, registration HB-KPA, was performing a private training flight at Biel-Kappelen (LSZP) when the aircraft veered off the runway. The pilot was conducting a solo flight, following a route that included the Chasseral and the towns of La Chaux-de .de Fods and Le Locle, before returning to the airfield for landing on runway 05.
During the final approach, the pilot encountered significant crosswinds. In an attempt to manage the wind, the pilot reduced the approach speed to approximately 60 KIAS with the flaps set to the 15-degree takeoff position. As the pilot initiated the landing flare, the aircraft drifted heavily to the left. In an attempt to execute a go-around, the pilot increased power; however, the aircraft's left wing struck the ground, causing the pilot to abort the go-around. The aircraft subsequently overran the left edge of the runway and came to a stop in an adjacent grain field. The pilot was able to taxi the aircraft back to the hangar under engine power, where the damage to the left wing was discovered.
The investigation
The SUST investigation focused on the flight parameters and environmental conditions during the landing phase. The investigation examined the aircraft's flight manual (AFM) specifications, the meteorological data, and onboard Flarm recordings. There were no technical malfunctions identified in the aircraft.
Data from the onboard Flarm device indicated that the ground speed was approximately 44 knots at 160 feet AGL and had decreased to 32 knots at the moment of ground contact. The investigation also reviewed the manufacturer's recommended approach speeds and the demonstrated crosswind capabilities of the aircraft.
Findings
- The primary cause of the incident was that the pilot maintained an approach speed that was too low for the flight configuration.
- While the aircraft's demonstrated crosswind limit is 22 knots, the actual wind component was approximately 9 to 14 knots, meaning the aircraft remained within its controllable limits regarding wind.
- The pilot's approach speed of 60 KIAS (with 15-degree flaps) was significantly below the AFM-recommended 66 KIAS for that configuration.
- Due to the low airspeed, the aircraft's ground speed dropped into the range of the stall speed during the final moments of the approach. This led to a partial, momentary stall when a wind gust hit the aircraft, causing the left wing to drop.
- The investigation noted that for light aircraft, the ratio of momentum to aerodynamic drag is lower than in larger aircraft, meaning speed decays much more rapidly during power reductions or wind gusts.
- There were no injuries to the pilot, and the aircraft sustained light damage.