What happened
On August 18, 2009, at approximately 17:40 local time, a Grob G103C glider, registration I-IVVN, crashed into a rocky ridge near Corno del Renon, Italy. The flight began at Bolzano Dolomiti Airport, where the glider was towed by a Robin DR 400 aircraft for a recreational flight. After releasing from the towline at an altitude of approximately 2,141 meters, the pilot began performing various spiral maneuvers to locate and utilize rising air currents.
As the aircraft approached a steep ridge, the pilot executed a tight left-hand turn to stay within a suspected thermal. During this maneuver, the aircraft's altitude dropped rapidly. The glider impacted a rocky outcrop at an altitude of approximately 2,023 meters. The impact was severe, causing the total destruction of the aircraft and resulting in two fatalities.
The investigation
The ANSV investigation examined flight data from a Colibri Data Logger, meteorological reports from the Corno del Renon station, and the wreckage distribution. Investigators analyzed the aircraft's flight path, noting that the pilot was flying at low speeds and low altitudes in a mountainous environment. The investigation also reviewed the pilot's credentials, finding a valid license and medical certificate, and confirmed that the aircraft's maintenance records were up to date.
Findings
- The primary cause of the accident was a loss of control during a steep turn intended to maintain position within an ascending air current.
- It is highly probable that the aircraft entered an aerodynamic stall due to an excessive bank angle or a sudden reduction in airspeed caused by a shift in wind direction (moving into a tailwind component).
- The pilot's proximity to the terrain—only about 50 meters above the ridge during the final stages of the turn—left insufficient altitude to recover from the stall.
- Contributing factors included reduced safety margins when performing spiral maneuvers in mountainous terrain and potential turbulence caused by the local topography.