Blanik L-13 crash during descent near Vernamiège, Switzerland, injuring two
On July 13, 1975, a Blanik L-13 glider crashed near Vernamiège, Switzerland, during a descent maneuver. The pilot and his son were on a leisure flight over the Alps when the glider stalled and impacted the ground at 18:10 local time. The pilot sustained serious injuries, while his son was slightly injured. The investigation concluded that the accident was caused by a stall during maneuvers performed with insufficient speed margin. The glider was destroyed in the crash.
- Cruise and descent: After an aerotow launch from Sion and mountain soaring, the pilot began descending from Mont Noble toward Sion using turns and spirals along the slope.
- Low height near slope: The pilot flew spirals close to a steep hillside at relatively low height, reducing margin for error and making attitude and speed control more difficult.
- Insufficient speed margin: During these slope-side spirals the glider was flown with an inadequate speed reserve for the bank angle and conditions, increasing stall risk.
- Tightened right spiral: While completing the second right-hand spiral near the slope, the turn was tightened with increased bank and back pressure, further reducing airspeed and raising stall speed.
- Abrupt nose drop: At the end of the second spiral the glider suddenly pitched into a steep dive, consistent with an aerodynamic stall and ensuing nose-down break.
- Unrecovered descent: The glider descended steeply along the slope, slightly banked right as if continuing an impossible spiral, without sufficient height to recover.
- Crash - serious injury: The glider impacted the hillside first with the right wingtip, then the nose and left wingtip, was destroyed, the pilot was seriously injured, and the passenger slightly injured.