Primary finding
Probable cause
The flight instructor’s failure to maintain directional control with a quartering tailwind.
Investigator assessment
Analysis narrative
The flight instructor and student pilot were practicing a tow rope failure and were landing the glider with a light, quartering tailwind. On final approach the glider drifted right of the runway centerline and just before touchdown, the right wing struck a tree, which resulted in substantial damage to the right wing and canopy. The flight instructor reported that the airplane had no preimpact mechanical malfunctions or failures that would have precluded normal operation.