Incident Overview
A single-seat glider experienced an inadvertent cockpit canopy opening while being towed aloft behind an airplane. The glider pilot immediately released the tow rope and attempted to close the canopy, but was unsuccessful.
Flight and Landing Attempt
Approximately 20 minutes after the canopy opened, the pilot entered the airport traffic pattern for landing. During the final approach, the pilot was unable to activate the dive brakes to shorten the landing distance because her left hand was occupied holding the canopy down. As a result, the glider crossed the runway threshold at about 300 feet above ground level and continued past the end of the runway for roughly one mile.
Off-Airport Landing
The pilot performed an off-airport landing. During this landing, the glider's right wing impacted a fence post, causing structural damage to the aircraft. The glider came to rest in an upright position, and the pilot was able to exit the aircraft unassisted.
Investigation
The investigation did not determine the reason for the inadvertent canopy opening.