On March 8, 1994, approximately 1500 mountain standard time (MST), a Schweizer 2-33A glider, N5790S, collided with taxiway markers during the takeoff roll at Heber Valley Airport, Heber City, Utah. The certified flight instructor and his dual student were not injured, but the aircraft sustained substantial damage. The dual student, who was attempting a takeoff for a local instructional flight, was operating in visual meteorological conditions at the time of the accident. No flight plan had been filed, and there was no report of an ELT activation. According to the flight instructor, the student pilot was making the takeoff with the assistance of a wing-runner. After the flight controls became effective, the wing-runner let go of the wing. Soon thereafter, the glider veered left, and the left wing dipped sharply. The flight instructor took control of the aircraft, but his remedial action was not sufficient to keep the aircraft from departing the side of the runway and striking a runway marker. The instructor pilot aborted the takeoff by releasing the tow line after the impact with the marker. In an interview with investigators, the instructor pilot said that he believed a variable crosswind switched to a quartering tailwind during the takeoff roll, resulting in a loss of flight control effectiveness.