Introduction
A student glider pilot was being towed by a tow plane for a local flight. Shortly after takeoff, the student observed that the tow rope had "some slack" and that the tow plane did not appear to be climbing "at the rate he should have been."
Sequence of Events
The student glider pilot made slight control adjustments to tighten the tow rope, but the rope "went slack" again at an altitude of 200-300 feet above ground level, and the airplane began to descend below the glider. The glider pilot then decided to release from the tow plane and turned back to the airport. During the turn, he observed the airplane drop its left wing slightly and then begin a turn to the right. The airplane subsequently impacted a quarry, and a post-crash fire ensued.
Examination and Prior Incidents
Examination of the airplane and engine revealed no pre-flight mechanical deficiencies. On a previous training flight involving the same student glider pilot and the accident tow pilot, the airplane began to descend during a climb when the tow pilot failed to realize that the throttle had vibrated back to a lower power setting after he took his hand off it.
Pilot Information
According to the operator of the airplane, the tow pilot had performed approximately 70 tows during the past year but had been "signed off" to fly without an instructor less than a month prior to the accident. The student glider pilot had accumulated approximately 50 hours of total flight experience.
Handbook Reference
The FAA Glider Flying Handbook states that one of the most dangerous occurrences during aerotow is allowing the glider to rise high above and losing sight of the towplane. The tension on the towrope by the glider pulls the towplane tail up, lowering its nose. If the glider continues to rise, the towpilot may not be able to raise the nose and may run out of up elevator authority. This situation can be critical if it occurs at altitudes below 500 feet AGL. Upon losing sight of the towplane, the glider pilot must release immediately.