Accident Sequence
During a glider tow operation, the glider pilot failed to ensure that the aircraft's spoilers were retracted in the locked position during takeoff. During the initial climb, the towplane pilot radioed 'SPOILERS, BOB, SPOILERS'. A witness observed the spoilers in the extended position. The glider pilot subsequently retracted the spoilers, during which the glider entered a nose-high, pitch-up attitude.
Realizing he was in a high tow position, and before he was able to manually release the tow line from the glider, the tow rope broke in overload. The break occurred within the specified tensile limits per regulatory requirements.
A witness observed the towplane climb to approximately 150 feet above ground level (AGL) and then pitch nose down, descending in an approximate 45-degree flight path to a wings-level ground impact. The aircraft impacted the terrain 40-50 degrees nose low, wings-level, with the engine developing power.
Examination Findings
Examination of the aircraft's tow hook release latch mechanism revealed the potential for binding of the release latch when the towed aircraft moved significantly above the horizontal (trail) position.