What happened
During a flight operation involving a glider, a witness observed the tow plane encounter a dust devil at an altitude between 100 and 200 feet AGL. Following this encounter, the glider also entered the dust devil and gained enough altitude to rise above the tow plane. This maneuver caused the tow rope to reach an angle of 30 to 45 degrees. Subsequently, the nose of the tow plane dropped, leading the aircraft to descend into the ground.
The investigation
Investigators examined the wreckage and the tow equipment following the accident. The tow rope had separated aft of the tow plane's tow ring. The portion of the rope containing the tow ring was located near the crash site, while the remaining length of the rope, which included the glider tow ring, was found further back along the flight path.
An inspection of the tow plane hook release mechanism revealed that it was in the open position. Investigators determined that the mechanism opened upon impact. This conclusion was supported by the specific separation point of the tow rope relative to the tow plane hook and the observed snap back of the remaining rope away from the site of the crash.