NTSB Identification: FTW97LA349.
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Accident occurred Sunday, September 14, 1997 in SUNDANCE, WY
Probable Cause Approval Date: 06/26/1998
Aircraft: AS+ Ltd AC-4B, registration: N3021
Injuries: 1 Uninjured.

NTSB investigators may not have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.

A glider launch was being conducted, using a vehicle tow and a mechanical advantage/pulley arrangement. During the launch, the tow rope became snagged on vegetation (alfalfa crop stuble), then slack developed in the tow rope as the rope came loose from the stuble. When slack was taken up, it 'jerked' the glider, which pitched up. The pilot released the tow rope, but the glider settled (stall) and rolled approximately 25 degrees left wing down. The wing contacted the ground, and the glider spun around and came to rest facing backwards. This resulted in substantial damage to the wings and fuselage.

The National Transportation Safety Board determines the probable cause(s) of this accident to be:

improper planning/decision by the pilot, which led to a snag and sudden slack in the tow rope, and necessitated an aborted launch (emergency landing) after initial liftoff. This in turn led to an inadvertent stall, a wing drop, and the left wing tip dragging the ground. A factor relating to the accident was: the restricted movement of the tow rope after it became snagged on the crop stubble.

Full narrative available

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