Incident Overview
A glider pilot participating in a national soaring championship reported that his flight was the last of several glider tows for the day. The launch procedure required each glider to have a tow rope laid out, with a ground crewmember hooking the Schweizer tow ring to the tow airplane's Schweizer tow latch, then attaching the Tost tow ring to the Tost-equipped glider. The glider was loaded with water ballast to operate at maximum gross weight for competition purposes.
Launch and Rope Release
The glider pilot stated that the takeoff roll and liftoff were normal. However, about 100 to 150 feet above ground, the tow rope spontaneously released from the tow plane. He immediately pulled his rope release handle and pitched forward to land in a grass overrun area past the departure runway, but the glider had too much airspeed and too little area to land. He then pulled up to avoid a solid line of trees, entered a gentle right turn, and impacted a favorable brushy area. The glider was destroyed during the impact sequence.
Post-Accident Findings
The glider pilot reported no preaccident mechanical malfunctions or failures with the glider that would have precluded normal operation. A Federal Aviation Administration (FAA) aviation safety inspector examined the tow rope and rings, finding them intact just beyond the end of the departure runway with no anomalies. Functional checks of the tow hitches on the tow airplane and glider also revealed no anomalies.
The tow airplane pilot, who reported this was his seventh and last tow of the day, noted that the tow rope was attached by a ground crewmember, and he was instructed to take up slack and launch as usual. The takeoff and climb out of ground effect were normal, but about 300 feet above ground, the tow airplane was climbing too fast, and he radioed, "Was that a rope break?" Receiving no response, he continued climbing and soon observed the glider was no longer on tow, witnessing the impact. He completed a normal landing, including a low pass and rope release, but felt a lighter than normal release pressure on the tow handle.
The ground crewmember who attached the tow rope stated that he ensured the tow rope ring was placed correctly in the mechanism, placed the latch over the top beam in the vertical position locking the ring in place, made sure there was no tension on the release cable, and used his weight in both a straight back and back and up direction to confirm the tow ring was securely locked.
Equipment and Contest Management
The glider contest manager reported that the accident tow airplane was the only one with a Schweizer tow hitch; the other tow airplanes were equipped with Tost tow hitches. The manager announced that for future contests, only tow airplanes with Tost tow hitches would be used.
The FAA Advisory Circular (AC 43.13-2B) describes the Schweizer tow hook as a simple over-center L-hook type with a rubber tension block to preload the release lever. Additionally, the FAA Glider Flying Handbook provides inspection guidance for the Schweizer tow hook, including checking the hook and release arm for damage, cracks, deformation, and freedom of movement; inspecting the rubber spacer; verifying the manual release lever is not obstructed; and checking the security of the release handle assembly and cable attachment.