ASK 13 tow rope entanglement leads to crash in Montricher during training flight
On June 14, 1992, a Schleicher ASK 13 glider experienced a tow rope entanglement during a training flight near Montricher, Switzerland. The rope detached from the tow plane and became entangled with a ground cable, causing the glider to crash into a field. Both the instructor and the student pilot sustained serious injuries. The glider was significantly damaged, but there were no fatalities. The incident occurred shortly after takeoff, and the weather conditions were not a contributing factor.
- Aerotow takeoff: During an instructional aerotow departure from Montricher runway 03, the ASK 13 with instructor and student began the initial climb after a normal ground roll.
- Tow hook wiring loop: On the towplane, the electrical lead to the tow-hook indicator was too long and formed a loop around the tow-hook release lever, preventing full closure of the hook latch.
- Tow rope releases: At about 20 m above ground as the combination approached the tree line, the partially latched tow hook on the towplane opened and the tow rope unexpectedly detached from the towplane while remaining attached to the glider.
- Instructor misdiagnosis: The student did not report that the rope had detached from the towplane, and the instructor, feeling the loss of tow at low height, assumed the rope had released from the glider side and focused on clearing the nearby railway line rather than operating the glider’s release.
- Rope snags power cable: With the rope still attached to the glider’s nose, it first brushed the treetops and then wrapped around the earth wire of the nearby railway power line, abruptly decelerating the glider and causing it to pitch down into a field despite the rope eventually breaking.
- Crash - serious injury: The glider crashed into a colza field about 60 m beyond the railway line, was heavily damaged, and both the student and instructor sustained serious spinal and leg injuries.