Ka 6 BR aborts aerotow at 5 m on tail noise, ground-loops in rapeseed

A Ka 6 BR was substantially damaged on an aborted aerotow at Grenchen (Switzerland); the pilot was uninjured. He held 41 hours total and 46 minutes on type, all flown in the prior 90 days. After a normal liftoff on aerotow he heard an unfamiliar noise from the tail and released the rope at about 5 m. The remaining runway was insufficient, so the pilot put the glider down in a rapeseed field beyond the runway end. The glider ground-looped (Ringelpietz), damaging the rear fuselage, elevator and rudder. The pilot suspected the noise came from the tail wheel still spinning after liftoff; the abrupt low release was the decisive driver.

1. Aerotow start ~15:00 LT: At about 15:00 LT on 24 April 2015 the pilot launched a Ka 6 BR on aerotow from Flugplatz Grenchen (LSZG). The ground roll and initial climb were normal.
2. 46 min on type, 41 h total: The pilot had converted to the Ka 6 BR only recently, with very limited flight time on the type before the accident flight.
3. Unfamiliar noise from tail: Shortly after liftoff the pilot heard a noise from the tail area of the glider that was unfamiliar to him.
4. Release at ~5 m: Interpreting the noise as a possible problem, the pilot aborted the takeoff and released the tow rope at an estimated height of about 5 m above the ground.
5. Runway too short for landing: After release the pilot realised that the remaining runway length was not enough for a landing on the runway.
6. Outlanding in rapeseed field: The pilot landed the glider in a rapeseed field located beyond the runway end.
7. Ground loop; tail damaged: The glider ground-looped in the field, damaging the rear fuselage, elevator and rudder; the pilot was uninjured and suspected the tail wheel had caused the noise.