What happened
On May 27, 2018, a Grob G103 Twin Astir glider, registration OY-XNZ, was performing a winch-less aero-tow takeoff from runway 11 at Viborg (EKVB) under visual flight rules. The tow aircraft, an Aeropro Eurofox K2 with registration OY-9448, was pulling the glider at a steady speed of 110 km/h.
Shortly after takeoff, while at an altitude of approximately 40 meters, the flight instructor in the glider noticed the airspeed dropping to roughly 80 km/h. Simultaneously, the pilot of the tow aircraft broadcast an engine failure emergency over the radio. In response to the loss of tension and speed, the instructor released the tow rope and lowered the glider's nose to attempt to regain airspeed. Due to the extremely low altitude, the instructor determined that an immediate landing straight ahead was the only viable option. The glider subsequently impacted a lake near Rindsholm Mølle. The impact caused substantial damage to the aircraft, including heavy damage to both wings and the shattering of the forward canopy. The glider remained buoyant in the three-meter-deep water, allowing the occupants to evacuate safely before being rescued by bystanders in a boat. The tow aircraft, OY-9448, performed an emergency landing in a field without further incident or injury.
The investigation
The Danish Accident Investigation Board conducted an initial safety investigation. Because the event involved an ultralight aircraft, the technical investigation of the tow plane, OY-9448, fell outside the Board's jurisdiction. The Danish Ultralight Pilots Union (DULFU) indicated they intended to conduct their own technical examination of the tow aircraft's engine issues.