What happened
On May 26, 2003, during a flight day at Biržai Aerodrome, a LAK-12 glider, registration LY-GFN, was being prepared for a training flight with water ballast. The glider was attached via a 38-meter towline to a Wilga-35A aircraft, registration LY-AKS, for a takeoff run on a heading of 270°.
As the aircraft reached speeds of approximately 50–60 km/h, the glider's right wing dipped and caught in the tall grass on the airfield. This caused the glider to pivot sharply to the right, resulting in it breaking away from the towplane. The sudden rotation forced the pilot of the towplane to abort the takeoff run. The glider continued to rotate around its vertical axis before coming to a stop approximately 90° from its original heading. There were no injuries to any personnel.
The investigation
The investigation was initiated two weeks after the event, following media reports. At the time the investigation began, the glider had already been removed from the site, and its damaged stabilizer had been sent to the manufacturer for repairs, which limited some investigative capabilities.
The investigation examined meteorological data, which indicated that while local club officials reported westerly winds, the actual wind at the time of the incident was likely from the southeast. The investigation also reviewed the airfield conditions, noting that the grass on the takeoff strip had not been mowed and was approximately 20–30 cm high.
Findings
- The pilot was properly rated and certified for the flight.
- The aircraft held a valid certificate of airworthiness, although its technical resource period had not been officially extended.
- The takeoff attempt did not comply with the flight leader's requirements, which mandated a strictly headwind takeoff.
- The airfield surface was not adequately prepared for LAK-12 operations due to the height of the grass.
- The primary cause was the attempt to take off in a quartering tailwind from a runway covered in tall grass.