Incident Overview
On 14 August 2013, at approximately 09:58 UTC, a LAK 12 glider, registration OK-1212, collided with a tow rope suspended from a Rallye 180T-D glider tug, registration D-ESKH. The occurrence took place 3 km north-northeast of the aerodrome reference point of Hosín Airport (LKHS). No injuries to persons were reported.
Sequence of Events
The pilot of the LAK 12 had taken off from Runway 24 at LKHS at 09:49 in aerotow and entered a thermal lift about 2.1 km southeast of the airfield. According to the GNSS flight recorder, the glider climbed in circles up to 1,271 m (840 m AGL). At 09:55:57, the pilot stopped circling, changed heading to 006 degrees, and glided northbound. He resumed circling at 09:57:57, then after one 360-degree turn continued gliding at 005 degrees heading. The pilot stated he was heading toward the first formed cumulus and was closely observing the surrounding airspace.
Meanwhile, the Rallye 180T-D had taken off from Runway 24 at 09:54, towing an ASTIR CS Jeans glider (OE-5165). The tug pilot was climbing in a straight direction at 060 degrees heading. The pilot of the towed glider suddenly spotted another glider approaching fast. Assessing a potential collision, he released the tow rope. Immediately, the towed glider began to ascend.
The LAK 12 pilot heard a loud engine sound from approximately the "7 o'clock" position and detected a glider tug on a collision course at about the same flight level. He pushed the control stick down forcefully. The risk of collision arose in an extremely short period, about 1.5 seconds. The LAK 12 pilot then observed the towed glider releasing and flying behind him. The glider tug passed directly above his cabin, estimated 2–3 meters above. He heard several intense bangs against the fuselage and a wing. The tow rope had struck the LAK 12 and caught in its fuselage, perforating the bottom part. The pilot then continued flying, examining controls and notifying the AFIS controller.
Aircraft and Personnel
The LAK 12, manufactured by AB "Sportine Aviacia" in 2000, serial number 6235, had a total flight time of 851 hours 58 minutes. Its last annual inspection on 7 November 2012 found it airworthy. The pilot, aged 29, held a valid glider pilot license and medical certificate, with 179 hours 57 minutes total glider flight time, of which 7 hours 58 minutes were in the LAK 12.
The Rallye 180T-D, registration D-ESKH, was operated by Flugsportcentrum Tirol. The tug pilot, aged 64, held a private pilot license with SEP, TMG, and TOW qualifications, and had 2,141 total pilot-in-command hours, including 144 hours in the Rallye 180T-D and 511 aerotows.
The towed glider pilot, aged 41, held a valid glider pilot license issued by Austrian Aero-Club.
All involved pilots were subjected to an indicative alcohol breath test by the Czech Police, with negative results.
Flight Data
GNSS flight recorder data for the LAK 12 and the towed glider (OE-5165) showed that the collision occurred between 09:58:47 and 09:58:57. At that time, the LAK 12 was at 1,207 m (703 m AGL) with an indicated airspeed of 93.7 km/h, heading 346 degrees. The towed glider, which had released earlier, was at 1,216 m (722 m AGL) at 99.1 km/h, heading 069 degrees, and its trajectory passed about 9 meters higher than the LAK 12.
Aftermath
The LAK 12 pilot, after receiving a visual check report that the glider appeared normal, landed safely at LKHS. The glider tug landed and found the tow rope had broken loose. The towed glider also landed without incident.