2012 Leverkusen glider tow accident

Overview and outcome On 23 July 2012, a tow accident occurred near the special landing site Leverkusen (EDKL), Germany. The aircraft involved were an Avions Pierre Robin DR 400 RP and an Alexander Schleicher ASK 21 glider. The tow pilot was killed and the tow aircraft was destroyed; the glider pilot was uninjured and the glider was undamaged. The accident caused agricultural and forestry damage. ## Flight sequence The tow combination took off at 12:44 local time from grass runway 15 for a private flight. The pilots had agreed on a release height of about 500 m. The glider pilot reported that the takeoff roll and initial climb were uneventful, but during the crosswind departure the tow aircraft suddenly entered a descent. He had to push the elevator to follow and then received the instruction to release the tow rope, which he did immediately. He observed the tow aircraft rapidly losing altitude. Witnesses reported that the tow aircraft was in a left turn with a high angle of attack and that the glider was higher than the tow aircraft, with the tow rope hanging slack. Another witness saw the glider release and the tow aircraft roll left into a near-vertical dive. The glider landed at 12:47 on runway 15. The tow aircraft struck the ground east of the airfield, about 700 m from the end of runway 15, after colliding with several trees at the forest edge. A high-voltage line ran parallel to the forest edge, but no collision marks were found on its cables. The aircraft caught fire after impact. ## Aircraft and maintenance The tow aircraft was a single-engine, piston-powered, low-wing, wood-structure aircraft with fixed landing gear and a hydraulically adjustable three-blade propeller. It was built in 1988, serial number 1845, powered by a Lycoming O-540-A4D5 engine and fitted with a Hoffmann HO-V 12 3 K-K 200CQ propeller. It was registered in Germany and operated by a club. At the time of the accident it had 5,747 hours and 16,285 takeoffs and landings. The last airworthiness inspection was on 6 April 2012, and a 50-hour maintenance check was performed on 6 July 2012 at 5,740 hours and 16,255 takeoffs and landings. The glider was a two-seat, glass-fibre-reinforced-plastic, mid-wing glider with a 17 m wingspan and fixed landing gear. It was built in 1989, serial number 21411, by Alexander Schleicher Segelflugzeugbau GmbH in Poppenhausen. It was registered in Germany and operated by a club. A tow rope with a brown weak link rated at 850 daN was used. ## Personnel The tow pilot was a 73-year-old male holding a German private pilot licence (PPL(A)) under JAR-FCL, first issued on 25 April 1986 and valid until 20 April 2015. He was rated for single-engine piston land aircraft as pilot in command, touring motor gliders, aerobatics, and glider towing without winch towing. His single-engine piston land aircraft rating was valid until 20 April 2013. His class 2 medical certificate, first issued on 14 March 1983, was valid until 9 December 2012, with a vision limitation requiring glasses and a spare. His personal logbook showed 1,799 hours and 6,799 takeoffs and landings, including 86 tow flights in the previous 90 days. He had also held a glider pilot licence since 1986. The glider pilot was a 71-year-old male holding a German glider pilot licence (GPL), first issued on 26 September 1978 and valid indefinitely. He was rated for gliders launched by aircraft tow and winch, and for self-launching motor gliders, as well as touring motor gliders in those launch methods. His class 2 medical certificate, first issued on 14 January 1978, was valid until 14 September 2012, with a vision limitation and a special approval for the review procedure. His logbook showed 20 aircraft-tow launches and 10 hours in the previous 12 months. ## Meteorology and data Weather was under high-pressure influence with scattered small cumulus, flight visibility greater than 10 km (CAVOK), air temperature 22 °C, dew point 7 °C, and pressure 1,027 hPa. At 13:00, wind at the airfield was from 150° at 10 knots. A Garmin 196 GPS in the tow aircraft was available for analysis, but its data ended at 12:29. A FLARM collision-avoidance device in the glider was also analyzed. FLARM data reconstructed the glider’s flight path: the tow combination lifted off at 10:43:14, climbed normally, then showed a brief altitude decrease and increase with corresponding speed changes. The highest speed occurred at a point where total-energy height indicated separation of the tow combination. ## Findings and probable cause The tow pilot held the required licence and ratings, had regularly performed tow flights, and was experienced. No medical impairments were found. The glider pilot was also properly rated and experienced. Both aircraft were properly registered and technically inspected, and the tow aircraft’s weight and centre of gravity were within limits. The high degree of destruction prevented technical investigation of the tow aircraft, and the tow rope was not found. The autopsy found that the tow pilot died from polytrauma to multiple body areas, with no evidence of internal disease or fresh or old heart attacks, and no blood alcohol concentration. The fire started after impact and was extinguished by the local fire brigade. The source does not state a probable cause.