History of the Flight
The accident occurred on 2 September 2020 at Bagnères-de-Luchon aerodrome (Haute-Garonne). A Robin DR400-180R registered F-HKZZ was towing a Schleicher Ka 6E registered F-CDRM. The aeroplane pilot took off from runway 01. Shortly after takeoff, at an estimated height of about 50 m, the tow cable slackened then suddenly tautened. The glider entered a nose-up attitude and rose higher than the aeroplane, slowing it and causing a nose-down attitude. Both pilots released the tow cable simultaneously. The glider pilot made a tight right turn and landed on the reciprocal QFU. The aeroplane collided with the runway. The aeroplane pilot was severely injured and the aeroplane was destroyed. The glider pilot was injured and the glider slightly damaged.
Meteorological Information
Météo-France estimated conditions at the aerodrome: northerly wind of 20 km/h gusting to 40 km/h, CAVOK, temperature 21°C. Witnesses reported a valley breeze from the north of about 20 km/h with gusts up to 30 km/h and thermal uplifts. The runway was tree-lined with turbulence.
Aerodrome Information
Bagnères-de-Luchon aerodrome is in a mountainous area requiring adapted runway circuits. The unpaved runway 01/19 measures 750 m long and 50 m wide. A taxiway is west of the runway; west of that is an area for paraglider landings.
Examination of Site and Wreckage
The aeroplane wreckage lay on runway 01, 55 m from the runway end and 15 m from the east edge. The 46 m long tow cable was about 100 m before the wreckage. Damage resulted from ground impact and emergency services. The aeroplane struck the ground with a slight left bank and stopped within a few meters. Flight and engine controls were continuous; elevator trim continuity could not be established. Flap position could not be determined due to impact stresses. Glider damage was limited to minor canopy damage.
Aircraft Information
The Flight Manual for the DR400-180R specifies rotation speed 100 km/h and optimum climb speed between 110 km/h (for low wing loading gliders) and more than 130 km/h (for high lift-to-drag gliders). The Schleicher Ka 6E is a light, single-seat glider with medium lift-to-drag ratio, made of wood and canvas, with a single hook near the landing gear. It is generally towed at about 110 km/h. Instructors noted that high tow speeds may cause pitch instability, possibly due to its one-piece horizontal tail.
Pilot Information
The 22-year-old aeroplane pilot held SPL (2018), PPL(A) (2016), and Brevet de Base (2014). He had about 210 flight hours in aeroplanes (130 as PIC) and 75 hours in gliders. He completed glider towing rating training on 24 August 2020, including dual flights and supervised solo flights. He had 37 tows total, 22 as PIC, all with F-HKZZ. On the accident day, he had completed three tows in the morning and three in the afternoon before the accident, involving composite gliders. The 36-year-old glider pilot held SPL (1999) with 255 flight hours (172 as PIC). She had eight hours in F-CDRM from three flights in August.
Statements
The aeroplane pilot reported observing the glider take off higher than usual (more than two or three meters). After rotation at 100 km/h, he felt yawing movements. He did not release the cable initially. When he looked again, the glider was higher and to the right. He had no memory of the rest. He stated he used towing speeds of 110-115 km/h for wood/canvas gliders and 130 km/h for composites. He noted conflicting instructions from instructors and no checklist on board. The glider pilot stated the takeoff run was nominal; the glider left ground before the aeroplane. She applied nose-down to maintain height. After aeroplane takeoff, speed was over 130 km/h indicated. At about 20 m height, turbulence increased; glider moved a lot, slightly higher than tug, stick fully forward. She intended to radio but had no time. The glider suddenly pitched up; she slid out of seat and hit canopy. She released the cable, stabilized with right turn, and landed on reciprocal QFU at high speed. Witnesses, including two instructors, saw the cable slacken then tauten, glider rise about 10 m above tug, slowing the aeroplane and causing nose-down. The aeroplane pilot released cable and attempted a pull-up but collided flat with ground. No engine malfunction was reported.
Examination of FLARM Data
FLARM data showed the combination reached about 110 km/h ground speed shortly after takeoff. Ten seconds later, speed decreased to 90 km/h at about 60 m height. At about 80 m, aeroplane speed dropped to less than 70 km/h while glider speed was around 100 km/h and increasing. The glider reached a maximum height of about 160 m.