What happened
On June 24, 2002, at approximately 17:45 local time, a Schleicher Ka 6 BR glider, registration PH-1204, was being towed for a non-commercial pleasure flight at the Ocaña aerodrome in Toledo, Spain. The takeoff was initiated by a Robin DR400-180R, registration EC-BTN.
During the initial climb, after both aircraft had traveled approximately 900 meters along the 1200-meter runway, the tow cable snapped. Following the breakage, the glider began a shallow left turn with very little bank. As the aircraft turned more than 90 degrees, the pilot increased the bank angle. At a low altitude of approximately 40 meters and a speed of roughly 70 to 80 km/h, the left wing descended abruptly. This maneuver caused the aircraft to stall, resulting in a rapid descent and a heavy impact with the terrain. The impact destroyed the aircraft and resulted in one fatality.
The investigation
The investigation examined the flight sequence, the condition of the tow cable, and the maneuvers performed by the pilot. Witnesses, including the pilot of the towing aircraft and observers at the aerodrome, noted that the glider had been flying at a height equal to or lower than the towing aircraft during the climb. This positioning likely caused the glider to be affected by the propeller slipstream, creating fluctuations in cable tension.
Technical analysis of the wreckage showed the aircraft hit the ground with a significant vertical component, with the left wing making contact first. Investigators also performed tensile testing on the tow cable. While the cable's strength generally met the minimum regulatory requirement of 5000 N, the portion of the cable nearest the breakage point showed a slight reduction in strength. Furthermore, the investigation found that the pilot was not familiar with the specific aerodrome procedures for handling a cable break, which recommended maintaining the current heading and landing immediately.
Findings
- The tow cable breakage was the primary event that initiated the accident sequence, likely caused by sudden tension spikes as the glider entered the propeller stream of the towing aircraft.
- The pilot initiated a turn at a low altitude and low airspeed, which increased the stall speed and induced a wing drop.
- The glider was flying below the towing aircraft, which contributed to unstable tension in the cable.
- The pilot was unaware of the local aerodrome's specific emergency procedures for a cable separation.