B1/2011L Collision between two sailplanes in Hattula on 12 June 2011

An aircraft accident occurred near lake Renkajärvi in Hattula, southern Finland, on Sunday 12 June 2011 at 15:57 Finnish local time, when two single-seat sailplanes collided in the air. The pilot of the other plane rescued himself with a parachute, and the other pilot was killed. Both sailplanes were destroyed.

The sailplanes involved were participating in Finnish Gliding Championships. The collision occurred in gliding flight in good weather conditions between the turnpoints of Forssa and Syrjäntaka, at a height of approximately 1400 m inside Pirkkala Military Control Area (Airspace class D) of which southern part was reserved for the competition. Both pilots were experienced sailplane pilots and competitors.

Before the collision, the planes were flying almost the same route and occasionally very close to each other. The collision happened when the lower flying plane increased altitude and reduced speed, finally hitting the bottom of the higher flying plane.

From the force of the impact, the rear fuselage and right wing of the lower plane broke off and the canopy was shattered. The plane went into a steep dive, and also the left wing broke off. The fuselage crashed into the ground at high speed. The pilot was found outside the wreckage. He had unfastened the seat belt but not launched the parachute. The bottom of the higher plane was cracked, its steering system was damaged and the canopy was broken. The pilot rescued himself with a parachute.

Both planes had two GPS devices, and their recordings were used in the accident investigation. The planes were also equipped with a FLARM system for collision avoidance. According to the rescued pilot, the FLARM did not alert before the collision, which may have been due to the limited capabilities of the system as described in its instructions manual.

The accident was caused by pilots’ insufficient situational awareness leading to the situation, where the planes got above each other and their flight paths intersected in the vertical direction. At the same time the pilots could not see each other. Contributing factor was the fact that the collision warning system did not alert.

The accident was caused as the planes got above each other in a position where the pilots could not see each other, and their flight paths intersected in the vertical direction. Contributing factors included the pilots’ insufficient situational awareness and the fact that the collision warning system did not alert.

Safety Investigation Authority, Finland issued a safety recommendation to the Finnish Aeronautical Association, urging them to hold a safety information session before every gliding contest. In addition, it was proposed that safety issues be addressed in the briefing session for each day of competition.

B1/2011L Report (pdf, 0.46 Mt)