Incident Overview
On 7 August 2009, two SZD-30 Pirat gliders collided in the air near the town of Osowa Góra. Both aircraft were conducting thermal soaring flights in the vicinity of an airfield. The collision occurred at approximately 16:40 local time at an altitude of about 1,650 meters, with cloud bases around 1,800 meters. Both gliders sustained damage but were able to land safely. The two occupants, both student pilots, were not injured.
Flight Details
The first glider, registered SP-2559, departed at 12:30 on a cross-country task from Bydgoszcz to Mrocza to Chełmno and back. After returning, the student pilot requested and received permission to continue thermal flying near the airfield. The second glider, SP-2732, took off at 13:25 with the task of a training thermal flight in the same area. Both gliders had functioning radio communication.
Before the collision, the two gliders were circling together in a thermal. The pilot of SP-2732 then departed toward the airfield, followed by SP-2559. At some point, the pilot of SP-2732 heard a whistling sound, and the left wingtip of SP-2559 struck the rear part of the right wingtip of SP-2732.
Aftermath
After the collision, the pilot of SP-2732 assessed the damage and confirmed that the glider remained controllable. He reported the collision by radio, deployed airbrakes, descended to 300 meters above the airfield, and landed safely at 16:50.
The pilot of SP-2559 reported degraded controllability to the Flight Manager, who instructed him to descend without overloading the structure, and to bail out if lateral control worsened further. After descending over an undeveloped area, the glider landed safely on the airfield.
Investigation Findings
The Polish State Commission for Aircraft Accident Investigation (PKBWL) determined the probable cause of the accident: improper observation of the airspace around the glider and failure to maintain separation in thermal flight by the pilot of glider SP-2559 relative to glider SP-2732. The commission did not issue any safety recommendations.