What happened
On July 2, 2015, a student pilot was conducting a cross-country flight for license requirements, flying a SZD-51-1 Junior glider, registration SP-3och, operated by Aeroklub Podhalański. After completing a successful 73.6 km triangle flight, the pilot returned to the Łososina Dolna airfield (EPNL) at an altitude of approximately 900 m AGL.
During the landing approach, the pilot encountered areas of sinking air. While entering the fourth turn of the landing pattern at approximately 150 m AGL, the pilot transitioned to a straight-in approach at 134 m AGL, but again encountered sinking air. The pilot attempted to pull the glider up to maintain altitude, but the aircraft lacked sufficient airspeed. The instructor, observing the flight from the ground, radioed a command to close the airbrakes. The pilot closed the airbrakes while flying over an orchard, but the low airspeed prevented the glider from maintaining the necessary glide path. The aircraft subsequently landed in an orchard approximately 45 m from the edge of the airfield, resulting in serious damage to the glider. The pilot sustained no injuries.
The investigation
The PKBWL investigation examined the technical documentation of the SZD-51-1 Junior, which was found to be in order. The investigation reviewed the flight logs, the pilot's training history, and the meteorological conditions. The commission analyzed the glider's polar curve and the pilot's use of flight tools, such as the MacCready ring, to determine the optimal airspeed for the encountered sink rates. The investigation also reviewed the radio communications between the instructor and the student pilot during the final stages of the approach.
Findings
- The primary cause of the accident was an incorrectly executed approach correction following the fourth turn, characterized by flying through a zone of increased sinking air at an insufficient airspeed and closing the airbrakes too late.
- The pilot's limited experience contributed to the inability to manage the sink rate effectively.
- The instructor's radio instruction was incomplete, as it advised closing the airbrakes but failed to instruct the pilot to increase airspeed to compensate for the sinking air.
- The commission noted that the student pilot demonstrated a weak understanding of cross-country flight tactics.