What happened
On April 16, 2016, a SZD-41A Jantar Std. glider departed for a thermal soaring mission near the Kraków (EPLL) aerodrome using a winch launch. After several minutes of flight, the pilot requested and received permission from the tower to transition to the northern side of the airfield to follow wind conditions.
At 00:24 UTC, air traffic controllers at the Kraków tower lost radio contact with the glider while it was operating within the CTR EPLL. Controllers and a regional aero club instructor attempted to re-establish communication via the tower frequency, telephone, signal pistols, and by placing landing instructions on the grass runway, but all attempts were unsuccessful. While the glider remained visually in contact with the tower, the loss of communication prompted safety measures, including the separation of a Boeing 737-800 operating in the area.
At 09:43 UTC, the pilot increased the volume on the radio receiver and successfully re-established contact with the tower, requesting a transition to the southern side of the airfield. Upon regaining communication, the supervising instructor ordered an immediate landing. The pilot complied and landed the aircraft at 09:53 UTC. A post-flight inspection of the radio equipment revealed no technical malfunctions.
The investigation
The investigation examined the pilot's actions, the aircraft's technical state, and the circumstances surrounding the loss of communication. The pilot held a valid glider license and medical certification. Records showed the pilot had completed four flights in the preceding 14 days without any reported communication issues. The aircraft's total flight time for the season was 5 hours and 21 minutes, with no recorded mechanical failures.
Findings
- The pilot failed to hear the tower's attempts to contact the aircraft because the radio volume was set too low.
- The pilot's attention was focused on thermal soaring flight tasks, leading to insufficient monitoring of radio communications and inadequate observation of the airfield environment.