What happened
On May 24, 2003, a flight training tow operation commenced at Riesa-Canitz airfield under good visual flight conditions. The formation consisted of a PZL 104 Wilga 3-5A acting as the tow aircraft and an SZD 38 A Jantar 1 glider. Following a normal takeoff, the formation entered an initial climb over rising terrain.
During the climb, the glider pilot observed that the tow aircraft was maintaining a low altitude relative to the terrain. Fearing an obstacle strike, the pilot radioed the crew of the Wilga, requesting they climb higher. Shortly after this communication, the glider pilot moved into a significantly higher position behind the tow aircraft, losing visual contact with the lead plane.
As the glider climbed above the Wilga, the tension in the tow rope increased sharply. The crew of the Wilga reported that the tail section of their aircraft was being pulled upward. The tow aircraft subsequently entered an uncontrolled flight state and crashed into a field approximately 2 km from the airfield. The glider, performing a high-banked turn, struck the wreckage of the Wilga from the opposite direction. The impact triggered a fire that destroyed both aircraft. The two crew members in the Wilga sustained two fatalities and one serious injury, while the glider pilot also suffered serious injuries.
The investigation
The BFU examined the aircraft, the tow rope, and the flight circumstances. The investigation found that the tow rope, measuring 30 meters, lacked the manufacturer-specified weak link of 690 daN. While the rope was found wrapped around the glider's wing, it had successfully released from the aircraft's coupling.
Investigators also reviewed the flight experience of the crew. The pilot in command of the Wilga had very limited experience in that specific model, having flown only six hours in the type and having acquired his towing authorization only one week prior to the accident. The experienced instructor in the right seat was unable to assist with the release mechanism due to the aircraft's design, which only allowed the release to be operated from the left seat.
Findings
- The primary cause of the accident was the failure to release the tow connection in a timely manner before the onset of uncontrolled flight.
- The glider pilot's decision to adopt an excessively high position behind the tow aircraft created extreme longitudinal accelerations and increased rope tension.
- The low altitude of the tow aircraft (below 100 meters) made it impossible for the pilot to recover from the resulting pitch instability.
- The pilot in command's limited experience with the Wilga contributed to the delay in executing the release.
- The use of a tow rope without the required strength-rated weak link was noted, though it could not be definitively determined if this would have prevented the accident.