What happened
On August 29, 1999, a pilot was performing a flight demonstration at an aviation event at the Cham-Janahof glider airfield. After taking off from runway 10, the pilot flew north of the runway at an altitude between 60 and 120 meters. While flying west, the pilot initiated a left-hand turn with a high degree of bank angle. Witnesses observed the aircraft pull up during the turn, followed by a series of rolls around the longitudinal axis. The aircraft then pitched forward at an angle of approximately 45 degrees.
At 15:06, the Cri-Cri MC 15/1537 struck the ground while flying east at a shallow pitch angle. The aircraft slid approximately 20 meters before coming to a halt. The pilot sustained fatal injuries and passed away later that day in the hospital. The aircraft was destroyed, though only minor damage was caused to the surrounding area.
The investigation
The BFU investigation examined the aircraft, the pilot's credentials, and the environmental conditions. The aircraft, a homebuilt twin-engine ultralight, was found to be in good condition with no mechanical defects contributing to the accident. The pilot was highly experienced, with approximately 1,000 total flight hours and a valid license.
Investigators also reviewed the radio communications and airfield activity. While the pilot had checked in with the airfield information desk, he did not provide details regarding his intended flight path. There was also a Cessna taxiing on the runway at the time; the pilot did not acknowledge information regarding this aircraft, possibly because he had switched to a different demonstration frequency.
Findings
Several factors contributed to the accident. The investigation noted that the aircraft's flight manual warns that stall signals in this model are very weak and that a stall can result in a sudden, asymmetric drop. The observed flight behavior—specifically the high bank angle and subsequent pitch—suggested a stall due to insufficient airspeed during the maneuver.
Contributing factors included:
- The pilot's failure to maintain a safe margin above the stall speed during a high-bank turn.
- Potential distraction caused by another aircraft taxiing on the runway.
- The presence of gusty winds, with gusts reaching 20 knots, which may have affected the aircraft's stability.
- The pilot's possible attempt to avoid flying over the spectators located south of the runway.