What happened
On August 7, 1999, at approximately 14:40, a PIK-11 aircraft, registration OH-YMD, crashed at Mikkeli Airport, resulting in the death of the pilot and the total destruction of the aircraft. The pilot had arrived at the airport earlier that day from Helsinki-Malmi and had intended to perform several low-level passes over the airfield to demonstrate the aircraft's capabilities to a group of visitors.
During the flight, the pilot performed several maneuvers at very low altitudes, flying just 2 to 5 meters above the runway. Witnesses observed the pilot reducing engine power to idle while flying over the airport buildings. Following this reduction in power, the pilot initiated a steep, approximately 45-degree climb. As the aircraft entered a near-vertical turn, it began to oscillate before pitching nose-down toward the ground. Although the pilot attempted to apply full power just before impact—noted by a sudden surge in engine noise—the aircraft was unable to recover from the dive and struck the ground near the end of runway 29, immediately catching fire.
The investigation
The investigation examined the aircraft's structural integrity, the engine's performance, and the pilot's flight maneuvers. Investigators performed a comparative flight test using a similar PIK-11 (registration OH-YMC) to understand the aircraft's handling characteristics. The test confirmed that initiating a steep climb at idle power significantly reduces airspeed and prevents the aircraft from reaching a safe altitude before the maneuver is completed.
Technical analysis of the engine revealed that the lack of an acceleration pump in the carburetor caused a momentary lean fuel-air mixture when power was abruptly increased, leading to a momentary stumble in engine performance. The investigation also noted that the aircraft's right wing was destroyed upon impact, while the left wing remained largely intact, suggesting the aircraft struck the ground with a significant right-wing roll.
Findings
- The primary cause of the accident was a vertical maneuver initiated at too low an altitude, which prevented the pilot from recovering the aircraft before ground impact.
- The pilot was flying at altitudes well below the legal minimum of 150 meters.
- The pilot was performing maneuvers classified as aerobatics without having received formal aerobatic training.
- The pilot's decision-making was compromised by a desire to perform for the spectators present at the airfield.
- The aircraft was operating with reduced engine power during the critical phase of the climb, which led to a rapid loss of airspeed and insufficient altitude gain.