What happened
On April 2, 1999, a PIK 20-E motor glider, registration PH-750, was involved in a fatal accident at the Terlet gliding airfield. The flight began with an attempt to start the aircraft's retractable engine on the ground, which was unsuccessful. To remedy this, the pilot opted for a winch launch, intending to start the engine in flight using the propeller's airflow, a technique known as windmill-starting.
After reaching an altitude of approximately 400 meters, the pilot deployed the engine. However, multiple attempts to start the engine via both the electric starter and the windmill method failed. These maneuvers, combined with the significantly degraded glide ratio caused by the extended engine, resulted in a rapid loss of altitude. As the aircraft approached the airfield, the pilot attempted to climb to avoid a wooded area. During this pull-up, one wing stalled, causing the aircraft to impact the ground in rough terrain near a forest edge. The aircraft was destroyed, and the pilot suffered severe injuries to his legs and feet.
The investigation
The investigation focused on the sequence of events leading to the loss of altitude and the subsequent stall. Investigators examined the aircraft's technical condition and found no mechanical defects; the engine, which had been inspected a week prior, showed no issues. The aircraft's weight and center of gravity were within legal limits.
Technical analysis revealed that while the pilot was experienced, the repeated attempts to start the engine through diving maneuvers and the aerodynamic drag from the extended engine significantly depleted the available altitude. The investigation also noted that the glide ratio of the PIK 20-E drops from 1:40 to approximately 1:16 when the engine is deployed, which drastically changes the flight characteristics during the landing circuit.
Findings
- The pilot's persistent attempts to start the engine in flight caused excessive altitude loss.
- The extended engine significantly increased drag, making it impossible to maintain the standard circuit altitude.
- The aircraft stalled during a low-altitude climb intended to clear trees while attempting to reach the airfield.
- The pilot's decision to climb to avoid obstacles at low speed directly led to the wing stall and subsequent impact.