What happened
On November 10, 2008, a D-8 Straton Moby Dick ultralight aircraft, registration OK-EUO 07, crashed near the village of Hrdlív, Czech Republic. The flight departed from Slaný Airport (LKSN) on runway 25R.
Immediately after liftoff, at an altitude of approximately 8 meters, the aircraft bounced and made contact with the runway. The pilot continued the takeoff, maintaining a very low altitude of 5 to 10 meters while flying a somewhat unstable and crosswind-affected path. During the second turn of the left circuit, the aircraft reached an altitude of roughly 150–200 meters. The aircraft then entered a left-hand spiral dive with a bank angle of 70° to 80°, descending steeply toward the ground until it disappeared from view. The aircraft was destroyed upon impact.
The investigation
The ÚZPLN investigation examined the pilot's recent training history, the aircraft's mechanical configuration, and the meteorological conditions. The investigation established that while the pilot had recently completed training on this specific type, he had performed his training flights in a different aircraft (OK-AUO 01) and had not yet performed any solo flights in OK-EUO 07 prior to the accident.
Investigators also examined the aircraft's longitudinal trim. The electric servo mechanism, which controlled the elevator trim on the right tailplane, was found in a position that rendered the aircraft nose-heavy. Because there was no electrical power source on board during the flight, the pilot was unable to adjust this trim. Additionally, the investigation noted that the pilot's recent medical certification was found to have been issued erroneously, as forensic experts identified chronic cardiovascular changes that could have impaired his ability to pilot the aircraft.
Findings
- The pilot entered a left-hand spiral dive, which was the primary cause of the accident.
- The pilot's lack of familiarity with the specific flight characteristics of OK-EUO 07 likely contributed to the loss of control.
- The aircraft was trimmed in a nose-heavy configuration, which increases the susceptibility to entering a spiral dive.
- The pilot's recent training was conducted in a different aircraft, and he had not yet experienced the handling characteristics of his own aircraft in a solo capacity.
- A vertical component of the wind may have exceeded the aircraft's operational limitations during the unstable takeoff.
- The pilot had significant chronic medical conditions that could have impacted his piloting capabilities.