What happened
On March 22, 2019, at approximately 08:15 UTC, an Enstrom 480B helicopter, registration OK-CLV, crashed in a field on the eastern edge of the village of Blažkov, near Nové Město nad Metují. The aircraft was engaged in a training flight for instrument flight procedures, conducted under a syllabus approved by a foreign client.
During the flight, which had been underway for approximately one hour, the student pilot performed two 360-degree left turns. Following these maneuvers, while maintaining a heading of approximately 060° at an altitude of 4,500 ft AMSL, the pilot initiated a right turn. After completing approximately 270° of the turn, the helicopter entered an unusual attitude, inverted onto its back with a nose pitch of approximately 20° below the horizon. The aircraft descended rapidly and impacted the ground, followed by an explosion. The impact and subsequent fire caused the total destruction of the aircraft. Both the student pilot and the instructor sustained fatal injuries.
The investigation
The ÚZPLN investigation examined the flight sequence, the technical condition of the Enstrom 480B, and the training system in place. Investigators reviewed cockpit recordings, video footage, and the aircraft's wreckage. The investigation also utilized the Functional Resonance Analysis Method (FRAM) to evaluate the training system's variability. The analysis focused on how subjective evaluations and lack of objective data in the training process contributed to the accident.
Findings
- The primary cause of the accident was the uncontrolled entry into an unusual attitude during a right-hand turn.
- The training system exhibited significant variability, particularly in the selection of instructors and the evaluation of practical tasks.
- Instructor evaluations were often based on subjective impressions rather than objective, measurable flight data.
- There was a lack of standardized criteria for assessing the readiness of students and the suitability of instructors for specific training tasks.
- The training process lacked mechanisms to detect and mitigate variability in student performance and instructor feedback before it escalated into a critical situation.