What happened
On March 11, 2022, at approximately 10:15 UTC, an ultralight helicopter CH 77 Ranabot, registration OK-WHA 83, crashed in a field northwest of Olomouc Airport (LKOL) in the Czech Republic. The flight was part of a planned trip to the Dolní Morava ski area.
Shortly after takeoff, while the aircraft was in its initial climb or transition to level flight, a critical situation developed in the cockpit. The pilot was transporting bulky items, including skis and ski boots, which were improperly secured. During the flight, one of the unsecured skis likely shifted in the cabin. The pilot attempted to manage this moving object, likely releasing the collective control lever to reach for the item. This loss of control, combined with the pilot's improper use of safety harnesses—which allowed his body to shift within the seat—led to an extreme engine-assisted descent. The resulting flight dynamics caused the main rotor blades to flap excessively and strike the tail boom. The impact caused the tail boom, stabilizers, and tail rotor to separate from the fuselage. The aircraft's torso entered an uncontrolled descent, striking the ground with the rotor head first, followed by a post-impact fire that completely destroyed the aircraft. The pilot sustained fatal injuries.
The investigation
The ÚZPLN investigation examined the wreckage, analyzed the mechanical condition of the components, and reviewed witness statements. Investigators found that the aircraft was mechanically sound, with no evidence of technical failure, fatigue, or engine malfunction prior to the crash. The investigation also focused on the cabin configuration, noting that while the aircraft was within its maximum takeoff weight, the cargo—including skis wrapped in sweatshirts—was placed in a manner that violated the flight manual. Furthermore, the investigation established that the pilot's use of the safety harness was improper, as only the lap belts were utilized, leaving the shoulder straps unattached.
Findings
- The primary cause of the accident was pilot distraction while attempting to manipulate an unsecured object in the cabin.
- The pilot's decision to transport bulky, unanchored cargo in the cabin was in direct violation of the aircraft's flight manual.
- Improper use of safety harnesses allowed the pilot's body to move unrestrained, negatively affecting the helicopter's center of gravity.
- The pilot's reaction to the shifting cargo—specifically releasing flight controls—triggered an extreme loss of control and subsequent structural failure due to rotor-to-tail boom contact.
- The pilot had significant experience with larger helicopters (such as the R 44) but had very limited experience with this specific ultralight type.