What happened
On March 4, 2024, at approximately 09:50 UTC, a Z-37A aircraft, registration OK-KJB, was performing aerial application of agricultural chemicals near the village of Prasek in the Hradec Králové district. After taking off from Chrudim and flying to the work area, the pilot began the first application pass at an altitude of approximately 15–20 meters.
During the application process, the pilot heard loud, unusual metallic noises coming from the underside of the aircraft near the spreader. Following the onset of these noises, the pilot deactivated the application equipment and decided to perform an emergency jettison of the spreader. During the descent of the discarded equipment, the spreader struck and severed two of the three high-voltage conductors on nearby power lines. The pilot was able to return to the Kobylice landing area without injury or damage to the aircraft.
The investigation
The ÚZPLN investigation examined the pilot's flight logs, the aircraft's maintenance records, the operator's Standard Operating Procedures (SOPs), and the wreckage of the spreader. The investigation noted that the pilot had performed a reconnaissance of the area via a single flyover and map review prior to the mission. Investigators also examined the operator's history, noting that the operator had reported three similar incidents involving damage to overhead power lines within a nine-month period.
Findings
- The primary cause of the incident was likely a technical malfunction of the application equipment, which prompted the pilot's decision to jettison the spreader.
- The pilot's reconnaissance of the application area was insufficient and did not comply with the operator's SOPs.
- The operator's SOPs lacked specific procedures for the ground inspection of application areas and did not include protocols for the pre-flight testing or operation of the application equipment.
- The pilot did not perform a functional check of the spreader during pre-flight preparations.
Safety action
- The operator should familiarize all flight personnel with this final report.
- The operator should update its SOPs to include mandatory ground reconnaissance of application areas and specific procedures for the operation and inspection of application equipment.
- The Civil Aviation Authority (ÚCL) should verify during audits that all aerial application operators include necessary procedures for approved operations within their SOPs.