Incident Overview
On 4 March 2024, a Z-37A Čmelák agricultural aircraft (registration OK-KJB) experienced a serious incident during an aerial chemical application flight near the village of Prasek in the Hradec Králové district. The pilot, conducting the first work flight of the day, jettisoned the aircraft's spreader after perceiving an abnormal sound from beneath the aircraft. The jettisoned spreader fell and damaged overhead high-voltage electrical wires. The aircraft landed safely at the departure airstrip and sustained no damage; no injuries were reported.
Aircraft and Operator
The aircraft was a Z-37A manufactured by LET, n. p. Kunovice, with serial number 802328. The operator is a legal entity. The pilot had performed similar operations in the same area on 1 March 2024, logging 14 flights totaling 2 hours 40 minutes. On the day of the incident, the pilot completed a pre-flight preparation at Chrudim Airport and then flew to the agricultural airstrip Králíky/Kobylice between 09:08 and 09:33 UTC. No malfunctions were noted during preparation or the transit flight.
Sequence of Events
After landing at Kobylice, the pilot inspected the area to be treated and then loaded 500 kg of application material between 09:35 and 09:45 UTC. The work flight began at 09:45 UTC with a takeoff from runway 27. According to the pilot’s testimony, after a left turn and climb, he aligned with the first work pass and descended to an altitude of approximately 15–20 meters above the terrain. Upon activating the spreader, he heard unusual metallic sounds from beneath the aircraft. He deactivated the spreader, initiated a climb, and broke off the pass with a right turn away from the built-up area of Prasek, heading back to Kobylice. During the turn, the persistent loud metal sounds prompted him to perform an emergency jettison of the spreader. He later stated that he did not consider the risk of the spreader striking power lines at the time of jettison. After jettison, he returned to the airstrip and landed on runway 09.
Damage
No damage occurred to the aircraft. The jettisoned spreader was damaged upon impact with the ground. Additionally, the spreader struck and damaged high-voltage electrical wires during its fall. No other property damage was reported.
Post-Incident Actions
After landing, the pilot and a mechanic inspected the aircraft, found no damage, and then drove to retrieve the spreader. The incident was reported to the Czech Accident Investigation Institute (ÚZPLN) on 5 March 2024. The investigation was conducted by a commission led by Ing. Josef Procházka.
Probable Cause
The investigation did not explicitly state a probable cause in the provided source material.