What happened
On June 21, 2009, at approximately 11:06 UTC, a tandem parachute jump ended in a fatal accident near the Chrást village, close to the LKMB airfield. The pilot and a passenger exited an AN-2 aircraft at an altitude of 3,000 meters. After a stable belly-to-earth freefall, the pilot initiated the deployment of the main Dual Hawk Strong Enterprises, HOP 3..' parachute.
During the deployment, the main parachute failed to inflate symmetrically, causing the tandem pair to enter a rapid rotation. The pilot attempted to jettison the malfunctioning main parachute; however, while the right lines separated correctly, the left lines remained trapped within the deployment bag due to a mechanical obstruction. As the rotation intensified, the pilot attempted to deploy the reserve parachute. Due to the high rotation and low descent rate, the reserve parachute failed to fully inflate and became entangled with the lines of the malfunctioning main parachute. The tandem pair struck the ground in a field near residential buildings, resulting in two fatalities.
The investigation
The ÚZPLN investigation examined the parachute equipment, the pilot's qualifications, and the maintenance history of the gear. Investigators reviewed video footage from a camera mounted on the pilot's arm and analyzed the physical state of the Dual Hawk system. The investigation focused on why the main parachute deployment was obstructed and why the reserve parachute failed to function as intended.
Findings
- The primary cause was a mechanical failure of the deployment system, specifically an improper attachment of the flexible hose end. This allowed the end to slip out of its housing and become caught in a line closure eye, which blocked the full opening of the deployment bag flaps.
- The main parachute's asymmetric inflation caused the rotation that prevented the reserve parachute from deploying effectively.
- The pilot was performing jumps on a Dual Hawk Strong Enterprises system without the required specific type rating, although he had completed training with the operator.
- The operator had failed to perform mandatory maintenance required by Service Bulletin #22 regarding the service life and inspection of the harness components.
- The pilot did not identify the visible displacement of the flexible hose prior to the jump, which was a defect that could have been detected during pre-jump inspections.