What happened
On October 18, 2005, an Aerospatiale SA315B Alouette III, registration JA6119, was performing logging operations in Misugi Village, Mie Prefecture. The aircraft, operated by Akagi Helicopter Company Limited, was engaged in transporting logs via a wire-rope sling between a lifting site on Mount Yagashira and a temporary operation site.
During the third round of shuttling, the crew attempted to lift a log from the mountain slope. However, the log had not been completely severed from its root. After several unsuccessful attempts to lift the load—including maneuvers where the crew changed the direction of the log's tilt—the aircraft suddenly tipped forward. The aircraft was effectively restrained by the wire rope attached to the log, which remained anchored to a stump. As the crew attempted to maneuver the aircraft, it plunged toward a valley, striking trees and the ground. Both the pilot-in-command and the fellow pilot sustained serious injuries.
The investigation
The investigation examined the flight sequence, the condition of the aircraft, and the operational procedures used during the logging process. Investigators reviewed statements from both pilots and the ground worker, and inspected the wreckage at the accident site. The investigation also looked into the maintenance of the aircraft and the company's training and skill-checking protocols.
Findings
- The primary cause of the accident was that the aircraft tipped forward and was restrained by the wire rope attached to a log that had not been fully detached from its root.
- The crew's decision to increase the collective pitch after the initial failed lift attempt exacerbated the forward-tipped attitude, leading to the crash.
- The forestry company failed to ensure that logs were completely severed from their roots prior to the commencement of lifting operations.
- The company's practice of having a highly experienced pilot act as a 'checker' for a subordinate's skills during active operations created a situation where the pilot-in-command could not effectively exercise their professional duties.