What happened
On 21 July 2012, at approximately 07:30 KST, an AS350B-2 helicopter, registration HL9196, crashed in Pyeongchon-ri, Guji-myeon, Dalseong-gun, Daegu-si, during an aerial application mission. The aircraft, operated by SN Air Co., Ltd., was performing agricultural spraying over local farmlands under visual flight rules. During its sixth application flight of the day, the aircraft struck a 154,000V high-voltage power line spanning a rice field. The impact severed the lines and caused the helicopter to crash upside down onto the roof of a nearby feed factory. The collision resulted in one fatality, involving the pilot in command, and the total destruction of the aircraft. The impact also caused damage to the factory roof and led to a fuel leak that contaminated stored products.
The investigation
The ARAIB investigation examined the flight history, aircraft maintenance records, and the pilot's training background. The investigation established that the aircraft was airworthy and within weight and balance limits at the time of the accident. Investigators also reviewed the meteorological conditions, which were well within visual meteorological conditions and not a contributing factor. The probe focused heavily on the pilot's recent experience in aerial application and the adequacy of the operator's training programs. Evidence showed that while the pilot was highly experienced in general flight, he had only accumulated 18.2 total hours of specific aerial application training and very few solo application hours prior to the event.
Findings
Investigators determined that the primary cause of the accident was that the pilot, while likely aware of the power lines, momentarily forgot their location due to the high cognitive workload required to manage multiple simultaneous tasks—such as monitoring spray controls, altitude, and obstacles—inside a sweltering cockpit. This lapse was exacerbated by the pilot's relative inexperience in specialized aerial spraying operations.
Contributing factors included systemic failures in the operator's training management. The investigation found that SN Air Co., Ltd. provided inadequate training regarding aircraft type transitions and aerial application techniques. Furthermore, the company's management of pilot qualifications was found to be deficient, as the pilot had received initial training from an unqualified instructor, and the company's internal regulations lacked sufficient standards for verifying instructor competency and evaluating training curricula.