What happened
On 17 July 2014, an AS365N3 helicopter, registration HL9461, crashed near Gwangju-si while performing a climb under instrument flight rules (IFR). The aircraft, owned by the Gangwon Fire Headquarters, was returning to its base from Gwangju Airport after participating in search operations for victims of the Sewol ferry disaster.
During the climb and straight flight phase, the aircraft entered an uncontrollable right roll and rapid descent. The impact and subsequent fire destroyed the aircraft. There were five fatalities among the crew and passengers, including the captain, the first officer, an aircraft mechanic, and two rescue workers.
The investigation
The ARAIB examined flight data, cockpit voice recordings, and maintenance records to reconstruct the flight profile. The investigation focused on the flight crew's actions during the transition to instrument flight and the management of pilot qualifications within the Air Rescue Corps. Investigators analyzed the meteorological conditions, the aircraft's automated flight control systems, and the communication between the crew members during the critical phases of the climb.
Findings
Investigators determined that the primary cause of the accident was that the flight crew applied the right pedal for unknown reasons during the climb, which triggered an irreversible right roll and rapid descent. This was compounded by the fact that the crew failed to monitor flight instruments closely enough to detect and correct the changing aircraft attitude before it became critical.
Several contributing factors were identified, including:
- The flight crew had proceeded with instrument flight despite being disqualified due to insufficient required training hours.
- The Air Rescue Corps failed to properly manage pilot training and qualification records.
- The crew demonstrated insufficient experience in instrument flight, poor pre-flight briefing, and inadequate coordination.
- The captain was operating under significant stress due to poor radio reception and a high workload during the initial phase of the instrument takeoff.
- There was a lack of effective oversight and command authority within the Air Rescue Corps regarding aviation safety advice.