What happened
On 11 September 2022, a Eurocopter EC120B helicopter, registration N409HH, departed from Sultan Abdul Aziz Shah Airport for a scheduled flight to Ipoh. While transiting near Bidor, Perak, the aircraft disappeared from radar contact. Air traffic control recorded a sudden, extreme descent of approximately 6,000 feet per minute just prior to the loss of signal.
Search and rescue operations were hampered by deteriorating weather and darkness, leading to the discovery of the wreckage in a forest reserve the following morning. The pilot, the sole occupant of the aircraft, sustained fatal injuries and was pronounced dead at the scene.
The investigation
Investigators from AAIB Malaysia examined the wreckage and analyzed radar and meteorological data. The investigation focused on the aircraft's flight path through a region under a thunderstorm warning. Technical experts from Airbus Helicopters and Safran also performed on-site examinations of the airframe and engine.
While the engine was found to be running during the initial stages of the accident sequence, the impact with the forest canopy caused significant structural damage. The investigation looked into the aircraft's instrumentation, specifically noting that the avionics push button had not been properly activated, which caused the de-energizing of the attitude indicator (artificial horizon).
Findings
Several critical factors contributed to the accident:
- Severe weather conditions: The aircraft encountered a thunderstorm cell and heavy rain, which significantly reduced visibility.
- Loss of instrument reference: Because the avionics button was not activated, the pilot lost access to the artificial horizon, making flight in instrument meteorological conditions (IMC) extremely difficult.
- Pilot proficiency: The pilot was found to be insufficiently experienced in managing the aircraft during adverse weather and was not fully proficient with certain cockpit switch operations.
- Loss of control: The combination of poor visibility and the lack of a functioning attitude indicator led to unintended flight in IMC, resulting in a loss of control and a high-speed descent into the trees.