What happened
On 29 September 2011, a CASA 212-200 aircraft, registration PK-TLF, was operating a non-scheduled passenger flight from Medan to Kuta Cane in South East Aceh. The flight, operated by Nusantara Buana Air, was being conducted under Visual Flight Rules (VFR) with 18 people on board, including two pilots, 16 passengers, two children, and two infants.
During the flight, the crew encountered heavy cloud cover. Despite the weather conditions not meeting VFR requirements, the flight crew decided to proceed through the clouds. The aircraft subsequently struck a 70-degree slope at an altitude of 5,055 feet within the Leuser Mountain National Park. The impact was severe, resulting in 18 fatalities and the total destruction of the aircraft.
The investigation
The investigation conducted by the NTSC focused on the flight's trajectory, weather conditions, and cockpit dynamics. Analysis of the Cockpit Voice Recorder (CVR) revealed that the pilots discussed the presence of high clouds and explicitly agreed to fly into the cloud cover because they could not find a gap to pass through.
Investigators also examined the cockpit environment, noting a lack of crew briefings or checklist usage during the flight. The investigation further looked into the training records of the crew, specifically regarding specialized maneuvers for mountainous terrain.
Findings
- The primary cause of the accident was a Controlled Flight Into Terrain (CFIT), triggered by the crew's decision to fly into clouds, which led to a loss of visual ground references.
- The flight crew experienced a loss of situational awareness due to the low visibility encountered while inside the cloud layer.
- There was a lack of effective crew coordination, characterized by a steep cockpit transition gradient where the pilot in command dominated the conversation, leaving the second in command hesitant to offer suggestions.
- The investigation found no evidence of aircraft mechanical failure or system malfunction prior to the impact.
- The crew had not received specific training in Approach and Landing Accident Reduction (ALAR) or CFIT prevention.
Safety action
The NTSC issued recommendations to the Directorate General of Civil Aviation (DGCA) to ensure the implementation of CFIT and ALAR training and to improve the oversight of operators through enhanced inspector surveillance.