What happened
On September 29, 2011, a CASA 212-200 operated by Nusantara Buana Air was performing a non-scheduled passenger flight from Polonia International Airport in Medan to the Alas Leuser Airstrip in Kuta Cane. The aircraft, registered PK-TLF, departed at 07:28 local time under Visual Flight Rules (VFR). The flight was carrying a total of 18 occupants, comprising two pilots and 16 passengers, which included two infants and two children.
At approximately 00:50 UTC, radar tracking last identified the aircraft at a position 35 nautical miles from the MDN VOR on radial 262 degrees. Following this period, the aircraft struck a terrain slope of 70 degrees at an altitude of 5,055 feet within the Leuser Mountain National Park. The impact occurred at coordinates N 030 24’ 00” E 0980 01’ 00”, roughly 16 nautical miles from Kuta Cane. The crash resulted in 18 fatalities and caused severe damage to the airframe.
Findings
Investigations into the accident identified several critical errors by the flight crew. Although the flight was conducted under VFR, both pilots decided to proceed into cloud cover. This decision led to a significant loss of situational awareness as the crew lost visual contact with the ground. Due to the low visibility, there was no effective recovery action taken before the aircraft struck the terrain.
Additionally, the investigation noted a lack of effective crew coordination, attributed to a steep cockpit transition gradient. The findings also highlighted that the crew failed to perform necessary briefings or utilize checklists during the flight.