What happened
On 9 May 2012, a Sukhoi RRJ-95B aircraft crashed into the steep terrain of Mount Salak in West Java, Indonesia. The aircraft was conducting a demonstration flight when it drifted from its intended orbit and struck an 85-degree slope ridge at approximately 6,000 feet. The impact resulted in all fatalities on board.
During the final phase of the flight, the aircraft's Terrain and Traffic Collision Avoidance System (T2CAS) issued multiple "Avoid Terrain" and "Terrain – Pull up" warnings. However, the flight crew did not execute an appropriate escape maneuver. The aircraft's descent into the terrain was compounded by the fact that the crew was engaged in prolonged, non-flight-related communication, which distracted the pilot flying from maintaining the necessary heading during the orbital maneuver.
The investigation
The investigation conducted by the KNKT examined the aircraft's flight recorders, the cockpit voice recorder, and the operational environment of the Jakarta Approach control. Investigators analyzed the functionality of the T2CAS and the Minimum Safe Altitude Warning (MSAW) systems.
Technical simulations revealed that the T2CAS was fully operational and that the pilot could have successfully avoided the terrain if an appropriate reaction had been taken up to 24 seconds after the initial warning. The investigation also looked into the air traffic control environment, noting that the Jakarta Radar service had not established minimum vectoring altitudes for the specific area and that the terrain data for Mount Salak had not been integrated into the radar system, preventing the controller from receiving an MSAW alert.
Findings
- The flight crew was unaware of the mountainous terrain in the flight path due to inadequate briefing, insufficient charts, and misleading information regarding the flight's nature.
- The pilot inhibited the T2CAS system, mistakenly believing the terrain warnings were caused by a database error.
- The crew's attention was diverted by intensive, non-essential conversation, leading to an unintentional exit from the intended orbit.
- The Jakarta Radar service lacked established minimum vectoring altitudes for the area and the MSAW system was not functional for the Mount Salamin vicinity because terrain data was missing.
- The air traffic controller's radar warning system was deactivated.
Safety action
Following the accident, several safety measures were implemented:
- The Indonesia Directorate General of Civil Aviation audited the air traffic services at Halim Perdanakusuma Airport and evaluated minimum vectoring altitude charts.
- The air traffic service provider, PT. Angkasa Pura II, inserted Mount Salak terrain data into the Jakarta Radar System and implemented new Standard Instrument Departure (SID) and arrival procedures.
- The aircraft manufacturer, Sukhoi Civil Aircraft Company, initiated refresher training for test pilots, specifically focusing on responding to T2CAS warnings and managing flight in mountainous regions.