Flight Details
On 19 December 1997, a SilkAir Boeing 737-300 aircraft, registration 9V-TRF, operated as a scheduled commercial international passenger flight under Instrument Flight Rules (IFR). The flight route was Singapore – Jakarta – Singapore. The initial leg from Singapore to Jakarta proceeded normally. After a routine turnaround at Jakarta's Soekarno-Hatta International Airport, the aircraft departed for the return flight to Singapore. The flight, designated MI185, took off from Runway 25R at 08:37:13 local time (15:37:13 UTC), with the Captain as the handling pilot. Clearance was given to climb to 35,000 feet (Flight Level 350) and to head directly to Palembang.
Accident Sequence
At 08:47:23, the aircraft passed Flight Level 245. Ten seconds later, the crew requested permission to proceed directly to PARDI2. The air traffic controller instructed MI 185 to stand by and continue flying directly to Palembang, reporting when reaching FL350. At 08:53:17, the flight reported reaching FL350. The controller then cleared the flight to proceed directly to PARDI and to report when abeam Palembang.
At 09:05:15.6, the cockpit voice recorder (CVR) ceased recording. According to the Jakarta ATC transcript, at 09:10:18 the controller informed MI 185 that it was abeam Palembang and instructed the aircraft to maintain FL350 and contact Singapore Control when at PARDI. The crew acknowledged at 09:10:26. No further voice transmissions from MI 185 were received. The last readable data from the flight data recorder (FDR) was recorded at 09:11:27.4. Jakarta ATC radar showed MI185 still at FL350 at 09:12:09. Eight seconds later, the radar indicated the aircraft was 400 feet below FL350 and entering a rapid descent. The final radar return at 09:12:41 showed the aircraft at FL195. The empennage subsequently separated in flight, and the aircraft crashed into the Musi river delta, approximately 50 km (30 nm) north-northeast of Palembang, at about 09:13. The accident occurred in daylight with good weather conditions. All 104 occupants were killed, and the accident was not survivable.
Investigation and Probable Cause
The National Transportation Safety Committee (NTSC) conducted an extensive and complex investigation. The investigation was hampered by the severe fragmentation of the wreckage, difficulties at the accident site, and the lack of information from the flight recorders during the final moments. Despite a thorough examination of all available data, the NTSC was unable to determine the reasons for the aircraft's departure from its cruising altitude of FL350 or the stoppage of the flight recorders. The NTSC concluded that the technical investigation yielded no evidence to explain the cause of the accident.