SilkAir Flight 185 was a scheduled international passenger flight operated by a Boeing 737-300 from Soekarno–Hatta International Airport in Jakarta, Indonesia to Changi Airport in Singapore that crashed into the Musi River near Palembang, Sumatra, on 19 December 1997, killing all 97 passengers and 7 crew members on board.
The investigation into the cause of the crash was led by investigators from the National Transportation Safety Committee (NTSC), who were joined by the National Transportation Safety Board (NTSB). The NTSB, which participated in the investigation due to Boeing's manufacture of the aircraft in the US, investigated the crash under lead investigator Greg Feith.
In its final report, the NTSC found "no concrete evidence" to support the pilot suicide allegation, with the previously suspected Parker-Hannifin hydraulic power control unit (PCU) having already been determined by the manufacturer to be defect-free. The final statement from the NTSC was that they were unable to determine the cause of the crash and was thus inconclusive. On the other hand, in a letter sent to the NTSC, the NTSB found that the crash was most likely the result of deliberate flight-control inputs that were "most likely by the captain".
Background
Aircraft
The aircraft involved was a Boeing 737-36N with serial number 28556, registered as 9V-TRF, and powered by two CFM56-3B2 engines. Having completed its maiden flight on 27 January 1997, the aircraft was delivered to SilkAir on 14 February, 10 months before the crash. At the time of the accident, it was the newest aircraft in SilkAir's fleet and had accumulated more than 2,200 flight hours in 1,300 cycles. This was the first and only fatal hull loss for SilkAir in the airline's history.
{|class="wikitable sortable"
|+ Victims' nationalities
|-
! Nationality
! Passengers
! Crew
! Total
|-
| Singapore || style="text-align:center;" |40 ||style="text-align:center;" | 6 || style="text-align:center;" |46
|-
| Indonesia || style="text-align:center;" |23 || ||style="text-align:center;" | 23
|-
| Malaysia || style="text-align:center;" |10 || ||style="text-align:center;" | 10
|-
| United States || style="text-align:center;" | 5 || ||style="text-align:center;" | 5
|-
| France || style="text-align:center;" | 5 || || style="text-align:center;" |5
|-
| Germany || style="text-align:center;" | 4 || || style="text-align:center;" | 4
|-
| United Kingdom || style="text-align:center;" | 3 || || style="text-align:center;" | 3
|-
| Japan || style="text-align:center;" | 2 || || style="text-align:center;" | 2
|-
| Bosnia and Herzegovina|| style="text-align:center;" | 1 || || style="text-align:center;" | 1
|-
| Austria || style="text-align:center;" |1 || || style="text-align:center;" | 1
|-
| India || style="text-align:center;" | 1 || || style="text-align:center;" | 1
|-
| Taiwan || style="text-align:center;" | 1 || || style="text-align:center;" |1
|-
| Australia || style="text-align:center;" | 1 || || style="text-align:center;" | 1
|-
| New Zealand || || style="text-align:center;" |1 || style="text-align:center;" | 1
|-
! Total
! 97
! 7
! 104
|}
Among those killed in the crash was Singaporean model and author Bonny Hicks.
Flight
Carrying 97 passengers and a crew of seven, the Boeing 737 departed Jakarta's Soekarno–Hatta International Airport's runway 25R at 15:37 local time (08:37 UTC) for an 80-minute flight to Singapore's Changi Airport. At the controls were Captain Tsu Way Ming (41) of Singapore, a former A-4 Skyhawk pilot, and First Officer Duncan Ward (23) of New Zealand. Generally fair weather was expected for the route, except for some thunderstorms near Singkep Island, south of Singapore. At 15:53, the crew reported reaching the cruise altitude of FL350 and was cleared to proceed directly to PARDI, and to report abeam Palembang. The cockpit voice recorder (CVR) ceased recording at 16:05. At 16:10, air traffic controllers informed the flight that it was abeam Palembang and instructed the aircraft to maintain FL350 and to contact Singapore Control upon reaching PARDI. First Officer Ward acknowledged this call. At 16:11, nearly 6 minutes after the CVR ceased recording, the flight data recorder (FDR) also stopped recording.
Flight 185 remained level at FL350 until it started a rapid and nearly vertical dive around 16:12. While descending through , parts of the aircraft, including a great extent of the tail section, started to separate from the aircraft's fuselage due to high forces arising from the nearly supersonic dive. Furthermore, the investigators had found the trim jackscrew for the horizontal stabilizer, which revealed that flight inputs from one of the pilots had moved the stabilizer from level flight to a full nose-down descent.
The American NTSB, which also participated in the investigation, concluded that the evidence was consistent with a deliberate manipulation of the flight controls, most likely by the captain.
In a letter to the NTSC dated 11 December 2000, the NTSB wrote: