SilkAir Flight 185
Encyclopedia
SilkAir
Flight 185, a Boeing 737-36N
, registration 9V-TRF, was a scheduled passenger flight from Jakarta
, Indonesia
to Singapore
, which crashed on 19 December 1997 into the Musi River
after abruptly plunging from its 35,000-foot (10,668-m) cruise altitude, killing all 97 passengers and 7 crew on board.
The cockpit voice recorder
and flight data recorder
stopped recording, at different times and for no apparent reason, minutes before the aircraft departed level flight and entered a steep vertical dive.
The crash was investigated by various groups, with different results. The Indonesian National Transportation Safety Committee
(NTSC), who were lead investigators, were unable to determine the cause, while the U.S. National Transportation Safety Board
(NTSB) concluded that the crash resulted from an intentional act by a pilot, most likely the captain
.
Carrying 97 passengers and a crew of seven, the Boeing departed Jakarta's Soekarno-Hatta International Airport
's runway 25R at 15:37 local time (08:37 UTC) for a planned 80 minute flight to Singapore Changi Airport
, with the captain at the controls. Generally fair weather was expected for the route, except for some thunderstorms near Singkep Island
, 120 km south of Singapore.
The jetliner was cleared to climb to flight level
350 (approximately 35,000 feet/10,668 m) above mean sea level), and to head directly to Palembang. At 15:47 the aircraft climbed through FL245 (24,500 feet/7,468 m). The crew then requested a clearance to proceed directly to PARDI. At 15:53 the crew reported reaching its cruise altitude of FL350 (35,000 feet/10,668 m) and was cleared to proceed directly to PARDI, and to report abeam Palembang. At 16:05 the CVR ceased recording. At 16:10 the controller informed the flight that it was abeam Palembang. The controller instructed the aircraft to maintain FL350 (35,000 feet/10,668 m) and to contact Singapore Control upon reaching PARDI. The crew acknowledged this call. At 16:11:27 the FDR ceased recording.
, near Palembang
, Sumatra
.
All 104 people on board, including the 41-year-old Singapore
an captain, Tsu Way Ming and the 23-year-old co-pilot, New Zealand
er Duncan Ward, died in the crash.
The aircraft broke into pieces before impact, with the debris spread over several kilometres, though most of the wreckage was concentrated in a single 60 metres (196.9 ft) by 80 metres (262.5 ft) area at the river bottom. There was not a complete body, body part or limb found, as the entire aircraft and passengers disintegrated upon impact. Only six positive identifications were later obtained from the few recovered human remains.
Among those killed in the crash was Singaporean model and author Bonny Hicks
.
(NTSC), which was assisted by expert groups from the U.S., Singapore and Australia.
Approximately 73% of the wreckage (by weight) was recovered, partially reconstructed and examined. Both "black boxes" — the Cockpit voice recorder
(CVR) and Flight data recorder
(FDR) — were successfully retrieved from the wreckage, and their data was extracted and analyzed.
On 14 December 2000, after three years of intensive investigation, the Indonesian NTSC issued its final report, in which it concluded that the evidence was inconclusive and that the cause of the accident cannot be determined:
The U.S. National Transportation Safety Board
(NTSB), which also participated in the investigation, disagreed with the NTSC and concluded that the evidence was consistent with a deliberate manipulation of the flight controls, most likely by the captain, which put the aircraft into a vertical dive and caused it to crash. In a letter to the NTSC dated 11 December 2000 the NTSB wrote:
In 2004, a Los Angeles
Superior Court jury
in the United States, which was not allowed to hear or consider the NTSB's conclusions about the accident, decided that the crash was caused by a defective servo
valve in the plane's rudder
resulting in a rudder hard-over. The rudder manufacturer, Parker Hannifin
, was ordered to pay the three families of victims involved in that case US$44 million. The company appealed the verdict, and the case was later settled out of court for an undisclosed amount.
(NTSB) and Flight International
criticized the National Transportation Safety Committee
(NTSC). Flight International called the NTSC report an "evasive and worthless report[...]" and the NTSB posted a lengthy critique of the NTSC report. The U.S. NTSB conducted extensive testing using simulators and computer modeling, which contradicted the Indonesian authority. There was unprecedented criticism from NTSB investigators, who were adamant the only way to achieve the flight profile that occurred immediately prior to impact, was "with sustained nose-down manual flight control input".
An official investigation by the Singapore Police Force
into evidence of criminal offence leading to the crash found "no evidence that the pilot, co-pilot or any crew member had suicidal tendencies or a motive to deliberately cause the crash of [the aircraft]."
Tsu was formerly a Republic of Singapore Air Force
pilot and had over twenty years of flying experience in the older T/A-4S Skyhawks as well as the newer T/A-4SU Super Skyhawks. His last appointment was instructor pilot of a Skyhawk squadron. Due to his flying experience, it was considered highly unlikely that the aircraft lost control or fell into a stall or spin, as he would have had the experience to avoid or overcome such conditions. The U.S. NTSB investigators found no mechanical malfunctions, and they concluded the accident could only be explained by intentional pilot action.
Tsu's announcement ended at 15:46. At 16:05, 19 minutes later, the CVR stopped recording. Six minutes later, at 16:11, the FDR stopped recording, and at 16:12 the aircraft plunged into its fatal dive.
and flight data recorder
stopped recording minutes before the abrupt descent, but not at the same time. A technical analysis of the sound signature of a CVR circuit breaker trip, as recorded by the CVR, was carried out by investigators and the evidence showed that the CVR stoppage was consistent with being manually initiated. The radio continued to work after the failure of the recorders, which indicates that power failure was not a cause.
and US Air Flight 427.
SilkAir
SilkAir Private Limited is an airline based in Singapore. It is a wholly owned subsidiary of Singapore Airlines and operates scheduled passenger services from Singapore to 31 cities in Southeast Asia, South Asia and China. It has its head office on the fifth storey of SIA Superhub 1...
Flight 185, a Boeing 737-36N
Boeing 737 Classic
The Boeing 737 Classic is the name given to the -300/-400/-500 series of the Boeing 737 following the introduction of the -600/-700/-800/-900 series. They are short- to medium- range, narrow-body jet airliners produced by Boeing Commercial Airplanes. The Classic series was introduced as the 'new...
, registration 9V-TRF, was a scheduled passenger flight from Jakarta
Jakarta
Jakarta is the capital and largest city of Indonesia. Officially known as the Special Capital Territory of Jakarta, it is located on the northwest coast of Java, has an area of , and a population of 9,580,000. Jakarta is the country's economic, cultural and political centre...
, Indonesia
Indonesia
Indonesia , officially the Republic of Indonesia , is a country in Southeast Asia and Oceania. Indonesia is an archipelago comprising approximately 13,000 islands. It has 33 provinces with over 238 million people, and is the world's fourth most populous country. Indonesia is a republic, with an...
to Singapore
Singapore
Singapore , officially the Republic of Singapore, is a Southeast Asian city-state off the southern tip of the Malay Peninsula, north of the equator. An island country made up of 63 islands, it is separated from Malaysia by the Straits of Johor to its north and from Indonesia's Riau Islands by the...
, which crashed on 19 December 1997 into the Musi River
Musi River (Indonesia)
The Musi River is located in southern Sumatra, Indonesia.It is about 750 kilometers long, and drains most of South Sumatra province. After flowing through Palembang, the provincial capital, it joins with the several other rivers, including the Banyuasin River, to form a delta near the city of...
after abruptly plunging from its 35,000-foot (10,668-m) cruise altitude, killing all 97 passengers and 7 crew on board.
The cockpit voice recorder
Cockpit voice recorder
A cockpit voice recorder , often referred to as a "black box", is a flight recorder used to record the audio environment in the flight deck of an aircraft for the purpose of investigation of accidents and incidents...
and flight data recorder
Flight data recorder
A flight data recorder is an electronic device employed to record any instructions sent to any electronic systems on an aircraft. It is a device used to record specific aircraft performance parameters...
stopped recording, at different times and for no apparent reason, minutes before the aircraft departed level flight and entered a steep vertical dive.
The crash was investigated by various groups, with different results. The Indonesian National Transportation Safety Committee
National Transportation Safety Committee
The National Transportation Safety Committee is an Indonesian government agency charged with the investigation of air, land, rail, and marine transportation safety deficiencies. It has its headquarters in Jakarta....
(NTSC), who were lead investigators, were unable to determine the cause, while the U.S. National Transportation Safety Board
National Transportation Safety Board
The National Transportation Safety Board is an independent U.S. government investigative agency responsible for civil transportation accident investigation. In this role, the NTSB investigates and reports on aviation accidents and incidents, certain types of highway crashes, ship and marine...
(NTSB) concluded that the crash resulted from an intentional act by a pilot, most likely the captain
Pilot in command
The pilot in command of an aircraft is the person aboard the aircraft who is ultimately responsible for its operation and safety during flight. This would be the "captain" in a typical two- or three-pilot flight crew, or "pilot" if there is only one certified and qualified pilot at the controls of...
.
Flight history
The Boeing 737-300 operating as Flight MI 185 was the newest in SilkAir's fleet, delivered to the airline on 14 February 1997, ten months prior to the crash.Carrying 97 passengers and a crew of seven, the Boeing departed Jakarta's Soekarno-Hatta International Airport
Soekarno-Hatta International Airport
Soekarno–Hatta International Airport , popularly abbreviated SHIA or Soetta is the main airport serving the greater Jakarta area on the island of Java, Indonesia. The airport is named after the first President of Indonesia, Soekarno, and the first vice-president, Mohammad Hatta. The airport is...
's runway 25R at 15:37 local time (08:37 UTC) for a planned 80 minute flight to Singapore Changi Airport
Singapore Changi Airport
Singapore Changi Airport , Changi International Airport, or simply Changi Airport, is the main airport in Singapore. A major aviation hub in Southeast Asia, it is about north-east from the commercial centre in Changi, on a site....
, with the captain at the controls. Generally fair weather was expected for the route, except for some thunderstorms near Singkep Island
Singkep
Singkep is an island in the Lingga Archipelago in Indonesia. Its area is . It is separated from the east coast of Sumatra by the Berhala Strait. It is surrounded by islands P. Posik to the west, P. Serak to the SW, P. Lalang to the South, and P. Selayar of Riau Islands between Lingga and...
, 120 km south of Singapore.
The jetliner was cleared to climb to flight level
Flight level
A Flight Level is a standard nominal altitude of an aircraft, in hundreds of feet. This altitude is calculated from the International standard pressure datum of 1013.25 hPa , the average sea-level pressure, and therefore is not necessarily the same as the aircraft's true altitude either...
350 (approximately 35,000 feet/10,668 m) above mean sea level), and to head directly to Palembang. At 15:47 the aircraft climbed through FL245 (24,500 feet/7,468 m). The crew then requested a clearance to proceed directly to PARDI. At 15:53 the crew reported reaching its cruise altitude of FL350 (35,000 feet/10,668 m) and was cleared to proceed directly to PARDI, and to report abeam Palembang. At 16:05 the CVR ceased recording. At 16:10 the controller informed the flight that it was abeam Palembang. The controller instructed the aircraft to maintain FL350 (35,000 feet/10,668 m) and to contact Singapore Control upon reaching PARDI. The crew acknowledged this call. At 16:11:27 the FDR ceased recording.
Crash
Flight 185 remained level at FL350 (35,000 feet/10,668 m) until it started a rapid and nearly vertical dive, as shown on Jakarta radar, around 16:12:18. The aircraft broke up in flight, crashing into the Musi RiverMusi River (Indonesia)
The Musi River is located in southern Sumatra, Indonesia.It is about 750 kilometers long, and drains most of South Sumatra province. After flowing through Palembang, the provincial capital, it joins with the several other rivers, including the Banyuasin River, to form a delta near the city of...
, near Palembang
Palembang
Palembang is the capital city of the South Sumatra province in Indonesia. Palembang is one of the oldest cities in Indonesia, and has a history of being a capital of a maritime empire. Located on the Musi River banks on the east coast of southern Sumatra island, it has an area of 400.61 square...
, Sumatra
Sumatra
Sumatra is an island in western Indonesia, westernmost of the Sunda Islands. It is the largest island entirely in Indonesia , and the sixth largest island in the world at 473,481 km2 with a population of 50,365,538...
.
All 104 people on board, including the 41-year-old Singapore
Singapore
Singapore , officially the Republic of Singapore, is a Southeast Asian city-state off the southern tip of the Malay Peninsula, north of the equator. An island country made up of 63 islands, it is separated from Malaysia by the Straits of Johor to its north and from Indonesia's Riau Islands by the...
an captain, Tsu Way Ming and the 23-year-old co-pilot, New Zealand
New Zealand
New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...
er Duncan Ward, died in the crash.
The aircraft broke into pieces before impact, with the debris spread over several kilometres, though most of the wreckage was concentrated in a single 60 metres (196.9 ft) by 80 metres (262.5 ft) area at the river bottom. There was not a complete body, body part or limb found, as the entire aircraft and passengers disintegrated upon impact. Only six positive identifications were later obtained from the few recovered human remains.
Among those killed in the crash was Singaporean model and author Bonny Hicks
Bonny Hicks
Bonny Hicks was a Singapore Eurasian model who gained her greatest notoriety for her contributions to Singaporean post-colonial literature and the anthropic philosophy conveyed in her works. Her first book, Excuse Me, are you a Model?, is recognized as a significant milestone in the literary and...
.
Victims
Silk Air issued a press release on December 19, 1997 with a passenger count by nationality, and another the following day with crew details and a complete passenger manifest.| Nationality | Passengers | Crew | Total |
|---|---|---|---|
| 40 | 6 | 46 | |
| 23 | 0 | 23 | |
| 10 | 0 | 10 | |
| 5 | 0 | 5 | |
| 5 | 0 | 5 | |
| 4 | 0 | 4 | |
| 3 | 0 | 3 | |
| 2 | 0 | 2 | |
| 1 | 0 | 1 | |
| 1 | 0 | 1 | |
| 1 | 0 | 1 | |
| (Taiwan Taiwan Taiwan , also known, especially in the past, as Formosa , is the largest island of the same-named island group of East Asia in the western Pacific Ocean and located off the southeastern coast of mainland China. The island forms over 99% of the current territory of the Republic of China following... ) |
1 | 0 | 1 |
| 1 | 0 | 1 | |
| 0 | 1 | 1 | |
| Total | 97 | 7 | 104 |
Investigation and final report
The accident was investigated by the Indonesian National Transportation Safety CommitteeNational Transportation Safety Committee
The National Transportation Safety Committee is an Indonesian government agency charged with the investigation of air, land, rail, and marine transportation safety deficiencies. It has its headquarters in Jakarta....
(NTSC), which was assisted by expert groups from the U.S., Singapore and Australia.
Approximately 73% of the wreckage (by weight) was recovered, partially reconstructed and examined. Both "black boxes" — the Cockpit voice recorder
Cockpit voice recorder
A cockpit voice recorder , often referred to as a "black box", is a flight recorder used to record the audio environment in the flight deck of an aircraft for the purpose of investigation of accidents and incidents...
(CVR) and Flight data recorder
Flight data recorder
A flight data recorder is an electronic device employed to record any instructions sent to any electronic systems on an aircraft. It is a device used to record specific aircraft performance parameters...
(FDR) — were successfully retrieved from the wreckage, and their data was extracted and analyzed.
On 14 December 2000, after three years of intensive investigation, the Indonesian NTSC issued its final report, in which it concluded that the evidence was inconclusive and that the cause of the accident cannot be determined:
The U.S. National Transportation Safety Board
National Transportation Safety Board
The National Transportation Safety Board is an independent U.S. government investigative agency responsible for civil transportation accident investigation. In this role, the NTSB investigates and reports on aviation accidents and incidents, certain types of highway crashes, ship and marine...
(NTSB), which also participated in the investigation, disagreed with the NTSC and concluded that the evidence was consistent with a deliberate manipulation of the flight controls, most likely by the captain, which put the aircraft into a vertical dive and caused it to crash. In a letter to the NTSC dated 11 December 2000 the NTSB wrote:
Lawsuits
In 2001, six families who had sued SilkAir for damages based on the allegation that the crash was caused by the pilot, were turned down by a Singapore High Court judge, who ruled that "the onus of proving that flight MI185 was intentionally crashed has not been discharged."In 2004, a Los Angeles
Los Angeles, California
Los Angeles , with a population at the 2010 United States Census of 3,792,621, is the most populous city in California, USA and the second most populous in the United States, after New York City. It has an area of , and is located in Southern California...
Superior Court jury
Jury
A jury is a sworn body of people convened to render an impartial verdict officially submitted to them by a court, or to set a penalty or judgment. Modern juries tend to be found in courts to ascertain the guilt, or lack thereof, in a crime. In Anglophone jurisdictions, the verdict may be guilty,...
in the United States, which was not allowed to hear or consider the NTSB's conclusions about the accident, decided that the crash was caused by a defective servo
Servomechanism
thumb|right|200px|Industrial servomotorThe grey/green cylinder is the [[Brush |brush-type]] [[DC motor]]. The black section at the bottom contains the [[Epicyclic gearing|planetary]] [[Reduction drive|reduction gear]], and the black object on top of the motor is the optical [[rotary encoder]] for...
valve in the plane's rudder
Rudder
A rudder is a device used to steer a ship, boat, submarine, hovercraft, aircraft or other conveyance that moves through a medium . On an aircraft the rudder is used primarily to counter adverse yaw and p-factor and is not the primary control used to turn the airplane...
resulting in a rudder hard-over. The rudder manufacturer, Parker Hannifin
Parker Hannifin
Parker Hannifin Corporation , originally Parker Appliance Company, usually referred to as just Parker, of Mayfield Heights, Ohio , is the global leader in motion and control technologies. The company was founded in 1918, and has been publicly traded on the NYSE since December 9, 1964...
, was ordered to pay the three families of victims involved in that case US$44 million. The company appealed the verdict, and the case was later settled out of court for an undisclosed amount.
Criticism of NTSC
The National Transportation Safety BoardNational Transportation Safety Board
The National Transportation Safety Board is an independent U.S. government investigative agency responsible for civil transportation accident investigation. In this role, the NTSB investigates and reports on aviation accidents and incidents, certain types of highway crashes, ship and marine...
(NTSB) and Flight International
Flight International
Flight International is a global aerospace weekly publication produced in the UK. Founded in 1909, it is the world's oldest continuously published aviation news magazine...
criticized the National Transportation Safety Committee
National Transportation Safety Committee
The National Transportation Safety Committee is an Indonesian government agency charged with the investigation of air, land, rail, and marine transportation safety deficiencies. It has its headquarters in Jakarta....
(NTSC). Flight International called the NTSC report an "evasive and worthless report[...]" and the NTSB posted a lengthy critique of the NTSC report. The U.S. NTSB conducted extensive testing using simulators and computer modeling, which contradicted the Indonesian authority. There was unprecedented criticism from NTSB investigators, who were adamant the only way to achieve the flight profile that occurred immediately prior to impact, was "with sustained nose-down manual flight control input".
Potential motives
In the aftermath of the crash, several potential motives for Captain Tsu's alleged suicide/homicide were suggested, including recent financial losses (his securities trading privileges had been suspended ten days prior to the accident due to non-payment), his obtaining an insurance policy on his life the previous week (the policy was to have gone into effect on the day of the accident), his receipt of several recent disciplinary actions on the part of the airline (including one that related to improper manipulation of the CVR circuit breaker), and his possible grieving over the loss of four squadron mates during his military flight training, which occurred years earlier on the exact date of the crash. He had also reportedly had several conflicts with Ward, and other co-pilots who had questioned his command suitability. Investigations later revealed that his total assets were greater than his liabilities, although his liquid assets could not cover his immediate debts, his monthly income was less than his family's monthly expenditure, and he had some outstanding credit card debts.An official investigation by the Singapore Police Force
Singapore Police Force
The Singapore Police Force is the main agency tasked with maintaining law and order in the city-state. Formerly known as the Republic of Singapore Police , it has grown from an 11-man organisation to a 38,587 strong force...
into evidence of criminal offence leading to the crash found "no evidence that the pilot, co-pilot or any crew member had suicidal tendencies or a motive to deliberately cause the crash of [the aircraft]."
Tsu was formerly a Republic of Singapore Air Force
Republic of Singapore Air Force
The Republic of Singapore Air Force is the air arm of the Singapore Armed Forces. It was first established in 1968 as the Singapore Air Defence Command...
pilot and had over twenty years of flying experience in the older T/A-4S Skyhawks as well as the newer T/A-4SU Super Skyhawks. His last appointment was instructor pilot of a Skyhawk squadron. Due to his flying experience, it was considered highly unlikely that the aircraft lost control or fell into a stall or spin, as he would have had the experience to avoid or overcome such conditions. The U.S. NTSB investigators found no mechanical malfunctions, and they concluded the accident could only be explained by intentional pilot action.
PA announcement
Captain Tsu made what appeared to be a routine PA announcement about the flight at 15:44:37, about seven minutes after takeoff, which was recorded by the CVR and transcribed by the NTSC:Tsu's announcement ended at 15:46. At 16:05, 19 minutes later, the CVR stopped recording. Six minutes later, at 16:11, the FDR stopped recording, and at 16:12 the aircraft plunged into its fatal dive.
CVR and FDR deactivation
The cockpit voice recorderCockpit voice recorder
A cockpit voice recorder , often referred to as a "black box", is a flight recorder used to record the audio environment in the flight deck of an aircraft for the purpose of investigation of accidents and incidents...
and flight data recorder
Flight data recorder
A flight data recorder is an electronic device employed to record any instructions sent to any electronic systems on an aircraft. It is a device used to record specific aircraft performance parameters...
stopped recording minutes before the abrupt descent, but not at the same time. A technical analysis of the sound signature of a CVR circuit breaker trip, as recorded by the CVR, was carried out by investigators and the evidence showed that the CVR stoppage was consistent with being manually initiated. The radio continued to work after the failure of the recorders, which indicates that power failure was not a cause.
Similar Incidents
The theory that the crash was caused by a defective servo valve in the plane's rudder, resulting in a rudder hard-over, has been compared to two other Boeing 737 crashes, United Airlines Flight 585United Airlines Flight 585
United Airlines Flight 585 was a scheduled domestic passenger airline flight from the now-decommissioned Stapleton International Airport in Denver to Colorado Springs Municipal Airport in Colorado Springs, Colorado....
and US Air Flight 427.
See also
- List of accidents and incidents on commercial airliners
- Air safetyAir safetyAir safety is a term encompassing the theory, investigation and categorization of flight failures, and the prevention of such failures through regulation, education and training. It can also be applied in the context of campaigns that inform the public as to the safety of air travel.-United...
- EgyptAir Flight 990EgyptAir Flight 990EgyptAir Flight 990 was a regularly scheduled flight from Los Angeles International Airport, California to Cairo International Airport, Egypt, with a stop at John F. Kennedy International Airport, New York...
- Boeing 737 rudder issuesBoeing 737 rudder issuesStarting in 1991, a number of accidents and incidents involving the Boeing 737 were the result of the airplanes' unexpected movement of their rudders. The rudder is controlled by the Power Control Unit . Inside the PCU is a dual servo valve which helps direct hydraulic fluid in order to move the...
- SilkAir 185: Pilot Suicide?
- Pacific Southwest Airlines Flight 1771
External links
- Final Report - National Transportation Safety CommitteeNational Transportation Safety CommitteeThe National Transportation Safety Committee is an Indonesian government agency charged with the investigation of air, land, rail, and marine transportation safety deficiencies. It has its headquarters in Jakarta....
- SilkAir Press Release
- SilkAir news releases regarding Flight 185
- The pilot who wanted to die, article by Geoffrey Thomas in The Sydney Morning HeraldThe Sydney Morning HeraldThe Sydney Morning Herald is a daily broadsheet newspaper published by Fairfax Media in Sydney, Australia. Founded in 1831 as the Sydney Herald, the SMH is the oldest continuously published newspaper in Australia. The newspaper is published six days a week. The newspaper's Sunday counterpart, The...
, October 7, 1999