"Some water?"
"No thanks."

The above exchange represents the last known conversation between SilkAir pilot Tsu Wai Ming and his co-pilot Duncan Ward before their plane, a Boeing 737 passenger jet, crashed into the Musi River in Indonesia with no clear explanation on December 19, 1997. All 104 passengers and crew were killed on impact. More than a decade and a half later, the crash of SilkAir Flight 185 remains one of the most controversial and poorly understood plane accidents in modern history. The main source of the confusion is the fact that both the cockpit voice recorder and the flight data recorder ceased to function 6 and 2 minutes before the crash, respectively. The two main investigatory bodies charged with solving the mystery could not agree on the cause of the accident while the only opinion rendered in a court of law on the subject came up with another reason altogether.


SilkAir is a company based in Singapore that primarily services southeast Asia with additional destinations in India, China, and Australia. As a subsidiary of the much larger Singapore Airlines, it is an extremely well-funded and well-staffed regional airline. Flight 185 was the regular flight between Singapore and Jakarta in Indonesia. This particular route would have been attractive for any pilot in the company because of the relatively short flight time (a little less than an hour and a half) and also the fact that the 737 that made the trip was SilkAir's newest acquisition, having been delivered in February of 1997. The routine flight had been made dozens of times between February and December without incident.

The Boeing 737 is by far the most common and most flown passenger jet in the world. While perhaps not as famous as its jumbo relative the 747, this venerable medium-sized plane is the backbone of much of the world's commercial aviation industry. To give you an idea of its importance, it is estimated that a 737 takes off or lands every five seconds somewhere in the world. Since its introduction in the 1960s, 737s have serviced over 12 billion (with a "B") passengers. If you consider that the plane seats anywhere from 85 to 215 passengers depending on its configuration, you can do the math and figure out how many flights these things have made.

The downside to being the world's most common passenger plane is that the 737 has been involved in over 300 events that are euphemistically referred to as "incidents." At least 150 have been completely destroyed in crashes and more than 100 have been hijacked. A series of seemingly random crashes in the 1990s called the safety and reliability of the 737 into question; perhaps not coincidentally, the 737 saw its smallest number of orders in this time period and had steadily lost ground to the Airbus A320, its main competitor, ever since. The possible implications of a major defect in the design or manufacture of the 737 cannot be overstated: if all of the world's 4,500 737s currently in operation were to suddenly be grounded, air traffic would grind to a screeching halt and it would be difficult for just about any carrier -- regardless of its size -- to operate effectively without its 737 fleet. For this reason, it is extremely important for the groups that investigate airplane safety to give the utmost care and attention to any "incident" involving a 737.

Of course, none of this was really a concern to Captain Tsu Wai Ming or those who flew with him. Flying a 737 would have been a breeze to him. Before joining SilkAir, he had been one of the best pilots in the Singaporean Air Force. His skills in a plane were so good, in fact, that he performed with the Air Force's aerobatic stunt group before retiring from service to pursue a career in the private sector. At the age of 41, he would have been at the height of his career as a pilot. His reputation was such that he had been given the prized position of instructor -- a step up in the commercial aviation world and usually the first stop on the way to a management position. Despite his skill and ambition, he was also known to be somewhat hard-headed and even a little brash.

Now considering that Tsu was a hot shot fighter pilot, this shouldn't be extremely surprising. Indeed, it would be unexpected if he weren't. But in an industry and in a part of the world where deference to authority is considered almost sacrosanct, he demonstrated a willingness to butt heads with both superiors and colleagues that did not do him any favors. He was involved in two events that seriously hurt his career in the space of just a couple of months in the run up to the crash of flight 185. First, he botched a landing by failing to slow down enough and to compensate, made a quick series of erratic turns in an effort to lose elevation and speed. When this didn't work, he had to try again to make the landing normally, which he did. His recklessness could have caused the plane to crash and he never wrote a requested report on the incident. More seriously, however, was a subsequent conversation he had with his co-pilot about the event. After this conversation -- which took place in the cockpit shortly before takeoff on another flight -- he disabled the cockpit voice recorder so the conversation would not be erased (many CVRs work on a loop, which means dialogue is periodically erased; this is to make sure the last and most relevant moments before a potential accident are recorded). The co-pilot refused to start the plane until it was reactivated, but Tsu was equally determined not to turn it back on. Eventually, Tsu relented, but this damaged his reputation enough to the point that he was demoted and had his instructor privileges revoked.

The Crash

SilkAir Flight 185 started off perfectly normally. The 737 took off just after 3:30 in the afternoon and Captain Tsu's welcoming announcement was as pleasantly banal as any you've heard. The main subjects were the weather, the time, and seatbelts. The mood in the cockpit was no less normal. Aside from standard communications with air traffic control, Tsu and Ward spoke primarily about their lunches. At 4:05, Tsu asked Ward if he wanted to relax outside the cabin to eat his lunch. Ward indicated he was fine. Tsu then asked if he wanted some water, to which Ward replied "no thanks." At this point, less than half an hour into the flight, the CVR shut off, so no further conversation between the two men was recorded. Shortly after this, though, Ward was able to make contact with the ground, showing that the radio was still functional and that there did not appear to be any electrical issues. At 4:11, the flight data recorder (FDR) also stopped. In the next 60 seconds, SilkAir Flight 185 fell out of the sky and into the water. Fishermen in the village of Palembang near the site of the accident were the first to report and respond to the crash. They took their boats to the wreckage of the plane, but found no survivors. Everyone on board Silkair Flight 185 perished instantly in the crash.

The main group investigating the crash was the Indonesian National Transportation Saftey Committee (NTSC). Because the NTSC did not have much experience with 737 crashes (or indeed plane crashes in general), they sought and received the assistance of the American National Transportation Safety Board (NTSB). This made sense considering the 737 was an American made plane and because the NTSB had (unfortunately) investigated many similar mysterious crashes. The decision to work together on the case would be pretty much the last thing the two organizations would agree upon. The contentious nature of the investigation would fuel the controversy that still exists about the precise nature of what really happened.

Whenever anyone is investigating anything with seemingly no cause, the first step is to usually figure out what didn't happen. Even though the plane had begun to disintegrate before crashing into the Musi River, about 3/4 of its mass was able to be recovered. Since there were no signs of fire, the NTSC and the NTSB could rule out some type of explosion, either internal or external. The wiring was determined to have been intact at the time of the crash, meaning that an electrical failure was extremely unlikely. The weather was clear during the flight, so powerful winds or rain could not have been the cause. Less than a minute passed between the time the plane began its fatal descent from 35,000 feet and its impact, and the engines were at full throttle, which would indicate there were no problems with power. At the end of the day, only two possible causes remained: a failure in some specific (but as yet unidentified) piece of hardware or human error.

In 1991, United Airlines Flight 585 fell out of the sky above Colorado Springs for no discernible reason, killing everyone on board upon impact. The NTSB investigation lasted for more than a year and a half and is to date only one of four in the organization's history whose cause is officially described as "undetermined." Flight 585 was a 737. In 1994, the same thing happened to USAir Flight 427, also a 737, with a similar outcome: all passengers and crew were killed. The suspect in both cases was a faulty rudder power control unit (PCU), but tests on the ground on both recovered PCUs demonstrated perfect functionality. It happened again in 1996 to Eastwind Airlines Flight 517, which was -- you guessed it -- a 737. Miraculously, the crew was able to stabilize the aircraft and land safety without a single death. The captain and co-pilot confirmed what had been previously suspected: the rudder made a sharp turn on its own and became jammed, causing the rapid bank and descent. Frustratingly, though, tests on the surviving plane's PCU showed no operating flaws. Then one of the investigators realized the problem: the tests did not adequately recreate the conditions in the air. When the PCUs were cooled to a temperature more similar to what would be expected in a plane at its cruising altitude, they jammed. Was this the fate of SilkAir Flight 185?

A less thorough investigation would likely have looked at this information and called it a day. The NTSB, however, was not satisfied with this explanation. Tests to recreate the path of the plane's final descent all repeatedly failed to do so, except for one: intentionally banking the plane onto its right side, holding the steering column down, and applying maximum thrust. A great deal of physical exertion is necessary to maintain the plane in this particular attitude. This means it could not have happened accidentally or without sustained pilot input.

Trained to look at every angle, the investigators began scrutinizing Captain Tsu more heavily. Analysis in the United States determined that both the CVR and the FDR of Flight 185 had been manually disabled when they shut off shortly before the accident. Tsu had previously been in trouble for manually disabling a CVR. On the extant portion of the CVR, Tsu can be heard repeatedly asking First Officer Ward if he wants to leave the cockpit to eat or relax; after Ward's final refusal, Tsu can be heard unlatching his seatbelt immediately before the recording stops. The controls were also found to have been pointed in such a way that would have caused the plane to dive nose-down, exactly the position the 737 had been in when it crashed. This indicates the pilot was still in control of the aircraft. Other personal issues involving Tsu came to light: he was in severe financial distress, he had been banned from securities trading a few days earlier, his professional life was on the rocks, and the day before the crash, a $600,000 life insurance policy Tsu had taken out on himself became active. The crash also occurred on the 17th anniversary of a deeply traumatic experience for Captain Tsu. During his time in Singapore's Air Force, Tsu and three other pilots were flying a routine patrol/training mission when he became ill and returned to base. Afterward, all three of his comrades simultaneously crashed their jets into a mountain obscured by clouds, dying instantly.

The NTSB determined that the cause of the crash was neither a PCU malfunction nor human error. "Error" implies something accidental or unintended. For the NTSB, there was nothing accidental about what happened: the crash of SilkAir Flight 185 was an act of premeditated mass murder/suicide and the culprit was none other than Captain Tsu Wai Ming. The NTSB theorized that Tsu had disconnected the CVR after leaving the cockpit, disengaged the FDR upon his return, and then either sent Ward out of the cockpit on some pretext or (more ominously) disabled him before putting the plane into a steep turn and sending it down to earth at over 400 miles per hour.

For its part, the NTSC was not swayed by this theory. Contradictory evidence called this scenario into question. For example, the type of life insurance Captain Tsu had was required by his employer. That it matured 24 hours before his death was coincidental. Likewise, although his finances were not great, his assets were greater than his debts, even if he was not entirely liquid at the time of his passing. The position of the flight controls, it could be argued, was not necessarily an indicator of intent to crash the plane. Tsu had gotten into hot water for his wild maneuvering in an (ultimately successful) attempt to save a previous flight he was piloting from crashing. Could his decision to put the plane into a nosedive have been an effort to correct a potential rudder malfunction or stall on Flight 185? The NTSC also argued that there was no direct evidence to support the idea that Captain Tsu had personally disabled the plane's flight recorders. It was, after all, an accident, so who knows what could have happened? And again, although the aircraft's PCU functioned normally in testing after the crash, it was not subjected to the same tests that those of other 737s were, so its potential for failure was unknown. The final NTSC report was released in 2000 and said that the cause of the crash could not be determined. Amazingly, the NTSB released an annotated version of this same report, clearly implicating Captain Tsu as the reason behind the crash.

Why did the NTSC fail to acknowledge the role of Captain Tsu Wai Ming in bringing down the plane? Did it really see no evidence supporting this theory? Apparently some lower-level investigators disagreed with the official findings and accepted the results of the NTSB investigation, but were overruled by their superiors. Politics likely played a role. Indonesia might have been fearful of offending Singapore, a country with whom they have significant cultural and economic ties. At the same time, however, the final NTSC report does not attribute any blame to the aircraft itself, which was probably an attempt not to offend the United States -- where Boeing is based. Because the NTSC was the official investigatory body regarding the crash, and their word was considered legally binding, Tsu's insurance policy paid out in full to his beneficiaries.

The saga of SilkAir Flight 185 was not over, however. Although many families accepted out-of-court settlements from SilkAir as a result of the crash, some did not. A series of wrongful death lawsuits against the airline began in 2001 in Singapore. All of these claims were flatly denied, however, as the Singaporean courts deferred to the NTSC investigation that failed to implicate the company or Captain Tsu as having been responsible for the deaths of their loved ones. In 2004, 15 more families sued the manufacturer of the rudder PCU, Parker Hannifin, in the United States. Strangely, the jury in this case was not permitted to hear the ample evidence that indicated Captain Tsu had deliberately crashed the plane, causing them to return a $44 million dollar verdict against Parker. The company appealed the verdict, but ultimately agreed to pay an undisclosed sum of money to each of the families with the understanding that they were not accepting responsibility for the crash.


Generally speaking, most major airplane crashes have wide-reaching implications for the airline company, the manufacturer, or both. Sixteen years after the fact, it's difficult to establish what exactly the legacy of SilkAir Flight 185 is. The ambiguous and conflicting nature of the various investigations and inquiries into the crash don't make matters any clearer. While the Federal Aviation Authority would ultimately order Boeing to upgrade the rudder power control units of all its 737s with redundant safety features, this was well in the works before the crash of flight 185. Because Indonesia does not consider him to be legally responsible for the accident, Captain Tsu Wai Ming's name is on the memorial to the crash in Palembang, a fact which galls those who believe him to be a mass murderer. SilkAir continues to be a powerful presence in Southeast Asian aviation and has an exemplary safety record; flight 185 is its only "incident." Obviously the families of those killed on flight 185 will never have their loved ones back, so perhaps the point is moot. One thing is for sure: unlike countless other famous plane crashes, the destruction of SilkAir Flight 185 has done absolutely nothing to make the world of aviation any safer.



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