On the first of January 2007, an Indonesian Boeing 737 with 102 passengers and crew on board disappeared amid heavy thunderstorms over the Makassar Strait. For days, searchers scouring both on land and in the water found no trace of the plane. When a signal from the black boxes was detected on the ocean floor three weeks later, it seemed that the truth would soon be found — but in fact, the ordeal was just beginning. Six months of bureaucratic bickering ensued while the airline tried to avoid paying for the recovery. All that time, the black boxes lay beneath 2,000 meters of water, holding within them the harrowing final moments of Adam Air flight 574. When the recorders were finally retrieved, they painted a shocking picture of a flight that was off course, battling powerful winds, its pilots trying desperately to fix a malfunctioning navigation system. The 737 then rolled steeply to the right and plunged into a dive, accelerating far beyond its maximum speed until the plane ripped itself apart in midair. Flight 574’s horrific end raised troubling questions. What was going on in that cockpit? How did the pilots lose control of the plane? And most of all, was something seriously amiss with this rapidly expanding budget airline? The answers would forever tarnish the reputation of Indonesia’s entire airline industry.
The early 2000s were a period of exponential growth in Indonesia’s airline industry. In seven years, passenger numbers quintupled, driving a frenetic expansion in the size and number of low-cost carriers. Among these was Adam Air, a budget airline founded in 2002 by wealthy businesswoman Sandra Ang and Agung Loksano, Speaker of Indonesia’s House of Representatives. The airline was named for Ang’s son Adam Suherman, who at the age of just 26 was appointed CEO. Adam Air was in every way a family-run operation: in addition to Suherman, two of his brothers and Loksano’s son also held high-level management positions. Catering to the explosion in demand, Adam Air grew rapidly, expanding its market share at a rate that surpassed impressive and bordered on alarming. By the end of 2006, after flying for less than four years, it had built up a fleet of 25 Boeing 737s and was the fastest-growing airline in Indonesia. They weren’t afraid to use underhanded means to accomplish this: Adam Air was repeatedly accused of false advertising, including promotional materials which described its 15-year-old 737–400s as “new,” among other questionable assertions. Its logo, which appeared to feature a silhouette of Icarus, also did not inspire confidence.
One of Adam Air’s planes was an 18-year-old Boeing 737–400 with the registration PK-KKW. One of several flights that this plane was scheduled to complete on New Year’s Day 2007 was flight 574, a routine trip from the city of Surabaya in eastern Java to Manado on the island of Sulawesi. In command was 47-year-old Captain Refri Widodo, an experienced pilot with over 13,000 flight hours. His copilot was First Officer Yoga Susanto, who had a fairly respectable 4,200 hours of his own. Joining them on the flight were four flight attendants and 96 passengers, totaling 102 people on board.
Widodo and Susanto were probably well aware that PK-KKW had a long history of problems with its inertial reference system (IRS). The IRS consists of two independent systems, one for each pilot, which measure pitch, roll, yaw, acceleration, heading, latitude, longitude, and a range of other attitude and position parameters. Each system has its own inertial reference unit (IRU) consisting of three gyroscopes, which provide data to each pilot’s attitude indicator and flight management system (FMS) display. For months, pilots had been reporting problems with the IRS, mostly that the two systems disagreed about the lateral position of the airplane, indicating that one of them was faulty. It did not appear that maintenance had managed to get to the root of the problem.
Adam Air flight 574 took off at 13:59 local time, heading northeast over the Makassar Strait to Manado. But it wasn’t long before the problem with the inertial reference system returned, and the position of the plane indicated by the two FMS displays began to differ. Which one was malfunctioning isn’t known for sure. But in any case, one of them was right and one of them was wrong, and the pilots needed to figure out which was which.
By the time the cockpit voice recording began at 14:28, Captain Widodo and First Officer Susanto were already discussing the problem. “Twenty-eight is the difference,” Widodo reported, confirming that there was a 28-nautical-mile discrepancy in the location of the plane on the two FMS displays. Complicating their task was the fact that the autopilot had apparently been following the wrong one for some time, because the plane was off course, drifting north of its assigned route. Area controllers in Makassar began to grow concerned. Amid conversations recorded in the control tower, one of the controllers could be heard exclaiming, “Where’s Adam direct to? My god, he’s flying north!”
In the cockpit, the pilots cracked jokes about the situation, probably to alleviate the tension: their situation was in fact not funny in any way, and they knew it. While most planes were diverting around a massive thunderstorm in the middle of the Makassar Strait, Widodo and Susanto wanted to figure out where they were before even considering a course correction. Powerful winds battered the plane as they entered the storm, and the pilots instructed the passengers to fasten their seat belts in preparation for possible turbulence.
At 14:42, still straying north of the proper airway and surrounded by thunderstorms, First Officer Susanto informed air traffic control that they were on a heading of 46 degrees direct to waypoint DIOLA, but that they were fighting against a powerful 74-knot crosswind. They still had no idea where they were. Their conversations became increasingly agitated:
“Verify position, we can get lost if it is like this!”
“We will get lost then!”
“Crazy, it’s crazy!”
“Look at the FMS!”
“We can’t just turn off one of the IRS!”
“It doesn’t seem we have it!”
“There isn’t anything!”
“Now the left one is good, the right one is different, you’re kidding!”
“Whoa, something is disengaged!”
“This is messed up!”
“Yes, this is already messed up!”
“It’s starting to fly like a bamboo ship!”
“We are wrong…”
“Do you see it’s messed up?”
“The EFIS [Electronic Flight Instrument Display] and FMS are messed up!”
“The FMS is confusing itself, that’s crazy!”
At 14:47, they finally decided to see if there was an official procedure for troubleshooting the IRS.
“Have a look at the QRH,” Captain Widodo suggested, referring to the Quick Reference Handbook of abnormal procedures. “If the IRS number two is switched off, see what happens.”
“IRS,” said Susanto, flipping through the booklet.
“Navigation, FMS, look at the FMS,” Widodo said.
Susanto finally found it. “IRS Fault,” he said, presumably looking at the IRS Fault procedure in the QRH.
“It’s not fault,” said Widodo. The IRS Fault light had not illuminated. Was this even the right procedure?
“It’s not fault,” Susanto repeated.
“The IRS is erroneous.”
“But the fault must be illuminated, captain,” said Susanto.
“It’s — it’s not fault.”
Looking through the IRS Fault section, they found two procedures, one for on the ground and one for in the air. “Yes, on the ground, in flight…” said Susanto. “This one on the ground. IRS Fault 11.4.”
“It’s not fault.”
“No no no… but the left one is good.”
“Yes, that is why,” said Widodo, agreeing with the suggestion that the IRS Fault light had not illuminated because the captain’s side IRS was working properly. “Can we just turn one of these IRS off?”
“It doesn’t seem we have to,” said Susanto.
On and on the conversation continued.
At 14:54, the controller, noticing that they were straying even farther off course, instructed them to fly on a heading of 70 degrees to waypoint DIOLA. How could they have been going toward to DIOLA on a heading of 46 degrees, as they had said earlier, if the controller saw them on the 70-degree radial? Clearly they had their position relative to DIOLA totally wrong. After eight seconds, the controller repeated the instruction again. Finally, First Officer Susanto acknowledged. The plane began to turn back to the east.
At 14:55, Captain Widodo ordered First Officer Susanto to ask air traffic control for their current position.
“Adam 574, position is 125 miles Mike Kilo Sierra, crossing radial 307 Mike Kilo Sierra,” the controller replied. This meant that they were 125 miles northwest of Makassar on a bearing of 307 degrees. The pilots could have used this information to determine which IRS was correct, but it’s not clear that they did.
After reading through the procedure, the pilots decided to try one of the troubleshooting methods suggested in the QRH. Each inertial reference system is designed to have multiple layers of functionality, allowing pilots to revert the affected IRS to aircraft attitude information only if there’s a problem with the navigational functions. To accomplish this they would need to move the affected IRS mode selector switch from “NAV” (navigation mode) to “ATT” (attitude mode). The procedure advised that after flipping the switch, the pilots would need to hold the plane straight and level for 30 seconds while the system reboots.
In fact, switching an IRS from navigation mode to attitude mode requires a fair amount of attention. As the IRS reboots, it has to go through an alignment process where it determines which way is up, which way is down, and which way the plane is moving. The autopilot, which relies on both inertial reference systems to verify attitude data, will disconnect. The attitude indicator on the affected side will go totally blank, displaying no pitch or roll information, and a couple of other systems (such as traffic collision resolution advisories) will become temporarily inoperative. After 30 seconds of stable, level flight, the gyros will successfully align and all these systems will come back, except for automated heading functions. From this point on the pilots would need to periodically feed their current magnetic heading into the flight management system, updating it every few minutes to account for magnetic drift.
At 14:56, Captain Widodo ordered First Officer Susanto to move the IRS mode selector to attitude mode. But Susanto still didn’t understand which IRS was faulty: was it the left one? Widodo told him it was the right one. Susanto then switched his own (right-hand) inertial reference system to attitude mode. All his screens went blank and the autopilot disconnected, triggering a loud alarm. Someone reached over and silenced it four seconds later.
As it turned out, the faulty navigation system wasn’t the only thing wrong with this plane. PK-KKW also had a tendency to pull to the right, caused by a slight mistrimming of the ailerons, which required constant correction in order to maintain straight and level flight. Up until now the autopilot had been applying a continuous left aileron input to keep the plane on the commanded course. Once the autopilot disconnected, Captain Widodo needed to take manual control and use his instruments to level the plane while the first officer’s IRS went through the alignment process. But he didn’t seem to have any idea that the autopilot had stopped flying the plane. Nor did either pilot seem to understand the importance of the 30-second waiting period; in fact, First Officer Susanto tried to enter their magnetic heading immediately, before the IRS had booted back up. Meanwhile, imperceptibly at first but gaining speed, the plane started to roll to the right.
Plowing onward through the clouds, surrounded by howling wind and driving rain, the pilots continued to fight with the IRS. Captain Widido made a couple of small inputs to try to level the plane but never seemed to grasp the fact that they were continuously turning to the right. The first officer’s IRS failed to align because they were in a turn, and his instruments didn’t come back after 30 seconds. They were starting to lose the plot.
At 14:58 the bank angle increased through 35 degrees, causing a robotic voice to call out, “BANK ANGLE! BANK ANGLE! BANK ANGLE! BANK ANGLE!”
“Put it back on NAV again, put it back on NAV again!” Captain Widodo exclaimed. The effects of switching the IRS to attitude mode left him spooked, but instead of following the airman’s proverb — “just fly the airplane” — he tried instead to undo the input that had gotten them into this situation.
The plane was now banking so far that the wings began to lose lift, causing the nose to drop. A chime sounded to inform the pilots that they were leaving their assigned altitude of 35,000 feet.
“Don’t turn it! This is our heading!” Captain Widodo shouted. They were banking past fifty degrees. What on earth was he thinking?
In the 48 seconds following the start of the warnings, flight 574 kept on rolling until it turned inverted, reaching a bank angle of 100 degrees. Losing lift, the plane pitched steeply nose down and entered a rapid descent. Suddenly realizing the gravity of the situation, Widodo grabbed the control column and pulled back sharply. But because the plane was upside down, pulling up caused them to dive straight at the ground instead. Massive G-forces smashed the passengers and crew into their seats as the plane hurtled into a terrifying inverted spiral dive, accelerating downwards at incredible speed. The chilling clackclackclack of the overspeed warning filled the cockpit as they rocketed through Mach 0.9.
“Pull up! Pull up! Pull up!” screamed First Officer Susanto. “Pull up! Pull up!”
But there was nothing they could do. The plane was pulling 3.5 G’s at an airspeed of 490 knots (900 km/h), far beyond what it was designed to endure. Two loud thunks reverberated through the plane as the incredible aerodynamic forces ripped off the horizontal stabilizer. The rate of descent reached 53,000 feet per minute. The plane began to disintegrate. In the cockpit, the only sound was the deafening roar of the wind. Finally, at a height of 9,000 feet, both black boxes went dead. What happened after that is a secret that the 102 passengers and crew took with them to their watery graves.
Back at the control center in Makassar, around ten minutes passed before controllers realized that flight 574 had disappeared from radar. Over the next several minutes, it became clear that the flight could not be raised by radio either. For two hours, they tried to get other planes to call flight 574 and asked nearby airports if the plane had diverted. But the 737 seemed to have vanished without a trace. Finally, at 17:24, the control center activated the full “aircraft in distress” protocol, and a search and rescue mission launched into action.
The search for the plane had very little to go on. Based on the last recorded radar position, it wasn’t even clear whether the plane had crashed on land or in the ocean. Military personnel began to scour the jungle-covered mountains of southwestern Sulawesi on foot, while boats crisscrossed the Makassar Straight in search of floating debris. Days went by, but nothing was found. Officials expanded the search area to the entire island of Sulawesi, and municipalities around the Makassar Strait were placed on lookout for debris that might wash up on shore.
On the 11th of January, a breakthrough finally came when fishermen off the coast of Sulawesi began to find floating debris, including heavily damaged pieces of the elevators, spoilers and horizontal stabilizer, along with a few mangled cabin furnishings and personal effects. Some of these pieces had likely been ejected from the plane in flight.
After around two weeks of searching, a US vessel carrying specialized equipment detected the “pingers” from the two black boxes, which appeared to be lying on the ocean floor around 1.4 kilometers apart amid the widely spread remains of the rest of the airplane. There was just one problem: the recorders lay at a depth of more than 2,000 meters, and no country in Southeast Asia had a submersible that could recover them from such deep water.
The Indonesian government expected that Adam Air would foot the bill to hire a foreign company for the salvage process. But to their surprise, Adam Air refused to pay a single penny: company executives didn’t seem to think that finding the cause of the crash was important, and that if the government was so interested in the matter, they ought to pay for it themselves. The cost could be in the tens of millions of dollars, and the cash-strapped government was not too keen on paying it either. With neither side willing to budge, negotiations stalled. For seven long months, family members and aviation safety experts waited, and waited, and waited, increasingly fearing that bureaucratic obstinance would leave the crash of Adam Air flight 574 forever a mystery.
Finally, in July 2007, Adam Air agreed to put up half the cost of one week of searching. Faced with this stingy offer or no offer at all, the Indonesian government agreed. By mid-August, a Phoenix International salvage ship equipped for deep water recovery missions was on its way to Indonesia from the United States.
Armed with the coordinates of the pingers which were detected during the original search, Phoenix International managed to locate both black boxes within five days; both were found within a few meters of where the coordinates said they would be. Investigators transported the recorders to a facility in Washington, D.C. for analysis. The data contained within them would be all they would get: there wasn’t enough time or funding to retrieve any other wreckage from the sea floor. Nor did the search find any bodies. In fact, judging by the condition of the debris, the crash was so violent that the 102 passengers and crew would have been all but vaporized on impact.
The flight data recorder and cockpit voice recorder revealed a bewildering series of events. Although the crew had entered their starting coordinates into the FMS correctly, the two inertial reference systems began to diverge almost immediately after takeoff. Presumably the autopilot was referencing the faulty IRS, because it began guiding the plane north of the proper track as soon as it was engaged. After about 20 minutes the discrepancy probably became large enough to trigger a caution message, at which point it occupied the majority of the pilots’ attention for the rest of the flight.
Although the IRS was not recovered and the cause of the glitch couldn’t be determined, the source of the problem didn’t really matter. An issue with the inertial reference system is not the end of the world, and it certainly doesn’t lead to a dramatic plunge into the sea. The answer lay not in the fault itself but in the way the pilots reacted. According to the principles of crew resource management, the captain should have designated one pilot who would be in charge of troubleshooting while the other flew the airplane. But in the event, both pilots were completely consumed with troubleshooting the IRS for nearly half an hour. Neither of them paid much attention to what the airplane was doing. Throughout this period they continued to diverge from the designated airway and flew into a severe thunderstorm, but despite attempts by air traffic control to get them back on course, they never took any real corrective action.
Based on the CVR, it seemed that the crew were confused by the fact that the IRS Fault light had not illuminated, even though there was clearly a problem with one of the inertial reference units. The checklist for an IRS Fault was designed around the assumption that the crew would use the procedure after observing the fault light. The success condition for the procedure would be met if the light went off, but in their case it never came on in the first place. Compounding the resulting confusion was a lack of understanding of what the procedure entailed. Although the checklist clearly stated that they would need to keep the plane straight and level for 30 seconds after switching the copilot’s IRS to attitude mode, they did not appear to understand that this would disconnect the autopilot. When it did disconnect, a loud alarm sounded, and someone even went so far as to manually shut it off, but still there was no verbal acknowledgement by either crewmember that the autopilot was no longer engaged. It’s quite probable that this action was automatic — they silenced the alarm without ever processing what it meant, because their minds were still fixated on the inertial reference system.
From this point onward, events escalated rapidly. Assuming that the autopilot was still holding them level, the captain didn’t intervene to steady the airplane, and the slightly mistrimmed ailerons caused a right roll to develop at a rate of about one degree per second. Consequently the IRS alignment process failed, leaving the first officer without most of his instruments for the rest of the flight. Once again, neither pilot understood why the process had failed, and they kept trying to figure it out even as the plane began to turn ever more steeply. When the bank angle warning sounded the captain did make a half-hearted attempt to level the plane, but he immediately returned to the IRS and kept his attention there until they reached a right bank in excess of 100 degrees. At this point he sealed their fate by pulling up before rolling wings-level, when he should have done it the other way around. Pulling back while upside down put them into such an extreme dive that within seconds the aircraft became unrecoverable.
To better understand the accident, Indonesia’s National Transportation Safety Committee, or KNKT, did a deep dive into Adam Air’s pilot training and maintenance programs. One of the first things they noticed was that Adam Air had given all its pilots copies of the operations manual downloaded from myboeingfleet.com, which were explicitly marked as not for operational use. They then found that Adam Air had not trained its pilots how to respond to failures of the IRS, or indeed almost any other automated system. They weren’t trained on how to react to an unexpected autopilot disconnect warning. And they hadn’t received upset recovery training, a standard module at major Western airlines, which among many other techniques teaches pilots to roll wings level before pulling up when in an inverted position. In all respects, the pilots were woefully unprepared for the situation they encountered. Without the requisite training, they bungled their way through the IRS troubleshooting process, making a series of ill-informed decisions, then lost control of a perfectly controllable airplane because they weren’t paying attention. It was a shocking indictment of the pilot training at Adam Air, but that turned out to be just the tip of the iceberg.
The KNKT soon discovered that Adam Air’s maintenance program was also woefully inadequate. Records showed that one of the inertial reference units on PK-KKW had been written up by pilots more than 100 times in the three months before the accident, usually because it was experiencing abnormal drift, just like on the accident flight. But Adam Air didn’t have a replacement easily available — ordering a new one would take six months — so every time a fault was recorded, mechanics would take out the unit and clean the connections, re-rack it, or swap it with the other IRU. It was obvious that none of these measures were fixing the problem. According to proper procedure, they should have inspected the associated wiring, and if that didn’t reveal the cause, the system should have been replaced. But poorly trained mechanics and a lack of spare parts — caused by management underestimating how many they would need — led to a culture where aircraft faults were usually “fixed” through the maintenance equivalent of turning it off and back on again. Although Adam Air supposedly had an approved reliability control program, based on the state of its airplanes the KNKT was forced to conclude that it only existed on paper.
Following the crash of flight 574, former Adam Air pilots claimed that they had been forced by management to fly unairworthy airplanes and sign off on maintenance logs that hadn’t been examined by engineers. Others revealed that Adam Air got around repair deadlines by swapping faulty parts to another aircraft to reset the repair period, then bribed regulators to look the other way. Yet another pilot said that after he refused an order by the airline to exceed his legal limit of five takeoffs per day, the airline retaliated by grounding him for a week. “Every time you flew, you had to fight with the ground staff and the management about all the regulations you had to violate,” he told the Associated Press.
The crash of Adam Air flight 574 was not the first eyebrow-raising incident at the airline, nor would it be the last. In February 2006, an Adam Air Boeing 737 with a faulty inertial reference system flew off course into a radar and radio dead zone over the ocean, causing the crew to get lost flying in circles for more than three hours. Eventually they managed to spot land, which turned out to be the rural island of Sumba, where they landed safely despite having no idea where they were. Adam Air claimed that there was nothing wrong with the plane, and had the pilots arrested by local authorities. Indonesia’s Directorate General of Civil Aviation (DGCA) was not convinced, however, and the agency ordered Adam Air to repair the navigation system and conduct a series of 13 flight tests to ensure it was working correctly. But, according the Asia Times, an Adam Air plane which was supposed to take KNKT investigators to the site of the incident “accidentally” left without them, and then the airline told them that their mechanics had magically fixed the issue and there was no need for further investigation.
Then, in February 2007, Adam Air flight 172, a Boeing 737, was landing in Surabaya when it touched down with such force that the fuselage broke, causing the tail section to collapse. Fortunately, no one was seriously injured, but five Adam Air 737s were ordered grounded for structural inspections, despite Adam Air’s complaints that this “punishment” was too “harsh.”
Finally, in March 2008, another Adam Air Boeing 737 skidded off the end of the runway while landing in Batam, causing major damage to the right wing. After the crash the crew severely mishandled the evacuation by failing to deploy any emergency slides. By this point it was clear that if left unchecked Adam Air would inevitably have another fatal accident. Days after the crash in Batam, a group of investors dumped their 50% stake in the airline, causing Adam Air to miss lease payments, which in turn forced their lessors to repossess half the fleet. Two days after that, the DGCA suspended the airline’s Air Operator Certificate, and revoked it entirely three months later. At last, Indonesia’s sketchiest airline was dead.
But even that wasn’t the whole story. In fact, it was no fluke that Adam Air continued flying for more than a year after the flight 574 disaster, despite the fact that it kept having crashes. Many believed, and not without reason, that Adam Air got away with all its blatant regulatory violations because its co-founder was also the Speaker of Indonesia’s House of Representatives. Indonesian newspapers alleged that he didn’t make an initial investment when the airline was founded, because his role was actually to help “smooth out” Adam Air’s relationship with regulators by using his position to twist arms and give out bribes. Then in August 2008 came a bombshell: Adam Air owner Sandra Ang was arrested by Indonesian police and charged with embezzling over $200 million from her own airline. Whether she was ever convicted is unclear, but if true, the massive embezzlement would suggest that Adam Air was a criminal enterprise from day one.
In the wake of the crash and the grounding of Adam Air, Indonesian regulators drafted a series of tough new rules for every airline in the country. But officials at the DGCA acknowledged that writing rules wasn’t the hard part: the hard part was finding inspectors who couldn’t be bribed. As long as a bit of well-placed cash could buy a regulatory violation, those precious few who really cared about safety would always find themselves fighting a losing battle.
In its final report on the crash of Adam Air flight 574, the KNKT made a number of important recommendations, many of which eventually found their way into the rulebooks. But despite this effort, it’s not clear that Indonesia’s aviation industry works any differently now than it did in 2007. In fact, although the rate of accidents has marginally decreased, plenty of signs suggest that things are fundamentally the same. In January 2021, 14 years almost to the day after the Adam Air crash, another 737 flying for another Indonesian budget carrier plunged into the sea with the loss of all 62 passengers and crew. Although the investigation into the crash of Sriwajaya Air flight 182 is still in its early stages, the known facts suggest an eerily similar sequence of events: following takeoff, a faulty autothrottle with a history of unaddressed problems caused one engine to stick at high power, leading to an uncommanded roll to the left. For some reason — we don’t yet know why — the pilots didn’t react until it was too late, by which time the plane had rolled upside down and started diving toward the ocean, falling 10,000 feet in just 20 seconds. None of those on board survived. In light of this latest disaster, the question therefore has to be asked: was anything learned from the crash of Adam Air flight 574? If an almost identical accident can happen in 2021, we must conclude that the answer is no.
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