Fire on the Mountain: The crash of Japan Airlines flight 123
Tags: Japan, Aviation

It doesn’t take a trained mechanic to understand why the splice, as constructed, would be a problem. In fact, using only one row of rivets where two were required reduced the strength of that joint by 70%. The 0.9-millimeter thick bulkhead skin has to accommodate a large structural load whenever the passenger cabin is pressurized during climb, and this load is transferred all around the bulkhead via the rivets connecting each section to the one next to it. But the bulkhead, like a chain, is only as strong as its weakest link. With each pressurization cycle, a force of 8.9 psi was applied to the bulkhead and then removed — a force sufficient to crack the weak splice section where the single row of rivets intersected the bulkhead skin. These cracks grew imperceptibly with every flight, slowly creeping toward each other across the surface of bulkhead.

The aft pressure bulkhead in its manufactured state is highly resistant to fatigue — in fact, it was designed to last longer than the airplane itself. As such, inspections of the bulkhead were mainly concerned with detecting corrosion associated with water leakage, a problem which had brought down at least one airplane of a different type in the past. In contrast, no serious fatigue of the bulkhead skin itself had ever been observed, and it was therefore not afforded any special attention during structural inspections. A cursory overview of the back side of the bulkhead was carried out at every 3,000-hour “C-check,” but the cracks on JA8119 remained too short to be detected visually for several years after they began to grow.

The aft pressure bulkhead of a Boeing 747, viewed from inside the pressurized area. (Melanie Lee)

The seventh and final C-check performed after the bulkhead repair came in December 1984, at which time the cracks are thought to have reached 10 millimeters in length. But studies have shown that inspectors will visually detect as few as one in ten such cracks. Even with several cracks present, there was never any guarantee that the inspector would spot them. More advanced inspection techniques could have detected the cracks, but these techniques were not used on the bulkhead because the probability of its failure due to fatigue was thought to be extremely remote.

Indeed, JA8119 passed through its December 1984 C-check without anyone realizing that its aft pressure bulkhead was a ticking time bomb. By August of the following year, the bulkhead had accumulated over 12,000 flights since the repair, and it was close to the breaking point.

◊◊◊

The 12,319th flight since the repair was to be Japan Airlines flight 123 on the 12th of August 1985. The late afternoon flight was almost fully booked: out of the plane’s 520 passengers seats, 509 were filled, which in addition to the three pilots and twelve flight attendants brought the total number of people on board to 524. In command of this vast passenger load was 49-year-old Captain Masami Takahama, an experienced instructor captain with 12,400 flight hours. Today he would be sitting in the first officer’s seat, because he was training 39-year-old First Officer Yutaka Sasaki to become a captain himself, and thus Sasaki was sitting in what would normally be the captain’s seat. Finally, rounding out the cockpit crew was 46-year-old Flight Engineer Hiroshi Fukuda.

Photos of the pilots of Japan Airlines flight 123, arranged from left to right by descending order of rank. (Source unknown because I can’t read it)

With First Officer Sasaki at the controls, flight 123 took off from Tokyo’s Haneda Airport at 18:12 local time for its short, 54-minute hop to Osaka. The brief flight called for a cruising altitude of just 24,000 feet, well below the levels where Boeing 747s will typically cruise, but high enough to create a large pressure differential between the inside and outside of the plane.

As flight 123 approached its cruising altitude some twelve minutes after takeoff, the pressure differential increased to the point that the fatally compromised aft pressure bulkhead could no longer hold itself together. The skin ripped open along the joint between the repaired section and the original bulkhead, and within milliseconds the pressurized cabin air blasted through the gap with tremendous force. The bulkhead broke into several pieces as a wall of air rushed backward into the unpressurized tail section, which was not designed to withstand such a pressure spike. Within moments of the bulkhead failure, the pressure wave blasted off a massive section of the aircraft’s tail, including the tail cone, the majority of the vertical stabilizer including the rudder, the auxiliary power unit, and several other critical structural components and control systems. A loud explosion rocked the plane and a powerful wind tore loose everything that wasn’t tied down, propelling papers and napkins and magazines back toward the hole as the inside and outside pressure violently equalized. Near the rear galley, ceiling panels tore themselves from their mountings and disappeared backward into the void. White fog suddenly filled the cabin as the water vapor in the air condensed instantaneously.

A detailed diagram of how the tail broke apart. Art by Matthew Tesch in Macarthur Job’s Air Disasters Vol. 2.

As soon as the explosive decompression occurred, the oxygen masks dropped in the cabin, and an automatic announcement began instructing the passengers on how to use them. Flight attendants rushed to help the passengers put them on. So did Yumi Ochiai, an off-duty Japan Airlines flight attendant traveling as a passenger, who got up from seat 56B to render assistance.

In the cockpit, the pilots heard the bang and felt the explosive decompression. “Something exploded?” someone exclaimed, shouting over the sudden noise.

“Squawk 77!” Captain Takahama said, switching their transponder to broadcast code 7700, the universal emergency signal. He then called Tokyo air traffic control and announced, “Tokyo, JL 123, request immediate… uh… trouble. Request return back to Haneda!” The controller quickly authorized them to turn right on a heading of 090˚ to return to the airport.

But Flight Engineer Fukuda had already spotted a much bigger problem: they were losing hydraulic pressure. The 747 had four independent hydraulic systems, but all of them broadly ran through the tail, because that’s where most of the flight controls are located. When the rudder control units and the APU departed the airplane, all four hydraulic systems were severed, and the hydraulic fluid quickly began leaking away. “Hydraulic pressure has dropped,” Fukuda said, warning the pilots of the growing problem.

With his hydraulic pressure slipping away, First Officer Sasaki was finding it increasingly difficult maintain the correct bank angle while turning back toward the airport. “Don’t turn it so much, it’s manual!” said Captain Takahama. “Turn it back!”

“It doesn’t turn back!” Sasaki exclaimed.

“Hydro all out?” Takahama asked.

“Yes!” said Fukuda.

Air traffic controllers could see that flight 123 had only made it half way through the 180-degree turn back to Haneda, and was now flying north. The controller asked the crew for the nature of their emergency, but there was no reply.

A photo taken by a passenger inside the cabin of flight 123 after the explosive decompression. Everyone in this photo, including the cameraperson, perished in the crash. (Original photographer unknown)

The loss of hydraulic pressure to the pitch controls had by now caused the plane to enter a phugoid cycle. In a phugoid cycle, a descending airplane gains speed until it starts to pull up by itself, entering a climb, which in turn causes it to lose speed until it heels over and enters a descent again (see below animation). In the case of flight 123, the plane quickly embarked on a phugoid motion with a 90-second period, an amplitude of 3,000 to 5,000 feet, and a pitch angle varying between 15 degrees nose up and five degrees nose down.

Simultaneously, the loss of at least 55% of the vertical stabilizer, including the rudder, introduced a component of Dutch roll on top of the phugoid cycle. In a Dutch roll, a plane without lateral stabilization starts to behave like a fishtailing trailer on the highway, rolling and yawing from side to side with a regular period. Following the separation of the stabilizer, flight 123 experienced a Dutch roll with a period of 12 seconds, during which it would roll fifty degrees to the right, then fifty degrees to the left, before repeating the cycle over and over again.

The combined phugoid and Dutch roll caused the plane to fly like a ship on a storm-tossed sea, rising and falling, rolling and plunging, swaying back and forth as it staggered forward, unstable on every axis of motion. The wild, rollercoaster-like swaying struck fear into the passengers and pilots alike. The crew tried desperately to dampen these extreme motions, but with all the hydraulic fluid now gone, their controls were completely ineffective.

This animation from the TV show “Mayday” approximates how the plane was flying. Note that the actual phugoid period was 90 seconds, considerably slower than this animation. (Mayday/Cineflix)

As the plane continued uncontrollably pitching and rolling, the crew resorted to the one thing they could still control: the engines. But trying to stabilize the plane using the engines alone would be a daunting task. In theory, it was possible to turn the plane using asymmetric thrust: accelerating the engines on one side while decelerating the engines on the other would cause the plane to turn in a particular direction. It was also theoretically possible to moderate the phugoid cycle by accelerating when the plane started to dive and decelerating when the plane started to climb. But to do both at the same time was impossible, because changes in engine power, especially asymmetrically, tended to exacerbate the Dutch roll; and if engine power was held steady to dampen the Dutch roll, this would exacerbate the phugoid motion. Furthermore, in the chaos of the emergency, the pilots had failed to put on their oxygen masks, and they began to suffer from hypoxia as the plane hurtled along at between 20,000 and 25,000 feet. Deprived of oxygen, their brains struggled to make sense of what was happening and what they needed to do about it, and for several minutes they became little more than passengers, carried along by the cold laws of aerodynamics.

How a Dutch roll works. (Roberto Merino-Martinez)

Confused as to why flight 123 was not turning back toward Haneda, the controller decided to give the crew more options, offering to guide them into Nagoya instead. But the pilots declined, insisting that they were returning to Haneda. Sensing that the crew were struggling to communicate clearly in English while under pressure, the controller allowed the conversation to switch to Japanese.

Meanwhile, the pilots kept trying to figure out what had gone wrong. “Is it to the rear?” Flight Engineer Fukuda asked, apparently talking to a flight attendant on the interphone. We only have his side of the conversation. “What has been broken? Where? So, it’s the baggage compartment. The furthest to the rear. Yes, I understand.” Possibly turning to the pilots, he said, “Listen, the baggage in the baggage compartment, the very rearmost part. The stowage space for baggage has collapsed, I think we better descend.” But the pilots had been trying to descend for several minutes, without success. Fukuda may have been too hypoxic to understand this.

It was only now, ten minutes into the emergency, that the pilots remembered to don their oxygen masks. By this time some of the passenger masks were starting to run out of oxygen, causing panic in the cabin. But in the cockpit, the oxygen helped the pilots regain their judgment and motor skills, and with some well-timed changes to engine power they managed to cut the amplitude of the phugoid cycle in half. Around this time Flight Engineer Fukuda called Japan Airlines to seek advice. An indicator was telling him that the rearmost exit door on the right side was open. “Listen, right now the R5 door has broken!” he said over the phone, thinking that the missing door could have somehow led to their difficulties. “Right now we’re descending!”

The path of flight 123 after the onset of the emergency. (BBC)

But in fact they were not descending. Still hurtling up and down between 20,000 and 22,000 feet, the plane strayed further and further inland, heading away from all major airports. On the ground, an eavesdropper listening to the air traffic control frequency must have caught wind of the unfolding emergency, because Japanese TV stations began to cut into scheduled programming with news that a 747 was in trouble. One station even patched through a live telephone conversation with a man watching the plane from the ground in real time as it passed near Mount Fuji.

In the cockpit, Captain Takahama and First Officer Sasaki fought to put the plane into a descent, desperately shouting at each other as they tried to stop the phugoid cycle: “Lower the nose!” “Nose up!” “Power!” In an effort to restore some stability to their flight path, Flight Engineer Fukuda lowered the landing gear. The resulting drag moderated the pitching motion but decreased lateral stability, making it harder to control the Dutch roll. Using differential thrust, the pilots finally managed to initiate a right turn toward Haneda, but they couldn’t stop turning right once they had started; the 747 made a steep 360-degree descending loop over the town of Otsuki, losing 5,000 feet in the process. Mount Fuji, three thousand feet below them, flashed across the windows of the terrified passengers.

A photo taken by a witness on the ground shows flight 123 missing its tailfin. (Japan Aircraft Accident Investigation Commission)

By the time flight 123 straightened itself out, it was down to 15,000 feet and heading east toward Haneda. But this fleeting moment of control was but an illusion. The 747 soon slipped into a left turn and climbed steeply, prompting ATC to ask if they had regained control yet.

Takahama replied, “Japan Air 123 — uncontrollable!” To his fellow flight crew, he added, “This may be hopeless!”

“The hydraulic quantity is all lost!” said Fukuda.

“It’s uncontrollable!” Takahama repeated.

Without warning, the plane entered another terrifying dive, losing thousands of feet in less than a minute. Mountains to the north of Mount Fuji loomed in the near distance as flight 123 fell to an altitude just 5,000 feet, lower than many of the surrounding summits. “Hey — a mountain!” Captain Takahama shouted. “Turn right! Mountain! Take control, right turn! We’ll hit a mountain! Max power!”

As if on cue, the 747 ascended back to 8,000 feet. The plane lost so much speed during the climb that the stick shaker activated, warning of an impending stall. “Oh no!” Captain Takahama shouted, “Stall! Max power, max power!”

A desperate battle then ensued to keep the plane from descending into the mountains. Captain Takahama tried his best to command when to move the throttles, endlessly shouting “Power!” “Lower the nose!” “Raise the nose!” “Max power!” as the plane repeatedly climbed, stalled, dived, and climbed again. But the engines don’t respond to thrust commands instantaneously, and it proved impossible to match their inputs precisely enough to regain control. The pilots tried repeatedly extending and retracting the flaps to increase and decrease drag, and therefore speed, but the flaps responded even more slowly than the engines. For several minutes the cockpit was filled with shouts of “Nose up!” “Nose down!” “Flaps up!” “Flaps down!” “Power!”

Illustration of the flight path by Matthew Tesch in Macarthur Job’s Air Disasters Vol. 2.

The Tokyo air traffic controller gave the crew their position — 102km northwest of Tokyo — and flight 123 acknowledged. This was the last anyone heard from the stricken plane. The crew ignored all further transmissions as they fought to keep the 747 above the mountaintops. Witnesses on the ground in the rugged mountainous region between Gunma and Nagano prefectures saw the plane swooping up and down among the peaks; one took a photo, capturing the silhouette of the plane with its tailfin conspicuously missing. Another witness who caught sight of the plane later said it was flying “like a staggering drunk,” lurching from side to side and up and down. On board the plane, passengers braced for the inevitable impact in various ways. Flight attendants tried in vain to keep people calm. At least one person took photographs of the inside of the plane, showing the oxygen masks hanging down over the crowded rows. Many wrote notes to loved ones on whatever paper they could find:

“To think that our dinner last night was the last time!”

“There’s little oxygen, I feel sick. Inside the plane, voices are saying ‘let’s do our best.’”

“Please look after the children.”

“The plane is turning around and descending rapidly. I am grateful for the truly happy life I have enjoyed until now.”

“I’m scared. I’m scared. I’m scared. Help me. I don’t want to die.”

A note written in a memo book aboard the doomed flight by Hirotsugu Kawaguchi, 52, to his wife and children. (Japan Bullet)

The crew fought until the very end; at no point did they give up, although they must have known their efforts were hopeless. Banking 50 degrees to the right, the 747 dipped behind a descending ridge of Mount Osutaka; this was the last anyone saw of the plane. In a steep, spiral turn, flight 123 plunged downward toward the mountain, reaching a descent rate of 18,000 feet per minute and a right bank of 80 degrees. “Raise the nose!” Captain Takahama kept shouting. “Raise the nose! Power!”

“SINK RATE,” said the ground proximity warning system. “WHOOP WHOOP, PULL UP! WHOOP WHOOP, PULL UP!”

As the right bank lessened, the plane started pulling out of the dive, but it was too late. The cockpit voice recorder captured Captain Takahama yelling, “It’s the end!”

/u/FACR_Gohan created this detailed animation of the crash of Japan Airlines flight 123 using real flight data. It is by far the most accurate video reconstruction of the accident. Watch the full reconstruction here: https://www.youtube.com/watch?v=PxT51aeUaHQ

At 18:56 and 22 seconds, the crash began. The right wingtip and number four engine struck trees on a ridgeline and were sheared off. The plane continued forward and struck another ridge right wing down, digging a deep trench through its summit. Debris tumbled down the mountainside as the wing disintegrated, but the 747 kept going, rolling over onto its back as it hurtled more than 500 meters across a ravine. Finally, the jet slammed upside down into the spine of yet another ridge, obliterating much of the aircraft in an enormous explosion that could be seen for miles. Huge pieces of the plane rolled down the steep slope into the ravine, knocking over trees and scattering burning debris over a vast area of ruined forest. After 32 minutes of terror, Japan Airlines flight 123 was down.

◊◊◊

At Haneda Airport and the nearby Yokota Air Force Base, controllers watched in horror as the fully loaded 747 disappeared from their radar screens. Several further attempts to contact the flight were made, all of them in vain. Just one minute after the crash, everyone’s worst fears were confirmed when a Japanese military aircraft reported “a huge burst of flame in the Nagano Mountains.”

Within minutes, a massive effort to find the crash site kicked into gear. The plane had gone down in a remote and rugged area inaccessible by road and out of the direct line of sight of potential witnesses in nearby villages, and no one knew exactly where to find its final resting place. But a crash site that large couldn’t stay hidden for long.

After hearing of the missing plane in the vicinity of its flight path, a United States Air Force C-130 managed to spot the burning wreckage of the 747 from the air around 25 minutes after the crash and informed Japanese authorities of the coordinates. They could see fire and debris strewn over a vast area, but little that was recognizable as part of an airplane. Over the radio, one of the crewmembers said, “I doubt if there will be any survivors.”

According to accounts by the C-130 crew, only made public years later, the Air Force offered to send a helicopter with rescuers equipped to descend to the wreckage, but the Japanese government never took them up on the proposition. Based on the terrain and the C-130 crew’s report, it was assumed that there could not possibly be any survivors, and in the absence of such urgency, local authorities preferred to organize the search themselves. It would prove to be a fatal miscalculation.

This was the sight which greeted the first aircraft to fly over the wreckage. (The Asahi Shimbun)

At 4:39 a.m., a Japan Air Self Defense Force helicopter circling over the night-darkened mountains became the next to spot the crash site, which stood out like a glowing scar high on the side of Mount Osutaka. The pilot reported flames “in about 10 spots over an area of 300 meters square,” but there was nowhere to put the helicopter down, and no sign of survivors. A Nagano Prefecture police helicopter flew over the site at 5:37 a.m. and reported much the same thing.

Meanwhile, a massive ground operation was taking shape in the nearby village of Ueno. During the hours after the crash, Japanese authorities had mobilized at least 8,000 people, 880 vehicles, and 37 aircraft to respond to the disaster, but so far none had actually reached the wreckage. That task would fall to a group of approximately 160 rescuers who assembled at Ueno Middle School during the night to prepare for an expedition to the crash site at the first light of dawn. The team departed at 6:30 a.m., initially driving up a disused logging road to the foot of the mountain, then continuing on foot up the steep forested mountainside for several kilometers, reaching the edge of the vast debris field sometime after 10:00.

The scene that greeted them could only be described as apocalyptic. Spot fires still burned amid a vast area strewn with tangled wreckage and the bodies of victims. Methodically searching through the widely scattered debris, they held little hope of finding anyone alive.

An early aerial view of the wreckage. The plane impacted the ridge upside down coming from the left. (Jiji Press)

Rescuers lift Keiko Kawakami into a helicopter for immediate transportation to hospital. (Source: probably NHK)

Then, as rescuers approached the remains of the tail section, which had continued over the ridge and tumbled into the ravine on the opposite side, someone spotted an unbelievable sight: a hand, raised feebly from amid the wreckage, waving for help. It was off-duty flight attendant Yumi Ochiai, still clinging to life amid the remains of what had once been row 56. Somehow, she had not only survived the crash but also lived through 16 hours overnight on the mountain waiting for rescue. In awe and disbelief, rescuers pulled her from the tangled debris and began administering first aid. But just moments later, there came a second miracle: hanging from the branches of a nearby tree, the rescuers found twelve-year-old Keiko Kawakami, the only survivor from her family of four, injured but alive. And not long after that, in what was left of row 54, they found two more survivors: 34-year-old Hiroko Yoshizaki and her 8-year-old daughter Mikiko, also seriously injured but alive. Word that survivors had been found spread like wildfire through the crowd of friends and relatives who had gathered in Ueno to await news of their loved ones. If these women had survived, then surely others had as well! But it was not to be. As they scoured the remainder of the wreckage field, the rescuers could find only bodies. Of the 524 people on board, just four had survived. All of them had been seated in the last seven rows.

Rescuers remove bodies from the scene of the crash. (The Japan Times)

From their hospital beds, the survivors shared their harrowing stories of the disaster. Hiroko Yoshizaki said she awoke in the wreckage after a terrible impact, only to find that her husband and seven-year-old daughter seated either side of her were dead. But when it seemed she would pass out from the pain, she heard Mikiko telling her to stay awake, that if she fell asleep she would die. Throughout the night Mikiko never stopped telling her mother not to fall asleep, which Hiroko credited with saving her life.

Yumi Ochiai gave the most chilling testimony of all. After helping the other flight attendants tend to the passengers, she saw that they were heading into the mountains, so she returned to her seat and fastened her seatbelt. Terrified passengers surrounded her, some of them crying, others frantically writing notes to their loved ones. Then the plane dropped sharply, she felt several impacts, and then the cabin ripped itself apart around her, throwing her through a churning cascade of seats and cushions and cabin panels as the tail section tumbled down the mountainside. After this washing machine of debris came to a stop, she found herself trapped between two collapsed seat rows, unable to move.

And then, as night fell around her, she said:

“After the crash, I heard harsh panting and gasping noises from many people. I heard it coming from everywhere, all around me. There was a boy crying ‘mother.’ I clearly heard a young woman saying, ‘Come quickly!’ Suddenly, I heard a boy’s voice. ‘Okay! I’ll hang on!’ he said. It sounded like the voice of a boy of about school age. In the darkness, I could hear the sound of a helicopter. I couldn’t see any light, but I could hear the sound, and it was quite near, too. We will be saved, I thought, and waved frantically. But the helicopter went farther away. ‘Don’t go!’ I waved desperately. ‘Help!’ But it faded. I could no longer hear the voices of the boy or the young woman.”

Yumi Ochiai had revealed a terrible truth about the crash of Japan Airlines flight 123: many more people had survived the accident, only to die on the mountainside waiting for rescue. Initial examinations by doctors confirmed her story: several of the victims appeared to have suffered injuries that would have been survivable if help had arrived sooner.

In this aerial photo, the tail section can be seen in the bottom of the ravine on the left, where it rolled after the crash. This is where the survivors were found. (Source unknown because I can’t read it)

Meanwhile, Japan’s Aircraft Accident Investigation Commission launched a massive inquiry into the cause of the disaster, which was (and remains) the worst aviation accident in history involving only one aircraft. Heading the investigation was Japan’s Minister of Transport, who coincidentally had flown into Tokyo that evening on JA8119 just minutes before it took off on its final flight.

In accordance with international rules, investigators from the US National Transportation Safety Board and from Boeing also hurried to Japan from the United States to participate in the investigation. But when they arrived, they found that the inquiry was struggling to get underway. The priority of Japanese authorities was to take care of the victims’ families and recover the bodies, and investigators weren’t even allowed to visit the site for several days. When they finally arrived, local police told them that they couldn’t take anything away from the site, because the police were conducting their own investigation, which they considered a higher priority! It took weeks to work out the conflicts between various agencies, and it would be more than a month before they were able to remove the wreckage from the mountainside for closer examination.

Military personnel work at the crash site. (Robert Wallis)

However, investigators knew from day one that whatever went wrong, it happened in the tail section. Just hours after the crash, a boat discovered a large chunk of the 747’s vertical stabilizer floating on the surface of Tokyo Bay and hauled it in to port. Furthermore, a grainy photograph taken by a witness during the last minutes of the flight clearly showed that the tailfin was missing. Initial suspicion about the status of the R5 door, derived from the flight engineer’s report over the radio, was quickly dispelled when investigators found the door in the wreckage at the crash site, still bolted into its frame. Most likely the “door open” light had illuminated due to warping of the rear fuselage, tricking Flight Engineer Fukuda into thinking it was the source of the problem.

The remains of the tail section in the bottom of the ravine. (Bureau of Aircraft Accidents Archives)

An examination of the aft pressure bulkhead revealed the smoking gun: at the junction of the original bulkhead skin and the spliced section, one row of rivets had been used where two were required. Metallurgical analysis of the fracture surface showed conclusively that the skin had failed in fatigue right along the row of rivets over the course of many pressurization cycles. When the bulkhead split open, air rushed backward into the tail with sufficient force to blow it right off the plane, taking with it the critical hydraulic lines that allowed the pilots to move the control surfaces.

Investigators arranged a series of simulator tests with representative crews to see if a safe landing could have been made given the same failures which occurred on flight 123. Even without all the extra noise, the lack of oxygen, and the fear of death, and with some foreknowledge of the nature of the emergency, none of the five crews in the experiment were able to land the plane. All eventually abandoned attempts to line up with the runway and chose to ditch in Tokyo Bay instead, and one got to 30 feet above the water with wings level, a relatively sedate descent rate of 500 feet per minute, and a speed of just under 200 knots. But at that speed, with no way to flare for touchdown, the plane surely would have cartwheeled on impact with the water and suffered a catastrophic breakup, resulting in widespread fatalities. It was thus considered that the crew of flight 123 never had any chance of making a safe landing — they were doomed from the moment the bulkhead failed.

The devastation caused by the impact of the 747 against the ridge is difficult to fathom. The area is visibly scarred to this day. (The Asahi Shimbun)

The nature of the failure illustrated a loophole in the failsafe design of the Boeing 747, and indeed every other airliner: the design was only failsafe so long as it was repaired and maintained properly. As manufactured, the bulkhead should not have failed within the lifetime of the aircraft, given proper inspections for water-related corrosion. The math still bears this out. But when the faulty repair compromised the bulkhead’s resistance to failure, none of the other checks and balances, such as inspections, were able to adjust to the new reality that the bulkhead was no longer failsafe. Everything was designed around the assumption that the bulkhead would remain in the “as manufactured” condition.

A great example of this problem was the pressure relief door inside the tail section. This door was meant to open in the event that pressurized air entered the tail, preventing the pressure from exceeding the design limits of the aft fuselage. Evidently, in the case of flight 123, it didn’t work. Japanese investigators believed that the door had opened as designed, but that it was simply too small to handle the amount of air that entered the empennage when the aft pressure bulkhead failed. According to Boeing, the door was designed to handle what they thought was the most likely bulkhead failure mode: the puncture of the skin within a single “bay” within a single section. For this purpose, they contended, it was entirely adequate. But the failure on Japan Airlines flight 123 occurred on the joint between two sections across several such “bays,” and was able to expand down the remainder of the joint in both directions, opening up a hole several meters long within a fraction of a second. So much air rushed through this hole that the pressure relief door could not vacate air quickly enough to reduce the pressure inside the tail before the structure failed under the load. However, many of the victims’ families, and some experts, contend that the simpler explanation is that the door didn’t open, and that Japan Airlines must have made some kind of maintenance error that prevented it from opening normally.

Another aerial view of the entire crash site, showing the main wreckage area and the tail section in the ravine. (The Asahi Shimbun)

But the comprehensive 332-page crash report published by the Aircraft Accident Investigation Commission did not answer one critical question: why? Why did the Boeing engineers who made the repair commit this horrendous error? Not only did the investigation fail to answer this question, it doesn’t appear that they ever asked it in the first place. A criminal investigation did result in charges against 20 members of the team which carried out the repair, but the charges were dropped after Boeing refused to cooperate, citing the US policy of not charging aviation personnel involved in accidents unless there is intent to do harm.

The lack of answers in this regard has led to an enduring belief among the Japanese public that Boeing wasn’t the real culprit. Boeing is rather accustomed to being used as a punching bag whenever one of its planes crashes — sometimes rightfully so, but often without cause. However, in the case of flight 123, the opposite happened: many in Japan believed, and still believe, that Boeing took the blame in order to protect its most prolific buyer of 747s. Japan Airlines, they say, is the company that really botched the repair.

Flight 123’s reconstructed aft pressure bulkhead on display in the JAL museum. (FlightGlobal)

Indeed, Boeing may have been deemed at fault, but in Japan, it was the airline that took the brunt of the fallout. The airline’s CEO immediately resigned. A Japan Airlines maintenance manager committed suicide soon after the crash to “apologize” for the disaster (some incredulous relatives suggested that maybe a Boeing manager should apologize the same way). Japan Airlines bookings fell by a third nationwide, and by more on the Tokyo-Osaka route. Airline employees were assaulted, spit on, and yelled at if they appeared in public in their uniforms. It took years for the airline to recover economically, and public trust in the company still hasn’t returned to its pre-disaster levels more than 35 years later.

A helicopter hovers over the wreckage the day after the crash. (Source unknown because I can’t read it)

The official report on the crash also tried to whitewash the mistakes made by Japanese authorities during the search and rescue operation. Despite the testimony of survivors and the apparently survivable injuries suffered by some of those who died, the official autopsy report listed the moment of impact as the time of death for all 520 victims, and the accident report claimed under the chapter on survival factors that everyone except the four survivors died instantaneously. The report then went on to say, “it is acknowledged that efforts to the maximum extent were made by every organization who participated in the activities.” Given the amount of contradictory evidence, this can only be considered a cover-up.

Ten years after the accident, the flight engineer of the US Air Force C-130 that found the crash site told military newspaper Stars and Stripes that United States air force personnel at Yokota Air Base could have gotten to the scene just two hours after the crash. The report claimed that by 9:05 p.m. a helicopter was already hovering over the crash site with two marines ready to rappel down to the wreckage, only to be called back to base, as the Japanese were said to be on their way. Although this story is often repeated in English-language media, it has never been independently verified.

Either way, the key factor in the decision to delay the rescue appears to have been the C-130 crew’s statement that they didn’t think there were any survivors. Believing there to be no particular urgency to get to the scene, Japanese authorities allegedly preferred to avoid the image of a foreign military being the first to respond to a domestic disaster. Another possible contributing factor may have been that Japanese bureaucratic structures are extremely risk-averse, and those managing the response were not keen on sending people blindly into the wilderness when evidence seemingly indicated that a rapid response was not needed. In either case, the result was that the Japanese who were said to be “on their way” turned out to be a massively over-equipped ground team that didn’t make it to the scene until twelve hours later.

The rear pressure bulkhead where it came to rest in the wreckage. (Kyodo News)

If there is one lesson to be drawn from this tragic failure, it’s that a rescue operation should always assume there are survivors until proven otherwise. Today, every search and rescue mission takes this to heart, and a miscalculation of this scale is unlikely to occur again.

Lessons were also learned in the areas of aircraft design and maintenance. Even before the cause of the crash was discovered, authorities ordered inspections to the tails of all Boeing 747s. Later, more concrete measures followed. The National Transportation Safety Board recommended that the tail of the 747 be redesigned to withstand a pressure spike caused by failure of the pressurized passenger cabin; and that if the tail were to fail anyway, that this would not cause the loss of all four hydraulic systems. In response to these recommendations, Boeing provided all 747 operators with a special cover that could be installed over the access hole at the base of the vertical stabilizer, which would prevent a breach of the aft pressure bulkhead from tearing off the tailfin. Boeing also launched a program of tests for structural elements to determine how they responded to undetected damage or improper repairs.

Relatives of victims visit the monument, erected at the crash site, listing the names of the 520 victims. (JIJI Press)

Today, the crash of Japan Airlines flight 123 still looms large in Japan’s public consciousness, and indeed the world’s. The accident has been the subject of numerous documentaries, movies, books, songs, and more. The sheer scale of the disaster, the 32-minute fight to survive, and the harrowing stories told by the tiny handful of survivors continue to captivate. As the Titanic is to the sea, so Japan Airlines flight 123 is to the air. We are drawn to heroism in the face of hopeless odds, hoping anew with each retelling that the pilots will find some way to save the plane, as we hope that Titanic will avoid the iceberg, knowing that they did not, that they could not, that the outcome is immutable. So many lives lost, an incomprehensible tragedy, and for what? Because one row of rivets was used where two were required. What a banal reason for such incalculable suffering. May we dare to hope that it will never be allowed to happen again.

__________________________________________________________

Join the discussion of this article on Reddit!

Visit r/admiralcloudberg to read and discuss over 190 similar articles.

You can also support me on Patreon.