38 years ago there was an accident that remains the most tragic single plane crash to this day. It is also one of the largest (in terms of number of victims) disasters in the history of aviation (in the record-breaking, tragic accident in Tenerife, two machines collided). As a result of the collision of a Jumbo Jet with a mountain, 520 people lost their lives.
12 minutes after take-off they heard an explosion. A moment later they lost control of the machine
It was August 12, 1985, the eve of the Japanese O-bon holiday, when millions of Japanese go to their homes or families. Japan AirLines Flight 123 was scheduled to be a routine flight from Tokyo to Osaka, Japan. A relatively short route (a little over 400 km long), according to the timetable it should take only 54 minutes.
This destination, despite the relatively short distance, was so popular that the Japanese airline Japan Airlines operated a Boeing 747-SR. A rather unusual version of the powerful transcontinental Jumbo Jet, specially adapted for short flights and frequent take-offs and landings. On the eve of the O-bon holiday, the machine was filled almost to the last seat. There were as many as 509 passengers willing to fly to Osaka.
The plane took off from the Japanese capital with a 12-minute delay, at 18:12. After a few minutes of flight, he was over Sagami Bay and approaching the cruising altitude of 7,300 meters. Exactly 12 minutes after take-off, however, the pilots heard a noise resembling an explosion. At the same time, an alarm sounded in the cockpit informing about the depressurization of the passenger cabin, and oxygen masks fell over the passengers’ heads.
There was a sudden decompression of the cabin, of which – as the aircraft’s systems did not inform about the causes of the failure – the crew in the cockpit were initially unaware of it at all. Worse still, the pilots quickly discovered that the machine was beginning to lose control. The response was immediate. The plane’s transponder was set to transmit code 7700 – the basic alarm signal informing ground control of the danger. After a while, the air traffic control tower in the capital of Japan was also contacted, asking for the possibility of turning around and making an emergency landing at the Tokyo-Haneda port (from which the pilots took off).
The controllers agreed and ordered us to head east towards the island of Izu Oshima (about 100 km south of central Tokyo), and then north towards Haneda Airport. However, the plane did not respond to the rotation of the steering wheel and began to behave unpredictably, heading northwest. Worse still, the machine began to descend and rise on its own by at least several hundred meters, drawing a shape similar to a sine wave in the sky. The behavior of the Boeing was completely incomprehensible to the pilots.
As the subsequent investigation showed, both the captain and the first officer failed to put on oxygen masks in time. Moreover, both pilots asked the flight engineer present in the cockpit several times whether there was a leak in the cabin, apparently unable to believe what had happened. Shortly after the alarm went off, the crew began to experience signs of oxygen deprivation, including body numbness and indecisiveness. Recorded conversations show that the pilots intended to put on masks, but – perhaps due to the effects of hypoxia – they never did so.
The controllers tried to help. The plane was detected by an American air base
The strange behavior of the machine and the incorrect flight direction were quickly noticed by controllers, who again contacted the plane’s crew, asking for confirmation of their intentions. Nine minutes after the failure occurred, the flight engineer noticed an alarm in the R5 (rear) door sensor and informed controllers that it may have fallen off, leading to cabin depressurization. Both traffic controllers and representatives of Japan Airlines, previously informed about the crisis, already knew that the situation was very serious.
The engineer also discovered zero pressure in the hydraulic system that normally allows pilots to control the control surfaces (i.e. the ailerons on the wings and the elevators and rudders on the tailplanes) in large planes such as the Jumbo Jet. This explained why the pilots could not control the machine. The lack of steering was also reported to the controllers. However, preparations were still underway at the Tokyo airport in the event of an emergency landing.
14 minutes after the failure, the pilots discovered that they could still maintain some control over the plane by properly adjusting the thrust of the engines. By increasing the power during the dive and reducing it during the climb, they managed to smooth out the flight a bit. By controlling the right and left engines independently, the pilots could also influence the direction of flight to some extent.
The crew was so absorbed in trying to control the powerful Jumbo Jet that they did not respond to calls from the US Yokota base controller, who managed to intercept Flight 123’s communications. The Americans tried at least twice to offer help, but their calls went unanswered.
Control lost contact with the plane’s crew. There was no way to avoid this mountain
Near Mount Fuji, Japan’s highest peak, the Boeing began a sharp dive, losing altitude at a rate of 900 meters per minute. The machine automatically headed into the mountainous terrain, and the pilots, already at an altitude of only about 2,100 meters, did their best to avoid the mountain peaks, only regulating the thrust of the engines. 25 minutes after the failure, the captain ordered their maximum power to climb higher (avoiding the mountains). When the nose of the machine rose too much, thrust was reduced to almost zero.
This only re-energized the previously suppressed “sinusoidal” flight of the aircraft. The pilots saved themselves by rapidly increasing the engine power again. Additionally, it was decided to extend the chassis using emergency (electric) systems (the hydraulic ones did not work). The legs and wheels extending beyond the plane’s outline create significant aerodynamic drag and allow for slightly greater controllability. The pilots also managed to extend the flaps, which increase lift and reduce speed.
However, all these treatments did not bring any special results. At 18:56, 44 minutes after take-off and 32 minutes after the failure, the plane hit the treetops on one of the hills and after a few seconds hit the slope of one of the mountains.
Rescuers arrived many hours too late. They did not expect any survivors
20 minutes after hitting the ground, the Japanese were contacted by the Americans from the Yokota base. The crew of an American C-130 Hercules transport plane flying nearby noticed a fire in the mountains, in a place where it could have caused a disaster. According to some reports, the Americans sent a rescue helicopter there, but the Japanese announced that they were conducting their own rescue operation, so the American rescuers were returned to the base.
The Japanese Self-Defense Forces helicopter was the first to reach the wreck. He reported detecting at least 10 sources of fire, but the mountainside was too steep to land. At the same time, the pilot of the machine stated that he did not see any survivors. It was dark a moment earlier, so rescuers from the Japan Self-Defense Forces, police and Coast Guard traveling by land did not expect any survivors, so they decided to set up camp on the way to the wreck and resume the operation at dawn.
Later it turned out to be a tragic mistake, due to which at least a few or a dozen people lost their lives. To the surprise of the rescuers, in the morning three people were found still alive near the wreck. It was a Japan Airlines stewardess who was on vacation, as well as a 34-year-old passenger and her 8-year-old daughter. Shortly afterwards, a 12-year-old girl was found in the crown of one of the trees and was brought safely to the ground. All four people had serious injuries, but they were the only survivors of the disaster. 505 passengers and the entire 15-person crew of the plane died.
According to the surviving stewardess, she heard the voices of at least several other people shortly after the crash, but they became silent over time. At the same time, she also heard the sound of a helicopter, but unable to move, she did not see it in the sky. Perhaps if the rescue operation had arrived earlier, more passengers could have been saved.
However, the rescue of the two women and two girls was hailed as a miracle, and a subsequent investigation showed that all four of them occupied seats in the last rows of seats, where the g-forces when they hit the ground were the least. This fact, combined with great luck, probably saved the lives of these four people.
It wasn’t the door that caused the disaster. The plane had no stabilizer
Initially, it was assumed that the disaster was caused by a leak in the R5 door, the failure of which was reported by the flight engineer during the dramatic flight. Only an inspection of the crash site showed that the sensor readings were incorrect. The door was found intact, attached to fragments of the plane’s fuselage. However, investigators were left without any clue for a short time.
During the investigation, a photo of the flying machine was found, taken by one of the witnesses from the ground. After digitizing and sharpening the photo, a model of a Boeing 747 was superimposed on it. It was discovered that the plane at the time the photo was taken was missing a fragment of the vertical stabilizer.
This element is located in the tail part of the aircraft and serves to stabilize the flight. The hydraulic control system cables also run inside the stabilizer (the movable part of the vertical stabilizer is responsible for the rudder, and the parts of the horizontal stabilizer are responsible for the elevator). The detachment of part of the fin broke the lines and caused a fluid leak (pressure drop signaled by the on-board engineer), which explains the sudden lack of steering and control over the machine.
It was the repair of the plane that contributed to the disaster. It was made by Boeing itself
The painstaking investigation also allowed us to trace the history of the machine and discover that it had undergone repair work a few years earlier. On June 2, 1978, the pilot of this 747, landing at the Osaka airport, raised the nose of the plane too much, causing the tail to rub against the runway. The damaged machine was taken to Boeing specialists, who found a breach in the structure of the tail and rear pressure bulkhead. The latter separates the pressurized (at high altitude) passenger cabin from the unpressurized part of the tail and is exposed to high forces.
It was learned that Boeing specialists replaced the damaged elements of the pressure bulkhead, securing them with one row of rivets, while the factory fastened them with two rows. The forces acting on the material and each of the rivets were twice as high as they should have been, which ultimately caused the pressure bulkhead to break and cause a sudden release of air, which tore a fragment of the vertical stabilizer. The pilots’ ability to keep the plane in the air without a stabilizer for over 30 minutes was considered an incredible feat. It was also found that such a plane could not land safely.
During the investigation, a number of experiments were carried out and when the mapped structure was subjected to similar forces, cracks were noticed gradually appearing. It was then calculated that the faulty protection should have failed after approximately 11,000 take-off and landing cycles. In fact, it endured 12,318 successful flights. The final evidence in the case were fragments of a torn pressure bulkhead found at the crash site and part of the fin of a powerful Jumbo Jet recovered from the waters of one of the Japanese bays. The last of the plane’s components (the oxygen mask) were found during road renovation near the crash site only in June 2022.
Source: Gazeta
Mabel is a talented author and journalist with a passion for all things technology. As an experienced writer for the 247 News Agency, she has established a reputation for her in-depth reporting and expert analysis on the latest developments in the tech industry.
