Japan Airlines Flight 123 — The aviation’s world Titanic.

Japan Airlines Flight 123 was a Boeing 747SR passenger flight that crashed on August 12, 1985, at Mount Osutaka, in Gunma Prefecture, Japan. The aircraft, a Boeing 747–146SR, suffered a catastrophic failure of its rear pressure bulkhead, which caused the tail section to separate from the rest of the aircraft and the plane to lose control. The crash resulted in the deaths of 520 people, making it the deadliest single-aircraft disaster in aviation history at the time.

The flight took off from Tokyo’s Haneda Airport at 6:12 PM local time, bound for Osaka International Airport. At around 6:54 PM, the aircraft’s tail section suffered a catastrophic failure, causing the tail to separate from the rest of the aircraft and the plane to lose control. The aircraft crashed into Mount Osutaka, killing all 15 crew members and 505 of the 509 passengers on board. Only four people survived the crash. The four people who survived were Hiroki Yoshizaki and Mikiko Yoshizaki, a mother and daughter duo, Yumi Ochiai (26), and a flight attendant who was not on duty at the time of the accident, and Keiko Kawakami (12).

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.

The investigation into the crash revealed that the cause of the accident was a faulty repair made to the aircraft’s tail section several years earlier. The repair had not been done properly, and over time, the pressure from the aircraft’s hydraulic system had caused the bulkhead to weaken and eventually fail. The investigation also found that Japan Airlines had not properly maintained the aircraft and had not properly trained its maintenance staff. I attach below a picture of the moment when the oxygen masks fell.

The crash of Japan Airlines Flight 123 had a significant impact on the aviation industry and led to numerous changes in aircraft design and maintenance procedures. It also highlighted the importance of proper training and maintenance for airline staff and the need for thorough and careful inspections of aircraft. The disaster serves as a reminder of the importance of ensuring the safety and reliability of aircraft, and the consequences of failing to do so.

A picture of the plane was taken at 6:47, 9 minutes before the moment of impact, and it shows us that the vertical stabilizer really came off.