Today, we are going to have a close look at world’s deadliest aircraft crash involving just 1 aircraft – Japan Airlines Flight 123 crash. How a 7 year old mistake took the lives of more than 500 people? Lets take a deep dive into the incident.
Japan Airlines Flight 123 crash
On 12th August 1985, a Boeing 747 operated by Japan Airlines crashed in Ueno Village of Tano District in Japan. This incident is considered as the deadliest incident in the history of Civil Aviation involving one aircraft. The crash resulted in death of 520 people.
Aircraft
The aircraft involved in this incident was a Boeing 747 registered as JA8119. It was delivered to Japan Airlines in February 1974. The aircraft was identified with Manufacturer Serial Number MSN 20783 and Line Number 230. Pratt & Whitney engines powered the Jumbo jet. It had more than 25,000 flight hours and 18,800 takeoff and landing cycles. Before this 1985 incident, the aircraft was involved in 2 minor incidents. While one is the cause of the 1985 mishap, other one is unrelated. Lets have a closer look at both the previous incidents, then we will jump onto the major one.
Previous incidents with the aircraft
4 years after the delivery of the aircraft, in June 1978, JA8119 was operating flight from Tokyo to Osaka as JAL115. Upon landing at Osaka International Airport Runway 32L, the aircraft bounced heavily. To control the aircraft, pilots pitched the aircraft up as a result of which the tail struck the ground. This tail strike resulted in opening the aft pressure bulkhead. It was repaired but the mistake during the repairing was the one and only reason behind the 1985 mishap.
One more incident in which JA8119 was involved occurred in August 1982. During landing at Chitose Airbase, the aircraft Engine number 4 hit the runway due to poor visibility. This was repaired and the aircraft was again operational.
Crew and Passengers
The information about the cockpit crew is available in the following table :
| Rank | Name | Age | Total Hours | Hours on B747 |
| Captain | Masami Takahama | 49 | 12,423 hrs | 4,842 hrs |
| First Officer | Yukata Sasaki | 39 | 3,963 hrs | 2,655 hrs |
| Flight Engineer | Hiroshi Fukuda | 46 | 9,831 hrs | 3,846 hrs |
Apart from the deck crew, there were 12 Cabin crew onboard the aircraft. Looking at the numbers, one can say that the cockpit crew was very experienced. The captain also served as a Training Instructor. All crew members belonged to Japanese nationality.
Talking about passengers, there were 509 of them in total. 487 Japanese, 4 Hong Kong national, 2 Italian, 3 South Korean, 6 American, 3 Indian and rest from other countries.
About the incident
On August 12th 1985, the aircraft was preparing for takeoff from Tokyo Haneda Airport to Osaka International Airport. It landed from Chitose Airbase 2 hrs ago. The aircraft took off from Tokyo Haneda. 12 minutes into the flight, when the aircraft was climbing, it suddenly underwent rapid decompression. As a result of this, the ceiling of rear lavatory came down. Due to this structural failure, all four hydraulic lines got ruptured. The aft fuselage was damaged, which resulted in unsettling of the vertical stabilizer. The featured image on this article clearly shows how the vertical stabilizer was missing.
Absence of vertical stabilizer directly means that the pilots had no control on the directional stability of the aircraft. The stabilizer is normally connected to the rudder, which pilots controls from their feet to control yaw of the aircraft.
Total loss of control
Just after the unsettling of Vertical stabilizer, the aircraft went into an uncontrollable condition. The captain informed the Tokyo Air Traffic Control Tower that the crew is declaring emergency and requested vectors to return to Haneda Airport. The ATC approved the request and directed the aircraft to turn right to 090 degrees. At this time, the aircraft got first bank angle warning as it entered a right hand bank of 40 degrees. When captain tried to counter the bank, he was unsuccessful as the stabilizer was missing. Due to this, the aircraft was not following the path provided by the Air Traffic Control Tower. When ATC asked the captain, he replied that the aircraft is uncontrollable.
The ATC even gave an option to land at Nagoya Airport, which was 72 nautical miles away. But the captain declined and intended to return to Haneda. At this moment in time, the aircraft had entered in a pattern. The pressure fluid was gone because of the rupture. The aircraft enters a nosedive and gains airspeed. Due to airspeed, the aircraft gains lift and stays. Then stalls and again enters in a nosedive. The aircraft entered into Dutch roll, means it was yawing right and banking left, and then yawing left and banking right.
Gaining limited control
The only way to control the aircraft in this situation is that use your engines and flap configurations. Flaps are the surfaces attached to the wings, which increase or decrease the surface area of the wing as required to produce drag or generate lift. The crew gained limited control of the aircraft by using differential thrust. This means that thrust on one engine is more than the other. The pilots were expecting that by doing so, they will try to somewhat stabilize the aircraft and land at Haneda Airport. Well, they were able to stabilize the aircraft.
But the situation became mess when they lowered the landing gear. Landing gear produces additional drag on the aircraft surface and hence, the minimum control deteriorated. Just after this, the flight engineer asked the captain if speed brakes will be needed. The query was left unanswered by the captain as he was busy fighting with the controls of the aircraft.
Japan Airlines Flight 123 Crash
At 06:47 PM, the aircraft was totally uncontrollable. On the left of the aircraft were mountains. Despite trying their best to turn towards right direction, the aircraft kept turning left. The captain realized the situation and said – “This maybe hopeless”. At around 8,000 feet, the aircraft stalled. To counter this, the captain increased engine thrust. The aircraft started an uneven climb. To prevent chances of another stall, the captain reduced the flaps to 5 units. As hydraulics were not working, the crew was using an alternative electric system to power the flap system. The captain then asked for flaps 10 and after 1 minute, to 25. As a result of differential thrust, the aircraft went into a right hand bank of 60 degrees. The aircraft nosedived and Ground Proximity Warning System (GPWS) got activated.
1.4 kilometers away from Mount Mikuni, the aircraft Engine Number 4 struck the trees on a ridge. Then, the right wing impacted the ridge. Soon after the impact, the aircraft exploded. Lives of 520 people gone within a span of minutes.
What caused Japan Airlines Flight 123 crash?
Now, lets talk about the reason behind the crash. If you are reading this article sincerely, you would know that I have already told the reason of the crash. The roots of this crash goes all the way to 7 years ago. In June 1978, this aircraft experienced tail strike at Osaka International Airport. This resulted in opening of aft pressure bulkhead. The Boeing team repaired the aircraft but made one mistake.
Boeing approved methods says that to repair a damaged bulkhead, there needs to be 3 row of rivets with one continuous splice. The Boeing repairing team, in case of JAL B747 cut the middle rivet and covered it with 2 parallel splices. This cutting reduces the effectiveness of one of the rows of rivets. As per investigation, this was bound to fail after 11,000 pressurization cycles. And it failed, which resulted in death of more than 500 innocent people.
Conclusion
An aircraft crash happens because of 2 reasons – either pilot error or mechanical error. A crash does not occur because of one event. But there are multiple chain of events, which results in a major mishappening. In this case, a 7 year old mistake from the Boeing repairing team took the lives of 500+ people. Japan Airlines President Yasumoto Takagi resigned. A maintenance engineer and a flight engineer associated with this incident committed suicide. The daughter of the captain is now a flight attendant with Japan Airlines.
End.
.png){kind=link}
.png){kind=link}
.png){kind=link}
.jpg){kind=link}
