The Japan Airlines 123 Flights Engineering Essay

This study paperss the concatenation of events before, during and after the Japan Airlines 123 Flight, registered under JA8119. It evaluates the cause and effects of the factors before the fatal flight, and connects with the factors during the flight and after the flight, non burying, it besides offers possible recommendations to better the safety of the air power industry.

The chief cause of the flight ‘s decease, was really simple, merely a really common tailstrike incident which was non repaired to specifications stated by the maker themselves. It was further neglected after go throughing through a cheque by the care applied scientist himself, which should hold grounded the aeroplane. Alternatively, it went on to wing another 12319 rhythms before its life ended on 12th August 1985. During the flights it has gone through, continous rhythm burden had caused heavy metal weariness on the fix and the force per unit area bulkhead itself. Time after clip, it accumulated, the clefts eventually nucleated together in the aft force per unit area bulkhead. It ruptured the vertical stabilizer, along with it the bosom of the aeroplane, the Central Hydraulic Unit. It drained the plane of its blood which was the hydraulic fluids that control the primary systems. After losing control, and contending with it for 32 proceedingss it crashed into two ridges of Mount Takamagahara in Ueno, Gunma Prefecture, 100 kilometer from Tokyo.

Based on research and findings, the air power industry has improved so far, with the new Boeing care processs which include more rigorous cheques on fix spots, with new installing of alleviation valves.

However, to us, it is non plenty, we would urge every bit good to include newer criterions, such that to let lesser impermanent fixs to go through through review, make fulling up the empty infinite with more portion replacings. It may take a longer clip, but safety is maintained.



This study is to document and cast more visible radiation on the timeline, concatenation of events happening before and after the tragic flight of JA8119. It besides includes the alteration of air power criterions, and the proposal of ways to increase consumer safety in air power.

Background Information

15 old ages have passed, and many do non retrieve the tragic flight of JA8119 on Flight 123. It happened to be the most deadly single-aircraft accident in air power history. The concluding flight besides occurred on 12th August 1985 which was the Obon vacation period where the Nipponese return to their hometown for sing their ascendant ‘s Gravess. The victim was a Boeing 747-SR46, which carried 524 riders on board, for which merely 4 survived. It suffered mechanical failures 12 proceedingss into the flight and 32 proceedingss subsequently crashed into two ridges of Mount Takamagahara in Ueno, Gunma Prefecture, 100 kilometres from Tokyo. The clang site was on Osutaka Ridge near Mount Osutaka.

Up to today, it still remains as the most tragic incident, due to its high figure of casualties and the happenstance of the type of tradition besides happening during the period.

Due to this, It raised world-wide consciousness towards the dangers of air power, doing the Flight Aviation Authority to revise its care steps, and made the aircraft maker Boeing, to revise its design on all of its ill-famed 747 platforms.

Method of Investigation

Information extracted from an episode from National Geographic ‘s Air Crash Investigations/May Day Series, Episode 2 “ Out of Control ” , studies on Aircraft Safety alterations, an existent blackbox recording of the existent incident, and assorted paperss on the cause and effects of the clang.

Scope of Investigation.

It is broken down into 3 subdivisions consisting by and large the Pre-incident inside informations, which would incorporate the tailstrike incident which occurred 7 old ages ago, taking to the analysis improper repairs done, followed by the slack attitude the land crew took. The 2nd subdivision would the the Incident Details, which will document the concatenation of events which occurred in the rear force per unit area bulkhead, comprising of rivet failure, bulkhead failure, explosive decompression, taking to the hydraulic failure and the pilot mistakes. Followed on in conclusion by station incident inside informations, documenting the refusal of US military base aid from Tokyo, taking to the late deliverance attempts which resulted in more deceases, and the lessons learnt from this incident. Last, Our ain recommendation on what could be farther done.

Pre Incident Details

2.1 Tailstrike Incident

A Boeing 747SR was geting on 2nd June 1978 at Osaka Airport. The conditions in the country was non optimistic at all, with rain that merely ended, ensuing in utmost heavy fog. The pilot, was in the skies during that period had merely been approved to set down. Due to low visibleness, he could barely see what was in forepart, and relied on his instruments as steering points. By the clip, the height metre read 100 pess, he had realized that he was excessively close to the track. It caused him to deploy the flairs really sharply. It touched down, but due to the drawn-out flairs, it gained altitude and increased the angle of onslaught, which resulted it to set down on its tail on its 2nd touchdown. This is known as a tailstrike incident.

Figure 1 – Extent of harm on the tail of JA8119

2.2 Botched Repair

The tailstrike incident suffered by JA8119, resulted in issues that were non appealing at all. The rear bulkhead had assorted abrasions, but on a closer expression, there were clefts, and it was already unacceptable to be approved for flight intents. However, they had to make a impermanent fix on the bulkhead still, and they were non following prescribed stairss to make so. Boeing stated in their manual for these processs:

A Continuous doubler home base on the bulkhead itself.

Followed on with 3 rows of studs on each side.

This is to reenforce the bulkhead, such like what the aims of a impermanent fix should be. Alternatively, the accredited applied scientists of Boeing stationed at the airdrome did this:

Two doubler home bases cut out from a immense splicing home base

Two rows of studs on one side, Single row of studs on the other.

( Wikipedia, 31 August 2010 )

Figure 2 – The Actual Repair ( National Geographic, 2007, Air Crash Investigation [ Online ] , Season 3 Episode 3 Part 4, Available from: [ Accessed 23rd May 2010 ] )

All of this was done by the applied scientists so that It would suit nicely. Which would subsequently transport a serious effect of servere failure during flight.

2.3 Metal Fatigue

Metal weariness, described as structural failure caused by consistent rhythm burden, which would intend as emphasizing on portion throughout a drawn-out continous clip. This is necessarily caused by the jury-rigged processs done by the applied scientists in Osaka Airport, as stated, in the old factor.

Figure 3 – Leftoverss of the rear bulkhead after shearing off during flight. ( National Geographic, 2007, Air Crash Investigation [ Online ] , Season 3 Episode 3 Part 4, Available from: [ Accessed 23rd May 2010 ] )

Due to the nature of aircraft parts to travel through consistent rhythm burden, the doubler home base which was done as a spot fix to the rear force per unit area bulkhead, if done in right would ensue in utmost weariness. This was precisely what happened.

The loss of one row of studs due to this process had caused them to take much higher emphasis than normal, such that holding 2 rows with one row alternatively of 3 would administer the burden unevenly, doing the stuff to see different rates of weariness, as a consequence. This would be the chief causation factor for the during flight incidents.

Negligence of Ground Crew

Normally, after a care undertaking has been completed, a senior applied scientist would make a cheque on it. This is where partially the mistake had fell on. The senior applied scientist did a cheque on the splicing home base fix on the rear bulkhead shortly after. In the beginning, the applied scientist did non O.K. of the fix due to the nature of the home base and the stud arrangements, but looking at it as a impermanent fix, he signed off declaring the plane of its worthiness. ( JST Failure Knowledge Database, August 23, 2006 )

This would be ruinous as no affair how minor a fix is, it should be done up to the best criterions to avoid accidents. This was non the instance.

3 Incident Detailss

3.1 Absorbing Failure

The cause of this was via the bungled fix that was non done up to maker criterions.

Figure 4 – L18 Stiffener Joint ( Dr. Yotarou Hatamura, 2005, JST Failure Knowledge Database [ Online ] , Crash of Japan Airlines B-747 at Mt. Osutaka, Available from: hypertext transfer protocol: // )

Refer to Figure 4, this diagram compares the existent fix with the directed fix specified by the maker, Boeing. The first drawing, get downing from the left, shows a full doubler home base with 3 rows of studs integral along a full home base attached to the damaged part, with a little smount of sealer near the L18 stiffener which do non perforate the doubler home base. The 2nd drawing, which is the existent fix done, was non up to standard in comparing with the first drawing. It shows a shredded splicing home base, which was in two pieces, and riveted with 2 rows of studs on the underside, with 1 row on the top. The lone major difference would be the higher sum of sealer near the L18 stiffener. Comparing it to the old drawing, the sealer, penetrated through the splicing fix. This increased the emphasiss taken by the break site and the studs. As illustrated by the drawings, the pointers would intend stress concentration, which had reduced, from two pointers to one. This cause the emphasis to be extremely concentrated at that place, multiple-site clefts started to organize near the fastener holes. This cause the studs to be overloaded and eventually failed.

Aft Bulkhead Failure

Once a fix is signed off as complete, it will ne’er be looked at once more. Such was the instance for the JA8119 after 12319 fight rhythms. During flight, the whole plane goes through rhythm lading due to the difference in air force per unit area environing it, it may look insignificant at earlier parts, but the accrued difficult force per unit area could do something to neglect without care. In this instance it was a bungled fix. Harmonizing to the FAA, the one “ doubler home base ” which was specified for the occupation ( the FAA calls it a “ splicing home base ” – basically a spot ) was cut into two pieces parallel to the emphasis cleft it was intended to reenforce, “ to do it fit. The unstable nature of this fix resulted in a 70 % lessening in Fatigue Resistance. Due to that fact that it did non decently cover up the break of the aft bulkhead, did it decline and allow loose during flight.

Figure 5 – Aft Pressure Bulkhead of JA8119 on Display ( Flight Global, 2010 [ Online ] , Available from hypertext transfer protocol: // ItemID=12345 )

Refer to Figure 5. The multiple-cracks that form on the bulkhead follows a similar form, which is that they started largely from the fastener holes, as they tear well near to the studs themselves. In the early old ages of the fix done, the clefts are little, but through 12300 rhythms, they became bigger and finally joined up. In the analysis study that was signed off, it was said that there were clefts from 30 of the 50 fastener holes of the country of fix, the entire length of the clefts of the fix spot was 270mm. Merely one ground could explicate the immense extent of the clefts, bulk of them had extended overtime and finally joined together, doing ruinous failures one time they became concentrated. It would shatter the force per unit area bulkhead all together.

Explosive Decompression

Refer to Fig.5, under high height conditions, the aircraft cabin is pressurized to maintain the right sum of O. It is necessary when an airlinerA reaches high heights, because the atmospheric force per unit area is excessively low to let people to absorb sufficientA O, doing height illness and finally hypoxia. ( Wikipedia, 24 July 2010 )

The air force per unit area difference in high heights can be really high, any decompression incident such as a little pinhole in the aircraft tegument would bring forth a big hushing sound which could depressurise a whole cabin in five seconds. The deficiency of O in the cabin will intend a 25 % decrease in O in our lungs, which will do sulky thought, dimmed vision, loss of consciousness and finally decease.

Figure 6 – Cabin Pressurisation Process ( The Informer-Truth and Travel,2010 [ Online ] , Available from: hypertext transfer protocol: // )

The aft force per unit area bulkhead failure caused it to rend apart, leting hypersonic air to hotfoot into the tail five which already caused explosive decompression. This finally blew off a part of the tail five which farther aggravated cabin decompression in the cabin, sing now that a immense hole had become a nothingness.

Hydraulic Failure

Figure 7 – Cause of loss of tail five during flight ( Dr. Yotarou Hatamura, 2005, JST Failure Knowledge Database [ Online ] , Crash of Japan Airlines B-747 at Mt. Osutaka, Available from: hypertext transfer protocol: // fn=2 & A ; id=CB1071008 )

Hydraulic lines are like the blood vass of a human being, one catch in any of them, would intend decease. As illustrated in Fig.6, the explosive decompression caused hypersonic air to tear the tail five and a portion of the tail.

Severed Hydraulic Lines

It besides shredded through one of the most of import parts of the aircraft, the Central Hydraulic unit which controls the moving of hydraulic fluid to and fro the rudders on the perpendicular stabilizer and the horizontal stabilizer. Beside them were the of import hydraulic lines which besides went off along with the Central Hydraulic unit.

Loss of Primary Controls

Once the hydraulic lines were cut off, the fluid escaped through the gaps, which within proceedingss, the pilot reported troubles in managing minutes before he lost full control, which would intend that the hydraulic lines are now empty. To salve the state of affairs, the pilots varied their push between the engines on the left and the right wing and besides they tried seting down the landing cogwheel and the flaps.

( National Geographic, 2007, Air Crash Investigation [ Online ] , Season 3 Episode 3 Part 2, Available from: [ Accessed 23rd May 2010 ] )

3.5 Human Mistake

Many were at mistake, but we could n’t perchance shrive no 1 of all incrimination. They did non set on O masks, no ground was stated why. There was a batch of pandemonium in the cabin every bit good. Due to this, they were likely in a province of Hypoxia as they did non make two things:

Report to the full on the state of affairs.

Tried to set down in Nagoya Airport which is on a additive way. Mention to Fig 7.

Unwittingly, they besides allowed the plane to procrastinate in its way, which aggravated its out of control, lifting and plunging in the skies. This was besides an accident that was the first of its sort, which would intend there was no preparation available for state of affairss like these. Any safeguards they had learnt was irrevelant to what they had encountered.

Figure 8 – Map of JA8119 Flight Path ( Christopher Kilroy,2008, Air Disasters [ Online ] , Particular Report: Japan Air Lines 123, Available from: Air )

Post Incident

4.1 Late Rescue

Rescue attempts came merely after 14 hours. This was justified when clang victim and subsister, Yumi Ochiai stated: ” Many more survived the clang, as their shriek died down through the dark. ”

( National Geographic, 2007, Air Crash Investigation [ Online ] , Season 3 Episode 3 Part 3, Available from: [ Accessed 23rd May 2010 ] )

4.1.1 Refusal of US Military Aid

Yokota US Military Air Base had sent a C-130 to reconnoiter. Which they had reported back to hold seen the clang site. Shortly after, a US chopper was sent to the clang site to help in the deliverance attempt. Meanwhile, deliverance squads have been assembled and were on their manner to the site.

4.1.2 Inaccessibility of country

As stated, it crashed into two ridges of Mount Takamagahara in Ueno, Gunma Prefecture, 100 kilometres from Tokyo. It was in a cragged part where roads do non straight lead to the clang site itself at all, and most of the wreckage lay on a downhill incline which meant more cautiousness was taken to entree to the site, bing more and more clip.

Figure 9 – Panel of JA8119 lying on a descent. ( Available from: hypertext transfer protocol: // )

Inclusion of new processs in guidebook.

The FAA accordingly issued the undermentioned airworthiness directives:

AD 85-22-12 which required a erstwhile ocular review of the aft side of the aft force per unit area bulkhead for grounds of fixs or harm.

AD 86-08-02, necessitating the add-on of a structural screen for the gap within the tail to supply entree to the perpendicular five of all B747 theoretical accounts. This is to forestall structural failure of the perpendicular five in the event of failure of the aft force per unit area bulkhead.

A.d. 87-12-04 to necessitate installing of a hydraulic fuse in the figure 4 hydraulic system on Boeing Model 747 series aeroplanes.

AD 87-23-10 was effectual December 10, 1987 and required review for harm and snap of the aft force per unit area bulkhead on Boeing Model 747 aeroplanes. This AD was subsequently superseded by AD 98-20-20 which added insistent reviews AD 98-20-20 was, in bend, superseded by AD 2000-15-08, which requires that a erstwhile review to observe snap of the upper section of the bulkhead web be accomplished repetitively, and adds extra insistent reviews to observe snap of the upper and lower sections of the aft bulkhead web. ( Aviation Safety Network, 11 October 2009 )

Relief valves were besides fitted into the Boeing 747, so that in the instance of any taking apart of the aircraft will non lose all of its hydraulic fluid, still holding a high per centum of control of the aircraft.


Overall, we can see a form which in the events happened, runing from the tailstrike incident in 12th August 1985, which led to a botched fix which sealed the destiny of the plane to its at hand decease. Last, the carelessness of the land crew who did passed the fix even though it was n’t on specifications. Throughout the flight, the plane suffered mechanical troubles 12 proceedingss into the flight due to the weakness of the studs, doing the rear force per unit area bulkhead to tear, leting hypersonic velocity air into the tail of the plane, necessarily rupturing off the top part of its tail five, along with it went the Central Hydraulic unit which was the bosom of the aeroplane. They lost all control all together shortly after losing all the hydraulic fluid, and with the instance of a depressurized cabin, they suffered from hypoxia which hampered their determination devising. 32 proceedingss later it crashed into two ridges of Mount Takamagahara in Ueno, even though the pilots tried all kinds of manuveurs to salve the plane from its destiny. Rescue attempts were besides hampered as the authorities rejected aid from an US airbase for unknown grounds, even though they were already on site. The location besides posed a job, being unaccessible from any route, and being on a downhill incline slowed down exigency services.

From this, we can see how serious a molehill can go a mountain in a affair of old ages. From abrasions, they became clefts and torus through an of import constituent. Maintenance was an issue here, as it was slack, even though Boeing had released new review and fix processs 2-3 old ages after the tragic accident which included 522 lives, have we larn? Possibly. China Airlines flight 611, crashed on 25th May 2002, which killed all riders and the crew, coincidentally bearing the same few causes such as blunder fix, metal weariness, concentrating failure & A ; multiple-site harm. This happened 20 old ages after the processs were implemented. In the universe, there will ever be a balance between evil and good, such like this instance. It could hold been them merely the applied scientists non following processs, the remainder of the states were. There is merely one thing that we can make to forestall all these, is to larn from our errors and ne’er to reiterate them once more. We can ne’er halt these incidences, which is why bar is more than plenty to maintain the industry traveling until today.


Looking into the above information collected, the recommendations are:

To include more rigorous cheques on the fix itself such as the creative activity of a little supersonic device to expose any spreads or rip offing in the fix processs

Replace parts if harm is far excessively terrible to be repaired. Rather than to make impermanent fixs that could set lives at a little hazard.

Primary Controls to hold failsafes every bit good, alternatively of holding it in the hydraulic grapevines merely.

One illustration would be on the 4th of December 1987, Boeing requested fuses to be installed as a secondary safety step in the primary control hydraulic lines in the instance of another bar step.