This photograph, taken on board a Boeing 747, gives us a rare glimpse of the cabin of an
airliner during a disaster, having been taken after a structural failure caused the rapid
decompression of the cabin.
Everyone in this photo, including the person taking the picture, perished in the resulting
crash.
The 1985 crash of Japan Air Lines Flight 123 is the deadliest single-aircraft accident
in global aviation history.
But to understand how it happened, we have to go back seven years before the disaster.
In 1978, the plane in question, a Boeing 747-146SR, was making a domestic flight from Tokyo's
Haneda airport to Itami Airport.
Upon landing, however, the plane bounced and pitched too far upwards, causing a severe
tail strike.
None of the 394 on board were killed in this incident, but 25 were injured, two seriously
so, and the plane's aft pressure bulkhead was cracked open.
The fuselage of an airliner is essentially a pressure vessel, and it's pressurised to
maintain a hospitable atmosphere for passengers, even when the plane is at very high altitudes,
where the low pressure would normally make it difficult to breathe.
The aft pressure bulkhead is the rear component of this pressure seal.
And the damage done to it in this incident was so extensive, that Japan Air Lines did
not have the expertise to fix it, and so contracted a Boeing repair team in Tokyo.
During a month-long reconstruction process, the Boeing team had to replace a large part
of the aft pressure bulkhead.
They fabricated a new portion of the bulkhead to be riveted onto the remaining part of the
original.
Normally each section of the bulkhead is secured to adjacent sections by two rows of rivets,
and the team adhered to this as they installed the new portion.
However, they were left with an overlap between two sections that only had enough space to
fit one row of rivets instead of two.
The procedure for solving such a problem involves introducing a splice plate between the two
sections of bulkhead.
The one row of rivets that can fit in the overlap will go through the splice plate,
and an additional two rows will further secure the splice plate to each bulkhead section
separately.
But the Boeing team made a grave error while performing this repair.
Somehow, instead of one splice plate connecting the two bulkhead sections, they ended up with
two separate splice plates, where one was meaninglessly bolted onto a single section
of bulkhead but not the other.
The result - there was only one row of rivets connecting the bulkhead sections.
The introduction of the splice plate was pointless.
Even worse, this strange configuration lead engineers to mistakenly place a seal between
the two splice plates, concealing the error.
Now unable to see the problem, a Boeing inspector approved the repair.
The plane would soon be in the air again, and with every cabin pressurization, the aft
pressure bulkhead is subjected to a large amount of force.
This puts strain on the overlap where there is only one row of rivets holding the sections
together.
Over time, this section will eventually fatigue.
By 1985, the pressurization cycle has been repeated for over 12,000 flights since the
repair.
That section of bulkhead should now be cracked, although the cracks appear so small, they
are never detected in any inspections.
On August 12, 1985, Japan Air Lines Flight 123 is scheduled to take the aircraft from
Haneda Airport to Itami Airport once again.
It takes off at 6:12pm. 12 minutes later, the aft pressure bulkhead fails mid-air.
The pressure seal has been broken, and the cabin is subjected to rapid decompression
- the plane is rocked and any unsecured items are blown to the rear of the craft.
Water vapor in the air condenses, creating a fog in the cabin.
The pilots feel an explosion, and immediately broadcast a
distress signal and ask to turn around for an emergency landing back at Haneda airport.
Tokyo Control approved a right hand turn to come back, and this was initiated by First
Officer Yutaka Sasaki, today sitting in the Captain's seat under training from veteran
Captain Masami Takahama.
Takahama is alarmed by the steep banking Sasaki seems to be performing for this turn, and
tells him to ease up.
Sasaki attempts to correct, but nothing happens.
As the confused pilots attempt to figure our why the controls aren't responding, Flight
Engineer Hiroshi Fukuda alerts them that the hydraulic pressure is dropping.
Unbeknownst to the pilots, the explosion they felt was the pressurised cabin air escaping
through the cracked bulkhead.
This occured with such force, that it tore off a massive section of the aircraft's tail,
including the vertical stabiliser and rudder.
As the tail came apart, all four hydraulic systems were severed and were now leaking
the last of their fluid, leaving the plane uncontrollable.
The plane abandons Sasaki's turning attempt halfway through, sending them on a northward
course.
The pilots struggle to understand what is happening, and with the cabin depressurised,
start to feel the effects of hypoxia - or oxygen starvation, adding to their confusion.
Tokyo Control goes without response, and Flight Engineer Fukuda must repeat himself as the
pilots repeatedly ask about the hydraulic pressure, seemingly unable to understand their
situation.
This photo taken by a passenger shows oxygen masks in use after the cabin lost pressure,
however, the pilots fail to don them.
Fukuda does suggest they put on their oxygen masks, and Captain Takahama agrees, although
they never actually follow through.
Their minds are preoccupied with trying to comprehend the emergent disaster they are
in, and the hypoxia is making coherent thought more strained.
With no control, the plane enters a phugoid cycle.
As it pitches downwards and descends, its airspeed increases which results in lift,
and the plane pitches back up.
However, this will cause a decrease in airspeed, and the cycle repeats in a rollercoaster motion.
For Flight 123, these cycles last 90 seconds each.
Simultaneously, the aircraft experiences Dutch roll.
With no vertical stabilizer, the craft yaws right while banking left, before yawing left
and banking right.
These motions became very profound, at some points the plane was banked fifty degreees,
with witnesses on the ground spotting the plane as it appeared to be drunkely staggering
through the air, like a ship rocking on rough seas.
One even managed to capture a photo, in which we can see the plane missing tailfin.
These continuing motions were very distressing for the 524 people on board, as evidenced
by the notes some wrote during the flight: “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.
Help me.
I don’t want to die.”
For over half an hour the pilots attempted to regain control over Flight 123, as it headed
North towards Mount Fuji.
They brought down the landing gear in an attempt to counteract the phugoid motion, and it did,
but it worsened the Dutch Roll.
They tried to turn the plane using asymmetric thrust; accelerating the engines on one side
while decelerating them on the other.
Despite their best efforts, the engine controls are not responsive enough to effectively respond
to and counter the forces already battling the aircraft.
At 6;56pm, the right wingtip and fourth engine collided with some trees on a mountain ridgeline
and were sheared off.
The plane continued on, the right wing striking another ridgeline and disintegrating, sending
the plane onto its back on another ridge, where it exploded.
20 minutes later, a United States Air Force C-130, from nearby Yokota Air Force Base finds
the wreckage.
The crew passes on the co-ordinates to the Japanese authorities, but looking down at
the fire pouring from the decimated plane, they add that the chance of survivors is slim.
It is 4:39am when a Japanese helicopter finally finds the wreckage, the fire on the mountainside
glowing through the night.
There is nowhere to put the helicopter down, but at a nearby village, rescue workers have
been preparing for an expedition at dawn.
They will find a horrific sight awaits them, the remains of the 747 are scattered all across
the mountainside, likewise the bodies of its passengers.
But unbelievably, they find four survivors.
In their hospital beds, they will recount the harrowing experience of the plane crash,
but worse still, their memories of lying in the wreckage, all throughout the night, taunted
by the sound of the 4am helicopter that passed overhead but did not stay, and haunted by
the screams and moanings of other passengers, that slowly faded through the night.
The survivors' stories revealed a horrifying detail, there had perhaps been more survivors
who eventually succumbed to their injuries due to the delayed response.
Doctors later confirmed this story; noting several victims appeared to have injuries
that would have been survivable with earlier help.
The long wait time was attributed to the seemingly slim chance for survival - given the difficult
terrain, the decision was made that it would make more sense to wait until they were fully
prepared before attending the crash site.
With 520 killed, Japan Air Lines Flight 123 remains the deadliest single-aircraft accident
in history.
Investigations revealed the faulty bulkhead repair to be the cause of the disaster, and
Boeing has since made changes to the way it installs and inspects the aft pressure bulkhead.
In further analysis and tests, it was also concluded that once the bulkhead had failed,
the pilots had no chance to recover the plane, and in fact, had actually kept it airborne
longer than the pilots running the simulations, despite the massive disparity in conditions
between simulating an event and having it actually occur spontaneously in a life or
death situation.
The disaster caused a large loss of public trust in Japan Air Lines, despite the faulty
repair being carried out by Boeing, and bookings with the airline fell by a third.
The president of Japan Air Lines resigned and a maintenance manager with the company
committed suicide in way of apology for the incident.
One of the inspectors that had cleared the plane as airworthy also committed suicide.
What's so surprising about this tragedy is the level to which we can put ourselves there.
There is a picture from the cabin, we can read the thoughts of victims in written notes,
and even hear them firsthand from miraculous survivors.
Of course, this all require the use of our imagination, which can never come close to
the actual experience.
The experience of tumbling out of control through the air, the experience of slamming
into the mountainside, the experience of waiting to die in the wreckage.
The experience of 520 people who spent their last moments on board Flight 123.