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Mar. 10, 2015 - Updated 04:16 UTC

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Plane-Crash Warning Signs

Kazuaki Hirama

Oct. 20, 2015

(Second of a two-part special report)

A Japan Airlines jetliner slammed into a mountain in August 1985, killing more than 500 people. It remains the world's deadliest single-plane accident. The plane departed from Tokyo bound for Osaka. But trouble began just 12 minutes after takeoff. The cockpit voice recorder caught JAL Flight 123 Captain Masami Takahama saying that something exploded, and the crew fighting desperately to bring the Boeing 747 under control.

"Power, power, flaps."

"I'm trying to raise them."

"It's going to stall."

"Head up. Head up."

"Power."

"Pull up. Pull Up."

"Oh no..."

Thirty years after the disaster, we take a closer look at what went wrong.

In the second part of our series on the disaster, we look at what caused the crash. Government investigators blamed faulty repairs 7 years before the crash. But what could have been done to prevent the disaster?

Two former pilots speak on camera for the first time about what it was like to fly the doomed plane before the accident. They say there were several unusual things about the jet JA8119, including problems with the steering.

The plane's wing dented a mountain ridge where the Japan Airlines jetliner went down, and the scars are still visible.

Government investigators released a report 2 years after the disaster.

It blamed the crash on a pressure bulkhead that separated the cabin from the tail section. The bulkhead was destroyed midflight, causing pressurized air to rush into the tail, blowing off the elevators and rudder. The damage left the plane impossible to control.

The report noted that the aircraft had an accident 7 years earlier. Its tail struck the runway landing at Osaka Airport. The plane underwent repairs, but the report said they were faulty, which led to the disaster.

The aircraft went on to fly 12,000 more flights after the tail-strike. Routine inspections found no major problems.

But former JAL pilot Hiroshi Iijima says he felt something was wrong with the aircraft after the repairs.

"I wondered why this plane was slightly different from others."
Hiroshi Iijima / Former JAL pilot

Iijima noticed the plane was burning more fuel than it was supposed to. So he put a question mark on a flight record for the plane. This was 10 months before it crashed.

"I had the impression that unlike other JAL planes, this particular aircraft was not in 'brand new' condition."
Hiroshi Iijima / Former JAL pilot

Why was the jumbo jet burning too much fuel? Ippei Kawakatsu, who served as co-pilot on the plane, had the answer. He says he noticed that the aircraft didn't fly straight when it levelled off after takeoff.

"After the tail-strike accident, pilots were talking to each other about a slight steering imbalance, from left to right."
Ippei Kawakatsu / Former JAL pilot

Kawakatsu felt the airplane was distorted. He says other pilots who had flown the aircraft also sensed the imbalance. They had to make adjustments on the rudder to compensate. He says the imbalance was more than one degree -- well beyond the normal 0.2 or 0.3 for jumbo jets.

If a jumbo jet flies one degree off course even for 10 seconds, it will take it about 30 meters off its planned flight path. The imbalance may have meant the plane was less aerodynamic, causing it to burn more fuel.

The problems didn't end there.

"There were dozens of reports that the toilet doors couldn't be locked or didn't shut properly. The storage lockers also didn't close."
Ippei Kawakatsu / Former JAL pilot

Kawakatsu reported the problems to the maintenance division. But strangely, he says, the troubles only occurred during flights. A detailed inspection was never conducted.

NHK obtained internal documents from Boeing, the company that manufactured the plane and repaired it after the tail-strike. The phrase "No edge margin" appears repeatedly.

That phrase suggests the bulkhead may have been distorted. It normally has a lower half and upper half that overlap. After the tail-strike damaged it, Boeing replaced the lower half. But the documents indicate that a gap remained between the 2 pieces. This might be a sign that the upper half was misshapen.

Did that structural imbalance have anything to do with the deadly crash? We visited an aeronautics expert to find out.

Professor Takashi Hiramoto of Teikyo University says it's possible the imbalance may have led to the disaster.

"If the plane was distorted, it could shift how weight is distributed. When one part is distorted, the weight that particular part should bear may be shifted to another part, which can accelerate metal fatigue of that part."
Takashi Hiramoto / Professor, Teikyo University

If a section of the plane's tail was left distorted after the repairs, other sections might have had to shoulder a heavier burden.

That could have weakened crucial parts like the rudder and elevators, and their destruction caused the pilots to lose control of the plane.

Hiramoto says the airline should have taken the pilots' complaints more seriously.

"If the plane is distorted, you find it hard to open or close doors. Once you start having those problems, you should consider the structure of the plane may be misshapen."
Takashi Hiramoto / Professor, Teikyo University


NHK World's Kazuaki Hirama joins NEWSROOM TOKYO anchors Sho Beppu and Aki Shibuya in the studio. He's been covering the issue.

Beppu: Kazu, as for the cause of the accident, government investigators pointed out a faulty repair that took place 7 years before the crash. The pilots you talked to explained what they felt and noticed since then, but was the airline addressing the pilots' complaints properly?

Hirama: We asked JAL whether they were aware of complaints that the plane was distorted. A company spokesperson replied in a written statement. We translated it to English. It said, "We cannot confirm such a phenomenon," which means they couldn't confirm there was a problem with the structure of the airplane. It also acknowledged that no specific actions were taken in response to the complaints. That's probably because the problems only occurred in mid-flight, so they were not evident once the aircraft was on the ground. The company also said they cannot comment on whether the distortion led to the deadly crash or not.

Beppu: The pilots you spoke to were able to discuss openly what they were feeling. But why are they speaking publicly about this now?

Hirama: I met many current and former JAL employees. Some of the retired pilots were feeling guilty. They wonder if they had done enough to flag problems with the plane. Most of them have now left the company, so it's easier for them to speak on camera.

Shibuya: Kazu, would JAL respond differently today if it received similar complaints?

Hirama: A JAL spokesperson says they reviewed their safety practices drastically in 2007. They introduced what they call a "non-disciplinary policy," which encourages employees to speak out about anything that they suspect might be a safety hazard. Pilots and other staff aren't punished, no matter what they report. They're also encouraged to relay mistakes they make at work. The idea is to learn what leads to errors and what can be done to prevent accidents. JAL says it embraced this policy after reviewing past accidents, including the 1985 crash.

Beppu: It's been 30 years since that accident. What can other airlines learn from it?

Hirama: After this crash, people in Japan were saying it shattered the "safety myth." This particular type of aircraft, the Boeing 747, was considered to be very reliable and safe. It has multiple safety features. But accidents do happen. I think that everyone in the aviation industry should never underestimate even subtle problems. The International Civil Aviation Organization is taking steps too. In 2011, the organization instructed all airlines around the world to train their staff on something called Threat and Error Management. The idea is to make workers aware of how to better detect threats early, and to deal with them to prevent accidents. I think everyone in the aviation industry should never compromise safety, and should always be looking for ways to detect problems early and minimize the risk of accidents.

Beppu: And to speak out if they detect them.

Hirama: That's right.