In 2002, Flight 6 1 1 mysteriously crashed in the air, killing all 225 people on board.

Text | Micro-historical Interpretation

Edit | Micro-historical Interpretation

China Airlines Flight 6 1 1 takes off as usual and will fly 1 hour for 40 minutes. With 206 passengers and 19 crew members, it crossed the Taiwan Province Strait and landed at the Hong Kong International Airport.

After reaching an altitude of 7800 meters, automatic driving began. This route is the most popular tourist route, and passengers are looking forward to the next journey.

However, I didn't expect that after the plane reached an altitude of more than 10,000 meters 20 minutes after takeoff, the signal of the plane suddenly disappeared on the screen of the ground air traffic control center.

Why did the plane mysteriously disappear? Was it hijacked? Or was there an air crash?

This plane, a famous Boeing 747, flew from Taiwan Province Province to Hongkong with 225 passengers and crew. This is a popular tourist route and everyone is very happy.

But who knows that the disaster came so quietly, the plane flew to the 350 empty floor, but the normal contact with the air traffic control center became the last call.

15: 28, the air traffic control center looked at the plane signal that suddenly disappeared. No matter how you contact the crew, you can't get a reply. It immediately reported and contacted the search team and began a large-scale search and rescue.

More than 1000 people participated in the search operation, whether fishing boats, maritime guards or soldiers went to sea for search and rescue.

It was not until three hours later that the news of the plane crash was confirmed. The search team found a large number of disabled children, passengers' luggage, documents and tableware on the sea 40 nautical miles away from Mudou Island in Penghu County.

What's more, some items were scattered in Taichung, and this accident made the person in charge of the investigation a headache.

China Airlines is basically the airline with the worst flight situation in the world.

A major accident happens almost every four years, and the accident on flight 6 1 1 is the most difficult to investigate. Because all the "evidence" sank to the bottom of the sea.

None of the passengers and crew survived, making the investigation extremely difficult.

Since the plane that was involved in the accident was made by Boeing, the US Transportation Safety Board began to intervene in the investigation.

With the expansion of the investigation team, soon, a large number of disabled children were salvaged from the bottom of the sea. How could the plane that was built with a lot of money suddenly disintegrate and be scattered all over the place? Is it true that the missile shot down?

On the day of the crash of China Airlines Flight 6 1 1, the mainland military was conducting military exercises in the Taiwan Province Strait. So the media in Taiwan Province province suspected that the plane was shot down by a mainland missile.

With the deepening of the investigation, more and more aircraft wreckage was salvaged.

People found that there was no trace after being hit by missiles, and the ground radar did not show any missiles, which gradually dispelled the idea of being shot down by missiles.

Then the investigators thought of the plane crash caused by the explosion of the fuel tank, and it took four years to solve the truth of the incident.

Because the cable system is very close to the fuel tank, it is likely to ignite and cause the fuel tank to explode.

Moreover, it was very hot on the day when the plane took off, and it was also very hot when China Airlines 6 1 1 took off. Investigators believe that high temperature may lead to excessive fuel temperature, which may lead to an explosion of the fuel tank.

So could that be the reason?

With a large number of aircraft wreckage being salvaged ashore, the salvaged fuel tank fragments showed no signs of explosion from the inside out.

Everything looks like an accident caused by the disintegration of the plane itself.

Moreover, judging from the display on the ground radar, it is also obvious that there were no other planes at that time, and the idea of plane collision was even more impossible.

This made the investigators fall into a new round of fog, and China Airlines even stopped the flight of the same series of Boeing 747 to prevent the same accident.

This makes investigators have greater psychological pressure. Later, the investigators found the first important information of the accident in the records of ground radar.

The radar tracked that the plane crashed in the process of taking off, and the signals in the picture changed from one to four, and then began to disperse, confirming that the plane did disintegrate at high altitude.

When further salvaging the wreckage, the investigators found a series of unusual small exhaust holes. When the aircraft cargo hold is depressurized, the release valve will automatically open to release the pressure on the floor.

There are 65 release valve devices on the 6 1 1 flight. 19 was salvaged from the sea by the investigated personnel, and four of them were open, which indicated that the lower part of the engine room suddenly lost pressure.

Using the research method and flight trajectory analysis technology of American Flight 800, we can understand the disintegration of the aircraft.

After the fragments are salvaged, each fragment should be numbered for inspection. The researchers selected 65,438+08 pieces and input the weight and shape data into a specific computer program for analysis.

These parts come from the front, middle and tail of the fuselage respectively. According to the crash site, the computer calculated the 18 wreckage.

Who gets off the plane first, the computer uses these data to simulate what happened when the plane disintegrated. The analysis results show that the tail wing leaves the plane first, and then it becomes the focus of investigators' research.

NTSB sent Frank Zach, a metallurgical expert, to assist in the investigation. When he went to No.640 disabled children, he found some unusual parts. This metal part was badly damaged.

From the aerodynamic point of view, when an aircraft flying at a speed of more than 800 kilometers per hour in the air, it will inject air, which will lead to the disintegration of the passenger plane structure.

This phenomenon is called overload rupture in the industry, which can be confirmed by the parts salvaged earlier.

When the metal cracks due to overload or excessive stress, it will present an angle, while the cracks on the wreckage of the aircraft 640 have no inclination.

It shows that this is not an excessive pressure.

But another natural enemy of aircraft structure: metal fatigue.

Investigators learned that the wreckage of the crash did not suddenly break when the plane crashed, but gradually separated from the fuselage of the plane. Another feature is that there is a metal patch on it, also called cladding reinforcement plate.

This kind of stiffener is common in long aircraft, such as cracks in aircraft skin and damage cracks. The enhanced version can restore the original strength of the aircraft skin.

Investigators retrieved the initial maintenance data, and the parts of Boeing 747 have been repaired. Frank found long longitudinal stripes on the cover plate.

It seems to be scattered between the reinforcing plate and the skin, and something leaks under the metal plate. Investigators cut off these materials and sent them to the laboratory for further study.

Frank found an obvious clue on the crack. These materials are covered with alumina produced by metal oxidation due to long-term exposure to oxygen.

Judging from this color, this crack has been around for a long time.

After opening the lid, the investigators finally saw the aluminum skin below, and also saw a scar longer than the reinforcing plate, which was beyond the repair scope of the reinforcing plate.

Looking through the plane for more than 20 years, all the maintenance records show that in the first half of the flight, when the plane landed, the tail was too redundant and too low, and it grazed the runway for a distance.

When the controller sees smoke and sparks coming from the tail of the plane when it lands, he will inform the pilot. This kind of situation usually happens when the take-off and landing angle is too large, which is called tail wiping.

This often happens, and some planes even install bumpers at the tail.

If the tail is too close to the ground, use physical buffer to protect the aircraft shell, and the damage caused by the tail rubbing on the ground will generally be repaired regularly.

Investigators found the maintenance records at that time in the aircraft log.

At that time, the repairman only stuck a large piece of aluminum plate on the damaged area, and did not follow the maintenance manual provided by Boeing.

It is clearly stated in the instructions that if there are many deep scratches on the plane that cannot be repaired, all the damaged areas can only be replaced. Now, investigators have found that the damaged metal has not been replaced, and the original plane has been scratched and still stays in its original position.

The technicians of China Airlines told the investigators that the scratched parts were too big to be disassembled, so they used the method of smoothing the scratches.

Then the repairman made a mistake, that is, he directly covered the scratched metal with reinforcing plates, and the added reinforcing plates did not exceed 30% of the damaged parts.

And in the maintenance records at that time, I also boasted how skilled I was.

The original damage was hidden by the reinforcing plate, which led to the assumption that the damaged parts were repaired according to normal maintenance procedures for more than 20 years.

In this way, an injured and dangerous plane has worked for more than 20 years, during which the flight record is even as high as more than 2,000 times. And every time I maintain it regularly, I don't see the cracks under the reinforcing plate getting bigger and bigger.

The repairman made a wrong decision at that time, which made countless families extremely sad. If you take maintenance records seriously, or you can be more careful every time you regularly maintain them.

Is it possible to have fewer tragedies? When a life stops, how many people will be sad and helpless? How do the family and friends who stay accept it?