Nine minutes after the aircraft took off, it suddenly lost control and fell rapidly. The aircraft body decomposed instantly, causing the largest accident in the history of civil aviation in New China. This is the "Xi'an Air Crash" that occurred in 1994. What exactly caused the tragedy?
The largest accident in the history of civil aviation in New China
In the early morning of June 6, 1994, Li Gangqiang was preparing for the flight that morning as usual. Li Gangqiang is a pilot of Northwest Airlines in my country. At the time, he was 46 years old and had more than 8,300 hours of flying experience. He was considered a mature and experienced officer.
On that day, he will fly aircraft No. 2610 from Xi'an to Guangzhou with Yang Min, a 25-year-old newcomer in civil aviation who has just exceeded 900 hours of flying time.
At 8 a.m., the pilot of Plane 2610 began to check various indicators of the aircraft to prepare for the next takeoff. "Everything is normal and you can take off." After 13 minutes of detailed inspection, Northwest Airlines Flight 2303 took off and started its journey south to Yangcheng.
At first, the aircraft behaved normally. According to the route, Li Gangqiang and others steadily raised the altitude of the plane. Once the plane reached the stratosphere of 10,000 meters, even if they were halfway through the flight, the changes started from that time.
24 seconds after the plane took off, although Li Gangqiang did not deliberately adjust the attitude of the plane, everyone felt that the plane was swinging involuntarily. Moreover, as the aircraft "swayed left and right", the structure of the aircraft also made disturbing noises.
"Oops! The plane is not under control. Is there something wrong with the mechanical structure of the plane? It has just taken off!" Realizing the seriousness of the situation, Li Gangqiang quickly informed Xianyang of the matter while continuing to climb. Airport control tower.
After the control tower learned about the situation, they were also very puzzled. Because the tower has never encountered a situation where the aircraft swings involuntarily and the aircraft body makes abnormal noises before. While comforting the crew of aircraft No. 2610, they urgently contacted their superiors and requested technical support from the manufacturer.
While the tower personnel were carefully monitoring the flight path of Plane 2610 and urgently notifying the Russian aircraft manufacturer to explore possible causes of the failure, Li Gangqiang and others were also doing their best to find ways to save themselves.
html At 18:16, the swing of aircraft No. 2610 became more and more serious. At this time, the plane swung left and right to an astonishing 30 degrees. The plane swayed left and right in the sky like a "drunkard" who lost his balance.
Li Gangqiang and Yang Min tried their best to control the attitude of the aircraft, while asking the mechanic Kang Youfa and the navigator Zhang Nanjing to find a way to solve the current fault as soon as possible.
"I can't control it manually, why not try autopilot?" The pilot team tried their best but still couldn't improve, so they could only place their hope in the aircraft's autopilot system , hoping that the aircraft's avionics system could automatically eliminate the aircraft's operation. fault occurred.
for five full seconds! After turning on the autopilot, the swing of the aircraft not only did not improve, but intensified. Seeing that if he didn't control it, the plane would roll uncontrollably in the sky, Li Gangqiang urgently flew the plane manually.
html At 18:22, 9 minutes had passed. Not only did the pilot team on board 2610 fail to control the aircraft, but even the Xianyang tower failed to provide a practical solution.
At this time, due to excessive force in controlling the aircraft, the co-pilot Yang Min had lost all control and had to temporarily retreat, and the pilot Xin Cai took over to fly the aircraft.
At this time, the flying situation was very dangerous. Not only did the aircraft deviate from the established route, but the nose of the aircraft began to rise, and the elevation angle reached 20 degrees. This means that the entire aircraft has begun to raise its head and is about to encounter the crisis of stalling.
As we all know, airplanes obtain lift by flying at extremely high speeds.Generally, only when the aircraft is slowing down for landing can it lift its nose and use air resistance to help the aircraft land safely. Suddenly raising the nose of the aircraft at high speed will cause the aircraft to stall and fall.
Friends who like military affairs will remember that there is a trick in aerobatics called the Cobra maneuver. The principle is that when the aircraft is flying at high speed, it suddenly lifts the nose of the aircraft and decelerates instantly, causing the aircraft to "hover" in the air.
This action tests the maneuverability and structural strength of the aircraft, and is also very dangerous. Because of the slightest mistake, the plane will " stall " and crash quickly. Unit 2610, whose nose had risen significantly at this time, also encountered the same problem.
The altitude of the previous plane was around 4700 meters. After the head-up danger occurred, the aircraft's speed dropped to 380 kilometers per hour for a short time and began to fall at a high speed. In just 12 seconds, the plane's altitude instantly dropped by nearly 2,000 meters, and its fuselage also rolled to the left at high speed.
From a distance, the aircraft seemed to have lost power at this time, and was diving at an angle of 60 degrees at high speed. Because dropped rapidly, the entire aircraft suffered a gravity of 2.7G, which far exceeded the structural strength of the entire aircraft body.
In the end, the plane's tail and right wing were torn off first. The entire aircraft completely disintegrated at an altitude of 2,884 meters. The remains of the aircraft were scattered within a radius of 7 kilometers. The place where the remains fell was like a hell on earth.
At this point, Northwest Airlines Flight 2610 crashed completely, killing all 160 passengers on board, including 14 crew members. A single accident caused the death of 160 people, which also made the "Xi'an Air Crash" the largest casualty accident in the history of civil aviation in New China so far.
Another footnote in the Tu-154 accident history
The occurrence of the "66 Xi'an Air Crash" not only ended the "zero accident" record of my country's civil aviation, but also added a heavy brush to the accident history of the Tu-154 aircraft. In fact, countries around the world generally don’t think highly of the Tu-154 aircraft because of its relatively high accident rate.
The Tu-154 aircraft was born in the 1960s. In 1966, the project was initiated by the former Soviet Tupolev Design Bureau, and the first test flight was carried out in 1968. As the successor of the Tu-104 and IL-18 passenger aircraft, the Tu-154 passenger aircraft is widely used in the third world and the CIS countries.
It is not groundless to say that the Tu-154 aircraft has a high failure rate. Since the Tu-154 aircraft was officially delivered in 1971, accidents have continued. By the time production ceased in 2006, a total of 935 Tu-154 aircraft had been produced, of which 62 crashed in accidents.
For example, in 1980, a Tu-154 aircraft that had just taken off from Almaty Airport crashed, killing all 163 people on board. Another example is that in 2011, a Tu-154 aircraft suffered a fuel tank explosion due to a malfunction during takeoff, and the aircraft crashed, killing three people.
Due to limited funds, our country was once a big buyer of Tu-154 aircraft. Since 1985, our country has successively introduced 30 Tu-154 aircraft from the former Soviet Union. This batch of aircraft will not be grounded until 2022.
As for the Tu-154 aircraft in our country, in addition to the "Xi'an Air Crash" mentioned in this article, there has also been a crash. In February 1999, a Southwest Airlines Tu-154 aircraft crashed due to mechanical failure during landing, killing 64 people.
Among the many accidents involving Tu-154 aircraft, the most famous crash was the crash of the Polish presidential plane in 2010.
At that time, Polish President Kaczynski set off from Poland to Russia. His trip was to participate in the 270th anniversary commemoration of the Katyn massacre. The "Air Force One" that the Polish president was riding on at that time was a Tu-154 aircraft.
When the plane was preparing to land at Smolensk, the weather above the airport was extremely bad and was not suitable for landing.However, the pilot of the presidential plane was stubborn and refused the advice of the airport tower and forced a landing, which eventually led to the accident.
In fact, by studying the accident history of the Tu-154 aircraft, we can find that although the aircraft did have many accidents, they had nothing to do with the structural and functional design, and were more caused by the mistakes of the pilots or ground technicians.
According to statistics from Flight Safety Network, a world-renowned civil aviation accident website, the crash rate of Tu-154 aircraft is 6.5%. At first glance, it seems that the plane crash rate is high and the safety is unreliable. But we must know that the Boeing 727 aircraft produced during the same period also had a 6% crash rate.
The Tu-154 is generally in service in third world countries and CIS countries. These countries have financial constraints and there are certain problems in the system management of related driving and maintenance. Poor management and human operation failures are the real reasons for frequent aircraft accidents.
Statistics on the causes of flight accidents in various countries around the world show that flight accidents caused by human errors account for about 70% to 80% of the total number of aircraft accidents. And the "June 6 Xi'an Air Crash" was also a flight accident caused by various carelessness or human errors.
Tragedy caused by "carelessness" from many parties
In view of the large number of victims of the "June 6th Xi'an Air Crash", the serious damage to the plane and the bad impact, it attracted the attention of the whole country. The accident investigation team at that time was personally led by the Vice Premier of the State Council, which shows the importance the country attached to the accident.
After the investigation team investigated the black box data and the remains of the aircraft instrument console, people were surprised to find that the accident was caused by carelessness.
First of all, the direct cause of the accident was that Northwest Airlines' mechanical engineers inadvertently inserted the control plugs of the aircraft's steering rudder and aileron backwards while maintaining aircraft No. 2610. In other words, the "Xi'an Air Crash" was an accident caused by the wrong plug. During the inspection of the instrument console by the
investigation team, technicians discovered that the green plug should have been inserted into the yellow socket, and the plug corresponding to the yellow socket was inserted into the green socket. According to the operation manual of Tu-154, this means that the plugs of the steering rudder and aileron are plugged in reverse.
Steering rudder, as its name suggests, its main function is to control the direction of travel of the aircraft. The ailerons adjust the attitude of the aircraft and maintain the balance of the fuselage through the lift of the left and right wings.
During flight, aircraft often encounter airflow impacts, causing the aircraft to bump up and down, swing left and right, or deviate from its course. In order to ensure the basic balance of the fuselage, aircraft will install dampers on the device for adjusting attitude or direction.
The so-called damper, its principle is similar to gyroscope , it refers to a device that can keep itself stable even if it is shaking. Dampers are important components for maintaining stability in aircraft, ships and high-rise buildings. When the
damper encounters shaking, its core will generate a corresponding damping force based on the swing amplitude to ensure its relative stability.
The plugs of the steering rudder and aileron are plugged into each other backwards, which means that the dampers inside these two parts of the aircraft are dysfunctional. The dampers that originally maintain the balance of the fuselage will not correct the attitude of the aircraft, but will intensify the swing and shaking of the aircraft's attitude.
This is the reason why the pilot crew members in the "Xi'an Air Crash" were unable to fly stably.
Secondly, inherent flaws in aircraft design increase the probability of maintenance accidents.
The Tu-154 is an aircraft designed by the Soviet Union in the 1960s. Nowadays, everyone’s impression of Soviet-made or Russian-made items is generally that they are durable but rough, and the Tu-154 aircraft is no exception.
is based on the purpose of reducing the incidence of failures and facilitating maintenance. For example, the internal structure design of American Boeing aircraft and European Airbus aircraft is often relatively "simple". Because they clearly understand that the more operable parts there are, the more room there is for human error.
Products made in Russia or the Soviet Union tend to be more "rough" in design, and the designs in many places are "raunchy". This inadvertently increases the possibility of human error. Many Tu-154 accidents are related to human operating errors. This is an example.
Although there is no problem with the aircraft structural design, it leads to more human errors. Isn't this itself a "design error"? This is very obvious in the "June 6 Xi'an Air Crash".
First, it allows people to frequently adjust the components that control the attitude of the aircraft. Maintenance personnel can frequently replace the controller plug, which itself increases the risk of aircraft maintenance.
Moreover, the steering rudder and aileron controllers use unified plugs, so there is no difficulty in plugging the two plugs into each other. Just imagine, if the two plug mechanisms are very different, can the wrong plug be avoided?
Secondly, Figure-154 uses green and yellow colors to distinguish the plugs of the steering rudder and aileron. However, in the eyes of some color-weak people, the difference between the yellow and green colors is not as great as imagined, and it is easy to make a mistake accidentally. This undoubtedly increases the possibility of operational errors.
Thirdly, the aircraft's own avionics system was defective and failed to detect the error of the steering rudder and aileron plugs being inserted into each other. When the investigation team reviewed the ground maintenance errors, they were surprised to find that the fuselage electronic system could not detect the abnormal operation of the steering rudder and aileron.
This is tantamount to increasing the possibility of the accident. Even if the wrong plug is plugged in, ground maintenance personnel will call up the background of the aircraft avionics system to check whether each component is working properly. However, during the aircraft maintenance period, the avionics system did not report an error in time. This completely eliminates the possibility of technicians discovering potential errors during the ground maintenance stage.
In summary, the occurrence of the "66 Xi'an Air Crash" accident has a certain relationship with the Tu-154's backwardness in design and avionics system.
Once again, Northwest Airlines’ internal management is in chaos, and many rules and regulations are not fully implemented.
When the investigation team retrieved the ground maintenance records of the accident aircraft, they found that Northwest Airlines’ ground service technicians did not strictly implement the three-reinspection system and missed many opportunities to discover problems.
First, the technical maintenance personnel did not implement the self-inspection system. At that time, the accident aircraft was inspected by two newcomers led by an "old technician" with ten years of work experience. It is understandable that the newcomers made operational mistakes, but it is unreasonable that the veteran technicians who were the "ballast stones" failed to discover this problem in time during the re-inspection.
Second, the ground crew technicians did not strictly follow the inspection and maintenance procedures. Under normal procedures, technicians need to test various parameters of the aircraft after adjusting various components of the aircraft. However, the technical team maintaining the accident aircraft did not complete all inspection procedures.
When the system showed that there was no problem with the damping test, they hurriedly ended the maintenance without completing the performance parameter test and test flight experiment, which laid the foundation for subsequent accidents.
What’s even more annoying is that the technical supervisor on duty that day signed off and left early without inspecting the maintenance of the accident aircraft. finally made a novice's small mistakes turn into an uncontrollable tragedy under layers of negligence and "carelessness".
In the end, the pilot made improper operation on the spot, causing the aircraft to miss the last opportunity to adjust and correct its direction.
During the final flight of Plane 2610, the pilot crew was always trying various methods to regain control of the aircraft. But until the plane disintegrated and crashed, they had not made any meaningful response to the trouble ticket displayed on the aircraft instrument panel.
They tried switching autopilot and changing pilots, but they did not try to check the various interfaces and plugs of the aircraft. The pilot, co-pilot, instructor and mechanic failed to discover the real source of the aircraft's danger in time.
When this kind of problem occurs, it can be attributed to the failure of the pilot team to adjust the panic state in time when facing a dangerous situation, unable to objectively and calmly examine the faults of the aircraft.
Secondly, it can also reflect that drivers and mechanics rarely simulate critical situations in their daily lives. As a result, the driving crew failed to accurately analyze and respond to the current situation when encountering a dangerous situation. In the end, they behaved at a loss in real danger and sat back and watched the accident happen.
Figure -154 in NATO 's weapon codename is "careless", which means "careless". html Plane No. 12610 caused the "Xi'an 66 air crash" due to the "layers of carelessness" of the ground crew, flight crew members and Tu-154 design. It has to be said that it is a different kind of coincidence and irony.
The "June 6 Xi'an Air Crash" was finally positioned as a classic civil aviation safety education textbook and entered into the history of civil aviation in New China. The accident also directly caused serious losses for Northwest Airlines, which was eventually acquired by Eastern Airlines in 2002.
I hope we can all learn lessons from these accidents one after another, improve aircraft and related management systems, and let China Airlines have a better and safer tomorrow!
References:
"Analysis of the Air Crash of Passenger Flight 2610" December 2006 Zhong Peidao
"Air Crash Caused by Plugs" 2007 Issue 04 "Labor Protection" Zhong Peidao
