Chapter 369: Thrilling! Thrilling!
In the Xianchi area control room, the controller had just finished lunch and came over to take over. Around two o'clock in the afternoon is a busy time, and the next peak period will be around nine o'clock.
As a controller, I don’t really like taking shifts at this time. Although it doesn’t affect my lunch, I just finished my carbohydrates and it’s time for lunch break, so I’m naturally prone to drowsiness. What’s worse is that this time is the peak season in the area. If there is a thunderstorm, there will be crews everywhere requesting headings, and I can hardly put down the microphone. At this time, the brain CPU is likely to be overloaded.
Just after sitting down, the controller saw the dense signal points on the radar, but he didn't feel too much pressure. Although there were many planes in his area this time, there was no thunderstorm in the area, and there was no turbulence that required a change of altitude, so the work was actually quite easy.
Receive planes from other areas and then deliver them to the next area safely.
After putting on the headphones, the controller unscrewed the thermos and drank a cup of strong tea. It was forbidden to use uncovered cups at the control desk, otherwise he would never put a lid on the teacup.
The controller yawned, adjusted a relatively comfortable posture, glanced at the screen, and saw that a Muhua Airlines plane was about to be transferred to the Rongfu area, so he was ready to contact. However , at this moment, an upward arrow suddenly appeared on the signal point of the flight number Chunxia 9334.
This arrow represents the rise and fall of the aircraft. A downward arrow means the aircraft is rising.
"Hmm?" The controller exclaimed softly. The altitude deviation of the aircraft reflected on the radar was not large, about one hundred feet, so there was no conflict.
This situation is rare, but it has happened. In this era, the relationship between pilots and air traffic controllers is relatively relaxed and harmonious. The air traffic controller did not react too much. Perhaps he suddenly encountered violent turbulence, or perhaps the trainee's hand shook while he was flying.
There is no problem because the altitude value set by the pilot on the MCP can be displayed on the screen.
That’s right, the controller’s monitoring system can directly see the altitude set by the pilot, and even the speed. This is due to the information exchange between the control system and the aircraft’s transponder.
In the early 2000s, civil aviation pilots were still as tough as the Air Force, with an incredible amount of hands-offs. The instructors' philosophy was simple: after a few pitfalls and plane crashes, they would have a good idea of what to do and how to avoid them.
Those who can graduate from an aviation school at least have no major problems with their skills. You will understand after experiencing it a few times yourself.
Some instructors will even choose to let students fly manually during a shorter flight. Sometimes it is normal to have a small deviation in altitude or heading. As long as there is no conflict, the pilot will tell the controller and no one will pay too much attention to it, let alone report it.
However, the controller suddenly thought that this flight was flying from Hanjing to Jianchuan. It would take more than three hours to fly. Three hours of manual flight, is that so abnormal?
Just when the controller was about to ask the crew, the original upward momentum stopped instantly. The controller smiled knowingly and even imagined the scene where the instructor started to curse.
Almost within a second or two, the aircraft signal began to show a descent rate. The controller leaned back, thinking that the crew was making corrections. He thought that the deviation was not large, so he decided not to mention it.
However, after the aircraft's altitude returned to 10,400 meters, the downward arrow behind the signal did not disappear. In just a moment, the altitude dropped directly below 10,400 meters.
The controller may have eaten too much and his brain was overloaded, and he was obviously stunned for a moment. As far as he could see, there was another China Airlines plane a thousand feet below Spring and Summer Flight 9334. The two planes were only one altitude layer apart, and the two planes had to strictly maintain their altitude.
Of course, the two planes were not flying in opposite directions, but converging at a certain point. However, even so, if Spring Airlines 9334 began to descend, it would be extremely dangerous, and it is very likely that the National Airlines plane would directly hit the Spring Airlines plane from the side.
This controller obviously had little experience. After a moment of hesitation, the descent rate of Chunxia 9334 flight suddenly increased.
In an instant, the signal points of Chunxia 9334 and the Guoda Airlines plane below all turned red. This was the radar-controlled anti-collision monitoring alarm.
The vertical separation between the two aircraft was now very small, and it was difficult to separate them vertically. The controller was sweating all over, grabbed the microphone, and shouted: "Chunxia 9334, turn right heading 270, emergency avoidance, emergency avoidance."
As the saying goes, mistakes are made in a hurry. As soon as the controller finished speaking, he noticed that there was a restricted area to the right of Chunxia 9334. He was immediately frightened and his face turned pale.
Perhaps the Spring Airlines crew reacted too quickly. As soon as the controller finished speaking, the aircraft signal point shifted slightly to the right.
The Spring Airlines plane was originally flying close to the restricted area, and now the signal point was close to the border of the restricted area. The controller was so scared that his legs almost went limp, and he shouted into the microphone with a trembling voice: "Spring... Spring... 9... 9999..."
The controller was so frightened that he couldn't even speak straight. He even forgot the flight number of Spring Airlines for a moment.
It was a matter of seconds, and because of such a small mistake, he could only watch the Spring Airlines plane fly towards the restricted area.
…
In the cockpit of Chunxia 9334, the captain instinctively pushed the stick up after realizing that he had pushed the stick too hard to correct the speeding and had broken through the altitude.
This instinct is almost imprinted in the pilot's genes. In principle, it is not wrong, but he did not notice that he had stepped on the accelerator to the maximum in order to slow down.
This action is actually nothing, if it is at a low altitude. Turbofan engines, especially CFM engines, have a very obvious flaw, that is, the throttle is very smooth to close, but it is relatively slow to close. Therefore, based on this reality, the automatic throttle follows the principle of fast increase and slow reduction when adjusting thrust, that is, when closing the throttle, it closes very slowly, but when it needs to close the throttle, it is much smoother.
The slow thrust increase of the CFM56 engine is particularly evident at high altitudes. Because of this, many operations that are performed at low altitudes cannot be used at high altitudes. For example, at low altitudes, it is normal to reduce the throttle and hold the stick to slow down.
This is not possible at high altitudes!
Once the throttle is fully reduced, it will take a long time to add it back. Moreover, the aircraft was already cruising at an altitude of more than 10,000 meters, which is a very high cruising altitude, and the air is quite thin. Once the throttle is fully reduced, even with the stick, the aircraft will still fall uncontrollably.
Not to mention, when the captain realized that he had exceeded the altitude, he instinctively pushed the stick again, which added fuel to the fire, and the plane rushed down like a broken dam.
Originally, the captain wanted to recover the over one hundred feet that had exceeded the limit, but with just a small push, the plane lost more than three hundred feet of altitude in the blink of an eye.
The captain was not stupid. His hair stood on end immediately. He realized that he had made a big mistake!
Fortunately, Xu Cang reacted quickly. After seeing the captain had reduced the throttle, he still increased the throttle himself even though the captain was holding the stick at the time.
However, precisely because the CFM56 engine was struggling to increase its thrust at high altitude, the aircraft was still rushing down sharply at the moment the captain pushed the stick.
To be honest, Xu Cang really didn't expect that the captain would dare to push the pole after taking it. He was really shocked.
Xu Cang survived until now by relying on instinct, which does not mean that other pilots can do the same. Xu Cang's instinct is to see through everything and complete the processing of information in a very short time. Other pilots are more mechanical muscle memory, they can not really understand the current situation.
So why do most pilots need training?
It takes a lot of training to correct these mistakes, the so-called mechanical muscle memory.
At first, Xu Cang saw that the captain pushed the stick too hard and deviated from the altitude, and he also increased the throttle, thinking that the captain should realize his mistake. However, this push on the stick really scared Xu Cang.
"You can't fly like that!"
Xu Cang could no longer sit idly by and grabbed the steering wheel.
Almost at the same time , on the navigation page, the plane that was originally at the ten o'clock position of the Chunxia 9334 plane and was only a thousand feet lower in altitude suddenly changed from a white hollow diamond to a solid yellow, and then without stopping, turned directly to red.
As the adjacent signal point turned red, an electronic alarm sounded in the cockpit: "Climb!"
To be honest, Xu Cang's main focus was on the PFD, and he didn't pay much attention to the navigation page. As the TCAS warning sounded, Xu Cang realized that there was another plane below him, and it was very close.
At this moment, the controller's anxious voice rang out in the cockpit at the same time: "Chunxia 9334, turn right heading 270, emergency avoidance, emergency avoidance."
At this moment, the captain immediately switched to a conflict avoidance maneuver, and the handling was very skillful, immediately disconnecting the autopilot and autothrottle. In the TCAS RA warning, a red trapezoid will appear in the PFD, and the pilot must control the aircraft to maintain the attitude outside the trapezoid.
At this point, the top of the trapezoid has touched the attitude of positive five degrees, which means that the pilot must increase the aircraft attitude to more than five degrees. The climb rate generated at this attitude can ensure that the conflict is avoided.
The TCAS air collision avoidance system is originally an interactive system. When the RA alarm appears on the Spring Airlines plane, the ATC Airlines plane below will also generate an alarm.
For example, now Xu Cang's plane is indicating to climb, then the TCAS alarm of the Guoda Airlines plane below is instructing the crew to reduce the attitude downward. In this way, the conflict can be resolved.
From a design principle perspective, the TCAS warning only provides guidance on pitch, but no avoidance guidance on roll.
From the perspective of control, the conflict should be resolved vertically first. If it cannot be resolved, then a horizontal solution should be considered. The Xianchi controller instructed the vehicle to turn right away, which really showed that he was being pushed into a corner.
At this time, the engine thrust has not been added. If the attitude is increased to plus five degrees according to the TCAS guidance, the speed will definitely not be able to be maintained and it will suddenly turn into a stall. If it stalls at an altitude of more than 10,000 meters and there is another plane below, it seems that it will not be much better than it is now.
However, when the captain was at a loss, the controller obviously came to his aid. The vertical separation could not be solved, and TCAS did not have roll guidance, but it made up for it.
The captain was so happy that he pressed the right steering wheel without thinking, and the slope directly exceeded 30 degrees. It was obvious that the captain was also in a hurry.
However, the captain had just pressed down the right steering wheel and had not held it for a second when he suddenly felt something grabbing the steering wheel.
"Damn it, the right side is a restricted area!"
Xu Cang's hands were so strong at this moment that he actually overrode the captain's control and turned the steering wheel 30 degrees to the left.
"What is banned?" The captain didn't react at first.
As the captain was asking the question, a second panicked voice from the controller came over the radio: "Chun...Chunxia 9...9999..."
Just by listening to the sound, you can imagine how scared the controller was.
Xu Cang didn't have time to call the controller at this time. Although he avoided the restricted area, the two large-angle turns actually caused another serious problem, which was the decomposition of lift.
In the absence of power, the lift of the Spring and Summer 9334 aircraft was not enough, and now in the steep turn, the lift was broken down, causing the lift to be greatly reduced. Even though the thrust was slowly added later, the aircraft's descent rate did not slow down, and it crashed straight into the Guoda Airlines aircraft below.
Originally, according to TCAS instructions, Chun Xia's plane should have climbed. However, due to actual performance limitations, the plane not only did not climb, but also descended. Therefore, the original requirement of at least five degrees was increased to seven degrees, and the voice warning changed: "Climb! Increase climb!"
The TCAS system is urging the crew to climb faster!
However, this is obviously unattainable.
The Auda Airlines plane below also generated a TCAS alert, requiring the crew to descend to a negative three degrees attitude.
Although the sudden conflict warning also scared the crew of Guoda Airlines, the captain of Guoda Airlines reacted promptly, immediately double-cut, adjusted the throttle, and pushed the stick to reduce the attitude. The aircraft immediately formed a descent rate of more than 1,600 feet.
The crew of Guoda Airlines was certainly a little nervous, but not to the point of being scared. Sometimes, nearby aircraft can easily trigger TCAS alerts due to excessive climbing rates, but as long as they follow TCAS guidance, there will basically be no problem.
"Brother, there's a plane above us that's 600 feet higher than us, and it's still descending." The co-pilot of National Airlines even had enough energy to observe the navigation page to guess which plane caused the traffic conflict.
The captain maintained his small attitude and muttered, "Did you adjust the altitude wrong?"
As the captain was diving down, his first thought was that the plane above was flying at the wrong altitude. In this case, once a conflict warning was issued, the crew of the plane above would have been able to react quickly, so there was no danger.
However, the co-pilot suddenly said: "They are still descending."
The aircraft's navigation page does not show much aircraft information, and one can only rely on the TCAS system to obtain information about aircraft within a certain horizontal distance range and a certain vertical distance range. At the same time, the signal will show a difference in altitude from one's own.
A positive value indicates how many feet above you are, in units of 100 feet; a negative value indicates how much below you are.
Just like the controller's monitoring radar, there will be an arrow representing ascent or descent after the altitude number. At this moment, there is a downward arrow behind the red signal point 05 above, indicating that the plane above is now only 500 feet higher than itself and is still descending.
"We're only 500 feet away and we're still descending. Are Chunxia and the others mentally ill? They can't understand TCAS?" The captain cursed and was just about to press the radio button on the control wheel to ask what was going on.
But before he pressed the button, the captain suddenly discovered a second yellow signal point appeared near him.
That was a plane more than a thousand feet below them. It turned out that there was another plane flying in the same direction two thousand feet below them, but due to the large height difference, it was not reflected on the navigation page. Now, as they descended, the signal of the plane below appeared.
A gap of more than a thousand feet could not be sustained for long at a descent rate of one thousand six hundred feet per minute, so the signal of the plane below turned yellow, which was the TA alert color.
Less than two seconds later, the plane below also turned red. Then, the TCAS alarm of the National Airlines plane began to sound a second completely different instruction: "Level Off!"
It turned from declining to flat.
To be honest, the captain of Guoda Airlines was also confused at this time. He could understand the logic of TCAS, the plane at the bottom must have been instructed to descend at a large value, and his side must not be able to ascend, so TCAS did not instruct him to change from descending to ascending, but directly changed to leveling.
In principle, there should be no problem as long as you follow the TCAS guidance.
But the Spring Airlines plane at the top did not follow TCAS.
The captain of National Airlines could figure out with his toes that the plane at the top must have been ordered to ascend, but in the end, that plane was still descending, which was madly squeezing his space for movement.
To be honest, the captain of NUS Airlines was a little panicked at this time. His mind was blank and he didn't even think about turning.
Even without the controller's instructions, at this time, it was obviously impossible to rely on pitch to solve the vertical separation problem, so the only option was to make a turn on one's own initiative.
The captain of NUS Airlines had encountered RA alarms before, but this was the first time he had seen a pilot being trapped from top to bottom.
For a moment, the captain of the National Airlines was a little confused and instinctively followed the instructions of TCAS to level the plane.
However, when he was leveling off, the captain of the National Airlines plane suddenly discovered that the Spring Airlines plane above was still descending, and the altitude gap was less than 400 feet.
At this moment, in the cockpit of Spring Airlines, the situation had reached a critical point. Since the captain initially pressed the right side, Xu Cang turned back to the left and happened to return to the original position, right above Guoda Airlines.
However, at this time, the altitude difference between the two planes was only more than 200 feet, and the thrust was only increased back to about 50, which was too slow.
What does more than 200 feet mean? At this moment, the descent rate of the Spring and Summer 9334 aircraft is still more than 1,500 feet, and it will only take more than six seconds to hit.
Originally, when Xu Cang was about to level the plane, he noticed that the altitude difference between the two was only two hundred feet. A thought flashed through his mind, but even as this thought came to his mind, the altitude was no longer two hundred feet.
If there were still 500 feet, Xu Cang would continue to turn left without hesitation. However, there were less than 200 feet left, which was too close. Even if the plane had power, it still had a descent rate of more than 1,200 feet, and it would take time to continue to form a left slope. Before it could really turn out, the two planes would collide.
So, he had to suppress the tendency to collide at the vertical height.
"It's going to hit, it's going to hit!"
At this time, Xu Cang pursed his lips and raised the pole, and the plane's attitude increased to ten degrees almost instantly. At an altitude of more than 9,000 meters, such a large attitude was too terrifying, not to mention that the plane's power was only increased to 60, which was by no means a power value that matched such a huge attitude.
In this case, the speed of the aircraft dropped from .79 to .62 in an instant. The speed reduction was so exaggerated that it was almost approaching the top of the red and black speed band.
The captain paused for a moment and said, "It's stalled!"
At this altitude and with this power, the speed dropped by 0.17 Mach in just a split second, which was extremely terrifying. At this speed, the aircraft would instantly fall into a deep stall once it entered a stall, and the aircraft would still have to rush down.
However, this is when Xu Cang's abilities were revealed.
The moment the aircraft's Mach number reached Mach .60, he immediately reduced the attitude to five degrees. At the same time, he freed his left hand, grabbed the flap handle, and without even looking, he moved the flap handle from the retracted position to flap five. Then, he maintained the five-degree attitude unchanged.
In this attitude, the aircraft should be able to maintain level flight under power. However, this is based on the normal speed of the aircraft. The aircraft speed is too low, and the lift of the aircraft is positively correlated with the speed, which leads to insufficient lift in the five-degree attitude.
Therefore, Xu Cang lowered the flaps to provide the lift that was initially missing.
In fact, Xu Cang's actions were against the rules. Boeing's flaps are not allowed to exceed an altitude of 20,000 feet in principle. Once exceeded, the flap structure may be damaged. However, if it is necessary to release the flaps above 20,000 feet, the corresponding flap speed must be reduced according to the additional altitude.
However, this reduction is basically measured by the indicated speed. But at more than 9,000 meters, the indicated speed is no longer meaningful, and only the Mach number is used. Therefore, Xu Cang can only descend at the fastest speed to reduce the speed to the minimum Mach number, and then release the flaps based on his feeling.
However, according to Xu Cang's feeling, even if the speed was reduced as much as possible, the flap structure would still be damaged after landing.
After Xu Cang's series of operations, the plane's descent rate instantly returned to zero, and even increased slightly.
It was just this tiny difference, and Xu Cang suddenly found a plane flying diagonally past him from the lower left. The distance was so close that the airflow generated by its passing even caused Xu Cang's plane to shake.
All this seemed complicated, but it was only a matter of seconds. The captain of the National Airlines was so nervous that he clenched his big toes. After the two planes missed each other, his face was covered in cold sweat, his left hand holding the steering wheel was shaking, and a large area of his shirt on the back was wet.
After making sure the danger was over, the captain of Guoda Airlines breathed a sigh of relief, silently switched on the autothrottle and autopilot, then pressed the radio button and let out a hysterical roar across the entire channel to express his regards to the relatives of Spring Airlines, the instigator of the incident: "Spring Airlines, fuck your mother!"
