Chapter 72: The God of Mental Arithmetic
The student sitting on the right opened his mouth wide when he heard this, while the Airbus student standing behind him looked at Jin Fuli subconsciously.
Is it possible that a Boeing pilot is flying an Airbus simulator? Is there such a thing?
"It doesn't matter! I said, as long as you can land the plane, I don't care what method you use, no matter who is flying it." Jin Fuli leaned back in his chair: "Xu Cang, you better think about it, this plane is not easy to land."
There was no anxiety or hesitation on Xu Cang's face. His eyes were calm as he looked into the water. "We are still 20 nautical miles away from the venue, and the altitude is over 20,000 feet. It's just right!"
It just so happened that these three extremely ordinary words sounded as unshakable as a mountain when they came out of Xu Cang's mouth, as if this project, which was extremely difficult in the eyes of others, was nothing special, and could determine the landing in the near future at an altitude of 20,000 feet.
Jin Fuli narrowed his eyes and said, "That requires you to always fly at the green dot speed. Without a reference, how can you fly?"
The green dot speed allows the aircraft that has lost power to fly at the best glide ratio. If calculated according to the best glide ratio, 20 nautical miles and an altitude of more than 20,000 feet can indeed reach the airport. But this is an ideal state, which is difficult to achieve most of the time, and naturally it is impossible to achieve the effect of flying 20 nautical miles at an altitude of more than 20,000 feet.
The difficulty lies in the fact that the green dot speed will keep changing according to the height and weight of the aircraft, and the height and weight of the aircraft itself are also constantly changing. Without a table for reference, it is difficult to adjust the green dot speed of the aircraft in a timely manner.
At this time, the aircraft's altitude margin is very small, and if there is a slight deviation, the aircraft will not be able to fly to the airport. In addition, Xu Cang also has to consider that after establishing the landing configuration, the aircraft's height-to-distance ratio will undergo unexpected changes, which is quite different from the smooth state.
In general, a glide landing with both engines turned off is a great test of the crew's computing ability. It is quite difficult even with the help of computers and manuals, not to mention without these additional help.
However, Xu Cang pointed to his brain and said, "It's okay. The data is all in my brain."
The Airbus trainees at the back all gasped. This Boeing guy was simply too arrogant. The green dot speed table was not just one or two lines, but a 4 by 11 table. If any data was wrong, the plane would not be able to land.
But when the passenger on the right seat saw Xu Cang's expression, he didn't look stubborn at all. It seemed that everything was natural and easy.
"Can he really fly an Airbus?" The hair of the co-pilot on the right seat was a little messy due to the wind from the air-conditioning vent. He was disheveled. When did the pilots of the Boeing fleet become so versatile? I have never heard of it!
Compared to the Airbus trainees' doubts, Jin Fuli clapped his hands and laughed: "Very good, very good! If you can land on the runway, I will let this kid pass today, although his performance makes me feel disgusted."
The student on the right seat lowered his head and said nothing, while the two people watching behind him were also trembling. Hearing what Jin Fuli said, the captain of the Airbus flight was indeed very angry.
Xu Cang didn't say anything else. He had already wasted enough time talking and there was no need to waste more time.
Now that ECAM ENG DUAL FAILURE is not available, the only way to deal with it is to rely on memory. But most pilots don’t know how to remember this, so without ECAM and the quick checklist, they will be dumbfounded.
But Xu Cang is different, he is always different from others!
"I say it and you do it, okay?" Xu Cang didn't dare to have too high expectations for the student on his right. If he couldn't even listen and do things, then Xu Cang would have to consider completing the task alone, even if it would only increase the difficulty for him.
But with the huge amount of mental arithmetic pressure that will come in the near future, it would be good to have someone else to help share the burden.
The student on the right seat was a little nervous at the moment. Xu Cang's voice was not loud, but full of majesty, as if he had returned to the state of the chief engineer of the General Administration. The student, whose mind was blank, had already begun to doubt himself. He didn't know if he could cooperate with Xu Cang well, and continued to fall into silence.
After waiting for a second or two without a response, Xu Cang had already lost his patience. He suddenly shouted, "Answer me!"
The sound was so loud that it almost overturned the entire simulated cabin, making everyone's ears buzz. It was truly like a sound from the sky falling, shaking everyone's heart.
Even a figure like Jin Fuli felt so excited that he could hardly control himself.
"What a powerful aura!" Jin Fuli never thought that there was any nonsense about showing off one's domineering attitude. He just thought that everyone has a pair of eyes and two hands, so what's the difference?
But seeing Xu Cang today with my own eyes, I can't help but sigh that people are indeed different.
The already panicked student on the right seat was so upset by Xu Cang's yell that even his lips were trembling. He didn't even know why he was afraid of a Boeing pilot, but he was just afraid!
However, the student on the right seat, who was obviously already confused, perhaps forced himself to calm down under Xu Cang's encouragement, swallowed his saliva, and said with all his might: "I can do it!"
"Okay!" Xu Cang didn't say much and went straight to the point: "Verify that the emergency power supply is connected."
The emergency power supply comes from the emergency engine. Similar to Boeing, the power of Airbus 320 mainly comes from generators driven by two engines. However, unlike Boeing 737, Airbus 320 also has an emergency engine, whose hydraulic power comes from the ram air turbine, which is a small fan extending from the belly of the aircraft. It will automatically extend in the event of serious hydraulic and electrical failures.
Under normal circumstances, the emergency power supply will automatically connect, but there may be problems, so it needs to be verified. This emergency power supply will provide the aircraft with a minimum amount of power and is quite necessary.
The student on the right seat quickly confirmed that the emergency power was connected, otherwise the instruments in the cockpit would have gone black.
"Thrust handle, slow down!" Xu Cang muttered, and pulled the thrust handle together.
After that, Xu Cang gave another order: "FAC1 close and then open!"
FAC stands for Flight Augmentation Computer. It is a very important device. There are two of them, namely FAC1 and FAC2. Under normal circumstances, FAC1 is the main one and FAC2 is the backup one. As long as one flight augmentation computer is still working during the flight, the normal operation can be basically maintained without much impact. However, if both fail, the impact will be relatively large, at least it will have an extremely adverse impact on the aircraft yaw, envelope, low energy warning and wind shear prediction functions.
In addition, the laws of flight operations will also be downgraded. Specifically, the pitch will be changed from the normal law to the backup protection law, and the roll and yaw will be downgraded to the direct law. The aircraft lacks protection for various characteristic speeds. During operation, the pilot may easily exceed the speed limit if he is not careful, which is very dangerous.
Therefore, Xu Cang had to restore the operation of at least one flight stabilization computer.
The student on the right seat was still quite useful at this time. He followed Xu Cang's instructions to turn off and then on a flight stabilization computer. Xu Cang's eyes were always on the status of the aircraft, but he could still spare some energy to monitor the student's actions to prevent him from making mistakes.
After confirming that the action was correct, Xu Cang immediately gave the order: "Engine mode selection, ignition position!"
At this moment, Xu Cang had already adjusted the aircraft speed to close to 280 knots within the range of the optimal pitch attitude. This is a very suitable speed for restarting the aircraft, except when the engine fails during high thrust operation. At this time , the speed should be greater than 280 knots to prevent the engine core from locking.
Xu Cang held up a finger: "We will only try to restart once."
In Jin Fuli's settings, the plane's engine had not been shut down for a long time, and the plane was not in a heavy rain environment, so there should be no need to restart it repeatedly. If it fails to start once, it is likely that trying again will be futile.
Moreover, the most important thing is that 280 knots is not the best gliding speed. This means that over the same horizontal distance, the aircraft loses more altitude at 280 knots than at the best gliding speed.
Xu Cang's altitude margin was originally very small, which greatly limited his room for trial and error. If he could reach an altitude of more than 30,000 feet now, he could try two or three times.
But the reality is that he only has one chance to restart!
Generally speaking, it takes thirty seconds to see the result after the engine ignites, but Xu Cang will not wait like that, and directly asks the student in the right seat to start the APU. At this time, the aircraft altitude is not particularly high, and the success rate of starting the APU is still relatively high. If the aircraft altitude is too high, sometimes the APU cannot be started.
As Xu Cang expected, the engine did not respond at all after the restart attempt. Although this attempt can be done without any assistance and without restrictions, and it will also help the engine start when the APU bleed air is available, Xu Cang does not plan to try it again.
At a speed of 280 knots, the altitude loss was faster than he expected. Theoretically, under windless conditions, at a speed of 280 knots, the aircraft would lose 1,000 feet in altitude for every 2.2 nautical miles it flew. However, at the green dot speed, the aircraft would lose 1,000 feet after flying 2.5 nautical miles. The difference of 0.3 nautical miles was still a world of difference in a life-and-death situation, especially when Xu Cang noticed that the aircraft was still in a weak headwind, which was one of the reasons for the aircraft's greater altitude loss.
He no longer had the chance to try again, so he planned to complete the landing with both engines shut down .
"Turn the engine master switch off for thirty seconds, then on!"
Under Xu Cang's command, the nervous mood of the student on the right seat began to gradually ease, and his movements became faster. However, these scenes were really strange to the Airbus students behind him.
A Boeing pilot was directing Airbus pilots to deal with a malfunction of the Airbus simulator. There was no sense of incongruity in the scene, as if Xu Cang was the captain of the Airbus, calm and composed.
If anyone dared to describe such a scene to them without seeing it with their own eyes, they would definitely call that person crazy.
One of the students nudged the person next to him with his elbow and whispered, "Brother Wang, did he do anything wrong?"
Another student named Wang Ge has already reached the seventh level of co-pilot skills. He has just passed the inspection of the bureau and entered the left-seat flight stage. At this time, the co-pilot's theoretical level is the best, so it is right to ask him.
The chest of the student named Brother Wang kept rising and falling. Regardless of whether Xu Cang had done anything wrong or not, his calm demeanor alone was enough to make people fascinated.
Jin Fuli next to him had his eyes getting brighter and brighter. This was no longer an unpolished jade, but a peerless jade that could already shine brightly.
Those blind guys in the Boeing fleet are really trash. They don't even want such people. Being blind is not an enough description.
Soon, Xu Cang ordered everyone to put on oxygen masks. After all, after the two engines were shut down, there was a problem with the aircraft's pressurization, and there was a risk of decompression.
After the APU is operational and the aircraft descends below 20,000 feet, verify that the wing anti-ice is off, the APU bleed air is on, and the engine main switches are again turned off and on one at a time.
At the same time, Xu Cang began to slow down the plane. He had confirmed that the engine would no longer be started, so he had to adjust the plane's speed back to the green dot speed.
At this moment, the weight of the plane was 13,000 pounds, about 60 tons, and the altitude was less than 20,000 feet, so the speed should be around 200 knots. Xu Cang quickly pulled the stick slightly, allowing the plane to gradually slow down to 200 knots, and then maintained this speed.
As mentioned before, in calm conditions, with the same loss of one thousand feet, a speed of 200 knots can cover 2.5 nautical miles, while a speed of 280 knots can only cover 2.2 nautical miles. The difference is quite obvious.
At 200 knots, the airplane's average rate of descent was about 1,600 feet per minute.
Seeing Xu Cang maintaining a speed of 200 knots, Jin Fuli nudged the Airbus student next to him and asked, "Is this the green dot speed?"
Even though Jin Fuli has been flying Airbus for so many years, he usually wouldn't remember this. The Airbus trainee had already checked it out: "Captain Jin, it's 200 knots. He really knows it."
Jin Fuli hummed, not showing any overly surprised expression. If Xu Cang was not the most shameless person in the world, then he must have been really confident and arrogant.
Obviously, Xu Cang is more inclined to the latter.
"Get ready." It can only be said that Xu Cang's hands were so steady that it was terrifying. He said that the speed needed to be 200 knots, and it really wasn't off by a knot. People who didn't know much about it would think that the airspeed indicator was stuck.
After the APU was connected, most of the power systems were restored. The student in the right seat asked subconsciously: "Which runway to use, what approach, blind landing?"
Xu Cang was stunned for a moment when he heard it, then waved his hand: "Forget it, I'm overthinking it, you can do whatever you want, in the end we still have to fly and see."
Due to the shutdown of both engines, the average descent rate will basically exceed the descent trajectory of the three-degree glide path, and it will not be able to keep up with the blind landing guidance. Therefore, it is impossible to fly a blind landing, and you can only make your own decisions based on visual observation.
It is even hard to say whether it landed on Runway 23 or Runway 05, as we can only see the height of the aircraft in the near distance. Judging from the current approach heading, it is estimated that Runway 05 was used.
"Just draw a distance circle, five nautical miles, ten nautical miles and twenty-five nautical miles." Xu Cang thought for a moment and said, "Choose the approach speed. Our flap extension plan will be different from usual. The flap and landing gear release will be subject to my command. You are responsible for speed control. Also, turn off the cabin and kitchen switches, and turn on the cabin signal board."
The reason for turning off the cabin and kitchen power switches is to unload the load on the power system and prevent some unexpected situations.
After the plane was below 15,000 feet, Xu Cang ordered to turn on the ram air switch and instructed: "After passing the transition altitude, adjust the air pressure reference, turn off the crew oxygen below 10,000 feet , notify the cabin of the upcoming landing at 2,000 feet, broadcast the anti-collision posture at 500 feet, and when touching down, turn off the engine main switch and APU main switch. Got it?"
As the plane's altitude decreased, the headwind became stronger and stronger. The actual altitude change of the plane was somewhat different from the description in the manual. Xu Cang had to make calculations based on the aircraft's data at all times. The pressure was gradually increasing. He could not fly with the student on the right seat all the time, so he just took this opportunity to explain everything that would happen next.
Logically speaking, these operations are not difficult, so it shouldn't be impossible to do them, right?
"We'll give you a OK day, visibility is 49.9, go ahead and fly!" Jin Fuli said casually.
OK day means CAVOK, there are no clouds in the sky and the visibility is four nines, which means the visibility is more than ten kilometers. This is the best weather and the vision is not obstructed at all.
To be honest, Jin Fuli was somewhat humane and did not mess up the cloud base or visibility for Xu Cang. However, as long as the visual approach standards were met, Xu Cang did not care.
Compared with the weather and approach, Xu Cang was a little worried about the plane's altitude at the moment. From the beginning of the operation, the plane's altitude margin was very small, and with the extra altitude lost by restarting the engine, the plane's altitude was already very dangerous.
However, if the green dot speed can be perfectly maintained, it is still possible to land on the runway, but the headwind in the high-altitude environment has a very bad negative effect.
It seems that the plane can't make it to the airport!
The most critical data for a dual-engine shutdown is the altitude. Once the altitude is not high enough, even a god like you can’t do anything about it.
Behind Xu Cang, Jin Fuli noticed Xu Cang's solemn face and suddenly realized a problem. He seemed to have forgotten to remove the high-altitude wind. In other words, he had not originally planned to set up a high-altitude headwind for Xu Cang.
To be honest, Xu Cang had done well enough, but even so, it seemed that the level was not high enough. Wasn't this project a dead end? What was the point of practicing something that was destined to end like this!
Jin Fuli looked at his watch and realized that he didn't have enough time to start over. He couldn't help but feel a little regretful. His careless mistake had ruined the project, which was a pity. However, he had already obtained the information he wanted.
"What's wrong? The plane can't land?" Although it was his own mistake, Jin Fuli would not admit it.
At this moment, the student on the right seat also noticed the impact of the headwind on the aircraft. He looked back at Jin Fuli with some uncertainty: "Captain Jin, this wind..."
The two Airbus trainees standing at the back also noticed that the altitude might not be enough. The Level 7 co-pilot trainee had a sharper eye and lamented: "What a pity, we just need a headwind, there is nothing we can do."
"Oh, since there's no other way, forget it. There's really no way to deal with the low altitude when both engines are turned off." Jin Fuli laughed and took advantage of the situation to back off. He was very natural: "It's almost time, let's pack up and go. We can handle it later..."
However, just as everyone was about to pack up, Xu Cang's cold voice rang out and entered everyone's ears: "Who said there is no way?"
The student on the right seat, who was about to unplug his headphones, held his hand in the air and looked at Xu Cang in surprise. Seeing that Xu Cang had no intention of leaving, he couldn't help feeling confused and turned around to look at Jin Fuli.
Jin Fuli made a mistake when setting up the simulator. He only remembered to set the ground wind to calm, but neglected to cancel the high-altitude wind. The already limited altitude suddenly became unusable. How could he fly?
Therefore, Jin Fuli's seemingly arbitrary conclusion that he could not fly was not unreasonable.
Jin Fuli was just packing up documents and materials. After hearing what Xu Cang said, he put the documents down and said earnestly, "No, Xu Cang, you should be able to see that the height is not enough."
"No!" Xu Cang said softly: "There is still a chance!"
The sound was like the cry of an oriole in an empty valley, soft and weak, just like Xu Cang's indecisive heart at the moment. The huge and complicated data kept impacting Xu Cang's mind. Even a talented person like Xu Cang felt dizzy and had difficulty finding the source of the solution.
It’s so messy, so messy!
Xu Cang's eyes kept shaking, just like his restless heart. He wanted to find a glimmer of hope in the vast ocean of data.
Jin Fuli frowned: "Xu Cang, what are you talking about? It's so obvious, I don't believe you can't see it."
"But you overlooked one thing." A trace of cold sweat seeped out of Xu Cang's forehead. It had been a long time since he had exerted such a huge amount of energy.
Seeing Xu Cang looking like he was about to collapse at any moment, Jin Fuli felt a little solemn in his heart: "Is there anything else I didn't expect?"
"The wind, it's the wind!"
Suddenly, Xu Cang's eyes stopped shaking. Everything became clear at this moment, and he finally found the solution to the messy data.
"Wind?" Jin Fuli looked at the Airbus students around him in confusion, "Wasn't I just talking about wind? Do you understand?"
The Airbus trainees next to him all shook their heads. Their thoughts were exactly the same as Jin Fuli's. Wasn't it because of the headwind that they concluded that the plane could not fly to this airport?
Could it be that this guy didn't hear it just now? That shouldn't be the case. He should have heard it anyway when he was so close.
Suddenly, Xu Cang's eyes sparkled with an incomparable light, and he suddenly laughed: "But...but the wind will change, don't you know?"
Jin Fuli was such an experienced person that he instantly understood what Xu Cang meant from his seemingly incoherent words. However, understanding was one thing, or rather, the more he understood, the more he felt that Xu Cang was delusional.
Jin Fuli remained silent and did not refute, which caused surprise among the Airbus students next to him. Could it be that Xu Cang was not speaking without reason? But this did not make sense at all!
"No!" The level 7 co-pilot was half a captain after all, and he had a lot of experience, so he began to figure out what was going on. After a while, he said with a gleam in his eyes, "That's right! This is not a real flight, it's a simulator, the wind changes are uniform, so we can calculate it! No, no, no..."
The Level 7 co-pilot kept shaking his head: "It's impossible. Even if the wind speed in the simulator changes evenly, how can we calculate the glide path by human power? It's impossible."
If this were a real flight, Xu Cang would be helpless. In real environments, wind direction and speed are uncertain. Although they follow a general rule, this kind of nonlinear change cannot be calculated.
But a simulator is a simulator after all. It cannot simulate the irregular wind direction and speed from high altitude to the ground in a real flight, at least not on this simulator.
On this simulator, the wind direction from high altitude to the ground is fixed, and the wind speed decreases evenly with altitude until it reaches zero on the ground. Such even and regular wind speed changes gave Xu Cang a little bit of calculation possibility!
However, this is only theoretical. In the eyes of the Level 7 co-pilot, theory often represents fantasy. A mirage, visible but untouchable.
The other two Airbus trainees had low technical skills and did not understand the current situation at all. Jin Fuli said in a low voice: "Xu Cang, I don't like this kind of behavior of making decisions based on guesswork. The plane can't land, it's not your fault, you don't need to be stubborn."
Obviously, like the level 7 co-pilot, Jin Fuli also felt that it was impossible for Xu Cang to calculate the accurate descent trajectory by manpower, even if the wind speed changes were uniform.
The only explanation is that Xu Cang was just guessing! And Jin Fuli really didn't like this approach.
"Xu Cang, have you forgotten that if the plane lowers its flaps and landing gear later, its altitude will drop faster!" Jin Fuli shouted coldly.
The manual recommends flaps 3 for a two-engine shutdown landing. But with flaps 3 and landing gear down, in no wind conditions, the aircraft loses 1,000 feet of altitude for every 1.2 nautical miles it moves, which is nearly twice the rate of altitude loss at green dot speed.
Xu Cang took a deep breath and felt that the world was open and his mind was clear. All the chaos and confusion seemed so clear. He could see clearly all the future descent trajectories of the plane.
"What if we land in a smooth configuration?" Xu Cang suddenly asked softly.
Jin Fuli was startled, and then he refuted: "Are you kidding? For a smooth landing, how fast would the touchdown speed be? The runway in Jianchuan is not long enough."
"That's enough!" Xu Cang laughed, "As long as we touch down at the head of the runway and not in other areas, it will be fine."
"Let's not talk about whether you can fly to the airport. Even if you can, you can't land at the head of the runway just because you say so. You have no power now, how can you guarantee that you can land at the head of the runway?" At this time, even the level 7 co-pilot couldn't help but question.
However, Xu Cang pointed down along the simulator backdrop, and in the weather with almost no obstruction, he pointed at the Jianchuan runway not far away: "See, that runway entrance sign? I will land there, not a point more, not a point less!"
