In the cockpit of the 1533 aircraft, Xu Cang discussed with Chen Guoli the plan to change the landing direction.
The workload for approach preparation was not large, so Xu Cang did not wait, but spoke to himself: "After descending to 10,000 feet, maintain altitude, fly low, maintain flaps 30, and keep the landing gear retracted. Then, ascend to an altitude of 1500 feet, turn slightly left, then turn right continuously, and change the landing direction."
Chen Guoli was doing his work while trying to understand what Xu Cang said.
If the sea pressure is corrected to 10,000 feet, then the vertical height from the airport is about 200 feet. Under normal circumstances, 200 feet is the decision altitude for a Class I blind landing.
However, the terrain of Qitai Airport is complex, and the decision altitude requirement is relatively high, which is directly doubled. The Category I blind landing decision altitude for Runway 28 is 400 feet.
However, although the snow was very heavy today, the visibility was probably very good, so it was still possible to maintain visual terrain separation. However, there was one thing Chen Guoli did not quite understand: "Since your idea was to fly in the opposite direction along Runway 28 first, and then turn 180 degrees continuously, why not stop descending at a higher altitude? And..."
After all, low-altitude passes always have certain risks, and to be honest, there was a problem with the configuration of Xu Cang's low-altitude pass. How could he not lower the landing gear when the flaps were at 30? Wouldn't this trigger a landing gear configuration warning?
However, Chen Guoli could probably understand Xu Cang's intention. Landing gear is different from flaps. Although flaps will increase drag, they will also increase lift. However, landing gear basically just increases drag.
If it is a twin-engine aircraft, it is not a big problem to fly low with the landing gear in high altitude areas like Qitai Airport. But if it is a single-engine aircraft, it will be a big problem. The aircraft may not be able to maintain its altitude, especially when turning continuously. The lift is broken down, and it will have to turn and lose altitude at the same time. The aircraft is already at a low altitude, so how can it dare to lose altitude randomly?
Therefore, instead of descending to a low altitude of more than 200 feet, it is better to maintain level flight at a higher altitude. For example, don't descend when there is still 1,000 feet from the ground, maintain level flight, fly towards the fifth leg of Runway 28, and then turn the landing direction at the appropriate altitude. Isn't it safer?
In addition, there was another thing in Xu Cang's words that puzzled Chen Guoli, and that was the issue of the final flap .
Why flap thirty?
"When flying with only one engine, shouldn't we use flap 15 to land?" Chen Guoli asked the question that was bothering him.
Xu Cang seemed to have an idea in mind, and he explained it slowly: "First, there is the issue of descent altitude. Due to the length of one side of Runway 10, we will definitely descend to an altitude of more than a thousand feet. Do you have any objection to this?"
"That's true." Chen Guoli agreed.
As mentioned before, one side of Runway 10 only extends six or seven nautical miles, because it faces the main range of Tianshan Mountain, and the mountain in front is like an axe chopped down diagonally, it is not straight up and down, but it is a little slanted outward from the top. This means that when you cut back to Runway 10 from the procedure, the height cannot be too high, otherwise you will be too close to the protruding part of the cliff. Therefore, it is better to cut in at an altitude of 1,400 to 1,500 feet above the ground, which is about a little more than six nautical miles from the airport.
Of course, considering the performance of single-engine climbing, the actual minimum altitude limit at the entry point is 1,100 feet, which is slightly lower. However, as long as the altitude is not too low, it is harmless to be a little higher.
Chen Guoli agreed with Xu Cang's statement, so the follow-up can be explained clearly.
"Let's take the standard 1,500 feet as an example. If we move horizontally to the final leg of Runway 28, then we should turn around and land five to six nautical miles from Runway 28. But what's below five to six nautical miles from Runway 28? Isn't that more dangerous?"
Chen Guoli understood immediately that there was a hill five to six nautical miles from runway 28. Previously, when he and the instructor from the National University flew here, because the blind landing on runway 28 of Qitai Airport was a little unstable, they manually increased the descent rate to catch up with the glide path. The main reason was that they were worried about the hill six nautical miles from the fifth side. If the unstable blind landing signal suddenly led them to a big dive near six nautical miles, the situation would be really bad.
As soon as we passed the six-mile hill, Chen Guoli pressed the APP. That's the reason.
Xu Cang continued, "In the area of ​​25 nautical miles around the Qitai Airport, if you want to find a continuous flat area with the largest range, it is only near the airport. Strictly speaking, even if you turn around on the fifth leg, the aircraft will still deviate from the fifth leg during the turn, which is inevitable. However, once you deviate from the fifth leg, you will actually be out of the terrain protection, so you can only choose a terrain that is as flat as possible. At least I think the terrain near the airport is safer than the fifth leg and six nautical miles. In addition, due to the radius problem of the turn, for example, if we choose the turning point at four nautical miles, it is indeed not a direct turn over the top of the mountain, but the trajectory during the process will cover there, which is actually quite dangerous. Therefore, we can only fly at a low altitude. Usually, it is safest to isolate the entire turning trajectory outside the six nautical miles of the mountain."
"I know. I'm worried about the dangers of low-altitude maneuvers. But that's a technical issue, and I can handle it. If I turn around at six knots or close to six knots, that's a performance issue, and I don't feel very good about it."
"Besides, due to the single-engine situation, the plane couldn't climb high. And Qitai Airport is too close to the main range of the Tianshan Mountains. If we want to ensure a safe and calm approach to Runway 28, we need to reach an altitude of at least 7,800 meters. Given the condition of the plane, this is basically impossible."
If Qitai Airport was not near the main Tianshan Mountains, but some of the branches, then it would be safe if it could reach 20,000 feet. And 20,000 feet is still achievable for a single-engine 737. The problem is that it is near the main branch, and accidents are very likely to happen at 20,000 feet, and it is impossible to get out of the mountainous area.
Since we can't leave the mountains, we must follow the procedures.
In general, it is impossible to reach high altitudes, and you will encounter hills at medium altitudes, so you can only turn around at low altitudes to adjust the landing direction. In any case, when the airport site was first discussed, it was the largest flat area nearby, and after artificial leveling, it was considered the best place for turning around.
Xu Cang thought for a moment: "As for the flap issue. According to the standard operating manual, for example, when it is a single-engine flight on the fifth leg, if a single-engine flight occurs at an altitude below one thousand feet, the landing flaps can be kept at 30 and the landing can continue. This means that at least from a performance perspective, a single-engine landing with flaps 30 is feasible."
"The runway at Qitai Airport is not long enough, the braking distance is not sufficient, and there is snow on the runway. If the aircraft lands with flaps 15, there is a possibility that it will not be able to stop."
"Then can you delay lowering the flaps a little bit? Not so early. What if the performance is not good enough?" Chen Guoli had tried to land with flaps 30 on a single engine in a simulator. It was definitely possible, but he had never done so in an actual flight.
Moreover, Xu Cang was going to do a big maneuver with flaps 30, so he was still a little worried. Therefore, Chen Guoli's idea was to keep flaps 15 first, wait until the plane turned back to runway 28, and then finally lower flaps 30.
This is relatively easier to accept.
However, Xu Cang asked in return: "When should we put flaps 30? When we fly at low altitude? When we turn? When we align ourselves at the end?"
"Finally..." Chen Guoli subconsciously planned to answer, but immediately felt something was wrong.
This is definitely not possible during low-altitude passes and turns, as these two stages are delicate tasks that require careful attention and can lead to problems. If the flaps are lowered at this time, the aerodynamic layout of the aircraft will undoubtedly change suddenly, and the aircraft's state will also change, which can easily disrupt the operator's rhythm.
After thinking about it, it seems that it is best to put it when it is aligned at the end, at least that's what Chen Guoli thought before.
But on second thought, Xu Cang planned to turn at low altitude to adjust the landing direction. Doesn't that mean that as soon as the plane turns around, it will almost land, and there will be no room for subsequent adjustments.
Because the descent attitude from flaps 15 to flaps 30 is completely different, and the aircraft attitude changes greatly in the initial stage of flap extension. In order to stabilize the descent attitude at flaps 30, the pilot needs to make slight adjustments.
However, since the final approach was too short, there was no room for adjustment, so the aircraft had to enter the runway and land in a less than standard situation.
When the road surface condition is good or the runway is long enough, if you simply want to land, there is nothing wrong with lowering the flaps before landing. You can do it as much as you want, and the worst that happens is that the touchdown point won't look very nice.
But here in Qitai, the runway is short and the surface is slippery. If the landing point moves slightly back, it would be fatal.
Moreover, the wind volume at Qitai Airport exceeds the standard, which makes it difficult to operate. Now Xu Cang is faced with even greater difficulty. Do you really think Xu Cang is a god who accepts everyone who comes?
Originally, Chen Guoli felt that Xu Cang had not considered the issue, but now it seemed that he had not considered it carefully enough and could not think deeply enough. However, Chen Guoli could understand Xu Cang's thinking.
That is, technical problems are most likely not the problem, but performance problems are the problem.
As long as the technical problem is feasible, just practice. If you still can't do it, it's because of your limited ability and you can't blame others.
But performance issues are different, that is an objective condition, just like the ceiling of an airplane, it can only climb so high, no matter who is sitting in the plane.
Xu Cang glanced at Chen Guoli who was lost in thought. It seemed that he had listened to him. At this moment, Xu Cang was responsible for controlling the rudder input of the aircraft and monitoring the aircraft speed.
The autopilot cannot control the rudder input, so the pilot has to do it himself. Moreover, the autothrottle cannot be used in the single-engine situation, so the autopilot and the autothrottle are not well coordinated, and the speed can only be controlled by the crew themselves.
However, compared to the time when he had to learn to control the aircraft himself, Xu Cang was now quite relaxed. From the current position, the middle part until he entered the side of Runway 10 was relatively comfortable, and Xu Cang could just keep flying on autopilot. But once he reached the starting section of Runway 10, he would have to control the aircraft manually.
After more than a minute, Xu Cang could roughly see the Qitai Airport in front of him on the left. The dark gray control tower was almost integrated with the cliff behind it. If it weren't for the layer of snow on the top of the tower, like a white hat, Xu Cang would have had a hard time finding it.
Moreover, from a distance, most of the airport was covered with white snow, and it was so white that it was difficult to tell where the runway was, where the taxiway was, and where the apron was.
"It's covered so quickly?" Chen Guoli had already reached an agreement with Xu Cang on the landing method. Of course, he was mainly the one who passively accepted it.
Now Chen Guoli was ready for the approach, his left hand on the steering wheel. Although he was a PM, his mind was tense. As the saying goes, a journey of a hundred miles begins with a single step. Don't let problems arise when you are close to victory.
Xu Cang looked at the snow outside the windshield, which melted immediately after falling on it. If he touched the two front windshields, he would find that they were warm, while the side windshields were cold.
However, a finger-thick layer of ice and snow had accumulated on the windshield frame, partition and windshield wiper arms, indicating that it was snowing heavily outside.
"I don't know how thick the snow is on the track. If it's too thick, it will be troublesome to land later." Chen Guoli muttered.
As he was talking, Chen Guoli also noticed the ice and snow on the wiper arm, so he looked behind his left window to see if there was any obvious ice accumulation on the wing surface and leading edge.
However, judging from the visual situation, the situation is still okay, but with such heavy snow, it is hard to say when the ground will freeze.
"Do we need to turn on the wing anti-icing?" asked Chen Guoli.
"hiss!"
Xu Cang was a little embarrassed. Judging from the ice and snow accumulation on the edge of the windshield frame and other places, it is indeed necessary to turn on the wing anti-icing. However, the wing anti-icing consumes too much bleed air. Turning on the wing anti-icing at high altitude can even cause the engine to suddenly shut down. Now the aircraft is a single engine, what if turning on the wing anti-icing affects the engine performance?
Xu Cang looked back at the condition of his right wing, which was indeed fine, with no obvious ice accumulation. At this moment, the plane was about to cross the field, and the plane was continuing to slowly descend, and the engine speed remained in a relatively small range.
After thinking for a moment, Xu Cang thought: "Turn on the wing anti-ice and remove it a little. When we cut into Runway 10, turn off the anti-ice. Then slow down and lower the flaps."
Xu Cang's idea was to extend the flaps while the wing anti-icing was on. Extending the flaps would require deceleration and the thrust would also be reduced. This way, the engine workload would not be too heavy, and adding the wing anti-icing load should be fine.
Otherwise, if the wing anti-icing is turned on when the aircraft is at high thrust, the engine is already running at high intensity, and if the load of wing anti-icing is added, won't it be exhausted?
When the aircraft speed slowly decreases, the flaps are about 15, and it is almost time to cut into the side of Runway 10. In the later stage, after aligning with the runway, the flaps are lowered to 25, 30, and the wing anti-ice is turned off.
Wing anti-icing has a de-icing function. The ice accumulation on the wings is not serious at first, so if you clear it in a short time, it will not affect the subsequent landing as soon as possible, which is the best of both worlds.
The only thing that Xu Cang was concerned about was the condition of the runway. He wanted the snow to be too thick and not fall off for a while, which would be a problem. The snow was indeed falling too fast. It had only been a short while, but Xu Cang could no longer tell where the runway was by visual inspection.
He was going to fly towards Runway 10, but there was no horizontal guidance or even guidance lights on Runway 10. After all, theoretically, the final distance of Runway 10 was only five to six nautical miles, which did not meet the design specifications of the instrument procedure.
There were no lights or guidance signals, and the localizer signal on Runway 28 did not have the capability to provide reverse guidance. We were completely in the dark.
However, if a line is extended from the positioning data of the head of Runway 10 in the navigation database, it should be possible to roughly maintain the direction of the runway by following this straight line.
This positioning data is very accurate, it is uploaded temporarily and will be deleted later. It is unlike many terrain data shown in the aeronautical chart, which are biased.
"I hope I can visually identify the runway after I go down." Xu Cang thought to himself.
From a high altitude, the airport was already covered in white, but it might be visible from a low altitude. Xu Cang slightly reduced the throttle, and when the speed dropped to nearly 230 knots, he ordered: "Turn on wing anti-ice, speed check, flaps one."
Chen Guoli nodded, checked the speed, and immediately put the flap handle to position 1, then turned on the wing anti-icing switch. Before that, Chen Guoli had closed the spare flap switch cover, so the flaps could be lowered normally.
Xu Cang kept an eye on the airspeed indicator, and as the flaps were extended, he retracted the throttle. He kept moving, the speed continued to drop, and then he ordered flaps five. Chen Guoli naturally did as he was told.
When the flap indicator just reached five and showed green, Xu Cang did not stop for a moment and glanced at the airspeed indicator: "Flap ten!"
"Flap ten?" Chen Guoli's hands were already on the flap handle, but he was stunned when he heard Xu Cang's order: "Did you say flap ten?"
Flap 10 is not a commonly used position. The flaps of Boeing 737 have multiple positions such as UP, 1, 2, 5, 10, 15, 25, 30 and 40. However, the flaps are not released one by one, but in a jumping order.
Generally speaking, taking flaps 30 in the landing configuration as an example, you should first extend flaps 1, then skip flaps 2 and extend flaps 5. Then, instead of flaps 10, extend flaps 15, and finally skip flaps 25 and extend flaps 30.
But if it is a 700 model, then after flaps 15, you should first put flaps 25, and then flaps 30.
Of course, if necessary, after flaps 30, the crew can lower the flaps to 40 depending on the situation. Because in the standard operating manual, flaps 30 and flaps 40 are both regular landing configurations.
Flap 10 is not used during normal flap release. Only during standby flap release, the flaps are first lowered to 10 after flaps 5 and then maintained.
The reason for doing this is that extending flaps to 15 is often tied together with the action of lowering the landing gear, and the standby flap extension speed is slow. If flaps 15 are extended according to the normal procedure, the aircraft may not be able to complete the establishment of the landing configuration before the stable approach altitude.
But if the flaps are extended to 15 in advance, the landing gear must also be extended. Extending the landing gear too early will add drag to the aircraft out of thin air and consume extra fuel, which is of course unnecessary .
Therefore, lower the flaps to ten first to shorten the time for the subsequent standby lowering to flaps fifteen, thus achieving the best of both worlds.
Apart from this time, Chen Guoli had never seen flaps 10 used at other times. However, just because it is not often used does not mean it is not allowed. Xu Cang's decision to use flaps 10 is definitely not against the rules.
"Yes, flaps 10. The altitude here is a bit high, so we'd better release the wheels later. We won't have the chance to make a go-around, so we'd better be cautious."
In fact, according to Xu Cang's estimation, if they lowered the wheels at this altitude, they would not really be unable to maintain their altitude. After all, the subsequent descent would basically be continuous rather than level flight.
However, as Xu Cang said, they had no chance to resume the flight. Because the approach procedure they were following was originally illegal, if they didn't land well once, Xu Cang himself didn't know where to go after the subsequent pull-up, so it was better not to take risks.
Chen Guoli responded. He was just curious and didn't say anything else. He put the flap handle to ten.
Just as Chen Guoli lowered flaps to ten and Xu Cang followed suit to adjust the speed window, Bi Lin's voice rang out over the radio: "Xu Cang, there is a lot of snow on the runway here. The initial feedback is that it has reached 18 millimeters. The crosswind at this runway is already exceeding the standard, and 18 millimeters of snow cannot fall. The ground management said that they can clear the grounding terminal within 20 minutes. How about landing at this runway and circling and ascending on the spot, spending some time in the sky. However, pay attention to the circling radius. Put down all the flaps and try to reduce the turning radius."
"Eighteen millimeters of snow, is it this thick?" Chen Guoli was startled and cried out, this snow thickness has greatly exceeded the limit. He thought the road surface was only covered with a thin layer, how come there was so much snow all of a sudden?
Chen Guoli thought about it for a moment and felt that something was wrong. Bi Lin also saw that this field was the flattest in the entire area, so it was safest to circle and ascend in this field. This was basically the same idea as Xu Cang's previous choice of turning at a low altitude to adjust the landing direction.
Chen Guoli did not object to this suggestion, but the question was what would happen after the snow on the road was cleared? How would the aircraft rejoin the procedure? Which procedure would it join?
Just as Xu Cang said just now, they had no chance to resume the flight, because once they took off, they would not know where to go, and there was no corresponding guidance in any procedure they knew.
Although the plane was flying in the wrong way now, at least it was following the procedure. Only the final turn after pulling up deviated slightly from the procedure. It was truly a compromise and a last resort.
But if they changed it to hovering and ascending on the spot, and then hovering and waiting at a certain altitude, then they would not have deviated slightly, but would have completely abandoned the procedure.
The runway behind is ready for landing. How can the aircraft exit the circling wait? It cannot just go in without leaving.
However, no matter what, Xu Cang still has to make the decision.
Chen Guoli looked at Xu Cang and saw that Xu Cang was thinking deeply. It seemed that he had thought of the key point. He did not elaborate, but just asked: "Xu Cang, what do you say?"
Xu Cang's eyes moved slightly, and he murmured, "Eighteen millimeters is too thick. The wind volume is already excessive, and the runway is still short. It's too risky."
Chen Guoli certainly understood these words, but the problem was the problem behind it: "It would be a big hassle to quit and rejoin the program later."
"When enemies come, we must fight them; when floods come, we must block them with earth. The snow on the runway is the most urgent. As for the chain problems that will be caused later, I'll think about it again." Xu Cang had almost no hesitation. Looking back and forth now, it would be better to settle the matter and let the airport clean the runway as soon as possible.
Although Chen Guoli felt that it was inappropriate to ignore a series of problems later in order to deal with the problem of snow on the road, Xu Cang's amazing no-radius turn had completely convinced him. Since Xu Cang had made up his mind, he just had to obey.
"If we don't land for the time being, should we retract the flaps?"
Xu Cang shook his head: "You don't have to retract all of them, just retract to flap five."
Xu Cang said, pressing the launch button: "If it's 18 millimeters, then it really can't fall. Okay! After I go down to this field, I will circle up, okay?"
As Xu Cang spoke, he caught a glimpse of the EGT display on the upper DU and was stunned. The EGT value of the No. 2 engine, which should have been quite stable, fluctuated up and down with great frequency, not intermittently, but constantly.
Chen Guoli also noticed Xu Cang's gaze, and looked in the direction he was looking. His expression suddenly changed: "What's going on?"
After turning around just now, both of them were immersed in great joy, and the originally tight line finally loosened a little. Moreover, although the EGT fluctuated greatly, it never exceeded the limit, so the performance was not obvious, and it was not easy to find if you didn't pay attention.
"N1 doesn't seem to change much, only the exhaust temperature is jumping. This is..." This type of EGT instability is most easily discovered when the aircraft is surging . However, if the aircraft is surging, the N1 speed should also change. There is no EGT value jumping. N1 is relatively stable.
Xu Cang forgot to look at the airport on the lower left. He could vaguely see that vehicles were gathering towards the runway, and fine indentations appeared on the white snow. It was obvious that the airport was moving very quickly.
However, an idea gradually formed in Xu Cang's mind: "No, that's the sequelae of the previous deployment of the EEC hard backup mode."
In order to ensure that the engine can operate normally for a long time, EEC will have overspeed protection for both N1 and N2. However, with the operation of EEC hard standby mode, Xu Cang artificially broke the overspeed protection of N1, which opened the engine restraint.
Granted, this would give the aircraft some extra thrust, but the engine was already unbridled and was beginning to spin out of control.
Chen Guoli understood what Xu Cang was going to say, but he looked at the display on the DU and suddenly felt a sense of relief: "Fortunately, fortunately, the EGT has fluctuated, but fortunately it is not over the limit, haha."
As soon as the word "ha" fell, the EGT value changed again. Before, the value was fluctuating within a stable range. But as soon as Chen Guoli finished speaking, the EGT value was not only fluctuating, but also slowly increasing, and the peak value of the fluctuation was about to touch the red line.
"Not good!" The smile on Chen Guoli's face didn't last more than three seconds, and he froze all of a sudden: "It's close to exceeding the limit."
"Damn it, there's still a problem." Xu Cang had this worry when he broke through the N1 speed limit through the EEC hard standby. Unexpectedly, the problem appeared when he was about to land: "Dean, it seems that I can't wait for 20 minutes. There is a problem with my No. 2 engine. I can't wait even five minutes!"
"What?" In the control room, Bi Lin and others' faces suddenly changed. It was impossible to clean the road surface in five minutes. What should they do?
"Xu Cang, what's wrong with the engine?"
Xu Cang did not hide it: "I just turned on the EEC hard backup mode manually, and N1 exceeded the limit."
Wang Li took the microphone from Bi Lin and his eyelids jumped: "What is the maximum value of N1?"
"It reached 110% for a short time, and most of the time it was between 105% and 106%."
"110%, the instantaneous peak speed of N1 has reached 110%!" Wang Li gritted his teeth. If there is no problem with the engine after exceeding this much, then there is a problem.
Wang Li paused for a moment and said, "Xu Cang, what's the situation now?"
"The EGT value of the No. 2 engine is fluctuating, and the peak value is approaching the red line. It looks like it will exceed the limit soon. We can't wait any longer."
Bi Lin shouted sternly, "Xu Cang, the No. 2 engine is dead and cannot be saved. Start the No. 1 engine now and terminate the verification!"
However, when Xu Cang heard this, he still hesitated: "Dean, what if the next aircraft also encounters similar problems of engine over-limit due to the use of EEC? I have to give them a solution, right?"
Zhou Yanping took a deep breath when he heard this: "Xu Cang, do you really think you are a god? You are going to step on all the thunders, right?"
Just by saying this, Xu Cang was so bold. The only engine that was still running was about to shut down. In these mountains, Xu Cang was still thinking about verifying it. It was really outrageous.
However, Zhou Yanping's perception of danger is different from Xu Cang's. In the same situation, Zhou Yanping felt that he had to terminate the verification without delay. Although Xu Cang was a little nervous, it was okay. At least he felt that everything was under his control, even though the No. 2 engine was shut down soon after.
In the cockpit, Chen Guoli, like Zhou Yanping, was tense: "Xu Cang, do we really have to wait?"
"It hasn't exceeded the limit yet." Xu Cang's eyes were fixed firmly on the airport on the lower left. As he watched, everything he saw began to form a holographic image of the terrain simulation in his mind.
To be honest, if they were to travel at a straight-line distance, even if both engines were shut down immediately, the altitude would definitely be enough, although due to the altitude, the descent would be faster here than on the plains.
But the problem is that due to terrain restrictions, the plane cannot fly directly to the field and needs to fly around the terrain, which increases the flight distance and makes the altitude a bit tight.
However, if it really came to that critical situation, Xu Cang would not mind relying solely on visual conditions to maintain the vertical separation of the terrain.
"You..." Chen Guoli was speechless for a moment.
Ordinary pilots would be extremely nervous if they lost one engine, let alone two. But for Xu Cang, everything seemed normal and simple.
Xu Cang pressed the button to speak: "I think we can give it a try..."
"What the hell!" Wang Li cursed immediately: "Xu Cang, stop the verification immediately, this is an order."
As soon as Wang Li finished speaking, Bi Lin said, "Xu Cang, you don't need to take this risk. You said that in order to prevent people from having their engines stalled due to EEC hard standby in the future, then why not just not let them use EEC hard standby?"
"I understand your reason for using the EEC hard standby, isn't it just to increase the extra thrust? Your current aircraft has a 24K thrust engine, and subsequent aircraft engines that perform missions at this airport will be limited to 26K. In this way, later aircraft can achieve the same thrust effect without using the EEC hard standby. In this way, the risk of over-limit flameout can be minimized. There is no need for you to take risks in person for problems that can be solved in hardware."
"Hey, that makes sense." Xu Cang suddenly understood what Bi Lin said. As Bi Lin said, since the problem of engine overload and flameout can be solved from the hardware, there is really no need for him to take risks.
Seeing Xu Cang agree, Chen Guoli heaved a sigh of relief and said, "Then I'll fire it?"
"Yeah!" Xu Cang nodded in agreement.
Chen Guoli and Xu Cang were both experts, so there was no need to waste time on the mid-air start checklist. Time also did not allow for that, so Chen Guoli just did it based on his memory.
"Let's use cross-bleed starting." Chen Guoli found the starting method from the starting envelope in his memory just by looking at the speed and altitude of the aircraft.
Xu Cang didn't say anything, which was considered as his agreement.
"Then... turn off the left component." Seeing that Xu Cang had no objection, Chen Guoli immediately started to act. He looked up again and saw the pipeline pressure gauge, and found that the pipeline pressure was less than 20: "Xu Cang, the pipeline pressure is not enough, please add some throttle."
"Step on the gas?" Xu Cang couldn't help but frown.
Chen Guoli naturally requested to increase the throttle of the No. 2 engine which was still running, which was also required in the checklist. The main reason was that the engine needed an air source to start, and now only the bleed air from the working No. 2 engine could be transmitted to the No. 1 engine through the isolation valve for its use.
However, if the pipeline pressure is too low, there will be insufficient air supply for starting the engine and the engine will most likely not start successfully.
But the problem is that the No. 2 engine is already close to exceeding its limit. Once the accelerator is stepped on, won’t it just add fuel to the fire?
Chen Guoli didn't notice this problem at first, but when he saw Xu Cang hesitate, and then saw the second engine exhaust temperature value that had just touched the EGT red line, he immediately understood.
Chen Guoli's face turned pale immediately. Isn't this a dead end?
Engine No. 1 needs an air source to start, but Engine No. 2, which can be used to supply the air source, cannot be throttled too much to provide enough air source due to an over-limit problem. What should be done?
"This shouldn't be the case. It should be easy to reach a pipeline pressure of 30 PSI. How could it not be reached?" Xu Cang became suspicious.
The pipeline pressure standard of 30 PSI is not high, and sometimes the working engine can reach it at slow thrust. Of course, under normal circumstances, the corresponding pipeline pressure can basically be reached when the speed of the working engine exceeds 50.
The speed of the No. 2 engine is not high now, but it is still around 55. It shouldn't be that the pipeline pressure is less than 30 PSI.
Hearing Xu Cang's doubtful words, a thought flashed through Chen Guoli's mind: "Is it because of the wing anti-icing? Has a large amount of bleed air been taken away?"
With the wing anti-icing system being a big gas consumer, it's possible that this thing has taken away the air supply to the No. 2 engine, resulting in insufficient air supply to the No. 1 engine.
Xu Cang licked his lips: "Turn it off!"
Chen Guoli dared not delay and immediately turned off the wing anti-icing switch.
When it was turned off, Chen Guoli thought he had found the crux of the problem. But after the wing anti-icing was turned off, the pipeline pressure only rose slightly, still not reaching the requirement of 30 PSI.
"What the hell?" Chen Guoli was about to curse. What the hell was this? Xu Cang was finally convinced to stop the verification, but the gas source for the first step of the startup went wrong. Was God trying to make things worse?
Chen Guoli wanted to ask Xu Cang to increase the thrust of the No. 2 engine a little bit, but when he saw the precarious EGT value, he finally gave up the idea.
If Xu Cang dared to step on the accelerator, the engine would be red hot within ten seconds. In order to ensure a continuous supply of air, the accelerator must be kept on during the starting process. Chen Guoli did not think that the No. 1 engine could be started within ten seconds.
"Xu Cang, what should we do now?" Chen Guoli began to panic.
Although there were many risks before, no matter what, although the No. 1 engine was shut down, there was a way to restart it, so he was able to keep his composure. But now there was no way back, and Chen Guoli couldn't help but feel a little numb.
He is not afraid of death, but that doesn't mean he doesn't want to live.
Xu Cang's face didn't look very good either. Perhaps it was because the thrust of the No. 2 engine was too small, or it might be because the altitude was relatively high and the air was thin, causing the pipeline pressure to be lower than usual.
No matter which one it is, their situation is not very good now.
Seeing that Xu Cang didn't say anything, Chen Guoli wanted to ask for help from the tower. However, the plane was still descending slowly at this moment. Judging from the situation displayed on the CDU progress page, the plane would land in less than four or five minutes, so he had to be faster.
"Tower, we are in the process of starting the engine, and the pipeline pressure..." Chen Guoli suddenly had an idea and ignored the communication. He turned to Xu Cang and said, "Since the No. 2 engine can't use bleed air, how about we use the APU to bleed air? The altitude is now below 17,000 feet, and there is no need for APU power supply. The APU's air source can supply the No. 1 engine to start."
There are many restrictions on the use of APU, which are divided into power supply, air supply, and power supply + air supply. At the same time, two additional situations will arise depending on whether it is on the ground or in the air.
If only air is supplied and the aircraft is in the air, the restricted altitude is 17,000 feet, which is within the restricted range.
Chen Guoli was pleasantly surprised at his own cleverness. This was definitely a good suggestion. However, if Xu Cang thought it was feasible, he would have to hurry up. After all, it would take time to start the APU, and then it would take a little more time to start the engine. Time was very tight.
Chen Guoli was talking halfway, which made the control tower very angry. They immediately asked, "What happened to the engine start?"
"It's okay!" Xu Cang replied directly, then turned to Chen Guoli: "No!"
"Why not?" Chen Guoli was stunned.
"Dual bleed air!" Xu Cang's eyes fell on the isolation valve: "If the APU bleed air is connected, the APU bleed air will rush back into the No. 2 engine. At that time, the No. 2 engine's ninth stage high-pressure turbine will bear the brunt, and the No. 2 engine will immediately shut down. Do you want to do this?"
Chen Guoli was so experienced that Xu Cang understood it with just a little guidance. Due to the existence of the isolation valve, the APU bleed air and the No. 2 engine bleed air were connected, but the bleed air from the two conflicted and repelled each other, which could easily cause danger. There was even a special double bleed air warning light on the panel of the air source system.
However, if the thrust of the No. 2 engine can be limited to slow speed, then even if there is a problem with double bleed air, it will not cause serious problems. But the problem is that if Xu Cang puts the No. 2 engine at slow speed, the aircraft will basically be in a powerless state, and it will be impossible to maintain the correct glide trajectory, and it will have to enter a life-and-death state in advance.
Chen Guoli felt like his brain was going to stop working. This wouldn't work, that wouldn't work, was he really going to have to wait for the No. 2 engine to shut down? The runway was covered in thick snow, and there was no way to land, so was he just going to wait to die?
However, just when Chen Guoli was almost in despair, he suddenly heard a sound of air leaking out. Chen Guoli knew what it was, it was the sound of someone squeezing open the oxygen mask.
Xu Cang picked up his oxygen mask and whispered, "Since the bleed air of the No. 2 engine will conflict with the bleed air of the APU, then shut down the bleed air and components of the No. 2 engine, but this way..."
"It will relieve stress!" Chen Guoli replied in a daze.
During the process of starting the engine, all components must be kept in the closed position. Now that even the bleed air of the No. 2 engine has been turned off, the bleed air components of the aircraft are equivalent to being completely turned off. If there is any pressurized air, it must be depressurized, so Xu Cang took out the oxygen mask.
“Do it!”
Xu Cang put on the oxygen mask, and this action already made his decision clear.
Chen Guoli couldn't help but admire Xu Cang's quick wit. Xu Cang was not only good at martial arts, but also had excellent adaptability. He thought of the solution and its side effects in just a split second.
However, there are no passengers in the cabin at the moment, so instead of shutting down both engines, it is better to just release the pressure.
Chen Guoli did not hesitate and put on his oxygen mask, and switched the communication panel to the MASK position. Then, without stopping for a moment, he directly shut down the bleed air and right assembly of the No. 2 engine. After that, he started the APU.
It takes some time for the APU to start, and during this process, Chen Guoli has been paying attention to the EGT value of the No. 2 engine. What makes him feel a little happy is that the EGT value of the No. 2 engine has not risen any further after approaching the red line, which means that it has stopped before the cliff.
However, this does not mean that everything is fine. It is just the last struggle before death.
"1533, has the engine started?" Wang Li's voice came from the radio.
Previously, the crew reported that there were problems with the engine start, but they only said half of the story, and the people in the tower control room had no idea of ​​the specific situation. However, according to the time, if there were no accidents, the No. 1 engine should have been started by now, and Wang Li wanted a definite answer.
Chen Guoli didn't think much about it: "There were some minor problems with our engine starting, and it's still in the starting process."
"This voice..." Zhou Yanping was a little surprised when he heard Chen Guoli's reply in the control room of the tower. He was not surprised by the content of Chen Guoli's words, but the voice.
The sound is like talking with your head in a vat, buzzing.
Wang Li gritted his teeth and said, "This is the sound you hear when you put on an oxygen mask. Damn it, what the hell are they doing?"
While waiting for the APU to start, the little pressurized air left in the cabin leaked out, and soon the cabin altitude warning sounded.
However, there was no need to deal with this deliberate decompression. Chen Guoli manually cut off the cockpit altitude audio warning and left it alone.
Soon after, Xu Cang had controlled the plane to cut into one side of Runway 10. Looking down, he could see some people and vehicles waiting beside the runway on the white snow.
These personnel and vehicles waited for the plane to circle and rise before entering the runway to clear the snow.
As soon as the plane was aligned with the runway, Xu Cang immediately turned off the autopilot and switched to manual operation. At the same time, he glanced at the APU start panel: "Is it not ready yet?"
Under normal circumstances, the APU should be ready at this time.
"Soon..." Chen Guoli was about to say soon, but the red light on the APU tachometer suddenly lit up. Chen Guoli opened his mouth and his face turned pale.
"No..." Chen Guoli was only shocked for a moment, then he went to retrieve the APU fault repair code on the CDU.
It can only be said that Chen Guoli knows a lot. This kind of operation of retrieving maintenance codes is usually only known by maintenance personnel, and basically no pilots know how to do it, but Chen Guoli is quite familiar with it.
Soon, Chen Guoli called up the APU maintenance code and muttered, "49-101000? Air...air intake failure!"
Suddenly, Chen Guoli thought of a possibility. Could it be that the ice and snow had blocked the APU's air intake? Given the APU's delicate nature, this could easily cause a startup failure.
"Xu...Xu Cang, the APU air intake is faulty and can't start!" Chen Guoli said in a trembling voice.
APU also needs air source to start. If the air inlet fails, no matter how many times you try, it will be in vain. Moreover, the APU air inlet does not have de-icing function.
Looking at the still white airport, Chen Guoli was almost in despair. He didn't expect that after passing the most difficult step, he would fail at the last moment. He hated it!
At this time, the plane's altitude had dropped below 10,000 feet. Xu Cang directly pulled off his oxygen mask and threw it aside.
"It doesn't matter, I'll handle it!" After saying that, Xu Cang pressed the button to speak: "Tower, get everyone near the runway to move away, I want to land!"
As soon as these words were spoken, Chen Guoli and the control tower were all shocked.
Wang Li was the first to roar: "Xu Cang, are you crazy? Eighteen millimeters, no, it's probably more than twenty millimeters now, you are looking for death! What's wrong with the engine starting? What went wrong again?"
At this time, even the most obtuse person in the tower control room could realize that the plane must have had another problem. Otherwise, Xu Cang would not have forced the landing.
"Engine No. 1 cannot start." Xu Cang only said: "I say it again, keep the personnel away from the runway! Otherwise, if something goes wrong, I will not be responsible!"
After hearing these words, Wang Li's face suddenly darkened. However, after hesitating for a moment, he immediately ordered the communicator: "Tell the ground staff to get away from the runway quickly!"
Bi Lin stood in front of the control room window, looking at the plane that was getting lower and lower, muttering , "Xu Cang, what are you going to do?"
In the cockpit, Chen Guoli could already feel Xu Cang's unshakable determination to land. However, how could he land with more than 20 millimeters of snow, and the wind volume exceeded the standard? This was indeed courting death!
"Xu Cang, are you sure?" Chen Guoli did not stop Xu Cang at this time. He just wanted to know whether Xu Cang was crazy or really prepared.
Xu Cang did not answer directly, but just said lightly: "Fasten your seat belts!"
"Damn it!" Chen Guoli's face changed drastically and he hurriedly tied the crotch strap.
At the moment when Chen Guoli fastened his seat belt, Xu Cang suddenly reduced the throttle again, and at the same time slightly pulled the stick, and the speed began to drop: "Lower the flaps, all the way to flap 30!"
"Where's the landing gear?"
"Follow my instructions later!"
Chen Guoli gritted his teeth and looked at the decreasing airspeed. He first lowered the flaps to fifteen, and then continued to lower them to thirty.
When the flap indicator turned to fifteen, the landing gear configuration warning sounded. Chen Guoli immediately cut it off manually and then ignored it.
After the flaps were fully lowered, Xu Cang slightly increased the throttle. As the plane descended, the situation at the airport gradually became clear. At high altitude, the airport was all white, but at low altitude, the outline of a runway could be vaguely seen. After all, the snow on the runway was previously cleared to both sides, which resulted in the thickness of the snow on the runway being slightly lower than on both sides, which made it possible to distinguish it.
At an altitude of 200 feet, Chen Guoli swallowed his saliva, his heart pounding. He knew it was inappropriate for him to speak at this time, but he couldn't help it: "Xu Cang, how are you going to land?"
Xu Cang suddenly grinned, as if he had discovered something very interesting: "Instructor, have you ever seen a low-altitude pass?"
"Of course I have seen it." Chen Guoli was startled: "What do you mean?"
Xu Cang narrowed his eyes slightly, and raised the corners of his mouth: "I mean a low-altitude pass at a height of one meter!"
Chen Guoli's body trembled: "What did you say?"
However, the moment Chen Guoli's voice fell, the plane had already entered the airspace above the runway. When the radio altimeter sounded at fifty feet, Chen Guoli tensed all his muscles.
On the control tower, everyone seemed to have stopped breathing, and they were all staring intently at how Xu Cang landed on the runway that was 20 mm thick.
Forty feet!
Thirty feet!
Twenty feet!
This series of high-level electronic messages hit Chen Guoli's heart again and again, making it almost impossible for him to breathe.
Suddenly, Chen Guoli heard Xu Cang step on the accelerator to the maximum.
With the roar of the engine, the plane instinctively descended a little more.
Ten feet!
Five feet!
At the moment the five-foot mark was reached, the plane seemed to be supported by something and no longer sank.
Chen Guoli's pupils suddenly contracted, and he suddenly realized that the plane was flying over the runway in a posture close to the ground. But in the eyes of the people on the tower, everything was different.
“The snow… is gone!?”
Zhou Yanping looked at the snow that was swept away by the plane and found it incredible.
Xu Cang, flying at a normal ultra-low altitude and with the powerful tail jet of his engine, blew away the snow on the road surface directly. Wherever he passed, the road surface turned dark brown.
"Is it possible?"
Wang Li had never thought that snow removal work could be completed in this way. This idea was simply out of the box and no one could match it.
On the ground, the ground staff who were already far away from the runway were still blown dizzy by the strong airflow. But compared to this, they found it even more unbelievable to see the runway that was basically cleared.
The scene before them truly opened the door to a new world for them.
While everyone on the tower was looking at Xu Cang's "snow removal" performance in shock, Bi Lin was just looking at the radar screen silently, and he discovered an even more horrifying reality.
That is, after Xu Cang entered the airspace above the runway, he always maintained an ultra-low altitude of three feet above the ground. Not too high or too low, just three feet, a real meter, without any error. This control ability is simply incredible.
You know, there is ground effect at low altitudes, which will affect the pilot's control. If it is too far from the ground, the engine's tail jet will not be very effective in clearing snow. But if it is too close, it is easy to hit the ground. The difficulty of mastering this is incredible.
Looking at the road passing by, Chen Guoli's mind went blank. He felt as if he was not sitting on a plane, but in an extremely stable car, driving on the road.
"Is this his strength?"
Just as Chen Guoli asked this question, he lowered his head slightly and suddenly discovered that the EGT indicator of the No. 2 engine had exceeded the limit and turned red.
No wonder. In order to maintain the low-altitude pass, Xu Cang stepped on the accelerator. The engine was already close to overloading, so how could it hold on now?
"Xu Cang, you're speeding!" Chen Guoli shouted.
When Xu Cang was flying at low altitude, he stepped on the throttle and never retracted it. Because Xu Cang knew that if he stepped on the throttle, the engine would be ruined. It didn't matter whether he retracted it or not. It was better to accumulate more energy for the plane, which would be reflected in the increase of speed.
However, with the throttle on high and the stick pressed, the plane's speed increased suddenly and exceeded the speed limit of flaps 30.
"Flap unloaded!"
"No matter!" Xu Cang shouted coldly.
At this moment, as the plane passed the end of the runway, the dying engine gasped twice, finally ushering in the end of its life. However, before it fell, it had already made its last effort.
At this moment, Xu Cang suddenly pulled the stick and turned slightly to the left, and shouted at the same time: "Lower the landing gear!"
Chen Guoli was stunned, gritted his teeth, and without caring about anything else, he directly lowered the landing gear handle.
As soon as Chen Guoli finished his move, Xu Cang only maintained the left turn slope for a moment and then immediately flattened it, then turned right continuously at the full slope while pulling the pole backwards.
Although the landing gear basically generates resistance, when it is first lowered, the aircraft will actually lift its head briefly due to the impact of the center of gravity brought about by its release, like a drowning person struggling to stick his head out of the water.
It was this fleeting force that made the plane rise slightly, like a dying man taking a breath. Moreover, the high speed brought by Xu Cang's tightening of the accelerator had worked.
Xu Cang had been carrying the stick to prevent the plane from falling during the turn. At this time, there was only one reason why the plane did not fall, and that was that it still had speed.
Height is speed, speed is height!
The high speed accumulated previously has become the weight to maintain the height!
Xu Cang's turning action was quite decisive, turning at a slope of more than 40 degrees. In a short while, Chen Guoli could already see the runway from the side. However, the moment he saw it, he was stunned.
There is no longer a vast expanse of white, but only a dark brown, regular runway with no snow.
"This..." Chen Guoli was the person involved and he couldn't figure out what was going on for a while.
When Xu Cang saw all this, his eyes flashed with brilliance. He maintained the slope and continued to turn.
Just as the three indicator lights on the landing gear all turned green, the nose of the plane was aimed right at the runway.
Because Xu Cang turned very early, the plane was already above the runway almost at the moment of its approach. At this moment, the plane's speed was close to the stick shaker, and Xu Cang could no longer continue to pull back, so he had to let it down a little, but not too much, otherwise the front wheel would touch the ground first, and the consequences would be disastrous.
No matter what, the plane's speed was low and its energy was low. Even Xu Cang was powerless. He let go of the thrust handle with his left hand and immediately lowered the flaps from thirty to forty.
The initial lift generated by the continued lowering of the flaps slightly offset the already uncontrollable sinking. However, after only a moment of slowing down, the plane finally crashed heavily onto the runway, as if the entire plane was about to fall apart.
As soon as the plane landed, Xu Cang instinctively pulled up the speed brake and pushed the steering wheel forward. Chen Guoli, who was standing next to him, burst into an excited roar after a brief moment of unconsciousness: "We... survived!"