Chapter 203: Shock! Shock!
Final approach of runway 31 at Lhasa Airport.
Prior to this , under the assurance of instructor Mo Shangyun, Xu Cang had gone to the airport to try out what this airport with an altitude of more than 10,000 feet was like. To be honest, although Xu Cang said he was worried, in fact, it was just talk. From the bottom of his heart, he really didn't think that the high plateau airport could be that scary.
After getting on the seat, the initial operating procedures are the same as those for ordinary flights. As instructor Mo Shangyun said, you only need to press the high-altitude landing switch when starting to prepare for the approach.
The runway of Lhasa Airport is 4,200 meters long, which is comparable to the runway lengths of many hub airports.
This is not because of the number of flights at the airport or the high level of the airport. Many high-altitude airports, even if they are small in size, have longer runways. The reason is that the air in high-altitude areas is thin. Under the same conditions, the take-off and braking distances are much longer than those at plain airports. Therefore, high-altitude airports must have longer runways, which is caused by objective conditions.
Only Runway 31 of Lhasa Airport has ILS, and the other opposite Runway 13 only has VOR/DME approach procedures. However, Xu Cang has seen the weather data of Lhasa Airport, and it is mostly north wind all year round, so most of the time only Runway 31 is used. It may be due to cost considerations that Lhasa Airport only built one runway for ILS.
Everyone talks about high plateau, high plateau, but where exactly is the height of these airports reflected?
Most plain airports intercept the glide path at a height of 1,200 meters, with lower ones at 900 meters and higher ones at 1,500 meters. However, the altitude of the glide path intercepted by the Lhasa Airport is 5,400 meters. A brief comparison will reveal the difficulty of this high-altitude airport.
At an altitude of 5,400 meters, some places with relatively low approach areas may not have switched to the approach control frequency. Moreover, at this altitude, the performance of the aircraft is far worse than at lower altitudes, which results in many operations of the aircraft being unable to be performed at high-altitude airports compared to plain airports.
Xu Cang was somewhat prepared mentally, but that didn't mean he was physically prepared as well.
Since the high-altitude landing switch was pressed at the beginning of the approach, the cabin pressurization logic of the aircraft changed. During the descent, the aircraft's cabin altitude gradually approached the altitude of the landing airport, so that after intercepting the final approach fix of 5,400 meters, the pressurization system had adjusted the cabin altitude to nearly 10,000 feet.
"The runway at Lhasa Airport is large enough, so we need to have enough energy when we enter the runway. Of course, we need to hold the stick up, and the approach altitude cannot be too high. Just increase the speed a little. The airport here is too high, and the thrust decays very quickly. We need to be decisive in adding throttle and cautious in reducing throttle. It takes a while for the turbofan engines of our aircraft to add thrust, not to mention at an altitude of 10,000 feet. At low altitudes, especially during the transition to the visual phase, if you feel that you are running low on energy or the aircraft is weak, don't hesitate to increase the throttle first. Once the aircraft really sinks too quickly at a low altitude, it will be useless to increase the throttle."
"Also, during the flare phase, the runway at Lhasa Airport is long, but relatively narrow, and there is an obvious downslope near the end of the runway on the fifth side of Runway 31. So after entering the visual phase, it is easy to give you the illusion that the aircraft is too high based on visual reference alone. However, with your technical descent rate, you should be able to control it well, so this visual difference will not cause you too much trouble. I just want to remind you."
During the descent on the final approach, Instructor Mo Shangyun was still tirelessly explaining some landing points to Xu Cang. If the person on the right seat was a co-pilot or a younger captain, Mo Shangyun would still explain it in detail.
Although the landing techniques are mentioned in the standard operation manual, in reality, each pilot has a different landing technique. Even the way pilots judge the relative position of the aircraft on the fifth leg is different.
In plain areas, many techniques are universal. However, in high plateau areas, some techniques are prone to problems. For example, some pilots cannot feel the energy of the aircraft through their body, so they can only rely on the simple standard of speed to judge.
But in fact, the speed standard is sometimes inaccurate. It does not mean that if the speed is higher than the approach speed, the aircraft energy is high, and if it is lower than the standard approach speed, the aircraft energy is low. There is indeed a strange state of high speed and low energy or low speed and high energy.
If you only rely on speed to judge, even if there seems to be some improvement in the early stage, you are essentially going further and further on the wrong path. If this misjudgment occurs at a low altitude, the sudden and large deviation is likely to make the pilot lose the chance to make the final correction, so that he can only take a go-around during a failed approach.
Some pilots may also be aware of this problem, so after entering the runway, they will make a final determination of the aircraft's status in order to decide on the adjustment of the throttle and leveling amount during the leveling phase.
Once above the runway, about fifty feet away, as long as the low energy is not particularly obvious, some pilots will try to reduce the throttle slightly to judge the energy of the aircraft.
However, because the most common coordination between stick and rudder in flight, it is necessary to pull the stick a certain amount while reducing the throttle in order to maintain the correct descent trajectory.
If the real energy is low, even with a slight throttle reduction and stick pull, the aircraft will experience a more obvious increase in sinking. At this time, you cannot continue to reduce the throttle, but instead hold the throttle tight. It may even be necessary to increase the throttle again in this final period of time.
If the true energy is normal, the action with the stick will offset the reduction in throttle, and there may be a slight decrease in speed, but the trajectory and sinking will usually not exceed the standard.
At this time, the pilot can judge that the energy of his incoming aircraft is normal, and the subsequent leveling work will be relatively comfortable.
If the aircraft has too much energy, and generally speaking, the pilot will feel the excessive energy when approaching, so the pilot needs to approach with the stick pressed against the ground. However, it does not mean that approaching with the stick pressed against the ground is necessarily excessive energy, and some of them are occasional .
Under this premise, after entering the airspace above the runway and reducing the throttle, the pilot can still clearly feel the need to continue to push the stick. This means that the aircraft has too much energy and needs to reduce thrust faster and earlier than normal leveling.
Aircraft energy is a more subjective standard. Some pilots prefer to call it whether the aircraft is powerful or not. That is to say, after flying for a long time, you can understand the state of the aircraft by feeling it when operating the aircraft.
Generally speaking, it is more reasonable to have the control wheel slightly lifted during the final descent. If a significant amount of force is required to maintain the aircraft's state, it can only mean that the aircraft's state is deviated, which is what some captains and instructors like to say, that the aircraft is not properly trimmed.
However, this slightly carried state is not always sinking. Some pilots like to fly with the stick because it makes the control feel stronger. Some pilots like to approach with the stick because the state of approaching with the stick makes them feel the worry of too much sinking, that is, the so-called aircraft is better to be big than small. In this case, landing will not cause a warning of large ground load, but in the case of too much energy, if the pilot hesitates to reduce the throttle, it is very likely to cause a warning of long drift distance.
Of course, some pilots would rather have a long drift distance warning than a high touchdown load warning, and there is a slight difference in severity between the two.
However, pilots with more mature landing skills usually do not make such a trade-off, because they can already clearly experience the energy of the aircraft. However, this more conventional method is not very useful at high-altitude airports.
Normal or high energy may be better, after all, there is room for maneuver. But if the aircraft itself has low energy, tentatively reducing the throttle when entering the runway may not have much impact at a plain airport, after all, there is still a last fifty feet interval for adding throttle. But at a high plateau airport, the energy is already low, and if the throttle is reduced, the aircraft will sink faster than at a plain airport, and in the last fifty feet, thrust may not be added.
At the high plateau airport, the plane's engine just has no power!
Therefore, Instructor Mo told Xu Cang to use more energy in the approach, that is, to approach with a slightly raised stick. In this way, even if the throttle is pulled back too quickly due to unfamiliarity with the throttle use at the high plateau airport during the later stage of leveling, there is still room for correction.
However, all of this is based on the 4,200-meter runway of the Lhasa Airport. After all, this runway stands out even among high-altitude airports, giving Xu Cang room for trial and error.
If it were for other ordinary pilots, Instructor Mo Shangyun would not really give enough time to let go, and secondly, the explanation would be more detailed. At least the description of the aircraft speed, attitude, and descent rate would be more precise, instead of just mentioning it in passing like just now.
Mo Shangyun believed that Xu Cang was a very talented pilot who could learn things at once and did not need to be taught step by step. For ordinary pilots, they should be allowed to follow the route they set, but for a pilot like Xu Cang, setting a limited route for him would make him feel uncomfortable, so he only needed to point in one direction.
"Yeah." Xu Cang agreed and disconnected the autopilot about five nautical miles away from the runway , while familiarizing himself with the control feel at such an altitude in advance.
Apart from anything else, the final airflow at Lhasa Airport was really too chaotic, and the wind was particularly strong, almost over ten meters per second. Originally, Xu Cang only set the wind correction to five knots, which was a lazy setting value, and of course the smallest wind correction value.
However, with a wind correction of five knots, Xu Cang always felt that he had to hold the stick to keep the plane on a relatively standard descent trajectory, which made Xu Cang feel a little uncomfortable. He didn't like this situation.
"Has the wind blew down?" Xu Cang asked casually.
"It's up to you. There aren't many gusts or crosswinds anyway. The standard wind correction value is easy to calculate. You can adjust it yourself." Mo Shangyun said with a smile.
The value of wind correction is related to both steady wind and gusts, and in steady wind it is also related to wind direction and speed. However, there was no gust on the final leg this time, at least that was what the tower reported, and the crosswind angle was very small, which can basically be considered as a headwind, so the wind correction calculation is relatively simple, otherwise trigonometric functions must be used, which is more troublesome.
After saying that, Xu Cang freed his left hand from the throttle lever and used it to control the steering wheel instead of his right hand, while he rubbed his temple with his right hand. He felt dizzy.
From Mo Shangyun's perspective, he thought Xu Cang was just wiping his sweat, and said in a rather amusing tone, "You are very skilled at operating with your left hand."
The co-pilot usually feels uncomfortable when he suddenly switches to the left hand because he has been using his right hand to control the steering wheel for many years, resulting in many deviations in operation. This situation is not uncommon, and even some captains who have been flying in the left seat for a long time will feel uncomfortable when they suddenly control the right seat.
However, for some reason, Xu Cang seemed to have no difference between the left and right dominant hands. The final airflow at the Lhasa Airport was not only very strong, but also quite chaotic. However, after Xu Cang switched hands, the control quality did not decline at all, as if Xu Cang was born without the need to adapt to this left-right hand switch.
"Ah! It's not that difficult." Xu Cang replied casually.
This was not Xu Cang deliberately showing off. He was born with no difference between the left and right dominant hands. At least it was not because he had experience as a left-hand pilot, but in his previous life, before he became a captain, Xu Cang had no burden at all for left-hand control.
Hearing what Xu Cang said, Shi Qi, who was sitting in the back, chuckled a few times. If this kind of left-right hand switching is really not difficult, there will be no senior co-pilot stage. This stage is used to accumulate left-seat time. In other words, there will be a special stage for pilots to use the process from right seat to left seat. This means that the authority also agrees that hand-changing operation has a significant impact on pilots and needs to be given an appropriate adaptation period.
However, compared to Xu Cang's overly arrogant words, Shi Qi still noticed something strange about Xu Cang: "What's wrong with you? Do you feel uncomfortable?"
"Is it altitude sickness?" Xu Cang scratched his head, looking very confused.
"Not really. What's the cabin altitude now? Nine thousand three hundred feet. It's quite high, but we two elderly people feel fine. You won't have altitude sickness, will you?" Mo Shangyun asked curiously.
"That's the truth. When I was learning to fly, I flew a small plane to 10,000 feet. The plane wasn't pressurized, and it actually felt fine."
The propeller planes that flew in the aviation school definitely did not have a pressurization system. Of course, those small planes usually did not fly too high, and the subjects were basically above 1,000 meters. However, sometimes it felt novel. Xu Cang had also driven a single-engine propeller plane to 10,000 feet, and vaguely remembered that it was nothing at that time.
However, that was a long time ago, and Xu Cang only broke through 10,000 feet a few times during his flying training stage. Maybe he had some reaction at the time, but he didn't write it down.
Shi Qi looked at Xu Cang from behind and saw that he looked fine, but he still asked with concern: "How do you feel now?"
"It's nothing serious." This wasn't Xu Cang trying to be strong, it was indeed no big deal: "Let's talk about it after we land. I haven't been exercising since I graduated from aviation school, and my body is not as good as before."
When he was in the aviation school, he not only had flight training, but also various physical training, plus there were many routine physical examinations, so he paid special attention to the maintenance of his body. But when he arrived at the airline, there was no one to supervise him, and for mature pilots, routine physical examinations were not so scary, so he naturally began to relax.
Seeing that Xu Cang still had the energy to chat, Mo Shangyun thought that Xu Cang should be fine, and echoed: "You young people are all like this now."
"Who said it wasn't?" Xu Cang opened his mouth, looking a little listless.
However, Xu Cang also put down his right hand and gripped the steering wheel again, while at the same time grabbing the throttle lever with his left hand and resumed normal operating posture.
"Please help me increase the wind correction to ten knots. Five knots is too small." Xu Cang is now the PF. He has disconnected the automatic driving and is in manual driving mode. It is inconvenient to operate the MCP board, so Mo Shangyun, the PM, does it for him.
"Ten knots, so much increase?" Although he said so, Mo Shangyun still followed Xu Cang's instructions and increased the approach speed in the speed box by another five knots.
Xu Cang immediately began to step on the accelerator, and continued to increase it to about 75, while holding the steering wheel to prevent the nose of the plane from rising, so that the speed could be increased. However, since the speed increase was not required, Xu Cang did not increase it too much, and just waited for the speed to increase slowly.
"Wait until the low-altitude wind speed slows down, and then slowly reduce it."
Sure enough, as the altitude decreased, the wind speed began to slowly decrease due to terrain obstruction and friction. However, Xu Cang did not immediately ask Mo Shangyun to adjust the wind correction value. It was not about 500 feet above the ground that Xu Cang said, "Add eight knots."
"You won't adjust it later, right?" Mo Shangyun asked with a smile, but his hands didn't stop moving at all, and he directly adjusted it down by two levels.
"It shouldn't change anymore, right?" Xu Cang glanced at Runway 31 and said, "The ground wind reported by the tower is about plus eight, so there's no need to change it."
Perhaps out of laziness, after Xu Cang turned the throttle to 71, his left hand never moved the throttle again. He only relied on controlling the pitch of the aircraft to control the speed and glide path.
However, if the aircraft is controlled solely by the elevator, the aircraft speed can only be maintained within a range due to the unstable external airflow, rather than being fixed at the set speed.
From the visual point of view, the actual flying speed was basically fluctuating within five knots of the set speed. Moreover, Xu Cang never seemed to deliberately try to keep the speed of the aircraft stable, and even the pitch control seemed rather perfunctory.
Seeing Xu Cang's actions, Mo Shangyun was amused: "You really don't want to move even a little more!"
"That's enough. There will be no warning anyway." Xu Cang laughed.
Although Xu Cang's speed fluctuated, it was strictly controlled within the range of five knots, without going beyond the limit at all. If the deviation was larger, there would at least be a soft warning of a slow approach speed.
"It's up to you!" Mo Shangyun knew that Xu Cang knew what was going on, so he didn't interfere and just watched from the side.
When passing the 200-foot altitude, Xu Cang entered the visual phase. As Mo Shangyun said, because the runway of Luoshui Airport is narrow as a whole and the head of the runway is next to a steep downhill slope, the pilots do have the illusion that they are above the glide path.
Any mature pilot does not need to refer to the PAPI light when performing visual flight. That is, he can roughly tell whether the aircraft is on the standard glide path based on visual feeling alone.
However, in some special cases, the visual perception of the human eye will be biased, especially when the surrounding reference objects are relatively normal. It is true that there are PAPI lights on Runway 31, and pilots can refer to the PAPI lights to confirm whether their descent is correct. However, once there is a deviation between their own visual perception and the PAPI lights, even if the pilot knows that the instrument is correct, this sense of disharmony will make the pilot feel very uncomfortable.
"The visual reference seems to be quite different." Xu Cang said with a smile, "It would be better to ask them to widen the runway. Otherwise, when I look at the PAPI lights, I feel like ants are crawling all over my body. It's very uncomfortable."
Even Xu Cang had an irresistible urge to push the stick, but the PAPI light told him that the plane was now on the correct trajectory, and if he pushed the stick, that would be a problem.
"It would be really fun if we could fly RNP approaches here in winter," Xu Cang said with a smile.
Since the glide path of RNP approach is affected by temperature, in winter, the temperature is low and the glide path is generally lower than that at standard temperature. In this way, the visual is high and the glide guidance is low, which will drive the pilot crazy.
Mo Shangyun was stunned for a moment: "What's wrong with the RNP approach?"
"Ah?" This time Xu Cang realized that Mo Shangyun didn't understand RNP approach yet, so he responded casually: "It's okay, we're about to land."
At this time, the plane was almost above the runway. At such a low altitude, the airflow was relatively stable, but the plane's speed was still controlled at the reference speed plus nine to ten knots, which was obviously too high.
"There's no need to go at such a high speed, right?" Mo Shangyun muttered, "The wind is only six meters high now, your speed is too high."
Mo Shangyun had intended to let Xu Cang enter the field at a faster speed, but Xu Cang's speed was too fast, and the reference speed plus seven knots was about the same. However, Mo Shangyun only said it and did not take action.
It doesn’t matter if it’s big. If it doesn’t work, just float for a while. There is more than 4,000 meters of runway anyway, you can do whatever you want.
"Go faster, save enough energy, and then I'll do it normally."
As soon as Xu Cang finished speaking, the plane passed over the runway entrance at an altitude of just over fifty feet, which was a good approach altitude.
As the plane approached, the altitude was good and the speed was sufficient. Xu Cang instinctively felt that the plane had enough energy. Therefore, he did not control the throttle reduction, but out of caution, he began to reduce the throttle from about 40 feet.
Even at a high-altitude airport, the reference speed plus nine to ten knots of approach speed is too fast. It is reasonable for Xu Cang to think that he does not need to be too cautious with the throttle.
Of course, Xu Cang was not crazy. If it was a plain airport, with such a high speed, if he started to reduce the throttle at 40 feet, he could basically slow down all the way and then establish the touchdown attitude. In other words, with such sufficient energy, instead of doing it step by step, he would reduce the throttle all at once. As long as he held the stick, the landing would most likely not be heavy.
But this is a high plateau airport, so even if the throttle is reduced early, Xu Cang still feels that it should be reduced a little. His first move was to reduce the thrust from 71 to about 60, and then began to pull the lever in coordination with the change of throttle.
The coordination between Xu Cang's throttle lever and the steering wheel was classic, like a sword that had been sharpened countless times and was flawless, and the two were changing at almost the same rate. Shi Qi was watching from behind, and it was a feast for the eyes. This kind of hand skills could not be achieved without seven or eight years of training.
As long as the throttle lever and the steering wheel work well together, the entire flattening curve will be very smooth without any discontinuity. At least from the current point of view, Xu Cang's landing flattening curve will be quite beautiful.
He is indeed a genius. Isn't it easy for Xu Cang to achieve this skill of water dripping through a stone?
However, what no one expected was that Xu Cang only moved the N1 about ten times, and the plane suddenly lost its strength like a deflated balloon, and began to sink rapidly in an unexpected manner.
“It’s raining so fast!”
Xu Cang, who had been handling the situation with ease before, suddenly felt his heart tighten and all the hairs on his body stood up. If this thing were to hit the plane, it would definitely damage the plane.
It can only be said that Xu Cang's sensing speed was extremely fast. In this situation, he increased both throttles to over 80. However, Xu Cang did not suddenly increase the pitch attitude, but just increased it a little bit.
Just as Mo Shangyun said before, the throttle lever was pushed up, but it took time for the two engines to increase from 60 to 80, and this process of increasing thrust was the most fatal.
When Mo Shangyun heard the noisy roar of the engine again, he cried out, "Oh no! This plane is sinking too fast. How can an N1 of 60 cause the plane to sink so much?
However, now is not the time to delve into the reasons. All I can say is that fortunately it was Xu Cang who was in control. His reaction speed was incredible. The moment the sinking accelerated, Xu Cang had already sensed it.
After all, Mo Shangyun only began to realize the problem after Xu Cang took action.
Thanks to Xu Cang's extremely quick reaction, the engine slowly added thrust within two seconds, but at this moment the aircraft's radio altimeter electronic message had already sounded five feet.
Almost the next second when the N1 tachometer on the DU was only over 80, the plane slammed down on the runway. This is the problem with turbofan aircraft. Not only does the engine take time to respond, but even if the thrust is increased, the aircraft cannot rise immediately due to its huge body.
Just with this one blow, Xu Cang felt his internal organs tremble. It was indeed a very heavy blow.
As soon as the plane landed, Xu Cang quickly slowed the throttle to slow speed, corrected the taxiing direction, and applied reverse thrust.
"Give it to me!" Mo Shangyun patted Xu Cang's left hand and grabbed the reverse push handle himself: "I'm afraid it will reach 2.0. This is really a heavy hit."
"It should be, but it's still a little bit harder. If I hadn't stepped on the throttle at the end, the plane would have been smashed to pieces." Shi Qi had just transferred to Boeing and although he was experienced, he had not yet fully adapted to the situation. His reaction was even slower than Mo Shangyun's. By the time he realized the problem, the plane had just landed.
At this moment, at least from the physical sense, the plane seemed to be fine, but Shi Qi was still frightened. It is true that Xu Cang's last throttle did not turn the tide, but at least it reduced the sinking a little at the last moment. It would not be just a 2.0 touchdown load, and the landing gear would be damaged.
Even at a high plateau, the plane slowed down more slowly, but after Mo Shangyun took over the control of the plane, he immediately switched to the maximum manual brake, almost stepping on the brake to the limit, and the plane still decelerated relatively quickly.
As the aircraft slowed down to below 60 knots ground speed, Mo Shangyun retracted the reverse thrust and continued to slow down.
The runway exit of Lhasa Airport only turns left at the end of Runway 31, so Mo Shangyun has to slide all the way to the end of the runway. After the plane slows down to less than 30 knots, it still takes a while to slide on the more than 4,000-meter runway.
During this period, Mo Shangyun really came to his senses. He used the rudder to control the plane's taxiing direction. He picked up the small towel beside him with his left hand and wiped his face. Then he said in fear: "It's really you, Xu Cang, who landed. If it were me, wouldn't the plane be smashed?"
"At the end, he increased the throttle significantly and stabilized the stick at the same time. This move was really exquisite." Shi Qi began to recall Xu Cang's operation at this time: "If it was another pilot, wouldn't he have increased the throttle and pulled the stick hard at the same time? If he did so, the plane would definitely hit the tail, which is also very dangerous. Xu Cang, you are still patient and only slightly pulled the stick. You have really seen big scenes and your mind is still clear."
The more Shi Qi thought about it, the more he felt that Xu Cang's skills had reached the level of perfection. It was precisely because the power of the turbofan engine increased slowly that if the stick was pulled back , the nose of the aircraft would inevitably pitch up, but in fact, because the power did not keep up, only the nose of the aircraft would pitch up and the aircraft would not rise, which caused the aircraft's pitch attitude to increase rapidly, and the aircraft was bound to touch the ground. With such a large attitude when touching the ground, it was quite possible that the tail of the aircraft would be scratched.
This is actually a bit like a zero-altitude go-around, but Xu Cang omitted the subsequent step of bringing the aircraft up. A major taboo in a zero-altitude go-around is to bring the stick up too hard, which is most likely to cause a tail strike.
However, the sinking change just now was something none of the three had expected. It was quite rare for him to remain rational despite the fear. It was not like the psychological quality of a young pilot in his twenties at all.
"Yeah, what the hell is this engine? The thrust decays too quickly. This plane was borrowed from Tiandong's Jianchuan branch. Did they give us an antique?"
Mo Shangyun was still complaining, but Xu Cang didn't answer. It wasn't that he didn't want to answer, but he was powerless to answer. From the moment the plane landed, he felt a pain in his heart, as if something was strangling his throat, and he couldn't even breathe.
Xu Cang didn't know what had happened to his body. He obviously didn't have any disease, otherwise he wouldn't be a pilot. But now the feeling of his body made him feel extremely scared, and the feeling of powerlessness seemed to bury Xu Cang deeply.
"We have to ask Tiandong Airlines later. This kind of aircraft flying at high altitudes is a hidden danger. What a crappy engine. At least we need to replace it..." Mo Shangyun said halfway when he suddenly felt something strange. He turned his head and saw Xu Cang's eyes slowly closing, and then his body became weak and he fell into a coma instantly!
