At this time, the area control allows Yan Zhen to rise, which is nothing more than that the next control area must reach a specific height to receive, such as 8100 meters, so it is necessary to go up to an altitude of 8100 meters to convert the frequency and enter the next control area.

This one is quite easy to understand.

Another scenario is that there will be a traffic conflict soon, and in order to avoid the hidden danger of conflict, the aircraft must vacate an altitude level.

Yan Zhen is also experienced, and he knows the distribution of the control area, when to hand over, and where to hand over. The domestic route is still relatively fixed, and the more you fly, the more you will have a general picture in your mind.

Although it is not possible to completely exact the position of the handover, at least the current position is still some distance from the control handover, which can be determined by Yan Zhen.

Combined with the control just now, then the upper height is used to avoid conflicts.

Yan Zhen was anxious, if there was another TCAS conflict warning, things would be complicated. However, the current situation is not something that he can go up to the altitude if he wants to, and the strong downburst does not allow the aircraft to form an effective positive ascent rate at all.

"Blue Sky 834X, now encountering a strong downward ......" Yan Zhen is ready to explain to the control to see if there are any other solutions, it is really not possible to go down the height.

It's just that if you avoid the conflict by lowering the height, there are thicker cumulus clouds below, and Yan Zhen is reluctant to go down until the last resort.

However, no matter how unhappy you are, avoiding conflict is an imminent danger, and there is no way to descend into the clouds.

Halfway through Yan Zhen's explanation, his radio communication was interrupted by the pilot of another flight, and Yan Zhen's words were directly overwritten.

This kind of behavior of interrupting the communication of other flights and occupying the radio channel is very impolite and taboo, and no pilot with a modicum of common sense would do this.

Now, however, it is happening......

Yan Zhen was suddenly a little angry, he had something urgent to explain, did the pilot of this flight not understand the rules? The captain of the flight will not be in charge?

The next moment, the voice of the interjecting pilot gradually turned anxious, and there was a tremor that was clear enough.

"5733 in the east, altitude 9500, severe turbulence in the clouds and moderate or above icing, request for immediate ascent." Needless to say, just from the shaky tones, you can hear what state the planes of the East are in now.

Sadly, it wasn't just severe jolting, but also moderate icing, any of which could make the captain on duty anxious. Now it's two big troubles at the same time, and it's no wonder that the crew on the plane isn't crazy.

Yan Zhen, who originally wanted to speak, forcibly suppressed the idea of interrupting the other party and obediently closed his mouth. From the tone of the Dongfang pilot just now, Yan Zhen felt that the crew's control over the plane was very weak now.

"Dongfang 5733, the high altitude is occupied, can you hold on for a while now?" As a result of Yan Zhen's request, the control did not agree to the Dongfang aircraft's request for altitude.

From this point of view, it was not just a matter of just controlling Yan Zhen and not allowing them to go to a high height, but it was really unusable to use a high height.

Vostok 5733: "Now we are struggling to maintain altitude, and the condition of the fuselage is quite serious, so we request that we immediately get out of the ice area." ”

Ice accumulation in aircraft is quite dangerous, and the icing of the wings will lead to a decrease in the lift coefficient, and the performance of the aircraft will be reduced a lot, up to about 30%, which is quite a terrible loss of lift.

Then there is the accumulation of ice in the pipes, the most obvious of which is the ice accumulation in the pitot tubes. The data provided by the pitot tube involves quite a bit of gauge indication, and if the pitot tube is clogged with ice, if not to mention anything else, the most intuitive display of airspeed will become inaccurate. How important the airspeed display is to pilots is that I believe many ordinary people who don't know how to fly can understand.

As a result, pilots are quite sensitive to ice accumulation, especially in severe ice conditions. Ice accumulation above moderate is considered a relatively serious ice accumulation. It is for this reason that pilots in the East are in a hurry to get out of the ice zone.

To produce ice accumulation, there must be low temperatures and visible water vapor. Now that the planes in the east are in the clouds, and the temperature is very low at high altitude, it is not surprising that there will be ice accumulation. In addition, the proximity of thunderstorms and the abundance of water vapor in the clouds have led to a high rate and degree of ice accumulation.

If they continue to fly in the icy area, the crews of the East can no longer predict what will turn out of the next flight. There have been too many accidents caused by ice accumulation in the history of civil aviation in the world, and the crews of the East do not want to write themselves in the history of air crashes.

"Dongfang 5733, you can't go up to the height now, can you descend now?" The control proposes another way, if it can't go up, it will go down, as long as it can be out of the cloud.

The Eastern crew barely had time to think, and immediately rejected the idea of control: "No, now our height is only scattered cumulus clouds, and there are all cumulus and cumulonimbus clouds below, and the ice situation below is definitely more serious." Now the ice accumulation of the plane is already very serious, and we cannot accept it if it descends into the clouds. ”

"Dongfang 5733, then do you think it's okay to yaw? Can yaw be out of the cloud? The regulator asked.

"No way!" At this time, it was the voice of another pilot who answered, which should have been replaced by the captain's communication: "The cloud area is very large, and it cannot be bypassed in a short time, and we now request an immediate ascent." ”

"Dongfang 5733, then I'll coordinate with the military to see if I can free up high-altitude airspace." The regulator replied.

In order to free up the airspace at high altitudes, it is necessary to let the aircraft that already occupy the high altitude yaw and give up position. However, the yaw area is now a restricted area for the military and cannot be entered at will, so they need to communicate with the military to see if they can temporarily open the restricted area for their deployment.

Dongfang 5733: "I'm sorry for you, please hurry, if not, we will decide to return." ”

Judging from the weather radar, there is still a large area of ice ahead. However, they have not been in the ice area for a long time, and if they turn back, they will still have a chance to leave the ice area.

If the control and the military cannot be coordinated, they will not be able to procrastinate, and returning is the safest way.

During the period of control coordination, another aircraft reported: "China Airlines 4863, which has suffered severe turbulence and is now unable to maintain altitude, has applied to withdraw from RVSM airspace." ”

RVSM stands for Minimum Vertical Separation, which according to international standards means that the vertical separation between FL290 and FL410 (including these two height layers) is reduced from 2,000 feet to 1,000 feet in the airspace where RVSM operation is implemented. That is, in the level flight cruising interval of 8900-12500 meters, the vertical standard between the two flight high-speed layers is reduced from 600 meters to 300 meters, so that the number of flight layers in this altitude range is increased from 7 to 13 layers. The introduction of RVSM operation is equivalent to increasing the bandwidth of the route and increasing the network speed.

Reducing the vertical spacing can indeed increase the en-route flow, but because the vertical spacing is reduced, the safety margin is also reduced, and the altitude accuracy of the aircraft is more and more demanding.

If the aircraft cannot maintain the correct altitude accurately, it will not be able to operate in the RVSM airspace and must immediately exit the RVSM airspace.

It is reasonable that China Airlines' aircraft could not maintain the specified altitude precisely due to turbulence, and had no choice but to exit the RVSM airspace.

"China Airlines 4863, maintained at an altitude of 7800 meters." The controller immediately commanded.

China Airlines 4863: "Under altitude 7800 meters to maintain, China Airlines 4863. ”

The China Airlines plane readily agreed to the descent order, and it seems that there was no serious ice accumulation in the area of the China Airlines plane.

At this time, the control remembered that the Dongfang plane had also reported that it was difficult to maintain the altitude, and asked the Dongfang aircraft at the stall: "Dongfang 5733, you just said that you can't maintain the altitude, what is the deviation now?" ”

If the altitude deviation is too large, then it is not up to the crew to decide whether the height can be lowered.

"Now the elevation changes within fifty feet." The crew of Voostok-5733 replied.

"Good! The result of the coordination will get back to you immediately. The regulator said.

"Xingfei 8777, you turn right to head to 050, and now there is a conflict." Regulatory Command Channel.

Xingfei 8777: "Turn right to 050, Xingfei 8777." ”

This Xingfei Airlines plane is the plane that is about to conflict with Yan Zhen's plane, and the change in the lift rate of the aircraft under its jurisdiction can be seen on the controlled radar. Even if I reminded the blue sky 834X just now, now the blue sky 834X still has no upward momentum.

As long as it is not the pilot's brain pumping deliberately does not rise, it is that the Blue Sky 834X may encounter some difficulties. In any case, it is always impossible to hope that the Blue Sky 834X will rise rapidly, and it is better for him to move the influential aircraft away.

"Xingfei 8777, my 050's course can only maintain thirty nautical miles, and the weather will enter before that." Xingfei 8777 gave the control a preventive shot in advance.

Control: "Got it, Blue Sky 834X, when will you be able to go up to 8100 meters?" ”

"We've had a downburst and can't go up for the time being." Yan Zhen replied.

"As soon as possible, you have an impact on that plane flying with Xingfei. He yawed at most thirty nautical miles before turning back to his course. The control told Yan Zhen about the situation.

"Okay, let's get it as soon as possible."

They are actually not much different from the altitude of 8,100 meters, as long as they avoid the downburst, they can reach it quickly after a normal ascent. At 30 nautical miles, the normal flight speed will take five or six minutes. Yan Zhen didn't believe that the range of the downburst could last for five or six minutes.

Judging from the radio communications, there is a large area of weather on the route now, and various calls requesting to adjust the altitude and course are very lively in the channel.

"Long Yue 4588, you can sail around on your own within twenty nautical miles on the right side of the route, and the weather will not affect the report." The frequencies are full of sounds of the crew applying for course. It is necessary to apply once every time a course is turned, and now the frequency of control is already very busy, and this non-stop application for course will occupy a lot of time, so that the crew who really needs it will not have time to speak.

It's not that the crew applies for a detour or occupies the channel, wasting time, if you don't get the consent of the control, change the course without authorization, and encounter some control that is not easy to talk to, you will be reported immediately, without discussion.

The controller is also well aware of this, and can only give the crew enough freedom within the scope of its ability to reduce its own working pressure.

Yan Zhen gradually recovered the rate of rise after the downburst oppression that lasted for about two minutes, and he reported the situation that he could now rise to the control.

The control is still prepared to wait for the blue sky 834X to maintain an altitude of 8100 meters, and then let the Xingfei 8777 turn back to the course, just in case.

After resolving the conflict, the pressure was slightly less, and then the co-pilot contacted the cabin to ask if there were any injuries to the passengers when they had just been violently bumped.

When he learned that everything was fine in the cabin, Yan Zhen was really relieved. Now that the plane has entered the clouds, just waiting to pass through the large area of weather in front of it, everything is bright.

As soon as the plane enters the clouds, the sound of raindrops hitting the fuselage can be heard in the cockpit. The sound was similar to the crisp sound of Xiaoice hail smashing on the iron plate.

Yan Zhen turned on the landing lights, and through the windshield, he saw dense raindrops coming towards the nose of the plane. The raindrops flying towards the back of the plane, against the backdrop of the landing lights, seem to be in a time and space tunnel, which is quite sci-fi.

After entering the rain zone, the plane began to enter a constant turbulence again. But the only thing that is fortunate is that the degree of this bump is intensive, and the small bump is still within the acceptable range of Yanzhen.

At some point, the crack-like arc began to climb on the left and right windshields. The arc on the windshield seems to come to life, spreading from the windshield wipers to the entire windshield in a breath, and then retracting in a second or two, and then gushing out, and so on.

It was the first time for the co-pilot to see this kind of windshield arcing, and he was really a little worried about whether the windshield would crack, and he really thought about it. In particular, if you turn your eyes, you can see thunderstorm clouds with electric lights churning on both sides. They are the lonely boat in the angry sea, chasing with the waves, looking weak and helpless.

This is where the difference in experience comes in. The wind shield arc has been encountered many times on Yan Zhen's side, and he has long been surprised, and even sighed: "There is enough charge in the cumulonimbus clouds, and it is really like this for those who are close to the thunderstorm clouds." ”

In cumulonimbus clouds, especially near thunderstorm clouds, a large amount of electric charge will accumulate in the cumulonimbus cloud, coupled with sufficient water vapor, which can easily cause partial discharge of windshield circuits.

A short period of windshield arc will not be a big problem, but if the arc discharge lasts too long, it is easy to lead to local high temperature, which can reach thousands of degrees, and long-term local high temperature may cause cracks in the windshield. If there is a crack in the windshield, it can be a big deal.

However, judging from the weather radar, it doesn't take much time to pass through cumulonimbus clouds, so Yan Zhen is not very stressed.

Yan Zhen, who was slightly relaxed, suddenly felt that something was wrong, he always felt that something was wrong, he thought for a moment, and finally knew what was wrong.

"Isn't it too quiet?" Yan Zhen frowned, looked at the co-pilot who was still a little unaware of the situation, and said, "When will we not hear the radio?" ”