A clear-sky disaster: how dangerous turbulence is. Technical Sciences - Indicator

On May 1, an Aeroflot Boeing 777 entered a zone of severe turbulence. 27 people were injured, mostly unfastened, while, according to passengers, the “Fasten seat belts” sign was not lit. The reason for what happened was the so-called TYAN - this is not a girl in anime slang, but clear-sky turbulence. In English it is called CAT - Clear Air Turbulence.

What it is? “Normal” turbulence is associated with cloud cover and its occurrence is easy to predict both visually and using weather radar. But the TYAN is not visible until you get into it: it arises due to collisions of air masses moving with a large difference in speeds. There are three main reasons:

Why is TIAN dangerous? As you already understood - serious injuries to passengers. Despite the fact that, according to information from medical institutions in Bangkok, where 27 Aeroflot passengers sought medical help, there were no patients in serious condition or with life-threatening injuries, and information about patients with compression fractures of the spine was not confirmed, 15 Russian citizens and two Thai citizens are currently hospitalized. Patients who remain under the supervision of doctors suffered bruises, and several people had broken limbs.

An unbelted passenger's head turns into a powerful sledgehammer

There are known cases of more serious injuries and even deaths due to traction accidents, as well as plane crashes: for example, in 1966, a Boeing 707 flying from Tokyo to Hong Kong simply suddenly disintegrated in the air, killing 124 people.

Buckle up.

In addition, severe bumpiness makes it impossible for pilots to perform even the simplest operations, such as reading instrument readings.

What to do? After the “Fasten your seat belts” sign turns off, it is not without reason that they say: “You can move freely around the cabin, but for your safety we recommend that you remain fastened throughout the flight.” It is not necessary to tighten it tightly: in this case, it will not restrict movement, but still will not allow you to break through the ceiling with your head.

An unbelted passenger can play as an astronaut and fly around the cabin in zero gravity.

In addition, it is always better to stow your hand luggage under your seat so that when the shelf opens during turbulence, your suitcase will not fall on your head. By the way, for the same reason, there is less chance of running into your neighbor’s suitcase.

And you certainly shouldn’t pretend to be a hero while valiantly standing in line for the toilet with the signs on: according to statistics, the most deaths not during disasters are people who sat on the potty during turbulence and unsuccessfully hit their heads.

It's not what you think. Just coffee on the ceiling. Or it could be on your lap.

If you're not wearing a seatbelt, remember to avoid carts.

The topic of turbulence inevitably comes up when talking about various flows of gases, liquids or plasma. Most movements of matter are turbulent in nature.

So what is turbulence? Turbulence is the definition of disordered, nonlinear motion. The concept of “turbulence” does not have a clear and unambiguous definition. In general, this is the vortex movement of flows caused by an increase in their speed.

When calculating other types of aircraft, a flow is considered to be turbulent if the value of the Reynolds hydrodynamic similarity criterion, derived from the Novier-Stokes equation, is more than 2320. Reynolds in his studies indicated the factors influencing the movement of the fluid: the flow becomes turbulent with an increase in the linear speed and density of the flow, diameter holes (tubes) and reducing the dynamic viscosity of matter.

An example of a turbulent flow is air flows, which are vortices of various sizes that arise when the wind direction abruptly changes: from vertical to horizontal and vice versa. Atmospheric turbulence leads to intermittency of wind, various vertical transfers of vapor, condensation nuclei and other particles with mass and shape, as well as energy in the form of heat from one layer of the atmosphere to another.

Turbulence in aviation

Turbulence is of particular importance during aircraft flights. Not everyone knows what turbulence is on an airplane. When vortices superimpose on each other, aircraft are exposed to multidirectional winds, as a result of which the lift force and angles of attack of the wings change. A similar situation overboard leads to shaking and vibration - the so-called “blank”.

There are moderate and strong blanks. During the first shock, changes in flight altitude and rocking of the aircraft are not so significant, and pilots do not experience difficulties in controlling the aircraft.

A strong bump is a more serious situation involving frequent rolls and yaws, accompanied by deterioration of controllability and stability in flight, as well as distortion of on-board instrument readings. Such a phenomenon, if appropriate measures are not taken, can create stress in parts and individual components, leading to significant breakdowns and deformations of equipment and air sickness among crew members and passengers.

When encountering turbulence, passengers often worry whether the pilot will be able to handle the situation. However, the qualifications and skills of the pilot can only be useful in the case of a very strong blank. In other cases, the turbulence zone does not have a strong effect on the flight - it is carried out on autopilot.

What are turbulence zones? As a rule, this is a space where the probability of getting into long-term turbulence reaches 100%.

Nowadays, almost any passenger can determine when and where the ship will shake during the flight. This became possible as a result of the creation of turbulence maps, where calmer zones are marked with lighter colors and vice versa. The online turbulence map is designed to reduce the anxiety of passengers and crew, allowing you to predict and prepare if the plane encounters turbulence.

Is turbulence dangerous for an airplane? Of course, such a phenomenon causes concern and fear, and, if possible, it is avoided. As a rule, atmospheric instability is not dangerous for the aircraft itself, since its design provides for such overloads. Most often, in 30% of cases, flight attendants are injured because they did not have time to fasten their seat belts in time.

The dimensions of the aircraft play an important role in the feeling of shaking during turbulence. The larger the plane, the less inconvenience it will be. Everyone sooner or later wonders where on the plane it shakes the least during turbulence? When choosing a location, you should be guided by the intensity of shaking in the cabin: the strongest is in the tail section.

Causes of turbulence

The following causes of turbulence are distinguished:

• thermal convection (due to uneven surface heating or mixing of cold and warm air with significant vertical temperature changes);
• due to friction of moving air currents on rough terrain;
• due to the heterogeneity of the nature of air flows in direction and speed, wave movements on inversion and isothermal layers (there are alternating downward and upward flows).

An example of thermal convection is the formation of cumulus clouds.

Before each flight, the crew and the pilot himself familiarize themselves with weather reports for the near future in order to choose the safest route. Particular attention is paid to the presence of cumulus clouds.

Cumulus clouds are dense atmospheric formations, most often separately located, with a lower boundary height of up to 1200 m and a length of up to several hundred meters. They are formed as a result of powerful vertical flows and have internal upward flows of up to 10-15 m/s.

From a flight safety point of view, it is prohibited for a ship to enter such clouds, as well as to fly under them. Cumulonimbus clouds are especially dangerous because, due to the presence of water particles, heavy precipitation and electrical discharges form in them. Therefore, it is recommended to lay a route at a distance of 10 km from thunderclouds at an altitude of more than 1 km above them. The flight is complicated not only by the high turbulence in the plane, which causes bumpiness, but also by poor visibility - up to 45m.

Zones of overlap between ascending and descending flows can extend over thousands of kilometers. Most cases recorded Most cases recorded on the eastern shores of the United States.

Clear sky turbulence

The absence of any clouds in the sky does not mean that there will be no turbulence. At altitudes above 5000 m, so-called clear-air turbulence can occur. This phenomenon is typical for mountainous areas on the leeward side of the slope. When flowing around mountains, the air flow deviates from the straight direction, becomes deformed and forms zones of increased turbulence. The distribution of zones varies in height: in the lower and upper parts it is maximum, and in the middle it is minimum.

If it is not possible to change the flight course, aircraft must strictly maintain a certain distance to avoid a collision.

Can a plane crash due to turbulence? Over the entire period, five major plane crashes occurred due to clear air turbulence. In conditions of complete absence of clouds, a plane flying from Tokyo to Hong Kong was destroyed. Experts have determined that the death of all flight passengers and crew was due to unusually high turbulence on the slopes of Mount Fuji.

Another example is the crash of an airliner landing at an airport in Alaska. The version of the tragedy due to turbulence was not immediately considered, since it contradicted the forecasts of the hydrometeorological center. However, subsequently an outflow of Arctic masses was recorded, which led to the formation of an anomalous air wave and a zone of turbulence.

On May 1, 2017, all domestic news channels reported that a Boeing 737 on a flight from Moscow to Thailand entered a clear-sky turbulence zone. It was impossible to establish the fact of the approaching air pocket and avoid the ship from falling into it, since not a single instrument recorded it. As a result of the Boeing's sudden jump of 200 m, passengers received multiple injuries and fractures.

According to statistics, on average about 1000 cases of precedents arise per year related to atmospheric instability in clear skies. They mainly lead to flight delays, which cause great material damage to airline carriers.

Actions of pilots when entering a turbulence zone

According to Captain Chesley Sallenburg, who landed a passenger plane on the Hudson, when a turbulent zone is encountered in the cockpit, one of two decisions is made: to go beyond the limits of instability by reducing altitude, or to enter cloudless space by gaining it.

In case the aircraft encounters turbulence, a set of rules and recommendations has been developed for the cockpit and crew. You need to run the following commands:

1. Switch the autopilot to manual control.
2. Enable the “Tighten belts” command.
3. Adjust speed to 340 km/h.
4. Do not allow a sharp change in altitude or aircraft roll of more than 10°.

If it is impossible to avoid the heavy bump zone, the crew commander is obliged to return the aircraft to the original or nearest airfield.

Thus, the phenomenon of turbulence in the sky does not pose a strong threat to the aircraft. Like imperfections on highways (bumps, stones), turbulence in the air requires only excessive attention from the aircraft commander.

Another horror story from the media shocked the country.
“A plane crashed” “A terrible hole in the air” “One step away from death”
Over the past three days, such headlines have not left the main printed pages, TV screens and Internet news feeds.
"The worse and scarier the better!" This slogan, apparently, has become the cornerstone of all rating channels and publications. Only the lazy did not suck up this news in horrifying detail.
It is useless to fight something like this.

There is a very cool song from the children's movie Pinocchio, which is “one hundred years old at lunchtime,” but it very accurately reflects today’s reality:
"...As long as there are fools in the world,
Therefore, we can live by deception.
What a blue sky
We are not supporters of robbery:
A fool doesn't need a knife, You'll lie to him like three boxes -
And do with him what you want!"

I never give any comments to the media about aviation accidents and events for one simple reason; they almost always distort the meaning of what was said and reshape the information received in their own way, to suit their own or someone else’s interests. (verified) That’s why I’m better Here I will try to explain what “Clear Air Turbulence” is, whether it is dangerous and how to behave on an airplane.
It hurt.
So
Air transport, like any other (railway, sea, road, horse-drawn, teleportation...), is a subject of increased danger, increased risk, both for its passengers and drivers, and for third-party traffic participants. Now I will not touch on everything else except the sky (we are talking about flights).
A lot is known about the planet's atmosphere. Of course, not all, but still enough to move around in it as safely as possible. (not absolutely safe, but as much as possible!)
It is known that the atmosphere consists of gas (there is all kinds of oxygen, nitrogen, carbon dioxide and other gases). Chemistry is responsible for the composition, physics is responsible for the properties. At the moment we are interested in the properties of the atmosphere.
For many years, smart people observed the atmosphere, made statistical records, invented and carried out experiments, tried to predict the weather and figure out why it rains in summer and snows in winter. All this led to the emergence of a separate science - METEOROLOGY (scientific and applied field of knowledge about the structure and properties of the earth's atmosphere and the physical and chemical processes occurring in it.) It must be said that this science has stepped quite far and many things and processes occurring in the planetary gas shell, have become very well understood and predictable.
For aviation, knowledge about the sky is the most important knowledge! It is impossible to create an aircraft (a balloon, an airship, an ekranoplan, an atmospheric aircraft...) without understanding what happens to it in the air and what effect this very air has on a foreign object that finds itself in its environment. And therefore, all heavenly chariots are calculated and built in such a way as to ensure their compatibility and integration into the sky, according to the tasks, goals and functions to be performed by these aircraft in flight. It is because of this that a passenger airliner does not look like a combat fighter, and a hot air balloon does not look like a kite. So how and what affects flight?
The main parameters of the sky are: Temperature, pressure, humidity. These are the very three pillars on which the rest of the cuisine of the atmosphere rests. All these parameters are constantly changing, which leads to various processes in the air that directly affect aeronautics. (wind, pressure, cyclones and anti-cyclones. Hurricanes, Typhoons, rain, snowfall, frost, drought, etc.)
I’ll tell you a terrible secret: the principle of airplane flight is based on the difference in air pressure under the wing and above the wing. The principle of balloon flight is based on the difference in air temperature inside the balloon and outside (the air inside the balloon is heated with a burner, the density of the air drops and it becomes lighter than the cold air outside). The airship stays in the air because the gas inside the balloon is different from the atmosphere and is lighter than the air around it. The kite flies because the wind blows and a rope holds it! As soon as you remove these principles from the flight equation of your celestial unit, it will immediately crash to the ground! (no one has yet canceled the force of gravity! Teleportation and antigravity are a little more complicated, but everything is also explainable, but more on that next time)

You've listened to (read) the blurry introductory part about "Clear Air Turbulence." Let's move on to specifics.

The atmosphere is heterogeneous and therefore, any aircraft located in it is subject to its influence. It can chatter (shake) anytime and anywhere, regardless of the flight altitude, the terrain over which we fly, the presence of clouds, wind, or time of day. There are clear zones and signs in the sky where there is a 146% chance that the plane will shake.
First. These are primarily clouds.
Clouds are the same air, but extremely saturated with water. This means that the density of the cloud is much higher than the density of the gas surrounding it. The temperature and pressure there are different. This in turn leads to instability of air masses near and inside the clouds themselves. The more powerful the cloud, the more powerful and diverse the processes occurring within and nearby.
First of all, this is the direction and strength of air flows. Up. down, sideways. The speeds of gusts and currents reach colossal values. Ascending and descending currents rush a huge mass of air in different directions. An airplane caught in such a mess will be thrown like a chip in a stormy mudflow. (But we know that “A tank won’t crush a flea!” The plane itself, in principle, doesn’t even give a damn about where it is thrown and thrown, because it is in the flow itself and tightly connected with it.)
The danger in large, thunderclouds comes from a completely different direction. There, inside, not everything is so smooth and even. There the air turns into water and ice, and ice is already serious. In addition to the danger of damage to the aircraft body from hail (it will break into pieces, oh hello!) there is the danger of severe icing. The rate of ice growth on the load-bearing surfaces of an aircraft is cosmic! Icing for an airplane is like tying a brick to a small fishing float! To put it simply, this will turn the aircraft into a piece of ice. There is no need to step on the tail of a sleeping snake, and if possible, it is better to walk around it than to step on it. We always avoid storm clouds and never push our luck. (but if you still got there, and this sometimes happens, then this does not mean at all that everyone has fucked up! You just need to leave the unfriendly area as quickly as possible. This is taught, and we know how to do it. And once again: Chatter , this is the most innocent thing that a thunderstorm threatens!)
The next place where it always shakes is the mountains.
When flying over mountainous areas, the turbulence (instability) of the atmosphere is always increased. This is due to vertical and horizontal changes in wind direction. Well, everything is simple here. The wind blew straight and blew. Bang! Mountain on the way! The wind began to bend up and to the side. The air flow swirls and swirls and rises, disturbing the calm atmosphere.
Do you know the difference between a tsunami and just a huge wave? The height of the tsunami wave may not be very large, but the mass of water that the tsunami carries and that follows this low wave is such that it is astronomical in size. A wave 2 meters high turns out to be almost endless! She goes and goes, and destroys everything in her path. At the same time, just a huge wave, even 10 meters long, does not cause any particular damage, just as it surged and ended. So it is with air currents in the mountains. The wind blows and blows, bends and bends, and rushes upward. This entire gas mixture rises high above the mountains and shakes the plane. (But we know that “A tank won’t crush a flea!” The plane itself, in principle, doesn’t even give a damn about where it is thrown and thrown, because it is in the flow itself and tightly connected with it. The plane becomes part of this flow!)
Further.
Coastline.
Where the sea ends and the mainland begins, the likelihood of roughness is very high. The fact is that the heating of the earth and water is not the same, (remember that one of the main indicators of the atmosphere is temperature), the air also does not warm up equally, and at this junction of cold and hot “depressions” arise (there is such a concept in meteorology, about this you can read in more detail yourself if you are interested. There is a lot of material on the Internet.), which in turn leads to the emergence of vertical and horizontal flows. You need to understand that these flows are not just flows similar to streams or even rivers, but air masses of unimaginable size! Millions, billions of tons of indignant gas! (But we know that “A tank won’t crush a flea!” The plane itself, in principle, doesn’t even give a damn about where it is thrown and thrown, because it is in the flow itself and tightly connected with it. The plane becomes part of this flow!)
Where else can it shake?
Probably many of you have experienced it yourself: the whole flight was calm, but when descending and landing, almost at the very ground, it starts to throw? That's right! This is called thermal flows (or "thermals"). Glider pilots are very familiar with this phenomenon. The nature of this turbulence is the same, uneven heating...
Well, now the sweetest part: "The turbulence of this very clear sky"
You may believe it or you may not, but this is a fact (just like the fact that the earth is round. I saw it myself!) in the sky there are rivers, rivulets, streams. Only the size of these rivers and streams is monstrous! Thousands of kilometers long, tens of kilometers high and hundreds of kilometers wide. The flow speed in these currents can reach half a thousand kilometers per hour! (Once I saw and experienced a wind whose speed was 400 km per hour over the Baffin Sea (this is between Greenland and Canada)) And now imagine, you are riding a bicycle along a path between residential areas, whistling your favorite melody, no you don’t suspect, and suddenly the houses end, and you run around the corner at speed, and there’s a gusty wind! How will you feel? That's it!
If you know that there will be wind around the corner (and this can often be determined visually by dust, leaves, and debris rushing around the corner), then of course you will take action. Either don't go there, go around, or be prepared for the wind to blow!
Same with Clear Sky Turbulence. This phenomenon has long been known and easily explained and, alas, it is not uncommon! There are even signs and places where you are likely to run into it, but they are too unpredictable.
Where are you most likely to encounter this phenomenon?
Typically, this is the boundary of the air flow at the entrance and exit to and from the flow. But the trouble is that it is almost impossible to see this flow with a modern radar, but it is even very difficult to feel its influence on yourself. If everything is simple with clouds and precipitation, then the direction and strength of the wind is a problem. There are weather maps that are issued by special bureaus constantly, with a certain frequency. They indicate the direction and speed of the wind at altitudes, indicate areas with an increased probability of turbulence, but all this is very, very approximate, since the atmosphere is too unstable and indicate the exact point with coordinates on the map where strong turbulence will occur and at what time - It's just not realistic. Approximate area and time period - yes, specific place and time - no! Statistics show that most often, airplanes get into such trouble over the oceans and when flying near the equatorial region of the earth. They fall where cyclones originate and where temperature changes are very fleeting and significant. Is it possible to somehow predict and avoid falling into these areas? Hardly ever. (or stop flying) You need to understand that no “Air Pits” actually exist. Air flow inseparable! There are areas in the sky (that appear and disappear) where several phases of the physical state of the atmosphere converge at one time and in one place. For example, a powerful upward or downward flow suddenly intersects with the boundary of the air flow and then a “ass with a handle” arises. But it is fleeting and changeable, this bad thing, just like the flow will shift in ten seconds, and the upward gust will disappear.
You can list for a long time the places and causes of bumpiness, but for an ordinary passenger this is somehow not very interesting, because he pays money for the fact that he wants to move from point “A” to point “Z” quickly, safely and comfortably. And he has the right to do so! But you still need to know what can await him, my beloved passenger. "Forewarned is forearmed!"
So. What about the plane? How does he cope with these shocks?
And the plane is made for this purpose, to live in this heavenly carousel. It is much easier and safer for an airplane to fly in the sky than on the ground! Don't believe me? See:
The B-777 weighs 350 tons! (THREE HUNDRED FIFTY TONS KARL!) Of this weight, 140 tons of liquid fuel, which fills the tanks and sways inside the tanks - glug-glug. Heavy engines, which can move a tank weighing 50 tons with their jet! (each engine!) hang under the wing and are secured with only three bolts. The fuselage itself with seats, suitcases, passengers, chicken and beer. Wings filled with fuel right down to the tonsils. This entire farm stands on the ground, on just three thin supports - the chassis and the earth - mother attracts all this to herself with a force of 350 thousand kilograms! (take a glass ball and place it on the point of a needle and press on top of it. What is it like?) What happens when the plane flies? What happens is that air begins to hold all this heavy crap! Every millimeter, every atom of the iron monster, the air flows around and supports with tenderness! Wings, stabilizer, fuselage, all this lies softly on the air flow! So where is it easier for an airplane?
A? What? Are their wings flapping? Ha! That's how they should wave!
Just for fun, take a good, high-quality, graphite, modern spinning rod and try, without tying bait to it, to wave it like crazy. Will you break it? I think it’s unlikely, get tired of waving! (I'm a fisherman myself, I know what I'm talking about)
The plane is akin to a glass ball that was thrown into a stormy spring stream. (It’s not for nothing that I mentioned the point of the needle and the glass ball) What will happen to such a ball if there are no stones or other balls on its way? Well, absolutely nothing! The ball will happily jump through the waves, squealing with pleasure.
Now comes the worst part!
Place mice in this glass ball, jumping along the waves of serene happiness... Can you imagine what the poor mice will experience?
Epilogue
(But we know that “A tank won’t crush a flea!” The plane itself, in principle, doesn’t even give a damn about where it is thrown and thrown, because it is in the flow itself and tightly connected with it. The plane becomes part of this flow!)
My dear passengers, the world is complex and not always friendly, but the world is fair and supportive of those who play by its rules.
Don't cross the road at a red light. Walk around the front of the tram, don’t walk under the cornice where icicles are dripping, wear a life jacket while in a boat, don’t drink hawthorn tincture for three rubles, don’t grab exposed wires, wear a seat belt when sitting on an airplane...
DO NOT STAND UNDER THE ARROW!
Good luck to you and have a good spring mood...
Your Pilot Lech.

Media playback is unsupported on your device

Consequences of turbulence on board Aeroflot

Three dozen passengers on the Moscow-Bangkok flight were injured when an Aeroflot Boeing 777 aircraft hit an air pocket. Some people have fractures, the Russian Embassy in Thailand reported. The airline itself called the incident “clear-sky turbulence.”

“The victims have multiple fractures. There are both Russians and foreigners among them,” Vladimir Sosnov, head of the consular department of the Russian Embassy, ​​told TASS.

The diplomat suggested that those who were not wearing seat belts were injured. They were all taken to hospital in Bangkok.

Aeroflot reported that there were 313 passengers on board, 27 of them were hospitalized, 11 have already been discharged. The airline did not specify the citizenship of the victims.

In turn, Sosnov from the embassy said that 24 Russians and three Thai nationals were admitted to the hospital. Earlier, the embassy reported that the injured Russians had fractures and bruises, and “some required surgery.”

“The information disseminated by a number of media outlets that as a result of the incident several passengers suffered a compression fracture of the spine does not correspond to reality,” Aeroflot emphasizes in a statement.

The company insists that there are no patients on board its plane in serious condition after the incident. Those who suffered broken limbs or bruises remained in the hospital.

“The condition of all the victims is assessed by doctors as moderate, there is no threat to life,” Oleg Salagai, a representative of the Russian Ministry of Health, confirmed to Interfax.

"Clear Sky Turbulence"

Interfax's interlocutor, in turn, told what happened in the sky.

“The Boeing 777 aircraft unexpectedly encountered a zone of severe turbulence before starting its descent. That is, there was no obligation to fasten seat belts at that moment,” he explained.

“As a result of a strong shock, the plane was thrown 100-200 meters up, some of the unfastened passengers were thrown into the aisle by inertia and were injured,” the source said.

According to him, as a result of the impact, the plane's cabin was partially spontaneously switched to emergency mode, and "oxygen masks were released over some seats."

“Some of the victims with the most serious injuries, including fractures, were immediately hospitalized,” the Interfax source added.

The Aeroflot airline itself stated that the crew could not warn passengers about the danger in advance in this situation.

“The turbulence that the Boeing 777 encountered is known in aviation as “clear sky turbulence,” Aeroflot said in a statement. “Its main feature is that it does not occur in clouds, but in clear skies with good visibility, where weather radar cannot detect its approach."

“Therefore, the crew does not have the opportunity to warn passengers about the need to return to their seats,” the airline explained.

According to an Interfax source, the plane was not damaged as a result of the incident and has already taken off on its return flight to Moscow.

On the night of May 1, an Aeroflot flight from Moscow to Bangkok fell into an air pocket. Due to “clear air turbulence,” unbelted passengers were unexpectedly thrown out of their seats and about 20 people were injured. the site figured out why unpredictable turbulence occurs and why it is dangerous.

27 victims

On the Aeroflot plane, the incident occurred late at night, 20 minutes before the start of the descent. The fasten seat belt sign was turned off. The plane first gained altitude sharply and then descended. Those who were not wearing seat belts were thrown out of their seats.

“As a result of a strong shock, the plane was thrown 100-200 meters up, some of the unbelted passengers were thrown into the aisle by inertia and were injured.”, Interfax reported, citing an informed source in the capital of Thailand.

According to the Flight Radar service, in a matter of minutes the airliner first rose 210 m, and then just as sharply returned to its previous course - from 10.6 kilometers to 10.8 and back. At the same time, his speed first fell sharply, and then recovered.

27 passengers received injuries of varying severity. Judging by the video from the salon, things were noticeably scattered. Those who were sitting in the back of the plane suffered the most; people with serious injuries lay right in the aisles.

Why are there holes in the sky?

The cause of the incident was determined to be “clear air turbulence,” a dangerous phenomenon that is particularly difficult to predict. To understand where it comes from, you need to understand how ordinary “air pockets” appear.

Passengers experience shaking when the plane changes from an updraft to a downdraft or vice versa. Also, the cause of “churning,” as pilots call it, can be a change in wind.

“The first thing you need to understand is that different parts of the earth have different surface temperatures,- explains Tom Bunn retired pilot, therapist and founder of a program to combat the fear of flying. — For example, the surface of a lake is colder than the surrounding shores, and plowed fields differ in temperature from unplowed ones. Warm air is lighter than cold air. Warm air rises and cold air sinks. When an airplane encounters changing air flow, we feel what is called an "air pocket."

Attention! You have JavaScript disabled, your browser does not support HTML5, or you have an older version of Adobe Flash Player installed.

“Air pockets” are manifestations of turbulence in flight. Turbulence is common and in most cases is not dangerous. The pilot compares this phenomenon to a car driving over potholes or a boat sailing through waves. The strongest “dips” usually occur in the area of ​​thunderstorms.

Jet stream and "wind shear"

Clear-air turbulence is the “turbulence” that occurs when there is a visual absence of clouds. This phenomenon is much more difficult to predict, since it occurs at a high altitude - in the troposphere (7 - 12 kilometers).

Clear-air turbulence usually occurs at the boundaries of the high-altitude jet stream under the influence of other atmospheric factors.

The jet stream is a narrow zone of strong wind in the upper troposphere. Wind speed on the axis can exceed 25 m/s. This current can reach hundreds of kilometers in width and thousands of kilometers in length, its vertical “thickness” is 2-4 km. Jets in currents move in the form of meandering “rivers of air” and are mainly directed to the east.

Also, the appearance of clear sky turbulence is facilitated by a temperature gradient (temperature difference in a certain direction), “wind shear” (a sharp change in wind speed or direction over a relatively small area) and “lee waves” (appear when the wind overcomes a mountain range and causes a turbulent horizontal vortex) .

“In our case, the consequences were minimal”

Standard aircraft radars cannot detect clear air turbulence. “Clear-air turbulence does not occur in clouds, but in clear skies with good visibility, where weather radar cannot detect its approach“Aeroflot representatives explained. — Therefore, the crew has no way to warn passengers about the need to return to their seats.”

However, there are ways to predict this phenomenon in advance. Russian scientists are able to determine using special lidars - an analogue of radar, which works based on data on light scattering.

As Aeroflot notes, clear sky turbulence is a common occurrence. About 750 such cases are recorded every year. The Russian airline's plane was ready for such loads. “In our case, the consequences were minimal, since Aeroflot’s fleet of aircraft is the newest and best”, said the pilot of the airliner.

However, the consequences of such incidents depend on the type of aircraft. There is a known case of the death of a Boeing 707 on Mount Fuji in Japan in 1966. As a result of the investigation, abnormally strong turbulence was recognized as the official cause of the disaster. in absolutely clear weather. The loads on the structures turned out to be much higher than permissible, which is why the aircraft collapsed in the air.