What is clear sky turbulence. Turbulence in the skies over Bangkok: a lot of work awaits investigators

The topic of turbulence inherently comes up with the mention of various flows of gases, liquids or plasma. Most of the motions of matter are turbulent.

So what is turbulence? Turbulence is the definition of disordered, non-linear motion. The concept of "turbulence" does not have a clear and unambiguous definition. In the general case, this is a vortex motion of flows caused by an increase in their speed.

When calculating aircraft of another kind, a flow is considered turbulent if the hydrodynamic Reynolds similarity criterion derived from the Novier-Stokes equation is more than 2320. In his studies, Reynolds pointed out the factors affecting the movement of fluid: the flow becomes turbulent with an increase in the linear velocity and flow density, diameter holes (tubes) and a decrease in the dynamic viscosity of matter.

An example of a turbulent flow is air flows, which are vortices of various sizes that occur when the wind direction changes abruptly: from vertical to horizontal and vice versa. Atmospheric turbulence leads to discontinuities in the wind, various vertical transport of steam, condensation nuclei and other particles of 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 flight aircraft... Not everyone knows what turbulence in an airplane is. When vortices are superimposed on each other, aircraft are exposed to multidirectional winds, as a result of which the lift and angles of attack of the wings change. A similar situation overboard leads to shaking and vibration - the so-called "blank".

Distinguish between moderate and strong blank. At the first jolts, changes in flight altitude and rocking of the aircraft are not so significant, and pilots do not experience difficulty in controlling the aircraft.

A strong blank is a more serious situation involving frequent rolls and yawing, accompanied by a deterioration in controllability and stability in flight, as well as distortion of the readings of on-board instruments. A similar phenomenon, if appropriate measures are not taken, can create stresses in parts and individual assemblies, leading to significant breakdowns and deformations of equipment and airborne illness among crew members and passengers.

When entering turbulence zones, passengers often feel anxious about whether the pilot will cope with 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 performed on autopilot.

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

Nowadays, almost any passenger can determine when and where the vessel will shake during the flight. This became possible as a result of the creation of turbulence maps, where quieter zones are marked with a lighter color and vice versa. The online turbulence map was created to reduce the anxiety of passengers and crew, and allows you to predict and prepare if the plane gets into turbulence.

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

The size of the aircraft plays an important role in the feeling of shaking during turbulence. The larger the aircraft, the less inconvenience is. Sooner or later, everyone asks the question of where on the plane the least shakes during turbulence? When choosing a place, one should be guided by the intensity of the shaking in the cabin: the strongest one is in the tail section.

Causes of turbulence

The following causes of turbulence are distinguished:

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

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

Before each flight, the crew and the pilot himself are familiarized with the 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 height of the lower boundary 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 ascending flows up to 10-15 m / s.

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

The overlapping zones of updrafts and downdrafts can extend over thousands of kilometers. Most cases recorded Most cases recorded on eastern shores USA.

Clear air turbulence

The absence of any clouds in the sky does not mean that there will be no turbulence. So-called turbulence can occur at an altitude of 5000 m. clear sky... This phenomenon is typical for mountainous areas on the leeward side of the slope. When the air flows around the mountains, the air flow deviates from the rectilinear direction, deforms 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 impossible to change course of flight, aircraft must maintain a certain distance in strict order to avoid collision.

Can a plane crash due to turbulence? Over the entire time, due to clear-sky turbulence, five major plane crashes... In the complete absence of clouds, an airplane flying from Tokyo to Hong Kong was destroyed. Experts found that unusually high turbulence near the slopes of Fuji was the cause of the death of all passengers on the flight and the crew.

Another example is the crash of an airliner landing at an Alaska airport. The version of the tragedy due to turbulence was not immediately considered, since it contradicted the forecasts of the hydrometeorological center. However, an outflow of Arctic masses was subsequently recorded, which served as 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, which was flying from Moscow to Thailand, entered a clear sky turbulence zone. It was impossible to establish the fact of an approaching air hole and avoid a ship falling into it, since not a single device recorded it. As a result of a sharp jump of the Boeing 200 meters, the passengers received multiple injuries and fractures.

According to statistics, about 1000 cases of precedents related to the instability of the atmosphere in a clear sky arise on average per year. Basically, they lead to flight delays, which causes great material damage to the airlines-carriers.

Pilot actions when entering a turbulence zone

According to Captain Chesley Sullenberg, who landed a passenger plane on the Hudson, when entering a zone of turbulence in the cockpit, one of two decisions is made: go beyond instability by lowering the altitude, or go into cloudless space by gaining it.

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

1. Set the autopilot to manual control.
2. Turn on the "Tighten Belts" command.
3. Adjust the speed to 340 km / h.
4. Avoid a sharp drop in altitude, aircraft roll of more than 10 °.

In conditions of impossibility of avoiding the zone of strong blank, the crew commander is obliged to return the aircraft to the original or the nearest aerodrome.

Thus, the phenomenon of turbulence in the sky for the aircraft does not pose a strong threat. Like imperfections on highways (bumps, stones), turbulence in the air only requires undue attention from the pilot-in-command.

On May 1, 20 minutes before the descent, the Aeroflot plane en route from Moscow to Bangkok fell into a short-term zone of severe turbulence. Passengers who were not wearing their seatbelt received injuries of varying severity, 25 of them were hospitalized after landing. 15 Russians still remain in a Bangkok hospital, the Russian Embassy in Thailand said.

Aeroflot: Clear Sky Turbulence Appeared Unexpectedly

According to the commander of flight SU 270 Moscow - Bangkok, Alexander Ruzov, the overload lasted 15 seconds, and after half a minute the airliner was brought back to the desired trajectory. This happened thanks to the competent actions of both the brigade and the crew, Ruzov noted in a telephone interview with one of the Russian TV channels. However, he expressed regret that passengers who were not wearing seat belts were injured.

The press service of Aeroflot explained that the plane was in the so-called "clear sky turbulence."

The press service of Aeroflot explained that the plane was in the so-called "clear sky turbulence." It does not appear in the clouds, but in a clear sky with good visibility, and the weather radar does not report an approach to it.

“Therefore, the crew has no way to warn passengers about the need to return to their seats,” explained the representative of the air carrier. According to him, in the world civil aviation there are about 750 clear air turbulence cases per year.

Aeroflot covered the costs of treating injured passengers. On Tuesday, this was confirmed by the president of the All-Russian Union of Insurers Igor Yurgens. According to him, the limit of the air carrier's liability insurance contract is sufficient to pay all compensation.

Aviation experts: “This amazing case to be investigated "

However, some experts doubted that Aeroflot's airliner really got into "clear-air turbulence." For example, a military meteorologist, reserve lieutenant colonel Yevgeny Tishkovets, in an interview with NSN, said that phenomena such as clear-sky turbulence are very easy to predict.

“The crew should have been informed about what awaits them ahead. Either they were informed and they violated the instructions, or they were not informed about it. "

“This can be calculated in several ways, but using computer technology, there are no problems at all. The crew should have been informed about what awaits them ahead. Either they were informed and they violated the instructions, or they were not notified about it, ”Tishkovets said, noting that he personally examined the upper layers of the troposphere at that moment and did not see any clear-sky turbulence.

Aviaexpert Oleg Panteleev, who heads the AviaPort agency, believes that the version of the aircraft malfunction in this case is not justified and is not motivated by anything.

“Unfortunately, the cases when intense air currents throw up or bring down planes by several hundred meters are quite common in aviation. And there are a lot of people affected by this all over the world. I believe that the passengers of Aeroflot got off easy yet, ”Panteleev shared his opinion with the“ Public Control ”.

He recalled that all airlines, without exception, recommend their passengers to stay fastened - even if the “Fasten your seat belts” display is off. This minimizes the risks in the event the vessel enters the turbulence zone.

Honored Pilot of Russia Vadim Bazykin called the incident with the Aeroflot aircraft surprising and requiring a thorough investigation. According to him, clear-air turbulence can be predicted because it often occurs at the water-land border - or in mountainous areas, where there is a difference in the temperatures of the air masses: warm air goes up, cold air goes down, crossing, they form a "bump".

Clear air turbulence can be predicted because it often occurs where there is a difference in the temperatures of air masses: warm air goes up, cold air goes down, crossing, they form a "bumpiness".

“We were not told such beautiful terms as clear-sky turbulence, and we were taught that if you saw a bumpiness, first of all turn off the autopilot, because, fighting the air currents, it only aggravates the situation, and manually aligning the plane is not difficult. The pilots of flight SU 270 Moscow - Bangkok turned off the autopilot after 15 seconds. Why it’s so late, we need to figure it out, ”Bazykin told Public Control.

At the same time, the expert noted that there are several ways to determine the clear air turbulence zone. For example, according to the data of meteorological stations, which mark different currents and directions of the wind, or according to the ground speed.

The Investigative Committee of Russia is conducting a pre-investigation check into what happened on board an aircraft en route from Moscow to Bangkok on May 1. Based on its results, a decision will be made to initiate a criminal case.

In addition, the Federal Air Transport Agency will investigate the state of emergency.

Passengers: "This is the feeling when you fly from floor to ceiling and do not control the situation, and people, things and seats are flying nearby."

What the passengers of the ill-fated flight experienced, they can hardly forget.

“Three hours ago I was on a plane flying from Moscow to Bangkok. Suddenly we found ourselves in a zone of turbulence. It was so terrible that people were thrown like crazy. There is blood everywhere, people with broken bones, noses, open fractures, children with head injuries, we can go on and on. Thank God we are all alive. I very much hope that Aeroflot will do the right thing with the victims. The airline staff did everything to help people on board. As for the pilot, I can say he saved us all. Honestly, I have never been so scared, ”Rostik Rusev, a passenger on flight SU 270 Moscow-Bangkok, wrote on Instagram. To his post, he attached a video filmed on the plane after passing through the turbulence zone.

“Unfortunately, my first news from Tai was like this ... We were on this flight and sat in the very tail. And we saw with our own eyes all this horror ... This is the feeling when you fly from floor to ceiling and do not control the situation, and people, things and seats are flying nearby. As luck would have it, we got off with bruises. This is really an accident, there were people with open fractures lying nearby. The entire tail section of the plane is covered in blood. It cannot be described in words. We're fine while we're in the hospital. Medicine in Tae na the highest level", - another passenger of the Aeroflot aircraft, named Margarita, said on her Instagram.

Cause of the plane incident Boeing 777 airlines "Aeroflot" operating a flight Moscow - Bangkok,. This was reported by the press service of the carrier. President of the Infrastructure Development Fund air transport Honored Pilot of the USSR Oleg Smirnov answered TASS questions, what kind of phenomenon is this, and what to do for the passengers of the plane that got into his zone.

What is turbulence?

Turbulence is the chaotic movement of air masses with different densities and temperatures. Smirnov says there are several types of turbulence. During a flight, airliners very often pass through its zone during takeoff and landing, especially in summer. It is caused by the fact that warm air currents coming from the ground collide with cold ones. At this time, the plane may shake, panels may creak. But this turbulence is absolutely safe for passengers and the liner - provided that travelers are sitting in their seats and wearing seat belts.

Extremely dangerous, according to Smirnov, is turbulence at medium and high altitudes. It usually forms in cumulus and thunderstorm clouds. They are clearly visible - both visually and on radars. Both international and Russian flight safety regulations require controllers and pilots to avoid entering these areas. “It is strictly forbidden to go into powerful cumulus and thunderstorm clouds,” Smirnov said.

Clear sky turbulence is different in that it occurs in an absolutely clear, cloudless space. It is invisible to the pilot's eye and is not detected by radars. Most often, it occurs due to a jet stream - a strong wind that blows at a speed of about 300 kilometers per hour. Last year, the world recorded 750 cases of aircraft hitting such turbulence.

Yes. After getting into turbulence, the aircraft can reach supercritical angles of attack (that is, the air flow will blow over the wing of the aircraft without creating lift), lose control and fall. Fortunately, pilots are trained to deal with this situation.

And what to do in case of clear-air turbulence?

Smirnov claims that the recipe is simple: if possible, stay fastened during the entire flight (by the way, this is also advised by the instructions for aviation security). If the flight attendant's command is heard to fasten the seat belts and remove the table, you should do this immediately. By the way, the pilots of the plane are strapped to the seat for the entire flight - until the end of taxiing. “Someone is uncomfortable, but you can be sure that if you find yourself in such a situation, you will remain in your seat and will not hit the ceiling of the plane,” said the honored pilot of the USSR.

In addition, Smirnov recommends, if possible, to abandon the use of heavy objects in flight, such as laptops. In the event that the plane gets into turbulence, the aircraft can easily be pulled out of the hands, and it can cause significant injury to you or other passengers.

All of these restrictions will have to be respected until scientists learn to recognize clear-air turbulence. According to Oleg Smirnov, developments in this direction have been going on for a long time: "They are working on such a device, and, I hope, they will soon present it and equip airplanes with it."

The actions of the crew of the Russian plane will be assessed by the investigators. They will interrogate the pilots and passengers on board, after which they will decide whether to open a criminal case or not.

As a result of hitting the plane air pit... They were all unfastened at the moment of turbulence. Eight had to be operated on. Why didn't the crew warn passengers about the danger zone? About "clear sky turbulence", a phenomenon that annually injures hundreds of passengers, report NTV correspondent Alexei Kvashenkin.

The flight to Bangkok was already coming to an end, it was less than an hour, but the “fasten your seat belts” display had not yet come on. Behind 7 hours of flight. Someone was finishing breakfast, someone was waiting in line for the toilet when the plane shook for the first time.

Olga Tarasova, passenger on flight SU270: “Nothing boded. It was light outside the window, we flew over the clouds. The sky was clear, and suddenly we felt like we were falling into some kind of abyss, as if on a roller coaster ”.

For a few seconds, the liner seemed to stand still, and then the most terrible seconds in the lives of passengers began.

Tamara Sipko, passenger of flight SU270: "The plane was falling, it was shaking, some things were flying."

Margarita Dovgaya, passenger of flight SU270: “We were thrown, torn from our seats, a very strong shaking began ,. People fell, panic and screams began. "

And the pilots at this time did everything possible to keep the huge liner.

Ilya Kuzma, flight simulator instructor: “Turbulence is an unpredictable thing. We do not know in which direction the liner will now throw, right, left, up, down. Piloting is getting pretty problematic. "

This is just a simulator, but the sensations are quite authentic. And here, in the cockpit, the question arises: could this situation have been prevented at all? Stopping the imitation of turbulence, the instructor pilot explains: there is indeed a special radar on board, but it is not an all-seeing eye.

Ilya Kuzma: “Turbulence zones, if they are created by cloud fronts, thunderclouds, precipitation, they will be displayed on the radar. If there is no precipitation or suspension, the turbulence zones are not visible. "

Most people are used to thinking that turbulence is a companion of bad weather. But so that like this, at a height of many kilometers, out of a clear sky? Most passengers have never even heard of this. And Flight 270 encountered just such a phenomenon.

Maxim Fetisov, spokesman for Aeroflot: "The locator cannot detect its approach, so our pilot could not foresee this turbulence and turn on the" fasten your seat belts "signal in time."

And the military meteorologist Yevgeny Tishkovets believes that the local meteorological services could calculate the dangerous zone.

Evgeny Tishkovets, Meteorologist: “Ground services did not predict this dangerous phenomenon, although it is predicted. It was announced that it was allegedly not predicted, it was invisible. It is not true".

But the crew is not to blame for this. Even by indirect signs, the pilots could not notice the danger in advance: the tropical climate is very insidious.

Victor Zabolotsky, Honored Test Pilot of the USSR: “These are tropical latitudes. This is very harsh. I got into such a phenomenon once. Frankly speaking, it is not pleasant enough. "

Clear-air turbulence is not such a rare occurrence. Airplanes hit it more than 700 times a year. As a rule, without consequences for passengers.

This is scary. It is not comfortable. Because of this, coffee and tomato juice spilled on my pants. This is called “turbulence”. And how dangerous is it really?

Once the plane I was flying got into a strong turbulence. This situation is a great way to feel like a tiny grain of sand, on which nothing depends. After that incident, I avoided planes like the plague for a year.

Fortunately, our flight ended safely. The same cannot be said about some other cases. Last February, a flight from Denver to Billings for four passengers and one flight attendant ended in intensive care. And in December, due to turbulence, 14 passengers of the Seoul-Dallas flight were injured, the plane made emergency landing in Tokyo.

These are just three examples that I could recall offhand. What do experts think about the real danger of an aircraft hitting a turbulence zone? Are belts a 100% guarantee of our safety?

Can a plane lose control and crash due to turbulence?

In short, the answer is no. And don't roll your eyes looking for killer arguments against such a response. You've probably already heard that the plane is the safest means of transportation. This despite the fact that land transport, unlike airplanes, cannot fall by definition. It seems more reliable than moving in an iron pipe dangling 10 kilometers above the ground.

But, despite the very unpleasant subjective sensations, turbulence by itself will never cause the plane to fall to the ground. Pilot Patrick Smith at AskThePilot.com explained that even the most severe movements of air masses cannot flip a plane or tear it apart.

Turbulence can cause damage. But this happens very rarely. In this regard, the incident of 1966 is often cited, when strong turbulence tore a Boeing 707 near Mount Fuji, to which the pilot wanted to fly closer to get a better view of the Japanese landmark. Gusts of wind in that place reached 140 miles per hour, which killed everyone on board.

But since then the engineers have done some serious work. Aircraft design has become more resistant to such loads. Modern passenger liners They are capable of taking off at an angle of 90 degrees to the horizon, so they are not afraid of any gusts of wind on Earth. The Dreamliner 787, for example, is equipped with special sensors to accurately predict the location of turbulence zones. At the same time, a combination of unfavorable weather conditions and other factors (for example, pilot error) can lead to disaster.

Professor Robert Sherman of the National Center for Atmospheric Research (USA) says history has recorded a couple of cases where very strong gusts of air tore the engines from the wings. But even in these circumstances, the plane landed safely at the airfield.

If the turbulence is severe, pilots can make route adjustments or land elsewhere. But even according to this scenario, the situation develops very rarely. However, conditions may not be dire enough to harm the aircraft. Usually an emergency landing is made due to the fact that one of the passengers neglected the command “Fasten your seat belts” and now he needs urgent medical attention.

Are passengers often injured due to turbulence?

Official statistics are silent here. Of course, national aviation agencies collect relevant data from airlines. But, as a rule, they only report serious injuries.

Professor Sherman says that in the United States, turbulence injury is reported if a passenger dies within 30 days of the incident or has been confined to a hospital bed for more than 48 hours. In addition, bone fractures, severe hemorrhages, nerve and ligament ruptures, second or third degree burns affecting more than 5% of the body surface, or internal organ damage are considered.

More “minor” injuries, if the patient spends no more than a day in the hospital, are not counted. Therefore, official statistics can give a grossly underestimated estimate.

According to a 2013 report by the US Federal Aviation Administration, 24 people were injured due to the plane hitting a turbulence zone. Of these, 13 were crew members. Most of the injuries are suffered by those who have not fastened their seatbelt. Therefore, two thirds of the victims are flight attendants.

How do pilots perceive an aircraft entering a turbulence zone?

They care about two things: the comfort of passengers and their own safety.

It should be borne in mind that in the air, pilots of different aircraft communicate with each other “in real time”. They report the observed phenomena in the atmosphere. If someone got into a “bumpiness”, then his neighbors in the sky will immediately know about it. Also, this information is transmitted to dispatchers on the ground.

Pilots can change their route slightly to avoid turbulence. But this results in additional costs of fuel and time. Therefore, some of them do not pay much attention to turbulence.

The situation becomes truly threatening in the case of the so-called clear sky turbulence. Sudden and powerful blows of air masses are like a bolt from the blue. They are the source of most of the injuries associated with turbulence. The pilots are unaware of the threat that awaits them.

Professor Sherman argues that clear sky turbulence occurs most often over mountainous areas.

Last year, five passengers on United Airlines Flight 1676 were injured in sudden, very violent air strikes. The plane abruptly went down, and unfastened passengers "soared" up from their seats, hitting their heads on the compartments for hand luggage and breaking through their bottom. One child jumped out of his chair and landed in a nearby seat.

Another incident involving an American Airlines flight from Seoul to Dallas was in the news. The plane made an emergency landing in Tokyo to send more than ten passengers injured by being caught in a winter storm to hospital. The turbulence was so intense that food and drink flew through the cabin like birds.

Such cases are very rare, but they have every chance of becoming a hit on YouTube, if one of the passengers has time to film what is happening on a smartphone camera.

Should I be afraid?

The short answer to this question is “no”. But if he did not reassure you, then know that the numbers are on the side of your safety.

Professor Sherman says the odds of a plane hitting a zone of severe turbulence is one in a million. The real occurrence of such hazardous areas in the atmosphere above, but pilots try to get around them.

But do not forget to follow the recommendations of the flight attendants. Fasten your belts when asked to do so, and try not to undo them unnecessarily. This way, you will remain unharmed even in the turbulence of clear skies.

Experts advise not to rush to unfasten and run to the toilet immediately after leaving the zone of turbulence or takeoff.

The safest position during the flight is to relax in the seat with a seat belt. Breathe deeply and evenly. Remember, turbulence is normal. Modern aircraft are very reliable. You are completely safe.