Aircraft rules are the most well-known, the most stringent, and the most frequently violated of all transport rules.

Everyone knows that on board the liner you can not drink (except for alcohol bought on board) and smoke, talk on the phone, joke about bombs. But at least half of the passengers do not turn off the phone on the plane: out of forgetfulness or out of spite. Others get drunk before departure and on board, smoke in the toilets and play daringly. The latest incident: a drunken couple was removed from the flight Irkutsk - Bangkok because of jokes about the "bomb".

As a rule, people simply do not understand why all these rigor is on board. Let's try to figure out: who came up with the rules and why we are obliged to comply with them.

1 last call

Why do you need to turn off your phone and other gadgets during takeoff and landing?

The ban on the use of electronic devices was introduced in the early 90s. Because of the fear that cell phones would interfere with on-board electronics. There are still rumors about disasters, allegedly caused by text messages and conversations on cell phones of passengers. For example: death passenger aircraft Saab 340 in Switzerland in 2000 (12 casualties).

There is also an international study: summarizing the statistics of flights of 125 airlines over seven years, 75 cases of impact on the devices of the liners of passengers' gadgets were revealed. Altitude and GPS positioning sensors are especially vulnerable.

True, in the first case, we are not talking about the official conclusion of the commission, but only about one of the versions of the death of the Saab 340. There is no evidence. There is no reason to believe that all 75 interference incidents were caused by passengers' gadgets.

This year, the European Aviation Safety Agency (EASA) finally announced that passenger devices do not threaten modern liners. Therefore, today a specific air carrier decides everything.

Russian airlines are still showing conservatism: our phones still need to be turned off or switched to flight mode. Significantly, the American Union of Flight Attendants also demands to leave the ban on the use of gadgets. True, for a different reason: stewards and flight attendants say that a person with a gadget in his hand simply does not hear any announcements in flight.

In addition, in a situation of strong turbulence, a smartphone and laptop flying out of your hands can cripple someone.

In general, when you get on board, just follow the instructions of the cabin crew. They ask you to turn it off - turn it off, do not ask - use it to your health.

2 Come on, put your suitcase away

Why raise the back of the seat, remove the table during takeoff and landing, and place luggage under the seat of the seat?

Pretty annoying situation. The passenger is awakened at the end of the flight and forced to sit in a chair for 40 minutes, instead of being able to take a little more sweet nap reclining. But if an accident occurs, then, as practice shows, the chances of survival increase with the fastest possible evacuation. There were cases when passengers survived under emergency landing and died from fire and smoke already on the ground - only because they stayed on board too long. The account in such cases goes on seconds. But you can quickly leave the plane, provided that the back of the seat in front of the seated passenger does not rest against your chest, and someone’s trunks are not scattered under your feet.

In addition, an unstowed table increases the likelihood of injury during landings with heavy braking. This doesn't just happen in emergencies. Some pilots deliberately land hard when landing on a wet runway. Explaining that if the landing gear "compressed" not gently, that is, the aircraft touched the ground and the landing gear abruptly took on its weight, then braking is more effective. The author of these lines recently experienced such a landing himself: we literally hung on our seat belts. But it's better than rolling out of a wet lane.

3 Light in the window

Why are the lights turned off during takeoff and landing?

The window shades are always open during takeoff and landing, so the passengers' eyes are adapted to the natural light overboard. If something unforeseen happens, it will be better if we keep our visual acuity. For example, when quickly leaving the plane.

It is also believed that the polymer curtains on the windows in the event of an accident can collapse and injure passengers.

Also, stewardesses and stewards can visually assess the condition of the aircraft through the windows, for example, see an engine fire. However, on new aircraft, this problem is dying off: the windows are made automatically dimmable. The dimming is not controlled by the passenger, but by the crew or flight attendants. You can close (up to 99% dimming) and open electronic shutters in a minute, both at the same time all, and selectively.

4 I see everything

Why are portholes round and not square?

Once upon a time, passenger planes had square windows. But in 1953, the British Comet jet crashed after takeoff. It was found out that microcracks appeared at the corners of its windows and the aircraft body was destroyed.

After that, the portholes began to be made round or oval. It is believed that the round shape is optimal in terms of strength. But there were planes even with triangular ones - for example, the French Caravels.

And the porthole of the modern "Dreamliner" cannot be called round. It is a large rectangle with rounded corners. This form allows, in the language of engineers, to bypass the places of concentration of fatigue stresses. God saves man, who save himself.

There are projects passenger aircraft and no windows at all. Instead, they will install huge flexible screens with a panoramic image of the surrounding space.

Illuminatorless technologies will first be tested on business jets. If the experiment turns out to be positive, then they will begin to introduce them on regular liners.

5 Flying but not flapping its wings

How dangerous are situations when the plane shakes and falls through?

One of the causes of aerophobia lies in the dysfunction of our vestibular apparatus, - says Alexei Gervash, pilot and founder of the "Fly Without Fear" center. - By transmitting false data to the brain about the "failure", "fall" or "rollover" of the aircraft, the vestibular system provokes the release of adrenaline.

Here is a typical passenger complaint: "The plane took off from the ground, and then there was a feeling that it was falling through, we were thrown up to the ceiling. Is this an air pocket?"

No, it's just the plane reached the design speed - continues Gervash. - The impression that you are pressed against the back of the chair - it really is. When a certain speed is reached, the aircraft "drops the gas" and the flaps retract. The human body moves on by inertia, and the plane has already "stopped" at the speed it needs. There is a slight negative overload, creating the illusion of sinking.

Everything is fine with the plane, all the problems are in us. Aerophobias are treated in special centers, for example, at the same Gervash.

Although I myself do it easier: in stressful situations in flight, I watch the flight attendants. The plane jumps over the "pits", everyone around is green with fear, and they are so rosy-cheeked and not at all frightened. You look at the stewardess and believe: this one will definitely fly. And so are you with her.

By the way

http://letaem-bez-straha.ru - here they treat aerophobias.

Round-shaped windows for providing light access, built into the sides of aircraft and ships, are a familiar sight. It is hard to imagine that they did not always have such outlines. So why are windows round? There are a number of explanations for this.

Portholes in ships

The windows built into the side of the ship hulls were not always round. In historical photographs, you can see ships with square and rectangular windows that look like familiar windows.

The more round shape, which is more familiar to us, is due to higher strength parameters. Roundness makes it possible to evenly distribute the load created by the difference in pressure and temperature. This "negates" the risk of cracks and, as a result, the rupture of the ship's hull. For the same reason, all bearing parts of ship hulls, as well as doors and hatches, are rounded.

The second reason for the widespread use of round-shaped windows is ease of manufacture.

Previously, window frames were made from billets cast from brass with subsequent processing on lathes. Round parts were much easier to make. In addition, during installation, it was easier to seal them, protecting them from leaks.

Modern round portholes on ships are completely waterproof. As an additional protection in case of severe weather or rough waters, the portholes are equipped with metal storm covers or removable shields.

Aircraft windows

Even before the middle of the last century, square windows were installed on passenger planes. Aircraft such as the Caravel had triangular windows at all.

The turning point was the tragedy that occurred in 1953. In those years, the jet aircraft industry was actively developing. One of the first to enter the world market was a supersonic liner called the Comet. In terms of technical characteristics in those days, he had no equal. But contemporaries remembered the supersonic liner for the reason that it crashed at the time of takeoff. 56 passengers died. During the following year, two more similar disasters occurred. "De Havilland Comed" was removed from flights, removed from production and began to find out the causes of accidents.

As it turned out later, the key cause of the tragedies was the depressurization of the aircraft body due to microcracks that appeared at the corners of the windows. For understanding, at the moment the aircraft climbed, there was a rapid drop in external pressure, while the pressure inside the aircraft remained more stable. The pressure difference provoked the expansion of the body. As a result: tension was created in the case material, it began to gradually change its shape. The square window acted as a kind of obstacle in the distribution of stress, forcing it to change its direction and thereby causing an increase in pressure. Peak stress points formed at the corners of the square windows, causing cracks to form in those places.

After that, the windows in the aircraft are made exclusively round or oval. In them, the pressure is distributed along the entire curve, minimizing the risk of deformation.

In fact, the windows of modern passenger aircraft, such as the wide-body twin-engine Boeing Dreamliner, are rather rectangular rather than round, with beveled and rounded corners. Such an engineering solution makes it possible to “bypass” the places where fatigue stresses are concentrated.

It is noteworthy that according to the instructions, the porthole shutters must remain open at the time of takeoff or landing of the aircraft. Such a precaution allows us to solve two problems at once: it allows passengers to more easily and quickly adapt to natural light overboard, and allows crew members to visually assess the state of the aircraft at any time with a cursory glance and, if necessary, take appropriate measures in time.

In addition, polymer curtains must be retracted for the reason that in the event of an emergency at the time of mechanical damage, do not injure nearby passengers.

Jet aircraft construction in the 1950s was just beginning. The first liner was the "Comet" - the brainchild of de Havilland

It was an ultra-modern jet passenger aircraft with unique for that time technical specifications and pressurized cabin. Unfortunately, in 1954, two "Comets" fell apart in flight, killing a total of 56 people.

The reason is ridiculously simple:

Square portholes.

It was one of those annoying little things that are easy to miss when designing; but as soon as anything happens, they become obvious even to a child.

Here's a chocolate bar. Where do you think it will break if you press on it?

That's right, along these recesses.

Now, a square window has four 90-degree notches, which means it has four weak points. If your house were pressed, then the crack would certainly go through the corner of some window:

Have you noticed that the windows in all planes are round? This is not done for beauty - the round shape does not allow tearing the plane into pieces. The pressure is distributed along the entire curve, instead of cracking at the corners (as it turns out) and tearing the plane to shreds.

Believe me, it wasn't easy to find out. Experts had no idea why the aircraft's structure was falling apart until they tested the structure by repeatedly simulating pressure on the cockpit. Of course, the fuselage, in the end, burst, and the gap began just from these notorious angles.

Since then, all planes have only round windows.(odnaknopka)(jcomments on)

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29.01.2018, 10:01

Many people ask the question: why are the windows in the aircraft rounded, and not square like ordinary windows or, for example, not triangular?

The answer is elementary simple. The very shape of the aircraft without corners, the rounded shape of the windows, as well as hatches and doors, is necessary for safety. Roundness allows you to evenly distribute the load from the difference in temperature and pressure, which prevents the occurrence of cracks, and subsequently depressurization of the cabin and rupture of the aircraft into pieces.

In more scientific terms, it looks like this: when the plane is gaining altitude, the external pressure drops faster than the internal pressure - this creates a pressure difference inside and outside the aircraft, causing the hull to expand.

When the body material changes its shape, stress is created in it. The material expands due to the fact that the stress is constantly increasing, eventually the stress reaches the limit that the material can collapse.

In airplanes, the shape of the windows greatly affects the voltage level. The stress easily passes through the material without damage if there are no obstacles such as a window in its path. this place he needs to change direction, and this causes an increase in pressure. This is called stress concentration.

Comparing the effect of round and square windows on stress concentration, you can see that square windows create a greater barrier to stress transmission. This means that stress is created at the corners of the square windows.

The limiting increase in the stress concentration causes the formation of cracks in the hull in these places. Such cracks led to tragic catastrophes until studies of destroyed aircraft made it possible to study the nature of the occurrence of stress in materials. That is, based on this, it becomes obvious why today the windows in airplanes are round, as well as all the bearing parts of the body, hatches, and doors are rounded. It's good that the designers have come to such a decision, and the passengers are now safe.