Technology

Why do birds collide with airplanes?

In the language of pilots, “strike” is not the best blowwhich can be done in bowling. As a rule, this word in aviation means the collision of birds with an airplane (with the addition of the word bird (bird), it turns out “bird strike”). In fact, birds encounter planes very often: it is possible that such an incident even occurred during your recent flight, you just don’t know about it. Typically, such incidents do not lead to serious consequences, a bird weighing less than 3 kg simply burns in the engine. However, sometimes planes are even forced to urgently land because of a collision with birds.

Only in Russia officially recorded about 7000 bird strike cases per year - in Europe this figure reaches 10 000. However, only about 5% of bird hits result in aircraft damage. But because of precaution, all planes after a collision return to the nearest airport, and passengers transfer to another flight with a different crew. In rare cases, the damage is too serious, and the pilots fall into emergency situations. This happened with the Ural Airlines Airbus A321, which landed on a field near the airport on August 15, 2019 due to a failure of both engines caused by a bird collision.

Airbus A321 Ural Airlines after landing on the field, August 15, 2019

Content

  • 1 Why do birds collide with airplanes
  • 2 What happens if the birds get into the engines of the aircraft
  • 3 How long can an airplane fly without engines
  • 4 How to land aircraft without engines
  • 5 What happens if a bird lands on a plane
  • 6 Why engines do not cover with a bird grill
  • 7 Avoiding bird collisions with aircraft

Why birds collide with airplanes

In general, birds do not fly high. Most collisions occur below 150 meters - that is, just during takeoff or landing. The speed of the aircraft at this moment is lower than at altitude, and fast evasion maneuvers are difficult to implement. The outcome for the most part depends on which part of the plane the bird is beating.

The greatest danger is the entry of birdsinto the engine. According to safety standards, large engines must withstand a collision with a bird weighing less than 3.5 kg without dangerous and quick release of sharp fragments of the blades from the engines. In fact, most engines can swallow a bird and only slightly damage the blades. Nevertheless, this is also damage: if a bird gets larger, a collision with it can cause engine failure. The blades will begin to break one after another, which will cause a fire.

Pilots can put out a fire in the engine andturn it off completely, then return to the airport of departure (if the incident occurred during takeoff) or complete the landing with one engine running. All pilots are trained to operate a single-engine aircraft, although it is very difficult: you have to switch completely to manual controllers and make a visual approach. Not so long ago, a Japanese airline was forced to make an emergency landing in New York because a bird hit the plane; another plane was forced to return to Cardiff Airport in Wales after the bird got into the engine.

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A selection of videos where planes collide with birds

What happens if the birds get into the engines of the plane

But a completely different case - when the birds fallin two engines at once. In this case, they, as a rule, do not fly alone, but in packs, and this is already dangerous. The scenario described above with the failure of one engine is repeated on the second, and the aircraft has no choice but to plan.

The actions of the pilots in this case are directly dependentfrom height. If the incident occurred at 3-4 thousand meters, they can still deploy the plane back to the airport and land it (or complete the planned landing), although we must admit that the collision with the ground will be very severe - it all depends on the pilot’s skills and his ability to “feel »Multi-ton car. But if the plane did not manage to gain altitude during takeoff (up to 1,000 meters), the birds fell into both engines and led to their failure, the pilots simply did not have enough height to maneuver. As a result, they decide to land the plane wherever they need - on the highway, field (as is the case with the board of Ural Airlines), water and any other suitable surface, if you can call it that.

How much a plane can fly without engines

If the liner has reached a level of 10,000 meters, hecan plan at a distance of 140-150 kilometers depending on the type of aircraft. That's just the birds do not fly at such an altitude, so all collisions occur much lower - at an altitude below 1,000 meters. This is not enough even to plan 30 kilometers. Forced planning may cause the nose of the aircraft to pull too high

How to land aircraft without engines

If the pilots understand that the plane cannotto reach the nearest airport, they decide to land in the wasteland (if any) or water (the so-called “splashdown” of the aircraft). In this they are helped by the APU - auxiliary power plant. This is a small engine equipped with a turbine that generates energy, which in turn activates the action of all the necessary units for the aircraft - from the steering wheels and altitude to the dashboard.

One vivid example of a splashdown isemergency landing of the A320 on the Hudson River, which occurred on January 15, 2009. US Airways airliner collided with a flock of Canadian geese 1.5 minutes after takeoff, and both engines failed. The crew safely landed the plane on the water of the Hudson River in New York. All 155 people on board (150 passengers and 5 crew members) survived. The plane just managed to gain a height of 975 meters: this was enough to deploy the liner, taking off north and south, to plan over the Hudson River without hitting the George Washington Bridge, and bring the liner down. Subsequently, the feature film Miracle on the Hudson was filmed on these events.

Water splashdown on the Hudson River, January 15, 2009

In fact, if you try to reproducesuch a situation on the flight simulator, in most cases, pilots will be able to return the liner to the departure airport. The problem is that in the simulator, it takes only 5 seconds to make a decision (and such situations are worked out only on simulators). In reality, pilots need 20-30 seconds to do this because of the stressful situation. Therefore, often pilots do not have enough time to land the plane without incident.

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A total of 21 cases of controlled forcedlanding of passenger airliners on water, in 10 of which no one died during landing. One of them is the landing of the Tu-124 on the Neva - an accident that happened in Leningrad (St. Petersburg) on ​​August 21, 1963. True, in that case the problem was not with the birds: due to the defect of the aircraft, fuel did not enter the engines, and they stopped.

Landing on the field is even more difficult -pilots need to take into account the roughness of the surface topography and calculate the correct speed to prevent the aircraft from stalling and sit "on the belly" as soft as possible. Such a landing is made without the extended chassis, since the landing gear with an uneven surface can damage the fuel tanks. The latter can lead to ignition of the aircraft, as happened with the Sukhoi Superjet 100-95B airliner. On May 5, 2019, during landing, the airliner received damage that caused a fire (the landing gear broke through the fuel tank), as a result of which the aircraft partially burned down.

So on August 15, 2019, the pilots of A321, we can say, performed a miracle.

What happens if a bird lands on a plane

Not only engines are at risk whenhit by birds. The windows in the cockpit can also break. But they are made of three layers of laminated acrylic and glass, designed to withstand hail in the heart of the storm, so the birds do not pose a problem for them. The presence of multiple layers also ensures the integrity of the aircraft even in the event of damage to the outer layers. Also, pilots are trained to turn on glass heating so that the ice does not freeze at height, before takeoff; so the glass becomes softer and more resistant to shocks. You can learn more about these technologies in our news channel.

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Although, sometimes birds do burst - geese and eagles, which weigh more than 5 kg, pose a special danger.

Why engines do not cover with a bird grill

Quite often the assumption arises thatmotors must be protected by a grid, but this is not so simple. The problem is that in order to effectively block the bird at a speed of 800 kilometers per hour, the mesh must be very strong and thick, but this will prevent air from entering the engine. Engines are effective because they are carefully designed to use the thinnest air at height, so the disadvantages of the protective grill outweigh the advantages. And if such a net gets into the engine, the consequences can be much more dire than from a collision with birds.

How to prevent birds from colliding with the plane

Both airplanes and airports are equipped with specialdevices that make birds scaring sounds. But, as you can see, this is not enough - even the acoustic guns and pyrotechnics do not guarantee that the birds do not appear on the windshield or in the aircraft engine. Therefore, birds regularly meet with airplanes, and a final solution to this problem has not yet been found.

Drones also pose a great danger - ifcollisions with birds are random, while quadrocopter pilots often fly specifically near airports. In December 2018, Gatwick Airport in the south of England did not work for 36 hours due to drones suddenly appearing in the sky. Due to the danger of a collision between passenger aircraft and drones, about 1,000 flights were canceled, as a result of which more than 140,000 people were forced to wait tens of hours to resume work. UAVs flying near airports are really dangerous. Faced with a small drone, the plane may crash.

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Currently, researchers from the UK,as well as from around the world, they are working on various sensors and materials that will be able to independently assess the state of the aircraft and eliminate the need to interrupt the flight after collisions with birds. The idea is to create a wireless system that can determine the location and extent of damage. Ultimately, pilots will be able to obtain information about the possibility of a safe continuation of the flight after an impact, since each return to the airport is economically disadvantageous for the airline. In case of more serious damage, the system will transmit data about them to Earth, so that the technicians at the time of landing already know what parts are needed.

In the meantime, there is no such system, warning sounds and careful pilot training will remain our only defense against bird hits.