In the language of the pilots, "strike" is not the best punch that can be scored in bowling. Usually this word in aviation means the collision of birds with an airplane (with the addition of the word "bird" results in a "bird strike"). In fact, birds often encounter planes: it is possible that such an incident occurred even during your last flight. You just do not know anything about it. As a rule, such incidents do not lead to serious consequences. A bird weighing less than 3 kg simply burns in the engine. Sometimes, however, airplanes are forced to land urgently due to a collision with birds.
Only in Russia were officially registered around 7,000 bird cases per year – in Europe there are 10,000. Right, only about 5% of bird strikes cause aircraft damage. However, as a precautionary measure, all aircraft return to the nearest airport after a collision and passengers transfer to another flight with a different crew. In rare cases the damage is too severe and the pilots get into emergency situations. This happened with the Ural Airlines Airbus A321, which landed on 15 August 2019 due to a collision of both engines due to a bird collision in a field near the airport.
Airbus A321 Ural Airlines after landing in the field, August 15, 2019
1 Why do birds collide with planes?
2 What happens when the birds get into the engines of the aircraft?
3 How long can a plane fly without engines?
4 This is how you land aircraft without engines
5 What happens when a bird lands in an airplane?
6 Why not cover engines with a bird grill
7 Avoiding bird collisions with aircraft
Why birds collide with aircraft
In general, birds do not fly high. Most collisions occur below 150 meters – just during takeoff or landing. The speed of the aircraft at this moment is less than altitude, and fast evasive maneuvers are difficult to perform. The result depends largely on which part of the plane the bird is beating.
The biggest danger is the intrusion of birds into the engine. In accordance with safety standards, large engines must be able to withstand a collision with a bird weighing less than 3.5 kg without dangerous and quick release of sharp saw blade fragments from the engines. In fact, most engines can swallow a bird and only slightly damage the blades. However, this is also a damage: when a bird gets bigger, a collision with it can lead to an engine failure. The blades begin to break one after the other, causing a fire.
Pilots can clear a fire in the engine and turn it off completely, then return to the departure airport (if the incident occurred during takeoff) or complete the landing with a running engine. All pilots are trained to operate a single-engine aircraft, though it is very difficult: they must completely switch to manual controls and be visual. Not so long ago, a Japanese airline had to make an emergency landing in New York because a bird hit the plane. Another plane had to return to Cardiff Airport in Wales after the bird got into the engine.
A selection of videos in which planes collide with birds
What happens when the birds get into the engines of the aircraft?
However, a completely different case is when the birds fall into two engines simultaneously. In this case, they usually fly not alone, but in packs, and that's dangerous. The one-engine failure scenario described above is repeated on the second engine and the aircraft has no choice but to plan.
The actions of the pilots are in this case directly dependent on the altitude. If the incident occurred at 3-4,000 meters, they can still bring the plane back to the airport and land there (or complete the planned landing), though we have to admit that the collision with the ground will be very serious – everything hangs from the pilot's abilities and his ability to feel "multi-ton car. But if the aircraft could not gain altitude during takeoff (up to 1,000 meters), the birds fell into both engines and led to their failure, the pilots just did not have enough altitude to maneuver. As a result, they decide to land the plane where they need it – on the highway, in the field (as is the case with the Ural Airlines board), on water, and on any other suitable surface, if you call it that can.
How much a plane can fly without engines
If the liner has reached a height of 10,000 meters, it can plan a distance of 140-150 kilometers, depending on the type of aircraft. It's just that the birds do not fly at such a high altitude that all collisions are much lower – at a height of less than 1,000 meters. That's not even enough for 30 kilometers. Forced planning can cause the nose of the aircraft to be pulled too high
This is how you land aircraft without engines
If the pilots understand that the plane can not reach the nearest airport, they decide to land in the wasteland (if present) or on the water (the so-called "splashdown" of the aircraft). The APU auxiliary power plant will help you. This is a small engine equipped with a turbine that generates power and activates the action of all the units required for the aircraft – from the steering wheels and the height to the dashboard.
An illustrative example of a splashdown is the A320 crash landing on Hudson, which took place on January 15, 2009. The US Airways airliner collided with a herd of Canadian geese 1.5 minutes after takeoff, and both engines failed. The crew landed the plane safely on the waters of the Hudson River in New York. All 155 people on board (150 passengers and 5 crew members) survived. The plane was just 975 meters high, enough to fly the liner north and south over the Hudson River without hitting the George Washington Bridge and lowering the liner. Subsequently, the movie Miracle on the Hudson was filmed for these events.
Splashing water on the Hudson River, January 15, 2009
If you try to reproduce this situation with a flight simulator, pilots can in most cases return the ship to the departure airport. The problem is that it takes only 5 seconds in the simulator to make a decision (and such situations are only worked out on simulators). In reality, pilots need 20 to 30 seconds to do this because of the stress situation. Therefore, pilots often do not have enough time to land the plane without incident.
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A total of 21 cases of a controlled emergency landing of passenger aircraft on the water are known, of which 10 died during the landing no one. One of them is the landing of the Tu-124 on the Neva – an accident that occurred on 21 August 1963 in Leningrad (St. Petersburg). However, in this case the problem was not with the birds: due to the aircraft's failure, no fuel entered the engines and they stopped.
Landing in the field is even more difficult – pilots must consider the roughness of the surface topography and calculate the correct speed to prevent stalling the aircraft and keeping it as soft as possible on the abdomen. Such a landing will take place without the landing gear being extended as the chassis with uneven surface can damage the fuel tanks. The latter can lead to the ignition of the aircraft, as is the case with the Sukhoi Superjet 100-95B. On May 5, 2019, the airliner suffered a fire damage on landing (the landing gear broke through the fuel tank), causing the aircraft to partially burn.
So we can say that the pilots of the A321 performed a miracle on August 15, 2019.
What happens when a bird lands in an airplane?
Not only engines are threatened by birds. The windows in the cockpit can break too. However, they are made of three layers of laminated acrylic and glass that withstand hail in the heart of the storm so the birds are no problem for them. The presence of multiple layers ensures the integrity of the aircraft even if the outer layers are damaged. The pilots are also trained to turn on the glass heater so that the ice does not freeze at high altitude before take-off. This makes the glass softer and more resistant to impact. For more information about these technologies, see our news channel.
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Sometimes birds burst – geese and eagles weighing more than 5 kg are a particular danger.
Why not cover engines with a bird grill
Very often it is assumed that motors should be protected by a grill, which is not so easy. The problem is that the net has to be very strong and thick so that the bird is effectively blocked at a speed of 800 kilometers per hour. This, however, prevents air from entering the engine. Engines are effective because they are engineered to use the thinnest air at height. Therefore, the disadvantages of the protective grid outweigh the benefits. And even if such a net gets into the engine, the consequences can be much more regrettable than in a collision with birds.
To prevent birds from colliding with the plane
Both airplanes and airports are equipped with special devices that scare birds. But as you can see, this is not enough – even the acoustic cannons and the pyrotechnics do not guarantee that the birds will not appear on the windshield or in the aircraft engine. Therefore, birds regularly meet with airplanes, and a definitive solution to this problem has not yet been found.
Drones also present a significant hazard. When collisions with birds are accidental, quadrocopter pilots often fly particularly near airports. In December 2018, Gatwick Airport in southern England did not work for 36 hours as drones suddenly appeared in the sky. Due to the danger of a collision between passenger aircraft and drones, about 1,000 flights were canceled, forcing more than 140,000 people to wait ten hours to get back to 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 and around the world are working on a variety of sensors and materials that will allow the condition of the aircraft to be independently assessed, eliminating the need to interrupt the flight after colliding with birds. The idea is to create a wireless system that can determine the location and extent of the damage. Ultimately, pilots can learn about the possibility of safe continuation of the flight after an impact, as any return to the airport is economically detrimental to the airline. For larger damage, the system sends data to the ground so that technicians already know which parts are needed at the time of landing.
In the meantime, there is no such system. Warning sounds and careful pilot training will remain our only defense against bird strikes.