Planes hitting birds have always been an important threat to aviation safety. Although the birds are small, they are very afraid of the aircraft, and their relative speed when they collide is extremely large, which will cause serious damage to the aircraft.
Recently, during the training process of the pilot of the naval aviation university carrier-based fighter, a bird collided head-on with the plane, staging a terrifying scene.
The accidental bird strike damaged 80% of the front cockpit of the aircraft, and due to the loss of canopy protection, a stream of air three times stronger than the 17th level wind poured into the cockpit. Fortunately, the pilot calmly handled it and finally landed safely.
For aircraft, birds have always been a safety hazard that cannot be ignored. According to statistics, about 7 times per 10,000 flights can occur.
In order to avoid the occurrence of aircraft hitting birds, many airports have come up with strange tricks to deal with them. An airport in Amsterdam, the Netherlands, came up with the idea of "walking pigs" near the runway, allowing the pigs to eat up the crop residue that attracts birds so that the birds would not come to feed near the runway, increasing flight safety.
Although this case helps flight safety, the probability of a bird collision incident still exists. Why are airplanes so afraid of birds? How to prevent it? Are you afraid of anything but birds? Come and find out!
Why are airplanes so afraid of birds?
Birds can be said to be natural enemies of flight safety, according to relevant research, a 2 kg bird, if it hits an aircraft flying at a speed of 900 kilometers per hour, the impact force of the moment is as high as 4 tons.
According to the relevant physics formula, if the bird is heavier and the faster the aircraft, the greater the harm caused. After the bird hits a certain part of the aircraft, the impact force exceeds the withstand force of the aircraft at the location where it is hit, then it will damage the aircraft skin, resulting in surface damage, which in turn will affect various equipment and devices inside.
According to relevant data, the most vulnerable position on the aircraft to be hit by birds is the wing, followed by the radome and windshield of the nose.
Hitting the radomes, wing leading edges, etc., can cause damage to the aircraft.
Hitting the windshield can cause the windshield to break and affect the safety of the pilot's life.
Hitting an engine can cause damage to the engine, causing a "stop" in the air, and an aircraft that loses power will be more difficult to salvage.
Once these pneumatic parts are hit by birds at high speed, they are easy to cause structural damage and will directly endanger flight safety.
How to prevent bird collisions?
Aircraft bird collision accidents are classified as Category A aviation accidents by the International Aviation Federation, and there are currently two methods to prevent bird collisions: to drive away birds, and to strengthen and enhance the structure and performance of the aircraft itself.
According to the International Civil Aviation Organization, at least 80% of aircraft bird strikes occur during take-off and landing.
There are more than 2,000 bird collisions in U.S. civil aviation every year, of which 96% of bird collisions occur below 2700 meters, of which 67% occur below 150 meters, and bird collisions below 35 meters account for half of all bird collisions.
According to the height of the accident, most of the airports are equipped with bird repellent equipment, and the bird repellent working height is from 3000 meters to the ground, especially at a height of 200 meters.
Dummies of airport bird drives
Airports are generally equipped with special bird repellent equipment and personnel to drive away flocks of birds through measures such as firing guns, setting up bird nets, playing mournful sounds, and making scarecrows. There are also places to drop bait during the breeding season of birds to reduce the fertility of birds.
Modern aircraft also adopt some bird-proof impact designs, which disperse the impact force through the energy-absorbing structure and reduce the damaged area of the fuselage structure. At the same time, the performance of single-engine landing is improved, and once the engine sucks in the birds, causing the engine to stop, it can be landed with another engine. Even if the fuselage structure is damaged, it can return to the airport at the first time.
Modern aircraft have done a fairly comprehensive job of bird collisions, and the occurrence of bird collisions during take-off and landing phases has been greatly reduced. For fighters, because their flight altitude changes too much in a short period of time and the flight airspace span is large, the risk of hitting birds is higher than that of passenger aircraft.
What are airplanes afraid of in addition to hitting birds?
Bird collision incident is only one of the factors affecting flight safety, for aircraft, in addition to fear of hitting birds, but also afraid of various meteorological elements that can affect flight safety. For example, thunderstorm weather, visibility, wind direction and wind speed, Cumulonimbus clouds, low cloud weather, etc.
When the aircraft enters the cruising altitude of 10,000 meters, the impact of meteorological elements on flight safety is greatly reduced. This is because extreme weather such as thunderstorms occur mostly at 3,000 to 9,000 meters, below the cruising altitude. These meteorological elements that have an impact on flight safety are mainly concentrated in the aircraft take-off and landing process.
If the aircraft encounters hail during flight, it can damage the aerodynamic rudder surface of the aircraft, resulting in poor aerodynamic performance and increasing the risk of accidents.
When thunderstorms occur, extreme phenomena such as ice accumulation, lightning strikes, and downshots can occur, which can also cause the aircraft to lose control.
Ice accumulation can cause the movable rudder surface on the wings of the aircraft to freeze, causing stalls;
Although modern aircraft have lightning protection measures, they may cause interference and damage to electronic equipment;
The strong downdraft generated by the downforce can cause the aircraft to drop altitude in a short period of time. If the aircraft encounters a downward strike during take-off and landing, it is very easy to cause serious flight accidents.
Extreme weather such as thunderstorms are visible, and accidents can be avoided as long as early warning is given in advance. However, the sudden change in wind speed poses a great threat to flight safety, especially the low-altitude wind shear, which occurs at an altitude of less than 600 meters, is characterized by invisibility, extremely short occurrence time, small scale and large intensity, which causes great difficulties to early warning.
When the low-altitude wind shear occurs, it exceeds the pilot's control ability over the aircraft, so the main countermeasure for the low-altitude wind shear is to use atmospheric wind field equipment such as laser wind measurement radar to monitor the route, combined with surface wind speed, weather radar and other equipment, which can capture and warn the dangerous wind field near the 3-nautical-mile area of the runway extension, and the success rate is more than 90%.
Even so, modern technology is still unable to achieve 100% early warning and circumvention, which leaves some hidden dangers for flight safety, which requires pilots and airport support departments to take closer cooperation measures to effectively reduce the probability of accidents.
Expert: Lin Wenjie, engineer, senior researcher of Chuantuo Think Tank