User:Hanaro4/Bird strike

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This page is about bird collisions with aircraft or other vehicles. For bird collisions with buildings, see Bird–window collisions and Towerkill.

Not to be confused with shrike.

F-16 jet fighter after bird strike

A bird strike (sometimes called birdstrike, bird ingestion (for an engine), bird hit, or bird aircraft strike hazard (BASH)) is a collision between a flying animal (usually a bird, occasionally bat) and a moving vehicle (typically an aircraft, occasionally high-speed train or automobile). The term is also used for bird deaths resulting from collisions with highrise buildings, towers (see bird–skyscraper collisions and towerkill) and tall structures such as overhead power lines and wind turbines.

A significant threat to aviation safety, bird strikes have caused a number of accidents with human casualties. Nevertheless, the number of major accidents involving civil aircraft is quite low, and the majority of bird strikes cause little damage to the aircraft despite usually being fatal to the bird(s) involved. Efforts have been made to mitigate both the risk and severity of bird strike incidents.

Factors affecting probability

A bird control vehicle belonging to Copenhagen Airport Kastrup, equipped with various tools

Bird strikes are more likely to occur at low altitudes. Strikes have been reported to occur most during the takeoff, climb, approach, and landing phases of flight. Many aircraft fly above the altitudes than birds typically fly, reducing risk of strike at higher altitudes. However, bird strikes have still been reported at high altitudes, some as high as 6,000 to 9,000 m (20,000 to 30,000 ft) above the ground. For instance, an aircraft over the Ivory Coast collided with a Rüppell's vulture at the altitude of 11,300 m (37,100 ft), the current record avian height.

Higher bird activity during certain seasons leads to more bird strikes. During winter, less bird strikes are recorded, whereas young birds fledging from nests in the summer and bird migration in spring and autumn leads to higher bird strike rates. The largest numbers of strikes happen during the spring and fall migrations. Bird strikes above 500 feet (150 m) altitude are about 7 times more common at night than during the day during the bird migration season.

Location affects bird strike probability since different bird species with distinct builds and behaviors reside in different locations. At airports, the presence of food, water and shelter increase bird strike probability.

The characteristics of an aircraft also affect the probability of a bird strike occurring. Turbofan engines, which the majority of commercial aircraft use, are more likely to ingest birds during a bird strike due to their large size and suction effect. An aircraft that is quieter is also more difficult for birds detect quickly enough to divert their flight path and successfully avoid collision.

Factors affecting severity

Inside of a jet engine after a bird strike

View of fan blades of a Pratt & Whitney JT8D jet engine after a bird strike

The majority of bird strikes do not cause actual damage to the aircraft. According to the FAA, only 15% of strikes (ICAO 11%) actually result in damage to the aircraft. For the strikes that do cause aircraft damage, the severity of the damage depends on the aircraft's velocity, the part of the aircraft that is struck, and the number and size of the bird(s) involved in the strike.

The aircraft's velocity and the total mass of the bird(s) involved in the strike contribute to the kinetic energy of the collision, which affects the severity of the strike. A higher aircraft velocity and larger total mass of the bird(s) involved in the strike leads to a higher collision kinetic energy, which increases the likelihood that the bird strike will result in aircraft damage. Because of this, it is more likely for bird strikes to cause damage at higher altitudes where the aircraft's velocity is higher and where larger birds fly.

The majority of bird strikes hit the front of the aircraft. The severity of the bird strike is typically much higher when the strike hits the engine(s), as this can lead to ingestion of the bird(s) into the engine and subsequent loss of engine power. Additionally, aircraft with two engines instead of three or four engines, which include the majority of the world's aircraft, are more susceptible to severe danger from ingestion since there is less redundancy.

Reporting and statistics

The International Civil Aviation Organization (ICAO) Bird Strike Information System (IBIS) collects data on wildlife strikes globally, with 214,734 reports from 156 states being included in the 2022 to 2024 analysis. However, globally, about 50% of all bird strikes still go unreported. Reporting for bird strikes is mandatory in some countries, such as in Australia and within the European Union, and is primarily voluntary in other countries, such as in the United States. Though it is a conservative estimate to account for incomplete reporting, bird strikes are estimated to cost at least $1 billion in damage annually to commercial aircraft worldwide.

Species

Following a strike, remains of the bird, termed snarge, are sent to identification centers where forensic techniques may be used to identify the species involved. These samples need to be taken carefully by trained personnel to ensure proper analysis and reduce the risks of infection (zoonoses).

Most bird strikes involve large birds with big populations, particularly geese and gulls in the United States. In parts of the US, Canada geese and migratory snow geese populations have risen significantly while feral Canada geese and greylag geese have increased in parts of Europe, increasing the risk of these large birds to aircraft. In other parts of the world, large birds of prey such as Gyps vultures and Milvus kites are often involved. In the US, reported strikes are mainly from waterfowl (30%), gulls (22%), raptors (20%), and pigeons and doves (7%). The Smithsonian Institution's Feather Identification Laboratory has identified turkey vultures as the most damaging birds, followed by Canada geese and white pelicans, all of which are very large birds. In terms of frequency, the laboratory most commonly finds mourning doves and horned larks involved in the strike.

Vultures and geese have been ranked the second and third most hazardous kinds of wildlife to aircraft in the United States, after deer (which encroach runways and collide with aircraft taking off and landing), with approximately 240 goose–aircraft collisions in the United States each year.

An animal hazard reported from London Stansted Airport in England is rabbits: they get run over by ground vehicles and planes, and they pass large amounts of droppings, which attract mice, which in turn attract owls, which then become another birdstrike hazard.