Wildlife collisions

What this relates to:

A birdstrike or collision with an animal during take-off or landing can cause damage to the aircraft, impairing flight safety.

Example:

During take-off, an aircraft strikes a bird, which gets ingested into the engine. The engine starts vibrating abnormally, forcing a return to the departure airport. Inspection reveals damaged fan blades, leading to flight cancellation and passenger rebooking.

Remarks on the 2024 figures:

The rate of wildlife collisions on Swiss aerodromes and in Swiss airspace increased from 2.8 incidents in 2023 to 3.3 in 2024 (per 10,000 flight movements). In absolute numbers, 388 incidents were recorded last year. The increase in these figures can be explained by the change in the behaviour of migratory birds, but some studies also mention the fact that new aircraft are bigger and less noisy, making it more difficult for wildlife to avoid them.

About 95% of the reported incidents related to commercial air transport, the remaining 5% to general aviation. As most propeller-driven aircraft travel relatively slowly, general aviation collisions tend to have a lower impact. According to studies, both pilots and birds have time to take evasive manoeuvre which is sometimes not the case with bigger commercial aircraft. Nevertheless, airspeed is not the sole factor that determines the severity of a collision – the size of the bird also plays a role. A large bird can cause severe damage even if the aircraft is flying slowly. In 2024, most collisions had at most negligible effects on aircraft: 5% of the collisions resulted in damage to the aircraft, with less than 1% classified as major.

Over 90% of collisions occurred within the perimeter of the aerodrome, i.e. during approach, landing or take-off. The remaining 10% occurred during cruise flight or in some other unknown flight phase. Birds were involved in more than 98% of cases, with the remaining 2% involving other wild animals. Almost 75% of collisions occurred in the second and third quarters of the year, hitting a peak of 66 in July.

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