Bird strikes are one of aviation’s biggest problems – and they are on the rise

On Sunday, a Jeju Air Boeing 737-800 crashed at Muan International Airport in South Korea, killing all but two of the 181 passengers and crew on board.

The details of the incident remain unclear, but it has emerged that the pilot alerted air traffic control of a bird strike shortly before landing, and the control tower issued a bird strike warning before the pilot made the mayday call.

“Staff members all said they had never seen so many birds before. They suddenly flew in from outside the airport,” an anonymous airport official told the South Korean site, OhmyNews.

Between 1990 and 2022, there were just shy of 300,000 “wildlife strikes” globally, according to a report by the US Federal Aviation Administration and the US Department of Agriculture.

With shifting migratory patterns, quieter planes and rising populations of large birds, the problem is only getting worse.

Why do bird strikes occur?

With somewhere between 50 billion and 430 billion birds worldwide, and around 115,000 aircraft take-offs and landings per day, bird strikes are inevitable. They are particularly common because birds are drawn to the sort of wide, open areas where airports tend to be built. It is not uncommon for airports to be surrounded by wetlands or open bodies of water, for example, which also serve as nesting and feeding territory for birds.

The vast majority of bird strikes (around 92 per cent) occur during take-off or landing, below 500ft. They tend to occur during the migratory season, when species go in search of food and warmer climates. However, due to climate change, these migratory patterns are becoming harder to predict.

A problem on the rise

In the majority of bird strike incidents, pilots are able to land the aircraft safely with little or no damage. Often, a bird strike will go unnoticed until the aircraft is inspected back on the runway and dents or blood are detected. But there are exceptions. Flocks of larger birds can destroy engines; it is estimated that between 1988 and 2022, 305 aircraft were destroyed by bird strikes, killing 464 people.

One of the highest-profile bird strikes occurred in 2009, when a US Airways flight departing from New York’s LaGuardia Airport was forced to make an emergency landing into the Hudson River after colliding with a flock of Canada geese. The story of how Captain Chesley “Sully” Sullenberger III safely landed the Airbus A320 near Midtown Manhattan was dramatised in the 2016 film Sully: Miracle on the Hudson.

After the incident, authorities in New York took the controversial step of culling hundreds of geese to prevent a repeat event, and wildlife biologists at JFK Airport provoked outrage after they shot two snowy owls to prevent them from colliding with aircraft. But the awareness around bird strikes following the “Miracle on the Hudson”, and resulting debate around bird culling around the world, failed to slow down the number of incidents that occur per year.

“Aircraft collisions with birds and other wildlife (wildlife strikes) have become a growing concern for aviation safety,” wrote the authors of the Federal Aviation Administration/US Department of Agriculture paper. In 1990, there were 1,800 incidents in the USA – in 2019, there were 17,357 reported incidents, equating to just shy of 47 daily events. Part of this is due to better reporting and the rapid growth of global air traffic, but there are other factors at play.

Thanks to successful environmental initiatives, populations of large bird species are growing globally. The population of resident Canada geese in the United States, for example, has increased from 1 million in 1990 to 4.5 million in 2021. Birds are also adapting to urban environments, creating a greater risk of collisions with aircraft.

Another factor is that planes are bigger than ever before, meaning birds have to fly further to avoid a collision. In addition, modern turbofan engines are quieter than in the past, making it more difficult for birds to detect oncoming aircraft. A similar phenomenon is occurring on the roads, where pedestrians are almost twice as likely to be hit by an electric or hybrid vehicle than by a petrol or diesel car, according to the Journal of Epidemiology and Community Health.

How pilots and airlines prepare for bird strikes

Brian Smith, a pilot with a British cargo airline who has previously flown with Ryanair, Emirates and Air2000 (later FirstChoice), says that bird strikes cannot be replicated on simulators and therefore no specific training takes place.

However, certain measures can help to prevent a serious collision, he says.

“In flight we rarely fly above 250 knots below 10,000ft and never below 5,000ft. This reduces the energy released if a bird should be struck at these lower altitudes, and therefore the damage they cause. During the approach we switch on all the external lights which birds do see and will invariably try to avoid.

“It is impossible to manoeuvre an aircraft away from a bird. Attempting doing so would almost certainly result in putting the aircraft into an undesirable attitude near the ground. In any case if you see a bird at all, it comes into your vision so fleetingly, that you generally only get a startle effect as it hits, or bypasses the aircraft.

“I have had a few in my time, mostly with Ryanair, who fly to more isolated and rural airports where it’s more prevalent. None of them were problematic and we were able to continue home to base.

“Measures to mitigate the risk are largely ground based, and undertaken by airport authorities. Migration patterns are well studied and can sometimes influence airport schedules but only in a very limited way. Bird scaring is carried out sometimes when birds are congregating. They use flares and sometimes raptors to scare them off,” Brian Smith added.

Patrick Smith, a US pilot and author of the book Cockpit Confidential, explains how aircraft are designed to withstand bird strikes.

“As you’d expect, aircraft components are built to tolerate such impacts. You can see web videos of bird carcasses being fired from a sort of chicken-cannon to test the resistance of windshields, intakes, and so forth,” he told Telegraph Travel in 2023.

“Birds don’t clog an engine but can bend or fracture the internal blades, causing power loss. The heavier the bird, the greater the potential for harm. Flying at 250 knots [the maximum allowable below 10,000ft, where most birds are found] hitting an average-sized goose will subject the plane to an impact force of over 50,000 pounds.”