MC Explains: Bird hits & what the DGCA is doing to ensure flight safety

Azerbaijan Airlines plane crash

The recent crash of the Jeju Air flight which resulted in the death of 179 of the 181 people travelling aboard the ill-fated Boeing has once again raised questions around the safety of air travel.

The Boeing model involved in the crash, the 737-800, is one of the world’s most popular aircraft with a generally strong safety record, and was developed well before the MAX variant involved in a recent Boeing safety crisis.

While South Korean officials have said that they are investigating the cause of the crash, including initial suggestions of a possible bird strike, aviation experts globally have questioned whether bird hits can bring down a 42,000 kg engineering marvel that flies on multiple engines.

Per data from India's aviation regulator, the Directorate General of Civil Aviation (DGCA), from 1,152 incidents in 2020, bird hits increased 27.25 percent to 1,466 in 2021. Since then, the figure has hovered around the 1,200 mark, with data for 2024 yet to be released.

One of the reasons for the increase in bird hits in 2021 was that airports were quieter than usual due to limited domestic and international flights in the wake of Covid. Quiet airports attract more birds as well as animals — there was a 93.33 percent rise in animal strikes in 2021 as against 2020.

Why are bird hits an issue?

A survey by the International Civil Aviation Organization (ICAO) of data from 91 countries found that airlines face an average of 34 bird strikes in a day.

Another survey by the National Business Aviation Association (NBAA) showed that 97.5 percent of wildlife strikes involve birds. In contrast, strikes involving terrestrial mammals account for 2.1 percent, followed by bats and reptiles at 0.3 percent and 0.1 percent, respectively. Collisions between birds and aircraft can occur at any point, from take-off to landing, resulting in damage to aircraft windshields, engines, and fuselages.

The majority of bird hits do not result in substantial damage to the aircraft or pose a danger to the passengers. Yet, more than 200 people have been killed worldwide as a result of wildlife strikes since 1988. The most dangerous bird strike is what's called a jet engine ingestion, in which a bird is swallowed by the aircraft’s engine.

According to ICAO, damage to aircraft by bird hits amounts to more than $1 billion annually. However, almost 92 percent of the air strikes are without any damage.

Most modern engines are required to be capable of ingesting birds that weigh about 1.8 kilograms while running at full power during the initial climb, without catching fire or making the engine impossible to shut down.

They are also required to operate at minimum 50 percent power for up to 14 minutes after the strike. This means that even if both the engines are hit by large birds, they can provide a combined thrust output of at least one engine, which is more than enough to return to the airport.

Smaller planes are generally bmore susceptible to the dangers of bird strikes than larger ones.

How can airplanes avoid bird hits?

After the recent incidents of bird hits in India, the DGCA on August 13 issued guidelines to airports across the country to mitigate incidents of collision of planes with birds and other animals. These include implementing a habitat management programme to reduce the population of hazardous wildlife around the airport, performing risk assessment procedures, and recording bird activity around airports.

The DGCA guidelines also include carrying out patrols and informing pilots whenever there is any wildlife activity.

Internationally, airports use three main ways to minimise the attraction of the airport environment to birds, including modifying bird habitats, controlling bird behaviour, and adapting flight times and paths.

Modifying bird habitats

Several methods can be used to modify bird behaviour to keep them away from airports, including removing food sources such as seed-bearing plants and insects from  airport premises. Covering ponds with netting can prevent birds from landing near airports. Destroying bushes and trees that offer attractive nesting sites can also help reduce the presence of birds.

Further, airports use sonic cannons, recorded predator calls, and other noises  to keep birds away. Lasers are also used at dawn and dusk to simulate predators and scare birds away.

In some countries, falcons are trained to keep birds away from roosting areas before they nest. Dogs are also trained to track bird movements across airports and chase them away.

Controlling bird behaviour

Some airports use pyrotechnics to drive away birds, says Michael Begier, National Coordinator of the Airport Wildlife Hazards Programme at the US Department of Agriculture.

"The flash, bang kind of stuff  gets their attention and pushes them away," he said. Loud explosions and whistling sounds, sparks — different birds respond to different things. Some even take flight at the mere sight of the wildlife vehicle that emits such sounds.

A banger shot from a pistol can travel 30-40 yards before exploding, while a shot from a  12-gauge shotgun can reach 70-100 yards.

A Purdue University study found that planes painted in dark colours attract more birds. Hence, brighter shades should be used to avoid them.

Adapting flight times and paths

Modifying flight paths and schedules can also help minimise bird strikes. While these methods may not be feasible at all airports, they can help the airport work in harmony with the surrounding wildlife . Adjusting flight times to avoid the busiest hours for bird activity, such as early mornings and late evenings, or peak migration periods can help address the issue.

According to the US Federal Aviation Administration's wildlife strike database, about 63 percent of bird strikes happen during the day, 8 percent during dawn and dusk, and 29 percent at night.

The landing phase of the flight is when 61 percent of bird strikes occur, while  36 percent occur during the take-off run and climb phases, with the remaining 3 percent occurring when the aircraft is en route.

Another suggestion to prevent such incidents is that engines should be covered with a grill. But the issue with that is to effectively block the bird at 800 km/h, the grill has to be significantly sturdy and thick, which will disrupt the air flowing into the engine.

Training spotters with binoculars to pinpoint hazardous birds and directing planes to different runways or approaches is also adopted by some airports.