Bird strikes – a serious threat in aviation

An International Civil Aviation Organization-backed 2014 study lists several reasons for bird strikes. Habitat features like open grass areas, water, etc. and the presence of shrubs and trees can act as bird attractants.

Many airports have considerable grass areas within their perimeters. Landfills and waste disposal sites near airports can increase the influx of birds. Airport locations can also influence increased bird movement. Airports in coastal regions have much more uncontrolled bird activity than inland airports.

Certain bird strikes pose a serious threat to aircraft. Flight deck windshields are made of three layers of glass-faced acrylic. Between them, there is a thin urethane layer and each panel has an anti-fog and anti-ice system.

Bird strikes – a serious threat in aviation

While small birds are not a serious problem, the outer layers can suffer cracks if a heavy bird hits the aircraft.

The presence of multiple layers ensures that the aircraft remains pressurised during bird collisions. The pilots are also trained to turn on window heating before take-off, which makes windows softer and less fragile.  

Plane engines, however, are vulnerable to disruption in the movement of the rotatory blades when a bird hits the turbine and gets caught in the engine. This can damage blades and cause a partial or total engine failure.

A flock of birds in front of an airplane at an airport, a concept picture about dangerous situations for planes

The good news is that plane engines are generally robust and can withstand some bird strikes. In case one engine is lost, the thrust from the remaining engines can be increased to limit the problem. Most aircraft can continue to fly even if one engine ceases to function.

A 2006 study on bird collisions conducted by the University of Nebraska showed that most strikes happen at an altitude lower than 500 feet.

Almost 70% of collisions happened during the initial stages of take-off or the final phase of landing and affected mostly the frontal aircraft regions like wings, jet engines and windshields. 

ALSO READ – IndiGo aircraft suffers engine damage after hit by a bird; returns safely to Guwahati

On June 19, two Delhi-bound airplanes of IndiGo and SpiceJet had to return to their airports of origin soon after takeoff due to bird strikes.

On June 19, two Delhi-bound airplanes had to return to their airports of origin soon after takeoff due to bird strikes. The first was an Indigo Airbus A320neo operating flight 6E-6394 from Guwahati to New Delhi. The aircraft’s number 1 engine was hit by a bird at an altitude of around 1,600 feet. The pilots declared PAN PAN and returned to Guwahati airport safely.

ALSO READ – DGCA initiates probe in turbulence at SpiceJet and IndiGo flights

The second incident involved a SpiceJet Boeing 737, which made an emergency landing at Patna airport in Eastern India after a bird hit one of its engines. Smoke and fire were seen coming out of the damaged engine, but thankfully the pilot made a safe landing, and nobody was hurt.

The measures include trimming of grass, spraying of insecticide, frequent runway inspections, deployment of bird chasers, and regular garbage disposal among others.

One method that airports use to manage the risk of strikes is modifying the habitat that surrounds the airport. The approach aims to make the area less desirable for birds, so they vacate and find nesting elsewhere. 

To do this, airports remove food sources, cover nearby water sources like ponds with netting (so birds can’t land), and keep the grass as short as possible so birds can’t shelter within it. If done right, the birds won’t have adequate resources for continued nesting, so are encouraged to relocate and leave to find somewhere else.

The Directorate General of Civil Aviation has instructed airports across the country to review their wildlife hazard management plans.

Airports in coastal regions have much more uncontrolled bird activity than inland airports.

In a letter to all airports, joint Director General Maneesh Kumar listed steps that need to be taken to prevent bird hits or animal intrusion. 

The measures include trimming of grass, spraying of insecticide, frequent runway inspections, deployment of bird chasers, and regular garbage disposal among others.

Airports have also been asked to convene meetings of the environment management committee and coordinate with local government authorities for action against sources which attract birds such as open disposal of garbage etc.

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