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Thinking

What makes bird strikes so hazardous for global aviation?

On January 15, 2009, a US Airways aircraft took off from New York City’s LaGuardia Airport. Two minutes after take-off, the plane was struck by a flock of geese and lost all engine power. With no option to reach an airport, the pilot expertly landed the aircraft on the city’s Hudson River, saving every person on board. The incident became known as the ‘miracle on the Hudson’. It was only a few birds that had caused the catastrophic failure of both jet engines that day.

Bird strike is quite common. In Australia, more than 16 000 bird strikes at airports across the country were reported between 2008 and 2017, according to Flight Safety Australia.

Bird strike can occur during any phase of flight, but the most vulnerable times are take-off, ascent, decent and landing, as birds fly at low altitude.

Bird strikes cannot be completely prevented, but the careful planning and implementation of dedicated systems may help to reduce these accidents.

Environmental scientists and planners have a role to play in bringing prevention initiatives to clients with their knowledge of wildlife migration patterns, habitat conservation and deterrent technology advancements.

The effects of bird strikes

The nature of the effect of a bird strike on an aeroplane depends on the size of the aircraft. Smaller aircraft will most likely experience structural damage such as damage to control surfaces or flight deck windscreens. Large aeroplanes powered by jet engines usually experience engine malfunction due to birds connecting with the engines. Jet engines are extremely vulnerable to bird strikes. Even the malfunction of one engine may compromise the safety of passengers and crew onboard.

A bird strike risk-based approach

There is no perfect solution to the issue of bird strikes. The primary defence stems from the structural integrity of an aircraft. However, this isn’t complete protection, and design requirements are mainly focused on large fixed wing transport aircraft, not smaller aircraft or helicopters.

There are opportunities to reduce the number of bird strikes and the severity of a strike around the airport as this is where management and control is most easily achieved.

Many states in Australia have guidelines for wildlife strikes but there is no uniformity of standards. In addition, the extent of bird hazard at any location is widely variable. This is where environmental scientists and specialists can work with individual airports to identify which systems they could introduce to help reduce the frequency of strikes. An important action is completing a risk management plan for bird strikes that account for the variations in wildlife and aircraft patterns, such as annual seasons, wind directions and habitat changes.

A risk management plan generally covers three categories:

  1. Habitat management:grass and surface water within the airport boundaries that might attract birds
  2. Habitat review:the area beyond the airport boundary that attracts wildlife and could affect the operational safety of aircraft
  3. At-airport control systems: bird activity monitoring and surveying, deterrence methods and alerting systems

Being on the defensive

Reducing the number and severity of bird strike incidents will benefit airports, the aircraft, passengers and crew, and of course the wildlife. Protecting wildlife in these cases mean that future generations of birds can flourish. So, what are some of the solutions?

Some airports use ground-based radars to help detect large flocks of birds. Some also use bird scaring techniques such as ground-based machines that broadcast the sounds of predatory creatures to help scare off other birds flying close to the airport.

Establishing and monitoring levels of wildlife activity is important. Migrating birds often follow well-defined paths in considerable numbers. By knowing the migration patterns of different birds, some smaller airports may be able to pause flights for a few minutes when the flocks are passing through at low altitude.

Habitat features including grass, waterways, shrubs and trees, provide food and roosting sites for birds. Even transient water accumulation on uneven pavements can be a significant bird attractant.

Netting waterways and repairing ground pavements to prevent water accumulation can help deter birds from within the airport boundary. Also grass height maintenance can be very important to keep birds from loitering day or night.

There are also innovative technologies that could potentially assist airports to better monitor bird activity and therefore lower the risk of bird strikes as aircraft take-off and land. A long running study is being investigated by Dr Yossi Leshem of Tel Aviv University. This study uses radar technology to track birds, historical records of bird flight movements, and weather data to predict bird flight patterns. This predictive information can be used to route aircraft around large flocks of birds and bats.

More recently, American and Canadian firms and airports have taken up the technology to reduce bird-aircraft strikes. This type of technology could be applied at airports in Australia.

To the future

Aircraft collisions with birds (bird strikes) at airports have always been a part of aviation. While there usually is only minor damage to the aircraft, they do pose a threat to air safety and the wildlife.

Birds often view airports as attractive open spaces to feed and rest. In addition, many modern aircraft have quieter engines which are less easily detected and avoided by birds. Therefore, the foundation of a risk management plan for any airport should be the implementation of initiatives that minimise food, water and shelter that are attracting birds and posing the greatest risk.

There is also a place for additional education for pilots and air carrier personnel with the accurate reporting of bird strikes and contingencies in place when there is suspected bird activity. Data collected on bird strikes and sightings in the air are an important part of planning the initiatives to reduce bird strike accidents.

Bird strikes are a lesser hazard to aviation than other well-known hazards such as loss of control in flight, controlled flight into terrain, and runway excursions, but they can and do present risks and it could be the development of radar technology that helps airports in the future to deter birds and minimise bird strike accidents.


About the author

Bram Mason is Aurecon’s Ecology Leader in Victoria with more than 20 years’ experience in the environment sector across multiple industries including state and local government, private advisory, not-for-profit and research. His specialist ecological advice to clients is on how to avid and mitigate impacts on natural systems and interpret environmental legislation. He assists clients with issues of a changing environment in a pragmatic, concise and honest way.

Throughout his career, he has worked with clients to gather information on the presence of wildlife and then construct risk-based approaches for mitigation measures to reduce significant impacts on wildlife where possible, or offset impacts where appropriate. Clients have included state rail and road authorities, water authorities, airports and energy companies. 

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