Bird strike

A BIRD STRIKE is defined as a collision between a bird or flock of birds and an aircraft in flight or on a take off or landing roll. The term usually covers other wildlife strikes - with bats or ground animals. It is a common threat to aircraft safety and has caused a number of fatal accidents.

Different factors can affect the likelihood of the bird strike

1. Location of the airport (the risk of the bird impact is higher if the airport is located close to the water surface - seas, rivers, lakes, residential area, city rubbish dumps, breeding places, agricultural fields as these places attract the birds)

2. Season of the year (there is high hazard during spring and autumn as it is migration time)

3. Time of the day (birds activity is more intensive in the morning when they rush to the breeding place and in the evening when they come back)

The seriousness of the bird strike depends on

• The size of the bird (The bigger the bird, the bigger the damage it causes the aircraft. Small birds simply die when they collide with the airplane, and the airplane moves on. Big birds can damage some parts of the airplane, which may or may not endanger the flight.)

• The speed of the aircraft on impact ( If it happens on the ground while taxing when the speed of the plane is low, the effect of the impact will be minimum, if the aircraft encounters the birds on cruising level or during rolling for take off when the speed is higher, the damage of the plane will be more serious.)

• The phase of the flight ( The majority of the strikes happen during take off, landing or approach phase)

Day to day flight altitudes for most birds are in the range from the ground to 500 feet. Though great number of bird strikes occurs till 50 feet during landing or take off. The hazard of risk decreases doubly till 500 feet. Outside that range, they rarely exceed 1000 feet except on long distance migration flights. These typically occur at a 5000 - 7000 feet altitude, but geese have sometimes been detected at over 20000ft.

• The place of impact

The most vulnerable parts of the aircraft are windscreen and engine.

In case of bird strike on windscreen it can cause windshield dirtiness that can lead to deterioration of view. In some cases the windshield can crack due to bird strike and it will lead to communication problems due to wind blast and sometimes pilots’ incapacitation or depressurization.

In case of bird strike on engine it can cause engine surge (as the blades may be distorted) or flame out (as bird’s feathers may ignite or crippled blades may be sucked to compressor and damage it) and as a result impairing flying characteristics of the aircraft. Bird strike can also cause engine failure and create emergency. Depending on how many engines were affected by the birds it may make levels and heading difficult to maintain or even forced landing outside the airport or ditching.

Another damage from the birds impact can be to extended landing gear assemblies in flight. It can lead to sufficient malfunction of brakes or nose gear steering systems and cause directional control problems during a subsequent landing roll.

Thus, the bird strike can result in

• Broken Windshield/Canopy

• Engine Failure (multi-engine)

• Engine Failure (single engine)

• Hydraulic Problems

• Handling Difficulties

• Electrical Problems

• Gear Problems

Birds that can pose risk to the aircraft in our region are: gulls, seagulls, sparrows, swallows, crows, geese, ducks, eagles, falcons, owls, pigeons, partridges, cranes, starlings, tomtits.

The opportunities to mitigate the risk of hazardous bird strikes in the first place are centered on airports, because this is where the greatest overall volume of conflict occurs, and because this is where management and control of the hazard is most easily achieved.

In order to prevent bird strikes different precautionary measures can be used

1. Habitat management, including reduction or elimination of trees, shrubs and other plants which provide food, shelter or roosting sites for birds.

2. Cooperation with local authorities to ensure that landfill waste disposal sites are not operated so as to create an aircraft hazard.

3. Cooperation with local farmers to limit the attraction of birds to fields.

4. Use of bird scaring techniques at the airports such as:

• Usage of sound systems emitting high frequency sounds or cries of prey birds

• Constant vigilance by special airport services who have to inspect the RW

• Switching on landing lights by pilots

• Usage of signal rockets for chasing away the birds

• Usage of cow scares

• Usage of specially trained falcons for scaring the birds away

• Keeping the grass near the RW cut so that birds can not settle there